release 7.4

todo
don't write the asm file twice
2026-10-22 05:02:58 +00:00 · 2021-11-30 22:50:12 +01:00 · 2021-11-30 22:45:43 +01:00 · 2021-11-30 03:47:57 +01:00 · 2021-11-30 03:05:25 +01:00 · 2021-11-30 02:32:37 +01:00
306 changed files with 20347 additions and 21061 deletions
@@ -26,8 +26,9 @@ parser.out
 parsetab.py
 .pytest_cache/
 .attach_pid*
+compiler/lib/

 .gradle
 /prog8compiler.jar
 sd*.img
-
+*.d64
@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="JavaProjectCodeInsightSettings">
+    <excluded-names>
+      <name>kotlin.Result</name>
+    </excluded-names>
+  </component>
+</project>
@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="CompilerConfiguration">
+    <option name="BUILD_PROCESS_HEAP_SIZE" value="1200" />
+    <bytecodeTargetLevel target="11" />
+  </component>
+</project>
@@ -1,6 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<project version="4">
-  <component name="Kotlin2JvmCompilerArguments">
-    <option name="jvmTarget" value="11" />
-  </component>
-</project>
@@ -1,9 +0,0 @@
-<component name="libraryTable">
-  <library name="antlr-4.9-complete">
-    <CLASSES>
-      <root url="jar://$PROJECT_DIR$/parser/antlr/lib/antlr-4.9-complete.jar!/" />
-    </CLASSES>
-    <JAVADOC />
-    <SOURCES />
-  </library>
-</component>
@@ -0,0 +1,19 @@
+<component name="libraryTable">
+  <library name="antlr.antlr4" type="repository">
+    <properties maven-id="org.antlr:antlr4:4.9.2">
+      <exclude>
+        <dependency maven-id="com.ibm.icu:icu4j" />
+      </exclude>
+    </properties>
+    <CLASSES>
+      <root url="jar://$MAVEN_REPOSITORY$/org/antlr/antlr4/4.9.2/antlr4-4.9.2.jar!/" />
+      <root url="jar://$MAVEN_REPOSITORY$/org/antlr/antlr4-runtime/4.9.2/antlr4-runtime-4.9.2.jar!/" />
+      <root url="jar://$MAVEN_REPOSITORY$/org/antlr/antlr-runtime/3.5.2/antlr-runtime-3.5.2.jar!/" />
+      <root url="jar://$MAVEN_REPOSITORY$/org/antlr/ST4/4.3/ST4-4.3.jar!/" />
+      <root url="jar://$MAVEN_REPOSITORY$/org/abego/treelayout/org.abego.treelayout.core/1.0.3/org.abego.treelayout.core-1.0.3.jar!/" />
+      <root url="jar://$MAVEN_REPOSITORY$/org/glassfish/javax.json/1.0.4/javax.json-1.0.4.jar!/" />
+    </CLASSES>
+    <JAVADOC />
+    <SOURCES />
+  </library>
+</component>
@@ -1,9 +0,0 @@
-<component name="libraryTable">
-  <library name="antlr-runtime-4.9">
-    <CLASSES>
-      <root url="jar://$PROJECT_DIR$/parser/antlr/lib/antlr-runtime-4.9.jar!/" />
-    </CLASSES>
-    <JAVADOC />
-    <SOURCES />
-  </library>
-</component>
@@ -1,9 +0,0 @@
-<component name="libraryTable">
-  <library name="dbus-java-3.2.4">
-    <CLASSES>
-      <root url="jar://$PROJECT_DIR$/dbusCompilerService/lib/dbus-java-3.2.4.jar!/" />
-    </CLASSES>
-    <JAVADOC />
-    <SOURCES />
-  </library>
-</component>
@@ -0,0 +1,25 @@
+<component name="libraryTable">
+  <library name="github.hypfvieh.dbus.java" type="repository">
+    <properties maven-id="com.github.hypfvieh:dbus-java:3.3.1" />
+    <CLASSES>
+      <root url="jar://$MAVEN_REPOSITORY$/com/github/hypfvieh/dbus-java/3.3.1/dbus-java-3.3.1.jar!/" />
+      <root url="jar://$MAVEN_REPOSITORY$/com/github/jnr/jnr-unixsocket/0.38.6/jnr-unixsocket-0.38.6.jar!/" />
+      <root url="jar://$MAVEN_REPOSITORY$/com/github/jnr/jnr-ffi/2.2.2/jnr-ffi-2.2.2.jar!/" />
+      <root url="jar://$MAVEN_REPOSITORY$/com/github/jnr/jffi/1.3.1/jffi-1.3.1.jar!/" />
+      <root url="jar://$MAVEN_REPOSITORY$/com/github/jnr/jffi/1.3.1/jffi-1.3.1-native.jar!/" />
+      <root url="jar://$MAVEN_REPOSITORY$/org/ow2/asm/asm/9.1/asm-9.1.jar!/" />
+      <root url="jar://$MAVEN_REPOSITORY$/org/ow2/asm/asm-commons/9.1/asm-commons-9.1.jar!/" />
+      <root url="jar://$MAVEN_REPOSITORY$/org/ow2/asm/asm-analysis/9.1/asm-analysis-9.1.jar!/" />
+      <root url="jar://$MAVEN_REPOSITORY$/org/ow2/asm/asm-tree/9.1/asm-tree-9.1.jar!/" />
+      <root url="jar://$MAVEN_REPOSITORY$/org/ow2/asm/asm-util/9.1/asm-util-9.1.jar!/" />
+      <root url="jar://$MAVEN_REPOSITORY$/com/github/jnr/jnr-a64asm/1.0.0/jnr-a64asm-1.0.0.jar!/" />
+      <root url="jar://$MAVEN_REPOSITORY$/com/github/jnr/jnr-x86asm/1.0.2/jnr-x86asm-1.0.2.jar!/" />
+      <root url="jar://$MAVEN_REPOSITORY$/com/github/jnr/jnr-constants/0.10.1/jnr-constants-0.10.1.jar!/" />
+      <root url="jar://$MAVEN_REPOSITORY$/com/github/jnr/jnr-enxio/0.32.4/jnr-enxio-0.32.4.jar!/" />
+      <root url="jar://$MAVEN_REPOSITORY$/com/github/jnr/jnr-posix/3.1.5/jnr-posix-3.1.5.jar!/" />
+      <root url="jar://$MAVEN_REPOSITORY$/org/slf4j/slf4j-api/1.7.30/slf4j-api-1.7.30.jar!/" />
+    </CLASSES>
+    <JAVADOC />
+    <SOURCES />
+  </library>
+</component>
@@ -0,0 +1,10 @@
+<component name="libraryTable">
+  <library name="glassfish.javax.json" type="repository">
+    <properties include-transitive-deps="false" maven-id="org.glassfish:javax.json:1.1.4" />
+    <CLASSES>
+      <root url="jar://$MAVEN_REPOSITORY$/org/glassfish/javax.json/1.1.4/javax.json-1.1.4.jar!/" />
+    </CLASSES>
+    <JAVADOC />
+    <SOURCES />
+  </library>
+</component>
@@ -0,0 +1,10 @@
+<component name="libraryTable">
+  <library name="hamcrest" type="repository">
+    <properties maven-id="org.hamcrest:hamcrest:2.2" />
+    <CLASSES>
+      <root url="jar://$MAVEN_REPOSITORY$/org/hamcrest/hamcrest/2.2/hamcrest-2.2.jar!/" />
+    </CLASSES>
+    <JAVADOC />
+    <SOURCES />
+  </library>
+</component>
@@ -0,0 +1,22 @@
+<component name="libraryTable">
+  <library name="io.kotest.assertions.core.jvm" type="repository">
+    <properties maven-id="io.kotest:kotest-assertions-core-jvm:4.6.3" />
+    <CLASSES>
+      <root url="jar://$MAVEN_REPOSITORY$/io/kotest/kotest-assertions-core-jvm/4.6.3/kotest-assertions-core-jvm-4.6.3.jar!/" />
+      <root url="jar://$MAVEN_REPOSITORY$/org/jetbrains/kotlin/kotlin-stdlib-jdk8/1.5.0/kotlin-stdlib-jdk8-1.5.0.jar!/" />
+      <root url="jar://$MAVEN_REPOSITORY$/org/jetbrains/kotlin/kotlin-stdlib/1.5.0/kotlin-stdlib-1.5.0.jar!/" />
+      <root url="jar://$MAVEN_REPOSITORY$/org/jetbrains/annotations/13.0/annotations-13.0.jar!/" />
+      <root url="jar://$MAVEN_REPOSITORY$/org/jetbrains/kotlin/kotlin-stdlib-jdk7/1.5.0/kotlin-stdlib-jdk7-1.5.0.jar!/" />
+      <root url="jar://$MAVEN_REPOSITORY$/io/kotest/kotest-assertions-shared-jvm/4.6.3/kotest-assertions-shared-jvm-4.6.3.jar!/" />
+      <root url="jar://$MAVEN_REPOSITORY$/io/github/java-diff-utils/java-diff-utils/4.9/java-diff-utils-4.9.jar!/" />
+      <root url="jar://$MAVEN_REPOSITORY$/org/jetbrains/kotlinx/kotlinx-coroutines-jdk8/1.5.0/kotlinx-coroutines-jdk8-1.5.0.jar!/" />
+      <root url="jar://$MAVEN_REPOSITORY$/org/jetbrains/kotlin/kotlin-reflect/1.5.0/kotlin-reflect-1.5.0.jar!/" />
+      <root url="jar://$MAVEN_REPOSITORY$/org/jetbrains/kotlinx/kotlinx-coroutines-core-jvm/1.5.0/kotlinx-coroutines-core-jvm-1.5.0.jar!/" />
+      <root url="jar://$MAVEN_REPOSITORY$/org/jetbrains/kotlin/kotlin-stdlib-common/1.5.0/kotlin-stdlib-common-1.5.0.jar!/" />
+      <root url="jar://$MAVEN_REPOSITORY$/io/kotest/kotest-common-jvm/4.6.3/kotest-common-jvm-4.6.3.jar!/" />
+      <root url="jar://$MAVEN_REPOSITORY$/io/kotest/kotest-assertions-api-jvm/4.6.3/kotest-assertions-api-jvm-4.6.3.jar!/" />
+    </CLASSES>
+    <JAVADOC />
+    <SOURCES />
+  </library>
+</component>
@@ -0,0 +1,24 @@
+<component name="libraryTable">
+  <library name="io.kotest.property.jvm" type="repository">
+    <properties maven-id="io.kotest:kotest-property-jvm:4.6.3" />
+    <CLASSES>
+      <root url="jar://$MAVEN_REPOSITORY$/io/kotest/kotest-property-jvm/4.6.3/kotest-property-jvm-4.6.3.jar!/" />
+      <root url="jar://$MAVEN_REPOSITORY$/org/jetbrains/kotlin/kotlin-stdlib-jdk8/1.5.0/kotlin-stdlib-jdk8-1.5.0.jar!/" />
+      <root url="jar://$MAVEN_REPOSITORY$/org/jetbrains/kotlin/kotlin-stdlib/1.5.0/kotlin-stdlib-1.5.0.jar!/" />
+      <root url="jar://$MAVEN_REPOSITORY$/org/jetbrains/annotations/13.0/annotations-13.0.jar!/" />
+      <root url="jar://$MAVEN_REPOSITORY$/org/jetbrains/kotlin/kotlin-stdlib-jdk7/1.5.0/kotlin-stdlib-jdk7-1.5.0.jar!/" />
+      <root url="jar://$MAVEN_REPOSITORY$/io/kotest/kotest-common-jvm/4.6.3/kotest-common-jvm-4.6.3.jar!/" />
+      <root url="jar://$MAVEN_REPOSITORY$/io/kotest/kotest-assertions-shared-jvm/4.6.3/kotest-assertions-shared-jvm-4.6.3.jar!/" />
+      <root url="jar://$MAVEN_REPOSITORY$/io/kotest/kotest-assertions-api-jvm/4.6.3/kotest-assertions-api-jvm-4.6.3.jar!/" />
+      <root url="jar://$MAVEN_REPOSITORY$/org/jetbrains/kotlinx/kotlinx-coroutines-jdk8/1.5.0/kotlinx-coroutines-jdk8-1.5.0.jar!/" />
+      <root url="jar://$MAVEN_REPOSITORY$/io/github/java-diff-utils/java-diff-utils/4.9/java-diff-utils-4.9.jar!/" />
+      <root url="jar://$MAVEN_REPOSITORY$/com/github/mifmif/generex/1.0.2/generex-1.0.2.jar!/" />
+      <root url="jar://$MAVEN_REPOSITORY$/dk/brics/automaton/automaton/1.11-8/automaton-1.11-8.jar!/" />
+      <root url="jar://$MAVEN_REPOSITORY$/org/jetbrains/kotlin/kotlin-reflect/1.5.0/kotlin-reflect-1.5.0.jar!/" />
+      <root url="jar://$MAVEN_REPOSITORY$/org/jetbrains/kotlinx/kotlinx-coroutines-core-jvm/1.5.0/kotlinx-coroutines-core-jvm-1.5.0.jar!/" />
+      <root url="jar://$MAVEN_REPOSITORY$/org/jetbrains/kotlin/kotlin-stdlib-common/1.5.0/kotlin-stdlib-common-1.5.0.jar!/" />
+    </CLASSES>
+    <JAVADOC />
+    <SOURCES />
+  </library>
+</component>
@@ -0,0 +1,56 @@
+<component name="libraryTable">
+  <library name="io.kotest.runner.junit5.jvm" type="repository">
+    <properties maven-id="io.kotest:kotest-runner-junit5-jvm:4.6.3" />
+    <CLASSES>
+      <root url="jar://$MAVEN_REPOSITORY$/io/kotest/kotest-runner-junit5-jvm/4.6.3/kotest-runner-junit5-jvm-4.6.3.jar!/" />
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+      <root url="jar://$MAVEN_REPOSITORY$/io/kotest/kotest-assertions-shared-jvm/4.6.3/kotest-assertions-shared-jvm-4.6.3.jar!/" />
+      <root url="jar://$MAVEN_REPOSITORY$/io/github/java-diff-utils/java-diff-utils/4.9/java-diff-utils-4.9.jar!/" />
+      <root url="jar://$MAVEN_REPOSITORY$/io/kotest/kotest-common-jvm/4.6.3/kotest-common-jvm-4.6.3.jar!/" />
+      <root url="jar://$MAVEN_REPOSITORY$/io/kotest/kotest-framework-engine-jvm/4.6.3/kotest-framework-engine-jvm-4.6.3.jar!/" />
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+      <root url="jar://$MAVEN_REPOSITORY$/com/github/ajalt/colormath/1.2.0/colormath-1.2.0.jar!/" />
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@@ -1,10 +0,0 @@
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@@ -0,0 +1,10 @@
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+    <SOURCES />
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@@ -0,0 +1,17 @@
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@@ -1,9 +0,0 @@
-<component name="libraryTable">
-  <library name="kotlinx-cli-jvm">
-    <CLASSES>
-      <root url="jar://$PROJECT_DIR$/compiler/lib/kotlinx-cli-jvm-0.3.1.jar!/" />
-    </CLASSES>
-    <JAVADOC />
-    <SOURCES />
-  </library>
-</component>
@@ -0,0 +1,15 @@
+<component name="libraryTable">
+  <library name="michael.bull.kotlin.result.jvm" type="repository">
+    <properties maven-id="com.michael-bull.kotlin-result:kotlin-result-jvm:1.1.12" />
+    <CLASSES>
+      <root url="jar://$MAVEN_REPOSITORY$/com/michael-bull/kotlin-result/kotlin-result-jvm/1.1.12/kotlin-result-jvm-1.1.12.jar!/" />
+      <root url="jar://$MAVEN_REPOSITORY$/org/jetbrains/kotlin/kotlin-stdlib-jdk8/1.5.10/kotlin-stdlib-jdk8-1.5.10.jar!/" />
+      <root url="jar://$MAVEN_REPOSITORY$/org/jetbrains/kotlin/kotlin-stdlib/1.5.10/kotlin-stdlib-1.5.10.jar!/" />
+      <root url="jar://$MAVEN_REPOSITORY$/org/jetbrains/annotations/13.0/annotations-13.0.jar!/" />
+      <root url="jar://$MAVEN_REPOSITORY$/org/jetbrains/kotlin/kotlin-stdlib-jdk7/1.5.10/kotlin-stdlib-jdk7-1.5.10.jar!/" />
+      <root url="jar://$MAVEN_REPOSITORY$/org/jetbrains/kotlin/kotlin-stdlib-common/1.5.10/kotlin-stdlib-common-1.5.10.jar!/" />
+    </CLASSES>
+    <JAVADOC />
+    <SOURCES />
+  </library>
+</component>
@@ -1,10 +0,0 @@
-<component name="libraryTable">
-  <library name="slf4j-api-1.7.30">
-    <CLASSES>
-      <root url="jar://$PROJECT_DIR$/httpCompilerService/lib/slf4j-api-1.7.30.jar!/" />
-      <root url="jar://$PROJECT_DIR$/httpCompilerService/lib/slf4j-simple-1.7.30.jar!/" />
-    </CLASSES>
-    <JAVADOC />
-    <SOURCES />
-  </library>
-</component>
@@ -0,0 +1,11 @@
+<component name="libraryTable">
+  <library name="slf4j.simple" type="repository">
+    <properties maven-id="org.slf4j:slf4j-simple:1.7.30" />
+    <CLASSES>
+      <root url="jar://$MAVEN_REPOSITORY$/org/slf4j/slf4j-simple/1.7.30/slf4j-simple-1.7.30.jar!/" />
+      <root url="jar://$MAVEN_REPOSITORY$/org/slf4j/slf4j-api/1.7.30/slf4j-api-1.7.30.jar!/" />
+    </CLASSES>
+    <JAVADOC />
+    <SOURCES />
+  </library>
+</component>
@@ -0,0 +1,13 @@
+<component name="libraryTable">
+  <library name="takes" type="repository">
+    <properties maven-id="org.takes:takes:1.19" />
+    <CLASSES>
+      <root url="jar://$MAVEN_REPOSITORY$/org/takes/takes/1.19/takes-1.19.jar!/" />
+      <root url="jar://$MAVEN_REPOSITORY$/org/cactoos/cactoos/0.42/cactoos-0.42.jar!/" />
+      <root url="jar://$MAVEN_REPOSITORY$/org/apache/commons/commons-text/1.4/commons-text-1.4.jar!/" />
+      <root url="jar://$MAVEN_REPOSITORY$/org/apache/commons/commons-lang3/3.7/commons-lang3-3.7.jar!/" />
+    </CLASSES>
+    <JAVADOC />
+    <SOURCES />
+  </library>
+</component>
@@ -1,12 +0,0 @@
-<component name="libraryTable">
-  <library name="takes-http">
-    <CLASSES>
-      <root url="jar://$PROJECT_DIR$/httpCompilerService/lib/cactoos-0.42.jar!/" />
-      <root url="jar://$PROJECT_DIR$/httpCompilerService/lib/commons-lang3-3.7.jar!/" />
-      <root url="jar://$PROJECT_DIR$/httpCompilerService/lib/commons-text-1.4.jar!/" />
-      <root url="jar://$PROJECT_DIR$/httpCompilerService/lib/takes-1.19.jar!/" />
-    </CLASSES>
-    <JAVADOC />
-    <SOURCES />
-  </library>
-</component>
@@ -1,10 +0,0 @@
-<component name="libraryTable">
-  <library name="unittest-libs">
-    <CLASSES>
-      <root url="file://$PROJECT_DIR$/compiler/lib" />
-    </CLASSES>
-    <JAVADOC />
-    <SOURCES />
-    <jarDirectory url="file://$PROJECT_DIR$/compiler/lib" recursive="false" />
-  </library>
-</component>
@@ -4,7 +4,7 @@
    <option name="perGrammarGenerationSettings">
      <list>
        <PerGrammarGenerationSettings>
-          <option name="fileName" value="$PROJECT_DIR$/parser/antlr/prog8.g4" />
+          <option name="fileName" value="$PROJECT_DIR$/parser/antlr/Prog8ANTLR.g4" />
          <option name="autoGen" value="true" />
          <option name="outputDir" value="$PROJECT_DIR$/parser/src/prog8/parser" />
          <option name="libDir" value="" />
@@ -16,7 +16,10 @@
      </list>
    </option>
  </component>
-  <component name="ProjectRootManager" version="2" languageLevel="JDK_11" default="false" project-jdk-name="Kotlin SDK" project-jdk-type="KotlinSDK">
+  <component name="FrameworkDetectionExcludesConfiguration">
+    <type id="Python" />
+  </component>
+  <component name="ProjectRootManager" version="2" languageLevel="JDK_11" project-jdk-name="Kotlin SDK" project-jdk-type="KotlinSDK">
    <output url="file://$PROJECT_DIR$/out" />
  </component>
 </project>
@@ -2,8 +2,11 @@
 <project version="4">
  <component name="ProjectModuleManager">
    <modules>
+      <module fileurl="file://$PROJECT_DIR$/codeGeneration/codeGeneration.iml" filepath="$PROJECT_DIR$/codeGeneration/codeGeneration.iml" />
+      <module fileurl="file://$PROJECT_DIR$/codeOptimizers/codeOptimizers.iml" filepath="$PROJECT_DIR$/codeOptimizers/codeOptimizers.iml" />
      <module fileurl="file://$PROJECT_DIR$/compiler/compiler.iml" filepath="$PROJECT_DIR$/compiler/compiler.iml" />
      <module fileurl="file://$PROJECT_DIR$/compilerAst/compilerAst.iml" filepath="$PROJECT_DIR$/compilerAst/compilerAst.iml" />
+      <module fileurl="file://$PROJECT_DIR$/compilerInterfaces/compilerInterfaces.iml" filepath="$PROJECT_DIR$/compilerInterfaces/compilerInterfaces.iml" />
      <module fileurl="file://$PROJECT_DIR$/dbusCompilerService/dbusCompilerService.iml" filepath="$PROJECT_DIR$/dbusCompilerService/dbusCompilerService.iml" />
      <module fileurl="file://$PROJECT_DIR$/docs/docs.iml" filepath="$PROJECT_DIR$/docs/docs.iml" />
      <module fileurl="file://$PROJECT_DIR$/examples/examples.iml" filepath="$PROJECT_DIR$/examples/examples.iml" />
@@ -0,0 +1,29 @@
+# .readthedocs.yaml
+# Read the Docs configuration file
+# See https://docs.readthedocs.io/en/stable/config-file/v2.html for details
+
+# Required
+version: 2
+
+# Set the version of Python and other tools you might need
+build:
+  os: ubuntu-20.04
+  tools:
+    python: "3.9"
+    # You can also specify other tool versions:
+    # nodejs: "16"
+    # rust: "1.55"
+    # golang: "1.17"
+
+# Build documentation in the docs/ directory with Sphinx
+sphinx:
+  configuration: docs/source/conf.py
+
+# If using Sphinx, optionally build your docs in additional formats such as PDF
+formats:
+  - pdf
+
+# Optionally declare the Python requirements required to build your docs
+python:
+  install:
+    - requirements: docs/requirements.txt
@@ -1,11 +0,0 @@
-language: java
-sudo: false
-# jdk: openjdk8
-# dist: xenial
-
-before_install:
-  - chmod +x ./gradlew
-
-script:
-  - ./gradlew test
-
@@ -0,0 +1,32 @@
+#### Just a few remarks upfront:
+* There is the (gradle/IDEA) module `parser`: that's the parser generated by ANTLR4, in Java. The only file to be edited here is the grammar, `prog8.g4`.
+* Then we have the module `compilerAst` - in Kotlin - which uses `parser` and adds AST nodes. Here we put our additions to the generated thing, *including any tests of the parsing stage*.
+  - the name is a bit misleading, as this module isn't (or, resp. shouldn't be; see below) about *compiling*, only the parsing stage
+  - also, the tree that comes out isn't much of an *abstraction*, but rather still more or less a parse tree (this might very well change).
+  - **However, let's not *yet* rename the module.** We'll find a good name during refactoring.
+
+#### Problems with `compilerAst`:
+* `ModuleImporter.kt`, doing (Prog8-) module resolution. That's not the parser's job.
+* `ParsingFailedError` (in `ModuleParsing.kt`): this exception (it is actually *not* a `java.lang.Error`...) is thrown in a number of places, where other exceptions would make more sense. For example: not finding a file should just yield a `NoSuchFileException`, not this one. The other problem with it is that it does not provide any additional information about the source of parsing error, in particular a `Position`.
+* During parsing, character literals are turned into UBYTEs (since there is no basic type e.g. CHAR). That's bad because it depends on a specific character encoding (`IStringEncoding` in `compilerAst/src/prog8/ast/AstToplevel.kt`) of/for some target platform. Note that *strings* are indeed encoded later, in the `compiler` module.
+* The same argument applies to `IMemSizer`, and - not entirely sure about that - `IBuiltinFunctions`.
+
+#### Steps to take, in conceptual (!) order:
+1. introduce an abstraction `SourceCode` that encapsulates the origin and actual loading of Prog8 source code
+   - from the local file system (use case: user programs)
+   - from resources (prog8lib)
+   - from plain strings (for testing)
+2. add subclass `ParseError : ParsingFailedError` which adds information about the *source of parsing error* (`SourceCode` and `Position`). We cannot just replace `ParsingFailedError`  right away because it is so widely used (even in the `compiler` module). Therefore we'll just subclass for the time being, add more and more tests requiring the new one to be thrown (or, resp., NOT to be thrown), and gradually transition.
+3. introduce a minimal interface to the outside, input: `SourceCode`, output: a tree with a `Module` node as the root
+   - this will be the Kotlin singleton `Prog8Parser` with the main method `parseModule`
+   - plus, optionally, method's for registering/unregistering a listener with the parser
+   - the *only* exception ever thrown / reported to listeners (TBD) will be `ParseError`
+   - anything related to the lexer, error strategies, character/token streams is hidden from the outside
+   - to make a clear distinction between the *generated* parser (and lexer) vs. `Prog8Parser`, and to discourage directly using the generated stuff, we'll rename the existing `prog8Parser`/`prog8Lexer` to `Prog8ANTLRParser` and `Prog8ANTLRLexer` and move them to package `prog8.parser.generated`
+4. introduce AST node `CharLiteral` and keep them until after identifier resolution and type checking; insert there an AST transformation step that turns them in UBYTE constants (literals)
+5. remove uses of `IStringEncoding` from module `compilerAst` - none should be necessary anymore
+6. move `IStringEncoding` to module `compiler`
+7. same with `ModuleImporter`, then rewrite that (addressing #46)
+8. refactor AST nodes and grammar: less generated parse tree nodes (`XyzContext`), less intermediary stuff (private classes in `Antrl2Kotlin.kt`), more compact code. Also: nicer names such as simply `StringLiteral` instead of `StringLiteralValue`
+9. re-think `IStringEncoding` to address #38
+
@@ -1,3 +1,10 @@
+
+This sofware license is for Prog8 the compiler + associated libraries.
+The software generated by running the compiler is excluded from this.
+
+
+
+
                    GNU GENERAL PUBLIC LICENSE
                       Version 3, 29 June 2007

@@ -1,5 +1,3 @@
-[![saythanks](https://img.shields.io/badge/say-thanks-ff69b4.svg)](https://saythanks.io/to/irmen)
-[![Build Status](https://travis-ci.org/irmen/prog8.svg?branch=master)](https://travis-ci.org/irmen/prog8)
 [![Documentation](https://readthedocs.org/projects/prog8/badge/?version=latest)](https://prog8.readthedocs.io/)

 Prog8 - Structured Programming Language for 8-bit 6502/65c02 microprocessors
@@ -7,9 +5,6 @@ Prog8 - Structured Programming Language for 8-bit 6502/65c02 microprocessors

 *Written by Irmen de Jong (irmen@razorvine.net)*

-*Software license: GNU GPL 3.0, see file LICENSE*
-
-
 This is a structured programming language for the 8-bit 6502/6510/65c02 microprocessor from the late 1970's and 1980's
 as used in many home computers from that era. It is a medium to low level programming language,
 which aims to provide many conveniences over raw assembly code (even when using a macro assembler).
@@ -19,29 +14,35 @@ Documentation
 Full documentation (syntax reference, how to use the language and the compiler, etc.) can be found at:
 https://prog8.readthedocs.io/

+Software license
+----------------
+GNU GPL 3.0, see file LICENSE
+
+- prog8 (the compiler + libraries) is licensed under GNU GPL 3.0
+- *exception:* the resulting files created by running the compiler are free to use in whatever way desired.
+

 What does Prog8 provide?
 ------------------------

 - reduction of source code length over raw assembly
+- fast execution speed due to compilation to native assembly code. It's possible to write certain raster interrupt 'demoscene' effects purely in Prog8.
 - modularity, symbol scoping, subroutines
 - various data types other than just bytes (16-bit words, floats, strings)
- automatic variable allocations, automatic string and array variables and string sharing
+- floating point math is supported if the target system provides floating point library routines (C64 and Cx16 both do)
+- strings can contain escaped characters but also many symbols directly if they have a petscii equivalent, such as "♠♥♣♦π▚●○╳". Characters like ^, _, \, {, } and | are also accepted and converted to the closest petscii equivalents.
+- automatic static variable allocations, automatic string and array variables and string sharing
 - subroutines with input parameters and result values
 - high-level program optimizations
 - small program boilerplate/compilersupport overhead
- sane variable initialization, programs can be restarted again just fine after exiting to basic
+- programs can be run multiple times without reloading because of automatic variable (re)initializations.
 - conditional branches
- floating point operations  (requires the C64 Basic ROM routines for this)
 - 'when' statement to provide a concise jump table alternative to if/elseif chains
- structs to group together sets of variables and manipulate them at once
 - many built-in functions such as ``sin``, ``cos``, ``rnd``, ``abs``, ``min``, ``max``, ``sqrt``, ``msb``, ``rol``, ``ror``, ``swap``, ``sort`` and ``reverse``
 - various powerful built-in libraries to do I/O, number conversions, graphics and more  
 - convenience abstractions for low level aspects such as ZeroPage handling, program startup, explicit memory addresses
- fast execution speed due to compilation to native assembly code
- variables are allocated statically
 - inline assembly allows you to have full control when every cycle or byte matters
- supports the sixteen 'virtual' 16-bit registers R0 .. R15 from the Commander X16, and provides them also on the C64.
+- supports the sixteen 'virtual' 16-bit registers R0 - R15 from the Commander X16, and provides them also on the C64.
 - encode strings and characters into petscii or screencodes as desired (C64/Cx16)

 *Rapid edit-compile-run-debug cycle:*
@@ -0,0 +1,10 @@
+plugins {
+    id "org.jetbrains.kotlin.jvm" version "$kotlinVersion" apply false
+}
+
+allprojects {
+    repositories {
+        mavenLocal()
+        mavenCentral()
+    }
+}
@@ -0,0 +1,52 @@
+
+plugins {
+    id 'java'
+    id 'application'
+    id "org.jetbrains.kotlin.jvm"
+    id "io.kotest" version "0.3.8"
+}
+
+java {
+    toolchain {
+        languageVersion = JavaLanguageVersion.of(javaVersion)
+    }
+}
+
+dependencies {
+    implementation project(':compilerInterfaces')
+    implementation project(':compilerAst')
+    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk8"
+    // implementation "org.jetbrains.kotlin:kotlin-reflect"
+    implementation "com.michael-bull.kotlin-result:kotlin-result-jvm:1.1.12"
+
+    testImplementation 'io.kotest:kotest-runner-junit5-jvm:4.6.3'
+}
+
+sourceSets {
+    main {
+        java {
+            srcDirs = ["${project.projectDir}/src"]
+        }
+        resources {
+            srcDirs = ["${project.projectDir}/res"]
+        }
+    }
+    test {
+        java {
+            srcDirs = ["${project.projectDir}/test"]
+        }
+    }
+}
+
+
+test {
+    useJUnitPlatform()
+
+    // Always run tests, even when nothing changed.
+    dependsOn 'cleanTest'
+
+    // Show test results.
+    testLogging {
+        events "skipped", "failed"
+    }
+}
@@ -0,0 +1,19 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<module type="JAVA_MODULE" version="4">
+  <component name="NewModuleRootManager" inherit-compiler-output="true">
+    <exclude-output />
+    <content url="file://$MODULE_DIR$">
+      <sourceFolder url="file://$MODULE_DIR$/src" isTestSource="false" />
+      <sourceFolder url="file://$MODULE_DIR$/test" isTestSource="true" />
+      <excludeFolder url="file://$MODULE_DIR$/build" />
+    </content>
+    <orderEntry type="jdk" jdkName="openjdk-11" jdkType="JavaSDK" />
+    <orderEntry type="sourceFolder" forTests="false" />
+    <orderEntry type="library" name="KotlinJavaRuntime" level="project" />
+    <orderEntry type="library" name="michael.bull.kotlin.result.jvm" level="project" />
+    <orderEntry type="module" module-name="compilerInterfaces" />
+    <orderEntry type="module" module-name="compilerAst" />
+    <orderEntry type="library" name="io.kotest.runner.junit5.jvm" level="project" />
+    <orderEntry type="library" name="io.kotest.assertions.core.jvm" level="project" />
+  </component>
+</module>
@@ -0,0 +1,3 @@
+package prog8.compiler.target
+
+class AssemblyError(msg: String) : RuntimeException(msg)
@@ -0,0 +1,41 @@
+package prog8.compiler.target
+
+import com.github.michaelbull.result.fold
+import prog8.ast.base.*
+import prog8.ast.expressions.Expression
+import prog8.ast.statements.RegisterOrStatusflag
+import prog8.ast.statements.Subroutine
+import prog8.compiler.target.c64.C64MachineDefinition
+import prog8.compiler.target.cbm.Petscii
+import prog8.compiler.target.cpu6502.codegen.asmsub6502ArgsEvalOrder
+import prog8.compiler.target.cpu6502.codegen.asmsub6502ArgsHaveRegisterClobberRisk
+import prog8.compilerinterface.ICompilationTarget
+
+object C64Target: ICompilationTarget {
+    override val name = "c64"
+    override val machine = C64MachineDefinition
+    override fun encodeString(str: String, altEncoding: Boolean): List<UByte> {
+        val coded = if (altEncoding) Petscii.encodeScreencode(str, true) else Petscii.encodePetscii(str, true)
+        return coded.fold(
+            failure = { throw it },
+            success = { it }
+        )
+    }
+    override fun decodeString(bytes: List<UByte>, altEncoding: Boolean) =
+        if (altEncoding) Petscii.decodeScreencode(bytes, true) else Petscii.decodePetscii(bytes, true)
+
+    override fun asmsubArgsEvalOrder(sub: Subroutine): List<Int> =
+        asmsub6502ArgsEvalOrder(sub)
+    override fun asmsubArgsHaveRegisterClobberRisk(args: List<Expression>, paramRegisters: List<RegisterOrStatusflag>) =
+        asmsub6502ArgsHaveRegisterClobberRisk(args, paramRegisters)
+
+    override fun memorySize(dt: DataType): Int {
+        return when(dt) {
+            in ByteDatatypes -> 1
+            in WordDatatypes -> 2
+            DataType.FLOAT -> machine.FLOAT_MEM_SIZE
+            in PassByReferenceDatatypes -> machine.POINTER_MEM_SIZE
+            else -> Int.MIN_VALUE
+        }
+    }
+}
@@ -0,0 +1,46 @@
+package prog8.compiler.target
+
+import com.github.michaelbull.result.fold
+import prog8.ast.base.ByteDatatypes
+import prog8.ast.base.DataType
+import prog8.ast.base.PassByReferenceDatatypes
+import prog8.ast.base.WordDatatypes
+import prog8.ast.expressions.Expression
+import prog8.ast.statements.RegisterOrStatusflag
+import prog8.ast.statements.Subroutine
+import prog8.compiler.target.cbm.Petscii
+import prog8.compiler.target.cpu6502.codegen.asmsub6502ArgsEvalOrder
+import prog8.compiler.target.cpu6502.codegen.asmsub6502ArgsHaveRegisterClobberRisk
+import prog8.compiler.target.cx16.CX16MachineDefinition
+import prog8.compilerinterface.ICompilationTarget
+
+
+object Cx16Target: ICompilationTarget {
+    override val name = "cx16"
+    override val machine = CX16MachineDefinition
+    override fun encodeString(str: String, altEncoding: Boolean): List<UByte> {
+        val coded= if (altEncoding) Petscii.encodeScreencode(str, true) else Petscii.encodePetscii(str, true)
+        return coded.fold(
+            failure = { throw it },
+            success = { it }
+        )
+    }
+    override fun decodeString(bytes: List<UByte>, altEncoding: Boolean) =
+        if (altEncoding) Petscii.decodeScreencode(bytes, true) else Petscii.decodePetscii(bytes, true)
+
+    override fun asmsubArgsEvalOrder(sub: Subroutine): List<Int> =
+        asmsub6502ArgsEvalOrder(sub)
+    override fun asmsubArgsHaveRegisterClobberRisk(args: List<Expression>, paramRegisters: List<RegisterOrStatusflag>) =
+        asmsub6502ArgsHaveRegisterClobberRisk(args, paramRegisters)
+
+    override fun memorySize(dt: DataType): Int {
+        return when(dt) {
+            in ByteDatatypes -> 1
+            in WordDatatypes -> 2
+            DataType.FLOAT -> machine.FLOAT_MEM_SIZE
+            in PassByReferenceDatatypes -> machine.POINTER_MEM_SIZE
+            else -> Int.MIN_VALUE
+        }
+    }
+}
+
@@ -1,14 +1,13 @@
 package prog8.compiler.target.c64

-import prog8.compiler.*
-import prog8.compiler.target.CpuType
-import prog8.compiler.target.IMachineDefinition
-import prog8.compiler.target.IMachineFloat
+import prog8.compiler.target.cbm.viceMonListPostfix
+import prog8.compilerinterface.*
 import java.io.IOException
+import java.nio.file.Path
 import kotlin.math.absoluteValue
 import kotlin.math.pow

-internal object C64MachineDefinition: IMachineDefinition {
+object C64MachineDefinition: IMachineDefinition {

    override val cpu = CpuType.CPU6502

@@ -17,29 +16,34 @@ internal object C64MachineDefinition: IMachineDefinition {
    override val FLOAT_MAX_NEGATIVE = -1.7014118345e+38        // bytes: 255,255,255,255,255
    override val FLOAT_MEM_SIZE = 5
    override val POINTER_MEM_SIZE = 2
-    override val BASIC_LOAD_ADDRESS = 0x0801
-    override val RAW_LOAD_ADDRESS = 0xc000
+    override val BASIC_LOAD_ADDRESS = 0x0801u
+    override val RAW_LOAD_ADDRESS = 0xc000u

    // the 2*256 byte evaluation stack (on which bytes, words, and even floats are stored during calculations)
-    override val ESTACK_LO = 0xce00        //  $ce00-$ceff inclusive
-    override val ESTACK_HI = 0xcf00        //  $ce00-$ceff inclusive
+    override val ESTACK_LO = 0xce00u     //  $ce00-$ceff inclusive
+    override val ESTACK_HI = 0xcf00u     //  $ce00-$ceff inclusive

    override lateinit var zeropage: Zeropage

    override fun getFloat(num: Number) = Mflpt5.fromNumber(num)

-    override fun importLibs(compilerOptions: CompilationOptions,compilationTargetName: String): List<String> {
+    override fun importLibs(compilerOptions: CompilationOptions, compilationTargetName: String): List<String> {
        return if (compilerOptions.launcher == LauncherType.BASIC || compilerOptions.output == OutputType.PRG)
            listOf("syslib")
        else
            emptyList()
    }

-    override fun launchEmulator(programName: String) {
+    override fun launchEmulator(selectedEmulator: Int, programNameWithPath: Path) {
+        if(selectedEmulator!=1) {
+            System.err.println("The c64 target only supports the main emulator (Vice).")
+            return
+        }
+
        for(emulator in listOf("x64sc", "x64")) {
            println("\nStarting C-64 emulator $emulator...")
-            val cmdline = listOf(emulator, "-silent", "-moncommands", "$programName.vice-mon-list",
-                    "-autostartprgmode", "1", "-autostart-warp", "-autostart", programName + ".prg")
+            val cmdline = listOf(emulator, "-silent", "-moncommands", "${programNameWithPath}.$viceMonListPostfix",
+                    "-autostartprgmode", "1", "-autostart-warp", "-autostart", "${programNameWithPath}.prg")
            val processb = ProcessBuilder(cmdline).inheritIO()
            val process: Process
            try {
@@ -52,7 +56,7 @@ internal object C64MachineDefinition: IMachineDefinition {
        }
    }

-    override fun isRegularRAMaddress(address: Int): Boolean = address<0xa000 || address in 0xc000..0xcfff
+    override fun isIOAddress(address: UInt): Boolean = address==0u || address==1u || address in 0xd000u..0xdfffu

    override fun initializeZeropage(compilerOptions: CompilationOptions) {
        zeropage = C64Zeropage(compilerOptions)
@@ -70,23 +74,22 @@ internal object C64MachineDefinition: IMachineDefinition {
            "sta", "stx", "sty", "tas", "tax", "tay", "tsx", "txa", "txs", "tya", "xaa")


-    internal class C64Zeropage(options: CompilationOptions) : Zeropage(options) {
+    class C64Zeropage(options: CompilationOptions) : Zeropage(options) {

-        override val SCRATCH_B1 = 0x02      // temp storage for a single byte
-        override val SCRATCH_REG = 0x03     // temp storage for a register, must be B1+1
-        override val SCRATCH_W1 = 0xfb      // temp storage 1 for a word  $fb+$fc
-        override val SCRATCH_W2 = 0xfd      // temp storage 2 for a word  $fb+$fc
+        override val SCRATCH_B1 = 0x02u      // temp storage for a single byte
+        override val SCRATCH_REG = 0x03u     // temp storage for a register, must be B1+1
+        override val SCRATCH_W1 = 0xfbu      // temp storage 1 for a word  $fb+$fc
+        override val SCRATCH_W2 = 0xfdu      // temp storage 2 for a word  $fb+$fc


        init {
-            if (options.floats && options.zeropage !in setOf(ZeropageType.FLOATSAFE, ZeropageType.BASICSAFE, ZeropageType.DONTUSE ))
-                throw CompilerException("when floats are enabled, zero page type should be 'floatsafe' or 'basicsafe' or 'dontuse'")
+            if (options.floats && options.zeropage !in arrayOf(ZeropageType.FLOATSAFE, ZeropageType.BASICSAFE, ZeropageType.DONTUSE ))
+                throw InternalCompilerException("when floats are enabled, zero page type should be 'floatsafe' or 'basicsafe' or 'dontuse'")

            if (options.zeropage == ZeropageType.FULL) {
-                free.addAll(0x04..0xf9)
-                free.add(0xff)
-                free.removeAll(listOf(SCRATCH_B1, SCRATCH_REG, SCRATCH_W1, SCRATCH_W1 + 1, SCRATCH_W2, SCRATCH_W2 + 1))
-                free.removeAll(listOf(0xa0, 0xa1, 0xa2, 0x91, 0xc0, 0xc5, 0xcb, 0xf5, 0xf6))        // these are updated by IRQ
+                free.addAll(0x04u..0xf9u)
+                free.add(0xffu)
+                free.removeAll(setOf(0xa0u, 0xa1u, 0xa2u, 0x91u, 0xc0u, 0xc5u, 0xcbu, 0xf5u, 0xf6u))        // these are updated by IRQ
            } else {
                if (options.zeropage == ZeropageType.KERNALSAFE || options.zeropage == ZeropageType.FLOATSAFE) {
                    free.addAll(listOf(
@@ -103,11 +106,11 @@ internal object C64MachineDefinition: IMachineDefinition {
                            0x7d, 0x7e, 0x7f, 0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87, 0x88, 0x89, 0x8a,
                            0x8b, 0x8c, 0x8d, 0x8e, 0x8f, 0xff
                            // 0x90-0xfa is 'kernal work storage area'
-                    ))
+                    ).map{it.toUInt()})
                }

                if (options.zeropage == ZeropageType.FLOATSAFE) {
-                    // remove the zero page locations used for floating point operations from the free list
+                    // remove the zeropage locations used for floating point operations from the free list
                    free.removeAll(listOf(
                            0x22, 0x23, 0x24, 0x25,
                            0x10, 0x11, 0x12, 0x26, 0x27, 0x28, 0x29, 0x2a,
@@ -115,34 +118,30 @@ internal object C64MachineDefinition: IMachineDefinition {
                            0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68,
                            0x69, 0x6a, 0x6b, 0x6c, 0x6d, 0x6e, 0x6f, 0x70, 0x71, 0x72,
                            0x8b, 0x8c, 0x8d, 0x8e, 0x8f, 0xff
-                    ))
+                    ).map{it.toUInt()})
                }

-                if(options.zeropage!=ZeropageType.DONTUSE) {
+                if(options.zeropage!= ZeropageType.DONTUSE) {
                    // add the free Zp addresses
                    // these are valid for the C-64 but allow BASIC to keep running fully *as long as you don't use tape I/O*
                    free.addAll(listOf(0x04, 0x05, 0x06, 0x0a, 0x0e,
                            0x92, 0x96, 0x9b, 0x9c, 0x9e, 0x9f, 0xa5, 0xa6,
-                            0xb0, 0xb1, 0xbe, 0xbf, 0xf9))
+                            0xb0, 0xb1, 0xbe, 0xbf, 0xf9).map{it.toUInt()})
                } else {
                    // don't use the zeropage at all
                    free.clear()
                }
            }
-            require(SCRATCH_B1 !in free)
-            require(SCRATCH_REG !in free)
-            require(SCRATCH_W1 !in free)
-            require(SCRATCH_W2 !in free)

-            for (reserved in options.zpReserved)
-                reserve(reserved)
+            removeReservedFromFreePool()
        }
    }

-    internal data class Mflpt5(val b0: Short, val b1: Short, val b2: Short, val b3: Short, val b4: Short): IMachineFloat {
+    data class Mflpt5(val b0: UByte, val b1: UByte, val b2: UByte, val b3: UByte, val b4: UByte):
+        IMachineFloat {

        companion object {
-            val zero = Mflpt5(0, 0, 0, 0, 0)
+            val zero = Mflpt5(0u, 0u, 0u, 0u, 0u)
            fun fromNumber(num: Number): Mflpt5 {
                // see https://en.wikipedia.org/wiki/Microsoft_Binary_Format
                // and https://sourceforge.net/p/acme-crossass/code-0/62/tree/trunk/ACME_Lib/cbm/mflpt.a
@@ -150,7 +149,7 @@ internal object C64MachineDefinition: IMachineDefinition {

                val flt = num.toDouble()
                if (flt < FLOAT_MAX_NEGATIVE || flt > FLOAT_MAX_POSITIVE)
-                    throw CompilerException("floating point number out of 5-byte mflpt range: $this")
+                    throw InternalCompilerException("floating point number out of 5-byte mflpt range: $this")
                if (flt == 0.0)
                    return zero

@@ -171,16 +170,16 @@ internal object C64MachineDefinition: IMachineDefinition {

                return when {
                    exponent < 0 -> zero  // underflow, use zero instead
-                    exponent > 255 -> throw CompilerException("floating point overflow: $this")
+                    exponent > 255 -> throw InternalCompilerException("floating point overflow: $this")
                    exponent == 0 -> zero
                    else -> {
                        val mantLong = mantissa.toLong()
                        Mflpt5(
-                                exponent.toShort(),
-                                (mantLong.and(0x7f000000L) ushr 24).or(sign).toShort(),
-                                (mantLong.and(0x00ff0000L) ushr 16).toShort(),
-                                (mantLong.and(0x0000ff00L) ushr 8).toShort(),
-                                (mantLong.and(0x000000ffL)).toShort())
+                                exponent.toUByte(),
+                                (mantLong.and(0x7f000000L) ushr 24).or(sign).toUByte(),
+                                (mantLong.and(0x00ff0000L) ushr 16).toUByte(),
+                                (mantLong.and(0x0000ff00L) ushr 8).toUByte(),
+                                (mantLong.and(0x000000ffL)).toUByte())
                    }
                }
            }
@@ -188,7 +187,7 @@ internal object C64MachineDefinition: IMachineDefinition {

        override fun toDouble(): Double {
            if (this == zero) return 0.0
-            val exp = b0 - 128
+            val exp = b0.toInt() - 128
            val sign = (b1.toInt() and 0x80) > 0
            val number = 0x80000000L.or(b1.toLong() shl 24).or(b2.toLong() shl 16).or(b3.toLong() shl 8).or(b4.toLong())
            val result = number.toDouble() * (2.0).pow(exp) / 0x100000000
@@ -1,24 +1,41 @@
-package prog8.compiler.target.c64
+package prog8.compiler.target.cbm

-import prog8.compiler.CompilationOptions
-import prog8.compiler.OutputType
-import prog8.compiler.target.IAssemblyProgram
-import prog8.compiler.target.generatedLabelPrefix
+import com.github.michaelbull.result.Ok
+import com.github.michaelbull.result.Result
+import com.github.michaelbull.result.mapError
+import prog8.compilerinterface.CompilationOptions
+import prog8.compilerinterface.IAssemblyProgram
+import prog8.compilerinterface.OutputType
+import prog8.compilerinterface.generatedLabelPrefix
+import prog8.parser.SourceCode
+import java.io.File
 import java.nio.file.Path
-import kotlin.system.exitProcess
+import kotlin.io.path.Path
+import kotlin.io.path.isRegularFile
+
+
+internal const val viceMonListPostfix = "vice-mon-list"
+
+class AssemblyProgram(
+        override val valid: Boolean,
+        override val name: String,
+        outputDir: Path,
+        private val compTarget: String) : IAssemblyProgram {

-class AssemblyProgram(override val name: String, outputDir: Path, private val compTarget: String) : IAssemblyProgram {
    private val assemblyFile = outputDir.resolve("$name.asm")
    private val prgFile = outputDir.resolve("$name.prg")
    private val binFile = outputDir.resolve("$name.bin")
-    private val viceMonListFile = outputDir.resolve("$name.vice-mon-list")
+    private val viceMonListFile = outputDir.resolve("$name.$viceMonListPostfix")

-    override fun assemble(options: CompilationOptions) {
+    override fun assemble(quiet: Boolean, options: CompilationOptions): Int {
        // add "-Wlong-branch"  to see warnings about conversion of branch instructions to jumps (default = do this silently)
        val command = mutableListOf("64tass", "--ascii", "--case-sensitive", "--long-branch",
                "-Wall", "-Wno-strict-bool", "-Wno-shadow", // "-Werror",
                "--dump-labels", "--vice-labels", "-l", viceMonListFile.toString(), "--no-monitor")

+        if(quiet)
+            command.add("--quiet")
+
        val outFile = when (options.output) {
            OutputType.PRG -> {
                command.add("--cbm-prg")
@@ -35,13 +52,11 @@ class AssemblyProgram(override val name: String, outputDir: Path, private val co

        val proc = ProcessBuilder(command).inheritIO().start()
        val result = proc.waitFor()
-        if (result != 0) {
-            System.err.println("assembler failed with returncode $result")
-            exitProcess(result)
+        if (result == 0) {
+            removeGeneratedLabelsFromMonlist()
+            generateBreakpointList()
        }
-
-        removeGeneratedLabelsFromMonlist()
-        generateBreakpointList()
+        return result
    }

    private fun removeGeneratedLabelsFromMonlist() {
@@ -71,3 +86,18 @@ class AssemblyProgram(override val name: String, outputDir: Path, private val co
        viceMonListFile.toFile().appendText(breakpoints.joinToString("\n") + "\n")
    }
 }
+
+
+internal fun loadAsmIncludeFile(filename: String, source: SourceCode): Result<String, NoSuchFileException> {
+    return if (filename.startsWith(SourceCode.libraryFilePrefix)) {
+        return com.github.michaelbull.result.runCatching {
+            SourceCode.Resource("/prog8lib/${filename.substring(SourceCode.libraryFilePrefix.length)}").readText()
+        }.mapError { NoSuchFileException(File(filename)) }
+    } else {
+        val sib = Path(source.origin).resolveSibling(filename)
+        if (sib.isRegularFile())
+            Ok(SourceCode.File(sib).readText())
+        else
+            Ok(SourceCode.File(Path(filename)).readText())
+    }
+}
@@ -0,0 +1,446 @@
+package prog8.compiler.target.cpu6502.codegen
+
+import prog8.ast.Program
+import prog8.ast.base.VarDeclType
+import prog8.ast.expressions.NumericLiteralValue
+import prog8.ast.statements.VarDecl
+import prog8.compilerinterface.IMachineDefinition
+
+
+// note: see https://wiki.nesdev.org/w/index.php/6502_assembly_optimisations
+
+
+fun optimizeAssembly(lines: MutableList<String>, machine: IMachineDefinition, program: Program): Int {
+
+    var numberOfOptimizations = 0
+
+    var linesByFour = getLinesBy(lines, 4)
+
+    var mods = optimizeUselessStackByteWrites(linesByFour)
+    if(mods.isNotEmpty()) {
+        apply(mods, lines)
+        linesByFour = getLinesBy(lines, 4)
+        numberOfOptimizations++
+    }
+
+    mods = optimizeIncDec(linesByFour)
+    if(mods.isNotEmpty()) {
+        apply(mods, lines)
+        linesByFour = getLinesBy(lines, 4)
+        numberOfOptimizations++
+    }
+
+    mods = optimizeCmpSequence(linesByFour)
+    if(mods.isNotEmpty()) {
+        apply(mods, lines)
+        linesByFour = getLinesBy(lines, 4)
+        numberOfOptimizations++
+    }
+
+    mods = optimizeStoreLoadSame(linesByFour, machine, program)
+    if(mods.isNotEmpty()) {
+        apply(mods, lines)
+        linesByFour = getLinesBy(lines, 4)
+        numberOfOptimizations++
+    }
+
+    mods= optimizeJsrRts(linesByFour)
+    if(mods.isNotEmpty()) {
+        apply(mods, lines)
+        linesByFour = getLinesBy(lines, 4)
+        numberOfOptimizations++
+    }
+
+    var linesByFourteen = getLinesBy(lines, 14)
+    mods = optimizeSameAssignments(linesByFourteen, machine, program)
+    if(mods.isNotEmpty()) {
+        apply(mods, lines)
+        linesByFourteen = getLinesBy(lines, 14)
+        numberOfOptimizations++
+    }
+
+    // TODO more assembly optimizations
+
+    return numberOfOptimizations
+}
+
+private class Modification(val lineIndex: Int, val remove: Boolean, val replacement: String?)
+
+private fun apply(modifications: List<Modification>, lines: MutableList<String>) {
+    for (modification in modifications.sortedBy { it.lineIndex }.reversed()) {
+        if(modification.remove)
+            lines.removeAt(modification.lineIndex)
+        else
+            lines[modification.lineIndex] = modification.replacement!!
+    }
+}
+
+private fun getLinesBy(lines: MutableList<String>, windowSize: Int) =
+// all lines (that aren't empty or comments) in sliding windows of certain size
+        lines.withIndex().filter { it.value.isNotBlank() && !it.value.trimStart().startsWith(';') }.windowed(windowSize, partialWindows = false)
+
+private fun optimizeCmpSequence(linesByFour: List<List<IndexedValue<String>>>): List<Modification> {
+    // when statement (on bytes) generates a sequence of:
+    //	 lda  $ce01,x
+    //	 cmp  #$20
+    //	 beq  check_prog8_s72choice_32
+    //	 lda  $ce01,x
+    //	 cmp  #$21
+    //	 beq  check_prog8_s73choice_33
+    // the repeated lda can be removed
+    val mods = mutableListOf<Modification>()
+    for(lines in linesByFour) {
+        if(lines[0].value.trim()=="lda  P8ESTACK_LO+1,x" &&
+                lines[1].value.trim().startsWith("cmp ") &&
+                lines[2].value.trim().startsWith("beq ") &&
+                lines[3].value.trim()=="lda  P8ESTACK_LO+1,x") {
+            mods.add(Modification(lines[3].index, true, null)) // remove the second lda
+        }
+    }
+    return mods
+}
+
+private fun optimizeUselessStackByteWrites(linesByFour: List<List<IndexedValue<String>>>): List<Modification> {
+    // sta on stack, dex, inx, lda from stack -> eliminate this useless stack byte write
+    // this is a lot harder for word values because the instruction sequence varies.
+    val mods = mutableListOf<Modification>()
+    for(lines in linesByFour) {
+        if(lines[0].value.trim()=="sta  P8ESTACK_LO,x" &&
+                lines[1].value.trim()=="dex" &&
+                lines[2].value.trim()=="inx" &&
+                lines[3].value.trim()=="lda  P8ESTACK_LO,x") {
+            mods.add(Modification(lines[1].index, true, null))
+            mods.add(Modification(lines[2].index, true, null))
+            mods.add(Modification(lines[3].index, true, null))
+        }
+    }
+    return mods
+}
+
+private fun optimizeSameAssignments(linesByFourteen: List<List<IndexedValue<String>>>, machine: IMachineDefinition, program: Program): List<Modification> {
+
+    // Optimize sequential assignments of the same value to various targets (bytes, words, floats)
+    // the float one is the one that requires 2*7=14 lines of code to check...
+    // The better place to do this is in the Compiler instead and never create these types of assembly, but hey
+
+    val mods = mutableListOf<Modification>()
+    for (lines in linesByFourteen) {
+        val first = lines[0].value.trimStart()
+        val second = lines[1].value.trimStart()
+        val third = lines[2].value.trimStart()
+        val fourth = lines[3].value.trimStart()
+        val fifth = lines[4].value.trimStart()
+        val sixth = lines[5].value.trimStart()
+        val seventh = lines[6].value.trimStart()
+        val eighth = lines[7].value.trimStart()
+
+        if(first.startsWith("lda") && second.startsWith("ldy") && third.startsWith("sta") && fourth.startsWith("sty") &&
+                fifth.startsWith("lda") && sixth.startsWith("ldy") && seventh.startsWith("sta") && eighth.startsWith("sty")) {
+            val firstvalue = first.substring(4)
+            val secondvalue = second.substring(4)
+            val thirdvalue = fifth.substring(4)
+            val fourthvalue = sixth.substring(4)
+            if(firstvalue==thirdvalue && secondvalue==fourthvalue) {
+                // lda/ldy   sta/sty   twice the same word -->  remove second lda/ldy pair (fifth and sixth lines)
+                val address1 = getAddressArg(first, program)
+                val address2 = getAddressArg(second, program)
+                if(address1==null || address2==null || (!machine.isIOAddress(address1) && !machine.isIOAddress(address2))) {
+                    mods.add(Modification(lines[4].index, true, null))
+                    mods.add(Modification(lines[5].index, true, null))
+                }
+            }
+        }
+
+        if(first.startsWith("lda") && second.startsWith("sta") && third.startsWith("lda") && fourth.startsWith("sta")) {
+            val firstvalue = first.substring(4)
+            val secondvalue = third.substring(4)
+            if(firstvalue==secondvalue) {
+                // lda value / sta ? / lda same-value / sta ?  -> remove second lda (third line)
+                val address = getAddressArg(first, program)
+                if(address==null || !machine.isIOAddress(address))
+                    mods.add(Modification(lines[2].index, true, null))
+            }
+        }
+
+        if(first.startsWith("lda") && second.startsWith("ldy") && third.startsWith("sta") && fourth.startsWith("sty") &&
+                fifth.startsWith("lda") && sixth.startsWith("ldy") &&
+                (seventh.startsWith("jsr  floats.copy_float") || seventh.startsWith("jsr  cx16flt.copy_float"))) {
+
+            val nineth = lines[8].value.trimStart()
+            val tenth = lines[9].value.trimStart()
+            val eleventh = lines[10].value.trimStart()
+            val twelveth = lines[11].value.trimStart()
+            val thirteenth = lines[12].value.trimStart()
+            val fourteenth = lines[13].value.trimStart()
+
+            if(eighth.startsWith("lda") && nineth.startsWith("ldy") && tenth.startsWith("sta") && eleventh.startsWith("sty") &&
+                    twelveth.startsWith("lda") && thirteenth.startsWith("ldy") &&
+                    (fourteenth.startsWith("jsr  floats.copy_float") || fourteenth.startsWith("jsr  cx16flt.copy_float"))) {
+
+                if(first.substring(4) == eighth.substring(4) && second.substring(4)==nineth.substring(4)) {
+                    // identical float init
+                    mods.add(Modification(lines[7].index, true, null))
+                    mods.add(Modification(lines[8].index, true, null))
+                    mods.add(Modification(lines[9].index, true, null))
+                    mods.add(Modification(lines[10].index, true, null))
+                }
+            }
+        }
+
+        var overlappingMods = false
+        /*
+        sta  prog8_lib.retval_intermX      ; remove
+        sty  prog8_lib.retval_intermY      ; remove
+        lda  prog8_lib.retval_intermX      ; remove
+        ldy  prog8_lib.retval_intermY      ; remove
+        sta  A1
+        sty  A2
+         */
+        if(first.startsWith("st") && second.startsWith("st")
+            && third.startsWith("ld") && fourth.startsWith("ld")
+            && fifth.startsWith("st") && sixth.startsWith("st")) {
+            val reg1 = first[2]
+            val reg2 = second[2]
+            val reg3 = third[2]
+            val reg4 = fourth[2]
+            val reg5 = fifth[2]
+            val reg6 = sixth[2]
+            if (reg1 == reg3 && reg1 == reg5 && reg2 == reg4 && reg2 == reg6) {
+                val firstvalue = first.substring(4)
+                val secondvalue = second.substring(4)
+                val thirdvalue = third.substring(4)
+                val fourthvalue = fourth.substring(4)
+                if(firstvalue.contains("prog8_lib.retval_interm") && secondvalue.contains("prog8_lib.retval_interm")
+                    && firstvalue==thirdvalue && secondvalue==fourthvalue) {
+                    mods.add(Modification(lines[0].index, true, null))
+                    mods.add(Modification(lines[1].index, true, null))
+                    mods.add(Modification(lines[2].index, true, null))
+                    mods.add(Modification(lines[3].index, true, null))
+                    overlappingMods = true
+                }
+            }
+        }
+
+        /*
+        sta  A1
+        sty  A2
+        lda  A1     ; can be removed
+        ldy  A2     ; can be removed if not followed by a branch instuction
+         */
+        if(!overlappingMods && first.startsWith("st") && second.startsWith("st")
+            && third.startsWith("ld") && fourth.startsWith("ld")) {
+            val reg1 = first[2]
+            val reg2 = second[2]
+            val reg3 = third[2]
+            val reg4 = fourth[2]
+            if(reg1==reg3 && reg2==reg4) {
+                val firstvalue = first.substring(4)
+                val secondvalue = second.substring(4)
+                val thirdvalue = third.substring(4)
+                val fourthvalue = fourth.substring(4)
+                if(firstvalue==thirdvalue && secondvalue == fourthvalue) {
+                    val address = getAddressArg(first, program)
+                    if(address==null || !machine.isIOAddress(address)) {
+                        overlappingMods = true
+                        mods.add(Modification(lines[2].index, true, null))
+                        if (!fifth.startsWith('b'))
+                            mods.add(Modification(lines[3].index, true, null))
+                    }
+                }
+            }
+        }
+        /*
+        sta  A1
+        sty  A2
+        lda  A1     ; can be removed if not followed by a branch instruction
+         */
+        if(!overlappingMods && first.startsWith("st") && second.startsWith("st")
+            && third.startsWith("ld") && !fourth.startsWith("b")) {
+            val reg1 = first[2]
+            val reg3 = third[2]
+            if(reg1==reg3) {
+                val firstvalue = first.substring(4)
+                val thirdvalue = third.substring(4)
+                if(firstvalue==thirdvalue) {
+                    val address = getAddressArg(first, program)
+                    if(address==null || !machine.isIOAddress(address)) {
+                        overlappingMods = true
+                        mods.add(Modification(lines[2].index, true, null))
+                    }
+                }
+            }
+        }
+
+        /*
+        sta  A1
+        ldy  A1     ; make tay
+        sta  A1     ; remove
+         */
+        if(!overlappingMods && first.startsWith("sta") && second.startsWith("ld")
+            && third.startsWith("sta") && second.length>4) {
+            val firstvalue = first.substring(4)
+            val secondvalue = second.substring(4)
+            val thirdvalue = third.substring(4)
+            if(firstvalue==secondvalue && firstvalue==thirdvalue) {
+                val address = getAddressArg(first, program)
+                if(address==null || !machine.isIOAddress(address)) {
+                    overlappingMods = true
+                    val reg2 = second[2]
+                    mods.add(Modification(lines[1].index, false, "  ta$reg2"))
+                    mods.add(Modification(lines[2].index, true, null))
+                }
+            }
+        }
+
+        /*
+        sta  A
+        sta  A
+         */
+        if(!overlappingMods && first.startsWith("st") && second.startsWith("st")) {
+            if(first[2]==second[2]) {
+                val firstvalue = first.substring(4)
+                val secondvalue = second.substring(4)
+                if(firstvalue==secondvalue) {
+                    val address = getAddressArg(first, program)
+                    if(address==null || !machine.isIOAddress(address)) {
+                        overlappingMods = true
+                        mods.add(Modification(lines[1].index, true, null))
+                    }
+                }
+            }
+        }
+    }
+
+    return mods
+}
+
+private fun optimizeStoreLoadSame(linesByFour: List<List<IndexedValue<String>>>, machine: IMachineDefinition, program: Program): List<Modification> {
+    // sta X + lda X,  sty X + ldy X,   stx X + ldx X  -> the second instruction can OFTEN be eliminated
+    val mods = mutableListOf<Modification>()
+    for (lines in linesByFour) {
+        val first = lines[1].value.trimStart()
+        val second = lines[2].value.trimStart()
+
+        if ((first.startsWith("sta ") && second.startsWith("lda ")) ||
+                (first.startsWith("stx ") && second.startsWith("ldx ")) ||
+                (first.startsWith("sty ") && second.startsWith("ldy ")) ||
+                (first.startsWith("lda ") && second.startsWith("lda ")) ||
+                (first.startsWith("ldy ") && second.startsWith("ldy ")) ||
+                (first.startsWith("ldx ") && second.startsWith("ldx ")) ||
+                (first.startsWith("sta ") && second.startsWith("lda ")) ||
+                (first.startsWith("sty ") && second.startsWith("ldy ")) ||
+                (first.startsWith("stx ") && second.startsWith("ldx "))
+        ) {
+            val third = lines[3].value.trimStart()
+            val attemptRemove =
+                if(third.startsWith("b")) {
+                    // a branch instruction follows, we can only remove the load instruction if
+                    // another load instruction of the same register precedes the store instruction
+                    // (otherwise wrong cpu flags are used)
+                    val loadinstruction = second.substring(0, 3)
+                    lines[0].value.trimStart().startsWith(loadinstruction)
+                }
+                else {
+                    // no branch instruction follows, we can remove the load instruction
+                    val address = getAddressArg(lines[2].value, program)
+                    address==null || !machine.isIOAddress(address)
+                }
+
+            if(attemptRemove) {
+                val firstLoc = first.substring(4).trimStart()
+                val secondLoc = second.substring(4).trimStart()
+                if (firstLoc == secondLoc)
+                    mods.add(Modification(lines[2].index, true, null))
+            }
+        }
+        else if(first=="pha" && second=="pla" ||
+            first=="phx" && second=="plx" ||
+            first=="phy" && second=="ply" ||
+            first=="php" && second=="plp") {
+            mods.add(Modification(lines[1].index, true, null))
+            mods.add(Modification(lines[2].index, true, null))
+        } else if(first=="pha" && second=="plx") {
+            mods.add(Modification(lines[1].index, true, null))
+            mods.add(Modification(lines[2].index, false, "  tax"))
+        } else if(first=="pha" && second=="ply") {
+            mods.add(Modification(lines[1].index, true, null))
+            mods.add(Modification(lines[2].index, false, "  tay"))
+        } else if(first=="phx" && second=="pla") {
+            mods.add(Modification(lines[1].index, true, null))
+            mods.add(Modification(lines[2].index, false, "  txa"))
+        } else if(first=="phx" && second=="ply") {
+            mods.add(Modification(lines[1].index, true, null))
+            mods.add(Modification(lines[2].index, false, "  txy"))
+        } else if(first=="phy" && second=="pla") {
+            mods.add(Modification(lines[1].index, true, null))
+            mods.add(Modification(lines[2].index, false, "  tya"))
+        } else if(first=="phy" && second=="plx") {
+            mods.add(Modification(lines[1].index, true, null))
+            mods.add(Modification(lines[2].index, false, "  tyx"))
+        }
+    }
+    return mods
+}
+
+private val identifierRegex = Regex("""^([a-zA-Z_$][a-zA-Z\d_\.$]*)""")
+
+private fun getAddressArg(line: String, program: Program): UInt? {
+    val loadArg = line.trimStart().substring(3).trim()
+    return when {
+        loadArg.startsWith('$') -> loadArg.substring(1).toUIntOrNull(16)
+        loadArg.startsWith('%') -> loadArg.substring(1).toUIntOrNull(2)
+        loadArg.startsWith('#') -> null
+        loadArg.startsWith('(') -> null
+        loadArg[0].isLetter() -> {
+            val identMatch = identifierRegex.find(loadArg)
+            if(identMatch!=null) {
+                val identifier = identMatch.value
+                val decl = program.toplevelModule.lookup(identifier.split(".")) as? VarDecl
+                if(decl!=null) {
+                    when(decl.type){
+                        VarDeclType.VAR -> null
+                        VarDeclType.CONST,
+                        VarDeclType.MEMORY -> (decl.value as NumericLiteralValue).number.toUInt()
+                    }
+                }
+                else null
+            } else null
+        }
+        else -> loadArg.substring(1).toUIntOrNull()
+    }
+}
+
+private fun optimizeIncDec(linesByFour: List<List<IndexedValue<String>>>): List<Modification> {
+    // sometimes, iny+dey / inx+dex / dey+iny / dex+inx sequences are generated, these can be eliminated.
+    val mods = mutableListOf<Modification>()
+    for (lines in linesByFour) {
+        val first = lines[0].value
+        val second = lines[1].value
+        if ((" iny" in first || "\tiny" in first) && (" dey" in second || "\tdey" in second)
+                || (" inx" in first || "\tinx" in first) && (" dex" in second || "\tdex" in second)
+                || (" ina" in first || "\tina" in first) && (" dea" in second || "\tdea" in second)
+                || (" inc  a" in first || "\tinc  a" in first) && (" dec  a" in second || "\tdec  a" in second)
+                || (" dey" in first || "\tdey" in first) && (" iny" in second || "\tiny" in second)
+                || (" dex" in first || "\tdex" in first) && (" inx" in second || "\tinx" in second)
+                || (" dea" in first || "\tdea" in first) && (" ina" in second || "\tina" in second)
+                || (" dec  a" in first || "\tdec  a" in first) && (" inc  a" in second || "\tinc  a" in second)) {
+            mods.add(Modification(lines[0].index, true, null))
+            mods.add(Modification(lines[1].index, true, null))
+        }
+    }
+    return mods
+}
+
+private fun optimizeJsrRts(linesByFour: List<List<IndexedValue<String>>>): List<Modification> {
+    // jsr Sub + rts -> jmp Sub
+    val mods = mutableListOf<Modification>()
+    for (lines in linesByFour) {
+        val first = lines[0].value
+        val second = lines[1].value
+        if ((" jsr" in first || "\tjsr" in first ) && (" rts" in second || "\trts" in second)) {
+            mods += Modification(lines[0].index, false, lines[0].value.replace("jsr", "jmp"))
+            mods += Modification(lines[1].index, true, null)
+        }
+    }
+    return mods
+}
@@ -0,0 +1,59 @@
+package prog8.compiler.target.cpu6502.codegen
+
+import prog8.ast.base.Cx16VirtualRegisters
+import prog8.ast.base.RegisterOrPair
+import prog8.ast.expressions.*
+import prog8.ast.statements.RegisterOrStatusflag
+import prog8.ast.statements.Subroutine
+
+
+internal fun asmsub6502ArgsEvalOrder(sub: Subroutine): List<Int> {
+    val order = mutableListOf<Int>()
+    // order is:
+    //  1) cx16 virtual word registers,
+    //  2) paired CPU registers,
+    //  3) single CPU registers (X last), except A,
+    //  4) CPU Carry status flag
+    //  5) the A register itself last   (so everything before it can use the accumulator without having to save its value)
+    val args = sub.parameters.zip(sub.asmParameterRegisters).withIndex()
+    val (cx16regs, args2) = args.partition { it.value.second.registerOrPair in Cx16VirtualRegisters }
+    val pairedRegisters = arrayOf(RegisterOrPair.AX, RegisterOrPair.AY, RegisterOrPair.XY)
+    val (pairedRegs , args3) = args2.partition { it.value.second.registerOrPair in pairedRegisters }
+    val (regsWithoutA, args4) = args3.partition { it.value.second.registerOrPair != RegisterOrPair.A }
+    val (regA, rest) = args4.partition { it.value.second.registerOrPair != null }
+
+    cx16regs.forEach { order += it.index }
+    pairedRegs.forEach { order += it.index }
+    regsWithoutA.forEach {
+        if(it.value.second.registerOrPair != RegisterOrPair.X)
+            order += it.index
+    }
+    regsWithoutA.firstOrNull { it.value.second.registerOrPair==RegisterOrPair.X } ?.let { order += it.index}
+    rest.forEach { order += it.index }
+    regA.forEach { order += it.index }
+    require(order.size==sub.parameters.size)
+    return order
+}
+
+internal fun asmsub6502ArgsHaveRegisterClobberRisk(args: List<Expression>,
+                                                   paramRegisters: List<RegisterOrStatusflag>): Boolean {
+    fun isClobberRisk(expr: Expression): Boolean {
+        when (expr) {
+            is ArrayIndexedExpression -> {
+                return paramRegisters.any {
+                    it.registerOrPair in listOf(RegisterOrPair.Y, RegisterOrPair.AY, RegisterOrPair.XY)
+                }
+            }
+            is FunctionCall -> {
+                if (expr.target.nameInSource == listOf("lsb") || expr.target.nameInSource == listOf("msb"))
+                    return isClobberRisk(expr.args[0])
+                if (expr.target.nameInSource == listOf("mkword"))
+                    return isClobberRisk(expr.args[0]) && isClobberRisk(expr.args[1])
+                return !expr.isSimple
+            }
+            else -> return !expr.isSimple
+        }
+    }
+
+    return args.size>1 && args.any { isClobberRisk(it) }
+}
@@ -10,11 +10,12 @@ import prog8.ast.statements.DirectMemoryWrite
 import prog8.ast.statements.FunctionCallStatement
 import prog8.ast.statements.Subroutine
 import prog8.ast.toHex
-import prog8.compiler.AssemblyError
-import prog8.compiler.functions.FSignature
-import prog8.compiler.target.CpuType
+import prog8.compiler.target.AssemblyError
+import prog8.compiler.target.Cx16Target
 import prog8.compiler.target.cpu6502.codegen.assignment.*
-import prog8.compiler.target.subroutineFloatEvalResultVar2
+import prog8.compilerinterface.CpuType
+import prog8.compilerinterface.FSignature
+import prog8.compilerinterface.subroutineFloatEvalResultVar2

 internal class BuiltinFunctionsAsmGen(private val program: Program, private val asmgen: AsmGen, private val assignAsmGen: AssignmentAsmGen) {

@@ -33,7 +34,7 @@ internal class BuiltinFunctionsAsmGen(private val program: Program, private val
        if(discardResult && resultToStack)
            throw AssemblyError("cannot both discard the result AND put it onto stack")

-        val sscope = (fcall as Node).definingSubroutine()
+        val sscope = (fcall as Node).definingSubroutine

        when (func.name) {
            "msb" -> funcMsb(fcall, resultToStack, resultRegister)
@@ -45,13 +46,15 @@ internal class BuiltinFunctionsAsmGen(private val program: Program, private val
            "sum" -> funcSum(fcall, resultToStack, resultRegister, sscope)
            "any", "all" -> funcAnyAll(fcall, func, resultToStack, resultRegister, sscope)
            "sin8", "sin8u", "sin16", "sin16u",
-            "cos8", "cos8u", "cos16", "cos16u" -> funcSinCosInt(fcall, func, resultToStack, resultRegister, sscope)
+            "sinr8", "sinr8u", "sinr16", "sinr16u",
+            "cos8", "cos8u", "cos16", "cos16u",
+            "cosr8", "cosr8u", "cosr16", "cosr16u" -> funcSinCosInt(fcall, func, resultToStack, resultRegister, sscope)
            "sgn" -> funcSgn(fcall, func, resultToStack, resultRegister, sscope)
            "sin", "cos", "tan", "atan",
            "ln", "log2", "sqrt", "rad",
            "deg", "round", "floor", "ceil",
            "rndf" -> funcVariousFloatFuncs(fcall, func, resultToStack, resultRegister, sscope)
-            "fastrnd8", "rnd", "rndw" -> funcRnd(func, resultToStack, resultRegister, sscope)
+            "rnd", "rndw" -> funcRnd(func, resultToStack, resultRegister, sscope)
            "sqrt16" -> funcSqrt16(fcall, func, resultToStack, resultRegister, sscope)
            "rol" -> funcRol(fcall)
            "rol2" -> funcRol2(fcall)
@@ -64,16 +67,288 @@ internal class BuiltinFunctionsAsmGen(private val program: Program, private val
            "peek" -> throw AssemblyError("peek() should have been replaced by @()")
            "pokew" -> funcPokeW(fcall)
            "poke" -> throw AssemblyError("poke() should have been replaced by @()")
+            "push", "pushw" -> funcPush(fcall, func)
+            "pop", "popw" -> funcPop(fcall, func)
+            "rsave" -> funcRsave()
+            "rsavex" -> funcRsaveX()
+            "rrestore" -> funcRrestore()
+            "rrestorex" -> funcRrestoreX()
            "cmp" -> funcCmp(fcall)
+            "callfar" -> funcCallFar(fcall)
+            "callrom" -> funcCallRom(fcall)
            else -> throw AssemblyError("missing asmgen for builtin func ${func.name}")
        }
    }

+    private fun funcRsave() {
+        if (asmgen.isTargetCpu(CpuType.CPU65c02))
+            asmgen.out("""
+                php
+                pha
+                phy
+                phx""")
+        else
+            // see http://6502.org/tutorials/register_preservation.html
+            asmgen.out("""
+                php
+                sta  P8ZP_SCRATCH_REG
+                pha
+                txa
+                pha
+                tya
+                pha
+                lda  P8ZP_SCRATCH_REG""")
+    }
+
+    private fun funcRsaveX() {
+        if (asmgen.isTargetCpu(CpuType.CPU65c02))
+            asmgen.out("  phx")
+        else
+            asmgen.out("  txa |  pha")
+    }
+
+    private fun funcRrestore() {
+        if (asmgen.isTargetCpu(CpuType.CPU65c02))
+            asmgen.out("""
+                plx
+                ply
+                pla
+                plp""")
+        else
+            asmgen.out("""
+                pla
+                tay
+                pla
+                tax
+                pla
+                plp""")
+    }
+
+    private fun funcRrestoreX() {
+        if (asmgen.isTargetCpu(CpuType.CPU65c02))
+            asmgen.out("  plx")
+        else
+            asmgen.out("  sta  P8ZP_SCRATCH_B1 |  pla |  tax |  lda  P8ZP_SCRATCH_B1")
+    }
+
+    private fun funcPop(fcall: IFunctionCall, func: FSignature) {
+        // note: because A is pushed first so popped last, saving A is often not required here.
+        require(fcall.args[0] is IdentifierReference) {
+            "attempt to pop a value into a differently typed variable, or in something else that isn't supported ${(fcall as Node).position}"
+        }
+        val target = (fcall.args[0] as IdentifierReference).targetVarDecl(program)!!
+        val parameter = target.subroutineParameter
+        if(parameter!=null) {
+            val sub = parameter.definingSubroutine!!
+            require(sub.isAsmSubroutine) {
+                "push/pop arg passing only supported on asmsubs ${(fcall as Node).position}"
+            }
+            val shouldKeepA = sub.asmParameterRegisters.any { it.registerOrPair==RegisterOrPair.AX || it.registerOrPair==RegisterOrPair.AY }
+            val reg = sub.asmParameterRegisters[sub.parameters.indexOf(parameter)]
+            if(reg.statusflag!=null) {
+                if(shouldKeepA)
+                    asmgen.out("  sta  P8ZP_SCRATCH_REG")
+                asmgen.out("""
+                    clc
+                    pla
+                    beq  +
+                    sec
+""")
+                if(shouldKeepA)
+                    asmgen.out("  lda  P8ZP_SCRATCH_REG")
+            }
+            else {
+                if (func.name == "pop") {
+                    if (asmgen.isTargetCpu(CpuType.CPU65c02)) {
+                        when (reg.registerOrPair) {
+                            RegisterOrPair.A -> asmgen.out("  pla")
+                            RegisterOrPair.X -> asmgen.out("  plx")
+                            RegisterOrPair.Y -> asmgen.out("  ply")
+                            in Cx16VirtualRegisters -> asmgen.out("  pla |  sta  cx16.${reg.registerOrPair!!.name.lowercase()}")
+                            else -> throw AssemblyError("invalid target register ${reg.registerOrPair}")
+                        }
+                    } else {
+                        when (reg.registerOrPair) {
+                            RegisterOrPair.A -> asmgen.out("  pla")
+                            RegisterOrPair.X -> {
+                                if(shouldKeepA)
+                                    asmgen.out("  sta  P8ZP_SCRATCH_REG |  pla |  tax |  lda  P8ZP_SCRATCH_REG")
+                                else
+                                    asmgen.out("  pla |  tax")
+                            }
+                            RegisterOrPair.Y -> {
+                                if(shouldKeepA)
+                                    asmgen.out("  sta  P8ZP_SCRATCH_REG |  pla |  tay |  lda  P8ZP_SCRATCH_REG")
+                                else
+                                    asmgen.out("  pla |  tay")
+                            }
+                            in Cx16VirtualRegisters -> asmgen.out("  pla |  sta  cx16.${reg.registerOrPair!!.name.lowercase()}")
+                            else -> throw AssemblyError("invalid target register ${reg.registerOrPair}")
+                        }
+                    }
+                } else {
+                    // word pop
+                    if (asmgen.isTargetCpu(CpuType.CPU65c02))
+                        when (reg.registerOrPair) {
+                            RegisterOrPair.AX -> asmgen.out("  plx |  pla")
+                            RegisterOrPair.AY -> asmgen.out("  ply |  pla")
+                            RegisterOrPair.XY -> asmgen.out("  ply |  plx")
+                            in Cx16VirtualRegisters -> {
+                                val regname = reg.registerOrPair!!.name.lowercase()
+                                asmgen.out("  pla |  sta  cx16.$regname+1 |  pla |  sta  cx16.$regname")
+                            }
+                            else -> throw AssemblyError("invalid target register ${reg.registerOrPair}")
+                        }
+                    else {
+                        when (reg.registerOrPair) {
+                            RegisterOrPair.AX -> asmgen.out("  pla |  tax |  pla")
+                            RegisterOrPair.AY -> asmgen.out("  pla |  tay |  pla")
+                            RegisterOrPair.XY -> asmgen.out("  pla |  tay |  pla |  tax")
+                            in Cx16VirtualRegisters -> {
+                                val regname = reg.registerOrPair!!.name.lowercase()
+                                asmgen.out("  pla |  sta  cx16.$regname+1 |  pla |  sta  cx16.$regname")
+                            }
+                            else -> throw AssemblyError("invalid target register ${reg.registerOrPair}")
+                        }
+                    }
+                }
+            }
+        } else {
+            val tgt = AsmAssignTarget(TargetStorageKind.VARIABLE, program, asmgen, target.datatype, (fcall as Node).definingSubroutine, variableAsmName = asmgen.asmVariableName(target.name))
+            if (func.name == "pop") {
+                asmgen.out("  pla")
+                asmgen.assignRegister(RegisterOrPair.A, tgt)
+            } else {
+                if (asmgen.isTargetCpu(CpuType.CPU65c02))
+                    asmgen.out("  ply |  pla")
+                else
+                    asmgen.out("  pla |  tay |  pla")
+                asmgen.assignRegister(RegisterOrPair.AY, tgt)
+            }
+        }
+    }
+
+    private fun funcPush(fcall: IFunctionCall, func: FSignature) {
+        val signed = fcall.args[0].inferType(program).oneOf(DataType.BYTE, DataType.WORD)
+        if(func.name=="push") {
+            asmgen.assignExpressionToRegister(fcall.args[0], RegisterOrPair.A, signed)
+            asmgen.out("  pha")
+        } else {
+            asmgen.assignExpressionToRegister(fcall.args[0], RegisterOrPair.AY, signed)
+            if (asmgen.isTargetCpu(CpuType.CPU65c02))
+                asmgen.out("  pha |  phy")
+            else
+                asmgen.out("  pha |  tya |  pha")
+        }
+    }
+
+    private fun funcCallFar(fcall: IFunctionCall) {
+        if(asmgen.options.compTarget !is Cx16Target)
+            throw AssemblyError("callfar only works on cx16 target at this time")
+
+        val bank = fcall.args[0].constValue(program)?.number?.toInt()
+        val address = fcall.args[1].constValue(program)?.number?.toInt()
+        if(bank==null || address==null)
+            throw AssemblyError("callfar (jsrfar) requires constant arguments")
+
+        if(address !in 0xa000..0xbfff)
+            throw AssemblyError("callfar done on address outside of cx16 banked ram")
+        if(bank==0)
+            throw AssemblyError("callfar done on bank 0 which is reserved for the kernal")
+
+        val argAddrArg = fcall.args[2]
+        if(argAddrArg.constValue(program)?.number == 0.0) {
+            asmgen.out("""
+                jsr  cx16.jsrfar
+                .word  ${address.toHex()}
+                .byte  ${bank.toHex()}""")
+        } else {
+            when(argAddrArg) {
+                is AddressOf -> {
+                    if(argAddrArg.identifier.targetVarDecl(program)?.datatype != DataType.UBYTE)
+                        throw AssemblyError("callfar done with 'arg' pointer to variable that's not UBYTE")
+                    asmgen.out("""
+                        lda  ${asmgen.asmVariableName(argAddrArg.identifier)}
+                        jsr  cx16.jsrfar
+                        .word  ${address.toHex()}
+                        .byte  ${bank.toHex()}
+                        sta  ${asmgen.asmVariableName(argAddrArg.identifier)}""")
+                }
+                is NumericLiteralValue -> {
+                    asmgen.out("""
+                        lda  ${argAddrArg.number.toHex()}
+                        jsr  cx16.jsrfar
+                        .word  ${address.toHex()}
+                        .byte  ${bank.toHex()}
+                        sta  ${argAddrArg.number.toHex()}""")
+                }
+                else -> throw AssemblyError("callfar only accepts pointer-of a (ubyte) variable or constant memory address for the 'arg' parameter")
+            }
+        }
+    }
+
+    private fun funcCallRom(fcall: IFunctionCall) {
+        if(asmgen.options.compTarget !is Cx16Target)
+            throw AssemblyError("callrom only works on cx16 target at this time")
+
+        val bank = fcall.args[0].constValue(program)?.number?.toInt()
+        val address = fcall.args[1].constValue(program)?.number?.toInt()
+        if(bank==null || address==null)
+            throw AssemblyError("callrom requires constant arguments")
+
+        if(address !in 0xc000..0xffff)
+            throw AssemblyError("callrom done on address outside of cx16 banked rom")
+        if(bank>=32)
+            throw AssemblyError("callrom bank must be <32")
+
+        val argAddrArg = fcall.args[2]
+        if(argAddrArg.constValue(program)?.number == 0.0) {
+            asmgen.out("""
+                lda  $01
+                pha
+                lda  #${bank}
+                sta  $01
+                jsr  ${address.toHex()}
+                pla
+                sta  $01""")
+        } else {
+            when(argAddrArg) {
+                is AddressOf -> {
+                    if(argAddrArg.identifier.targetVarDecl(program)?.datatype != DataType.UBYTE)
+                        throw AssemblyError("callrom done with 'arg' pointer to variable that's not UBYTE")
+                    asmgen.out("""
+                        lda  $01
+                        pha
+                        lda  #${bank}
+                        sta  $01
+                        lda  ${asmgen.asmVariableName(argAddrArg.identifier)}                
+                        jsr  ${address.toHex()}
+                        sta  ${asmgen.asmVariableName(argAddrArg.identifier)}
+                        pla
+                        sta  $01""")
+                }
+                is NumericLiteralValue -> {
+                    asmgen.out("""
+                        lda  $01
+                        pha
+                        lda  #${bank}
+                        sta  $01
+                        lda  ${argAddrArg.number.toHex()}
+                        jsr  ${address.toHex()}
+                        sta  ${argAddrArg.number.toHex()}
+                        pla
+                        sta  $01""")
+                }
+                else -> throw AssemblyError("callrom only accepts pointer-of a (ubyte) variable or constant memory address for the 'arg' parameter")
+            }
+        }
+    }
+
    private fun funcCmp(fcall: IFunctionCall) {
        val arg1 = fcall.args[0]
        val arg2 = fcall.args[1]
-        val dt1 = arg1.inferType(program).typeOrElse(DataType.STRUCT)
-        val dt2 = arg2.inferType(program).typeOrElse(DataType.STRUCT)
+        val dt1 = arg1.inferType(program).getOr(DataType.UNDEFINED)
+        val dt2 = arg2.inferType(program).getOr(DataType.UNDEFINED)
        if(dt1 in ByteDatatypes) {
            if(dt2 in ByteDatatypes) {
                when (arg2) {
@@ -90,13 +365,13 @@ internal class BuiltinFunctionsAsmGen(private val program: Program, private val
                            asmgen.assignExpressionToRegister(arg1, RegisterOrPair.A)
                            asmgen.out("  cmp  ${arg2.addressExpression.constValue(program)!!.number.toHex()}")
                        } else {
-                            asmgen.assignExpressionToVariable(arg2, "P8ZP_SCRATCH_B1", DataType.UBYTE, (fcall as Node).definingSubroutine())
+                            asmgen.assignExpressionToVariable(arg2, "P8ZP_SCRATCH_B1", DataType.UBYTE, (fcall as Node).definingSubroutine)
                            asmgen.assignExpressionToRegister(arg1, RegisterOrPair.A)
                            asmgen.out("  cmp  P8ZP_SCRATCH_B1")
                        }
                    }
                    else -> {
-                        asmgen.assignExpressionToVariable(arg2, "P8ZP_SCRATCH_B1", DataType.UBYTE, (fcall as Node).definingSubroutine())
+                        asmgen.assignExpressionToVariable(arg2, "P8ZP_SCRATCH_B1", DataType.UBYTE, (fcall as Node).definingSubroutine)
                        asmgen.assignExpressionToRegister(arg1, RegisterOrPair.A)
                        asmgen.out("  cmp  P8ZP_SCRATCH_B1")
                    }
@@ -124,7 +399,7 @@ internal class BuiltinFunctionsAsmGen(private val program: Program, private val
 +""")
                    }
                    else -> {
-                        asmgen.assignExpressionToVariable(arg2, "P8ZP_SCRATCH_W1", DataType.UWORD, (fcall as Node).definingSubroutine())
+                        asmgen.assignExpressionToVariable(arg2, "P8ZP_SCRATCH_W1", DataType.UWORD, (fcall as Node).definingSubroutine)
                        asmgen.assignExpressionToRegister(arg1, RegisterOrPair.AY)
                        asmgen.out("""
                            cpy  P8ZP_SCRATCH_W1+1
@@ -143,7 +418,7 @@ internal class BuiltinFunctionsAsmGen(private val program: Program, private val
            throw AssemblyError("should not discard result of memory allocation at $fcall")
        val nameRef = fcall.args[0] as IdentifierReference
        val name = (nameRef.targetVarDecl(program)!!.value as StringLiteralValue).value
-        val size = (fcall.args[1] as NumericLiteralValue).number.toInt()
+        val size = (fcall.args[1] as NumericLiteralValue).number.toUInt()

        val existingSize = asmgen.slabs[name]
        if(existingSize!=null && existingSize!=size)
@@ -156,7 +431,7 @@ internal class BuiltinFunctionsAsmGen(private val program: Program, private val
            if(resultToStack)
                AsmAssignTarget(TargetStorageKind.STACK, program, asmgen, DataType.UWORD, null)
            else
-                AsmAssignTarget.fromRegisters(resultRegister ?: RegisterOrPair.AY, null, program, asmgen)
+                AsmAssignTarget.fromRegisters(resultRegister ?: RegisterOrPair.AY, false, null, program, asmgen)
        val assign = AsmAssignment(src, target, false, program.memsizer, fcall.position)
        asmgen.translateNormalAssignment(assign)
        asmgen.slabs[name] = size
@@ -168,7 +443,7 @@ internal class BuiltinFunctionsAsmGen(private val program: Program, private val
            asmgen.out("  jsr  prog8_lib.func_sqrt16_stack")
        else {
            asmgen.out("  jsr  prog8_lib.func_sqrt16_into_A")
-            assignAsmGen.assignRegisterByte(AsmAssignTarget.fromRegisters(resultRegister ?: RegisterOrPair.A, scope, program, asmgen), CpuRegister.A)
+            assignAsmGen.assignRegisterByte(AsmAssignTarget.fromRegisters(resultRegister ?: RegisterOrPair.A, false, scope, program, asmgen), CpuRegister.A)
        }
    }

@@ -178,13 +453,13 @@ internal class BuiltinFunctionsAsmGen(private val program: Program, private val
            asmgen.out("  jsr  prog8_lib.func_${func.name}_stack")
        else
            when(func.name) {
-                "sin8", "sin8u", "cos8", "cos8u" -> {
+                "sin8", "sin8u", "sinr8", "sinr8u", "cos8", "cos8u", "cosr8", "cosr8u" -> {
                    asmgen.out("  jsr  prog8_lib.func_${func.name}_into_A")
-                    assignAsmGen.assignRegisterByte(AsmAssignTarget.fromRegisters(resultRegister ?: RegisterOrPair.A, scope, program, asmgen), CpuRegister.A)
+                    assignAsmGen.assignRegisterByte(AsmAssignTarget.fromRegisters(resultRegister ?: RegisterOrPair.A, false, scope, program, asmgen), CpuRegister.A)
                }
-                "sin16", "sin16u", "cos16", "cos16u" -> {
+                "sin16", "sin16u", "sinr16", "sinr16u", "cos16", "cos16u", "cosr16", "cosr16u" -> {
                    asmgen.out("  jsr  prog8_lib.func_${func.name}_into_AY")
-                    assignAsmGen.assignRegisterpairWord(AsmAssignTarget.fromRegisters(resultRegister ?: RegisterOrPair.AY, scope, program, asmgen), RegisterOrPair.AY)
+                    assignAsmGen.assignRegisterpairWord(AsmAssignTarget.fromRegisters(resultRegister ?: RegisterOrPair.AY, false, scope, program, asmgen), RegisterOrPair.AY)
                }
            }
    }
@@ -263,7 +538,7 @@ internal class BuiltinFunctionsAsmGen(private val program: Program, private val
    private fun funcRor2(fcall: IFunctionCall) {
        val what = fcall.args.single()
        val dt = what.inferType(program)
-        when (dt.typeOrElse(DataType.STRUCT)) {
+        when (dt.getOr(DataType.UNDEFINED)) {
            DataType.UBYTE -> {
                when (what) {
                    is ArrayIndexedExpression -> {
@@ -306,7 +581,7 @@ internal class BuiltinFunctionsAsmGen(private val program: Program, private val
    private fun funcRor(fcall: IFunctionCall) {
        val what = fcall.args.single()
        val dt = what.inferType(program)
-        when (dt.typeOrElse(DataType.STRUCT)) {
+        when (dt.getOr(DataType.UNDEFINED)) {
            DataType.UBYTE -> {
                when (what) {
                    is ArrayIndexedExpression -> {
@@ -321,7 +596,7 @@ internal class BuiltinFunctionsAsmGen(private val program: Program, private val
                            val ptrAndIndex = asmgen.pointerViaIndexRegisterPossible(what.addressExpression)
                            if(ptrAndIndex!=null) {
                                asmgen.assignExpressionToRegister(ptrAndIndex.second, RegisterOrPair.X)
-                                asmgen.saveRegisterLocal(CpuRegister.X, (fcall as FunctionCallStatement).definingSubroutine()!!)
+                                asmgen.saveRegisterLocal(CpuRegister.X, (fcall as FunctionCallStatement).definingSubroutine!!)
                                asmgen.assignExpressionToRegister(ptrAndIndex.first, RegisterOrPair.AY)
                                asmgen.restoreRegisterLocal(CpuRegister.X)
                                asmgen.out("""
@@ -364,7 +639,7 @@ internal class BuiltinFunctionsAsmGen(private val program: Program, private val
    private fun funcRol2(fcall: IFunctionCall) {
        val what = fcall.args.single()
        val dt = what.inferType(program)
-        when (dt.typeOrElse(DataType.STRUCT)) {
+        when (dt.getOr(DataType.UNDEFINED)) {
            DataType.UBYTE -> {
                when (what) {
                    is ArrayIndexedExpression -> {
@@ -407,7 +682,7 @@ internal class BuiltinFunctionsAsmGen(private val program: Program, private val
    private fun funcRol(fcall: IFunctionCall) {
        val what = fcall.args.single()
        val dt = what.inferType(program)
-        when (dt.typeOrElse(DataType.STRUCT)) {
+        when (dt.getOr(DataType.UNDEFINED)) {
            DataType.UBYTE -> {
                when (what) {
                    is ArrayIndexedExpression -> {
@@ -422,7 +697,7 @@ internal class BuiltinFunctionsAsmGen(private val program: Program, private val
                            val ptrAndIndex = asmgen.pointerViaIndexRegisterPossible(what.addressExpression)
                            if(ptrAndIndex!=null) {
                                asmgen.assignExpressionToRegister(ptrAndIndex.second, RegisterOrPair.X)
-                                asmgen.saveRegisterLocal(CpuRegister.X, (fcall as FunctionCallStatement).definingSubroutine()!!)
+                                asmgen.saveRegisterLocal(CpuRegister.X, (fcall as FunctionCallStatement).definingSubroutine!!)
                                asmgen.assignExpressionToRegister(ptrAndIndex.first, RegisterOrPair.AY)
                                asmgen.restoreRegisterLocal(CpuRegister.X)
                                asmgen.out("""
@@ -473,7 +748,7 @@ internal class BuiltinFunctionsAsmGen(private val program: Program, private val
            asmgen.out("  jsr  floats.func_${func.name}_stack")
        else {
            asmgen.out("  jsr  floats.func_${func.name}_fac1")
-            assignAsmGen.assignFAC1float(AsmAssignTarget.fromRegisters(resultRegister ?: RegisterOrPair.FAC1, scope, program, asmgen))
+            assignAsmGen.assignFAC1float(AsmAssignTarget.fromRegisters(resultRegister ?: RegisterOrPair.FAC1, true, scope, program, asmgen))
        }
    }

@@ -481,7 +756,7 @@ internal class BuiltinFunctionsAsmGen(private val program: Program, private val
        translateArguments(fcall.args, func, scope)
        val dt = fcall.args.single().inferType(program)
        if(resultToStack) {
-            when (dt.typeOrElse(DataType.STRUCT)) {
+            when (dt.getOr(DataType.UNDEFINED)) {
                DataType.UBYTE -> asmgen.out("  jsr  prog8_lib.func_sign_ub_stack")
                DataType.BYTE -> asmgen.out("  jsr  prog8_lib.func_sign_b_stack")
                DataType.UWORD -> asmgen.out("  jsr  prog8_lib.func_sign_uw_stack")
@@ -490,7 +765,7 @@ internal class BuiltinFunctionsAsmGen(private val program: Program, private val
                else -> throw AssemblyError("weird type $dt")
            }
        } else {
-            when (dt.typeOrElse(DataType.STRUCT)) {
+            when (dt.getOr(DataType.UNDEFINED)) {
                DataType.UBYTE -> asmgen.out("  jsr  prog8_lib.func_sign_ub_into_A")
                DataType.BYTE -> asmgen.out("  jsr  prog8_lib.func_sign_b_into_A")
                DataType.UWORD -> asmgen.out("  jsr  prog8_lib.func_sign_uw_into_A")
@@ -498,7 +773,7 @@ internal class BuiltinFunctionsAsmGen(private val program: Program, private val
                DataType.FLOAT -> asmgen.out("  jsr  floats.func_sign_f_into_A")
                else -> throw AssemblyError("weird type $dt")
            }
-            assignAsmGen.assignRegisterByte(AsmAssignTarget.fromRegisters(resultRegister ?: RegisterOrPair.A, scope, program, asmgen), CpuRegister.A)
+            assignAsmGen.assignRegisterByte(AsmAssignTarget.fromRegisters(resultRegister ?: RegisterOrPair.A, false, scope, program, asmgen), CpuRegister.A)
        }
    }

@@ -506,20 +781,20 @@ internal class BuiltinFunctionsAsmGen(private val program: Program, private val
        outputAddressAndLenghtOfArray(fcall.args[0])
        val dt = fcall.args.single().inferType(program)
        if(resultToStack) {
-            when (dt.typeOrElse(DataType.STRUCT)) {
+            when (dt.getOr(DataType.UNDEFINED)) {
                DataType.ARRAY_B, DataType.ARRAY_UB, DataType.STR -> asmgen.out("  jsr  prog8_lib.func_${function.name}_b_stack")
                DataType.ARRAY_UW, DataType.ARRAY_W -> asmgen.out("  jsr  prog8_lib.func_${function.name}_w_stack")
                DataType.ARRAY_F -> asmgen.out("  jsr  floats.func_${function.name}_f_stack")
                else -> throw AssemblyError("weird type $dt")
            }
        } else {
-            when (dt.typeOrElse(DataType.STRUCT)) {
+            when (dt.getOr(DataType.UNDEFINED)) {
                DataType.ARRAY_B, DataType.ARRAY_UB, DataType.STR -> asmgen.out("  jsr  prog8_lib.func_${function.name}_b_into_A")
                DataType.ARRAY_UW, DataType.ARRAY_W -> asmgen.out("  jsr  prog8_lib.func_${function.name}_w_into_A")
                DataType.ARRAY_F -> asmgen.out("  jsr  floats.func_${function.name}_f_into_A")
                else -> throw AssemblyError("weird type $dt")
            }
-            assignAsmGen.assignRegisterByte(AsmAssignTarget.fromRegisters(resultRegister ?: RegisterOrPair.A, scope, program, asmgen), CpuRegister.A)
+            assignAsmGen.assignRegisterByte(AsmAssignTarget.fromRegisters(resultRegister ?: RegisterOrPair.A, false, scope, program, asmgen), CpuRegister.A)
        }
    }

@@ -527,7 +802,7 @@ internal class BuiltinFunctionsAsmGen(private val program: Program, private val
        outputAddressAndLenghtOfArray(fcall.args[0])
        val dt = fcall.args.single().inferType(program)
        if(resultToStack) {
-            when (dt.typeOrElse(DataType.STRUCT)) {
+            when (dt.getOr(DataType.UNDEFINED)) {
                DataType.ARRAY_UB, DataType.STR -> asmgen.out("  jsr  prog8_lib.func_${function.name}_ub_stack")
                DataType.ARRAY_B -> asmgen.out("  jsr  prog8_lib.func_${function.name}_b_stack")
                DataType.ARRAY_UW -> asmgen.out("  jsr  prog8_lib.func_${function.name}_uw_stack")
@@ -536,26 +811,26 @@ internal class BuiltinFunctionsAsmGen(private val program: Program, private val
                else -> throw AssemblyError("weird type $dt")
            }
        } else {
-            when (dt.typeOrElse(DataType.STRUCT)) {
+            when (dt.getOr(DataType.UNDEFINED)) {
                DataType.ARRAY_UB, DataType.STR -> {
                    asmgen.out("  jsr  prog8_lib.func_${function.name}_ub_into_A")
-                    assignAsmGen.assignRegisterByte(AsmAssignTarget.fromRegisters(resultRegister ?: RegisterOrPair.A, scope, program, asmgen), CpuRegister.A)
+                    assignAsmGen.assignRegisterByte(AsmAssignTarget.fromRegisters(resultRegister ?: RegisterOrPair.A, false, scope, program, asmgen), CpuRegister.A)
                }
                DataType.ARRAY_B -> {
                    asmgen.out("  jsr  prog8_lib.func_${function.name}_b_into_A")
-                    assignAsmGen.assignRegisterByte(AsmAssignTarget.fromRegisters(resultRegister ?: RegisterOrPair.A, scope, program, asmgen), CpuRegister.A)
+                    assignAsmGen.assignRegisterByte(AsmAssignTarget.fromRegisters(resultRegister ?: RegisterOrPair.A, false, scope, program, asmgen), CpuRegister.A)
                }
                DataType.ARRAY_UW -> {
                    asmgen.out("  jsr  prog8_lib.func_${function.name}_uw_into_AY")
-                    assignAsmGen.assignRegisterpairWord(AsmAssignTarget.fromRegisters(resultRegister ?: RegisterOrPair.AY, scope, program, asmgen), RegisterOrPair.AY)
+                    assignAsmGen.assignRegisterpairWord(AsmAssignTarget.fromRegisters(resultRegister ?: RegisterOrPair.AY, false, scope, program, asmgen), RegisterOrPair.AY)
                }
                DataType.ARRAY_W -> {
                    asmgen.out("  jsr  prog8_lib.func_${function.name}_w_into_AY")
-                    assignAsmGen.assignRegisterpairWord(AsmAssignTarget.fromRegisters(resultRegister ?: RegisterOrPair.AY, scope, program, asmgen), RegisterOrPair.AY)
+                    assignAsmGen.assignRegisterpairWord(AsmAssignTarget.fromRegisters(resultRegister ?: RegisterOrPair.AY, false, scope, program, asmgen), RegisterOrPair.AY)
                }
                DataType.ARRAY_F -> {
                    asmgen.out("  jsr  floats.func_${function.name}_f_fac1")
-                    assignAsmGen.assignFAC1float(AsmAssignTarget.fromRegisters(resultRegister ?: RegisterOrPair.FAC1, scope, program, asmgen))
+                    assignAsmGen.assignFAC1float(AsmAssignTarget.fromRegisters(resultRegister ?: RegisterOrPair.FAC1, true, scope, program, asmgen))
                }
                else -> throw AssemblyError("weird type $dt")
            }
@@ -566,7 +841,7 @@ internal class BuiltinFunctionsAsmGen(private val program: Program, private val
        outputAddressAndLenghtOfArray(fcall.args[0])
        val dt = fcall.args.single().inferType(program)
        if(resultToStack) {
-            when (dt.typeOrElse(DataType.STRUCT)) {
+            when (dt.getOr(DataType.UNDEFINED)) {
                DataType.ARRAY_UB, DataType.STR -> asmgen.out("  jsr  prog8_lib.func_sum_ub_stack")
                DataType.ARRAY_B -> asmgen.out("  jsr  prog8_lib.func_sum_b_stack")
                DataType.ARRAY_UW -> asmgen.out("  jsr  prog8_lib.func_sum_uw_stack")
@@ -575,26 +850,26 @@ internal class BuiltinFunctionsAsmGen(private val program: Program, private val
                else -> throw AssemblyError("weird type $dt")
            }
        } else {
-            when (dt.typeOrElse(DataType.STRUCT)) {
+            when (dt.getOr(DataType.UNDEFINED)) {
                DataType.ARRAY_UB, DataType.STR -> {
                    asmgen.out("  jsr  prog8_lib.func_sum_ub_into_AY")
-                    assignAsmGen.assignRegisterpairWord(AsmAssignTarget.fromRegisters(resultRegister ?: RegisterOrPair.AY, scope, program, asmgen), RegisterOrPair.AY)
+                    assignAsmGen.assignRegisterpairWord(AsmAssignTarget.fromRegisters(resultRegister ?: RegisterOrPair.AY, false, scope, program, asmgen), RegisterOrPair.AY)
                }
                DataType.ARRAY_B -> {
                    asmgen.out("  jsr  prog8_lib.func_sum_b_into_AY")
-                    assignAsmGen.assignRegisterpairWord(AsmAssignTarget.fromRegisters(resultRegister ?: RegisterOrPair.AY, scope, program, asmgen), RegisterOrPair.AY)
+                    assignAsmGen.assignRegisterpairWord(AsmAssignTarget.fromRegisters(resultRegister ?: RegisterOrPair.AY, false, scope, program, asmgen), RegisterOrPair.AY)
                }
                DataType.ARRAY_UW -> {
                    asmgen.out("  jsr  prog8_lib.func_sum_uw_into_AY")
-                    assignAsmGen.assignRegisterpairWord(AsmAssignTarget.fromRegisters(resultRegister ?: RegisterOrPair.AY, scope, program, asmgen), RegisterOrPair.AY)
+                    assignAsmGen.assignRegisterpairWord(AsmAssignTarget.fromRegisters(resultRegister ?: RegisterOrPair.AY, false, scope, program, asmgen), RegisterOrPair.AY)
                }
                DataType.ARRAY_W -> {
                    asmgen.out("  jsr  prog8_lib.func_sum_w_into_AY")
-                    assignAsmGen.assignRegisterpairWord(AsmAssignTarget.fromRegisters(resultRegister ?: RegisterOrPair.AY, scope, program, asmgen), RegisterOrPair.AY)
+                    assignAsmGen.assignRegisterpairWord(AsmAssignTarget.fromRegisters(resultRegister ?: RegisterOrPair.AY, false, scope, program, asmgen), RegisterOrPair.AY)
                }
                DataType.ARRAY_F -> {
                    asmgen.out("  jsr  floats.func_sum_f_fac1")
-                    assignAsmGen.assignFAC1float(AsmAssignTarget.fromRegisters(resultRegister ?: RegisterOrPair.FAC1, scope, program, asmgen))
+                    assignAsmGen.assignFAC1float(AsmAssignTarget.fromRegisters(resultRegister ?: RegisterOrPair.FAC1, true, scope, program, asmgen))
                }
                else -> throw AssemblyError("weird type $dt")
            }
@@ -610,11 +885,11 @@ internal class BuiltinFunctionsAsmGen(private val program: Program, private val
            val firstName = asmgen.asmVariableName(first)
            val secondName = asmgen.asmVariableName(second)
            val dt = first.inferType(program)
-            if(dt.istype(DataType.BYTE) || dt.istype(DataType.UBYTE)) {
+            if(dt istype DataType.BYTE || dt istype DataType.UBYTE) {
                asmgen.out(" ldy  $firstName |  lda  $secondName |  sta  $firstName |  sty  $secondName")
                return
            }
-            if(dt.istype(DataType.WORD) || dt.istype(DataType.UWORD)) {
+            if(dt istype DataType.WORD || dt istype DataType.UWORD) {
                asmgen.out("""
                    ldy  $firstName
                    lda  $secondName
@@ -627,7 +902,7 @@ internal class BuiltinFunctionsAsmGen(private val program: Program, private val
                """)
                return
            }
-            if(dt.istype(DataType.FLOAT)) {
+            if(dt istype DataType.FLOAT) {
                asmgen.out("""
                    lda  #<$firstName
                    sta  P8ZP_SCRATCH_W1
@@ -645,7 +920,6 @@ internal class BuiltinFunctionsAsmGen(private val program: Program, private val

        // optimized simple case: swap two memory locations
        if(first is DirectMemoryRead && second is DirectMemoryRead) {
-            // TODO optimize swap of two memread values with index, using the same pointer expression/variable, like swap(@(ptr+1), @(ptr+2))
            val addr1 = (first.addressExpression as? NumericLiteralValue)?.number?.toHex()
            val addr2 = (second.addressExpression as? NumericLiteralValue)?.number?.toHex()
            val name1 = if(first.addressExpression is IdentifierReference) asmgen.asmVariableName(first.addressExpression as IdentifierReference) else null
@@ -668,6 +942,49 @@ internal class BuiltinFunctionsAsmGen(private val program: Program, private val
                    asmgen.out("  ldy  $name1 |  lda  $name2 |  sta  $name1 |  sty  $name2")
                    return
                }
+                addr1==null && addr2==null && name1==null && name2==null -> {
+                    val firstExpr = first.addressExpression as? BinaryExpression
+                    val secondExpr = second.addressExpression as? BinaryExpression
+                    if(firstExpr!=null && secondExpr!=null) {
+                        val pointerVariable = firstExpr.left as? IdentifierReference
+                        val firstOffset = firstExpr.right
+                        val secondOffset = secondExpr.right
+                        if(pointerVariable != null
+                            && pointerVariable isSameAs secondExpr.left
+                            && firstExpr.operator == "+" && secondExpr.operator == "+"
+                            && (firstOffset is NumericLiteralValue || firstOffset is IdentifierReference || firstOffset is TypecastExpression)
+                            && (secondOffset is NumericLiteralValue || secondOffset is IdentifierReference || secondOffset is TypecastExpression)
+                        ) {
+                            if(firstOffset is NumericLiteralValue && secondOffset is NumericLiteralValue) {
+                                if(firstOffset!=secondOffset) {
+                                    swapArrayValues(
+                                        DataType.UBYTE,
+                                        asmgen.asmVariableName(pointerVariable), firstOffset,
+                                        asmgen.asmVariableName(pointerVariable), secondOffset
+                                    )
+                                    return
+                                }
+                            } else if(firstOffset is TypecastExpression && secondOffset is TypecastExpression) {
+                                if(firstOffset.type in WordDatatypes && secondOffset.type in WordDatatypes) {
+                                    val firstOffsetVar = firstOffset.expression as? IdentifierReference
+                                    val secondOffsetVar = secondOffset.expression as? IdentifierReference
+                                    if(firstOffsetVar!=null && secondOffsetVar!=null) {
+                                        if(firstOffsetVar!=secondOffsetVar) {
+                                            swapArrayValues(
+                                                DataType.UBYTE,
+                                                asmgen.asmVariableName(pointerVariable), firstOffsetVar,
+                                                asmgen.asmVariableName(pointerVariable), secondOffsetVar
+                                            )
+                                            return
+                                        }
+                                    }
+                                }
+                            } else if(firstOffset is IdentifierReference || secondOffset is IdentifierReference) {
+                                throw AssemblyError("expected a typecast-to-word for index variable at ${firstOffset.position} and/or ${secondOffset.position}")
+                            }
+                        }
+                    }
+                }
            }
        }

@@ -677,7 +994,7 @@ internal class BuiltinFunctionsAsmGen(private val program: Program, private val
            val elementIDt = first.inferType(program)
            if(!elementIDt.isKnown)
                throw AssemblyError("unknown dt")
-            val elementDt = elementIDt.typeOrElse(DataType.STRUCT)
+            val elementDt = elementIDt.getOr(DataType.UNDEFINED)

            val firstNum = first.indexer.indexExpr as? NumericLiteralValue
            val firstVar = first.indexer.indexExpr as? IdentifierReference
@@ -703,15 +1020,14 @@ internal class BuiltinFunctionsAsmGen(private val program: Program, private val

        fun targetFromExpr(expr: Expression, datatype: DataType): AsmAssignTarget {
            return when (expr) {
-                is IdentifierReference -> AsmAssignTarget(TargetStorageKind.VARIABLE, program, asmgen, datatype, expr.definingSubroutine(), variableAsmName = asmgen.asmVariableName(expr))
-                is ArrayIndexedExpression -> AsmAssignTarget(TargetStorageKind.ARRAY, program, asmgen, datatype, expr.definingSubroutine(), array = expr)
-                is DirectMemoryRead -> AsmAssignTarget(TargetStorageKind.MEMORY, program, asmgen, datatype, expr.definingSubroutine(), memory = DirectMemoryWrite(expr.addressExpression, expr.position))
+                is IdentifierReference -> AsmAssignTarget(TargetStorageKind.VARIABLE, program, asmgen, datatype, expr.definingSubroutine, variableAsmName = asmgen.asmVariableName(expr))
+                is ArrayIndexedExpression -> AsmAssignTarget(TargetStorageKind.ARRAY, program, asmgen, datatype, expr.definingSubroutine, array = expr)
+                is DirectMemoryRead -> AsmAssignTarget(TargetStorageKind.MEMORY, program, asmgen, datatype, expr.definingSubroutine, memory = DirectMemoryWrite(expr.addressExpression, expr.position))
                else -> throw AssemblyError("invalid expression object $expr")
            }
        }

-        val datatype = first.inferType(program).typeOrElse(DataType.STRUCT)
-        when(datatype) {
+        when(val datatype: DataType = first.inferType(program).getOr(DataType.UNDEFINED)) {
            in ByteDatatypes, in WordDatatypes -> {
                asmgen.assignExpressionToVariable(first, "P8ZP_SCRATCH_W1", datatype, null)
                asmgen.assignExpressionToVariable(second, "P8ZP_SCRATCH_W2", datatype, null)
@@ -729,21 +1045,23 @@ internal class BuiltinFunctionsAsmGen(private val program: Program, private val
                asmgen.translateNormalAssignment(assignSecond)
            }
            DataType.FLOAT -> {
-                // via evaluation stack
-                asmgen.translateExpression(first)
-                asmgen.translateExpression(second)
-                val assignFirst = AsmAssignment(
-                        AsmAssignSource(SourceStorageKind.STACK, program, asmgen, DataType.FLOAT),
+                // via temp variable and FAC1
+                asmgen.assignExpressionTo(first, AsmAssignTarget(TargetStorageKind.VARIABLE, program, asmgen, DataType.FLOAT, first.definingSubroutine, "floats.tempvar_swap_float"))
+                asmgen.assignExpressionTo(second, AsmAssignTarget(TargetStorageKind.REGISTER, program, asmgen, DataType.FLOAT, null, register=RegisterOrPair.FAC1))
+                asmgen.translateNormalAssignment(
+                    AsmAssignment(
+                        AsmAssignSource(SourceStorageKind.REGISTER, program, asmgen, datatype, register = RegisterOrPair.FAC1),
                        targetFromExpr(first, datatype),
                        false, program.memsizer, first.position
+                    )
                )
-                val assignSecond = AsmAssignment(
-                        AsmAssignSource(SourceStorageKind.STACK, program, asmgen, DataType.FLOAT),
+                asmgen.translateNormalAssignment(
+                    AsmAssignment(
+                        AsmAssignSource(SourceStorageKind.VARIABLE, program, asmgen, datatype, "floats.tempvar_swap_float"),
                        targetFromExpr(second, datatype),
                        false, program.memsizer, second.position
+                    )
                )
-                asmgen.translateNormalAssignment(assignFirst)
-                asmgen.translateNormalAssignment(assignSecond)
            }
            else -> throw AssemblyError("weird swap dt")
        }
@@ -783,7 +1101,7 @@ internal class BuiltinFunctionsAsmGen(private val program: Program, private val
                    sta  P8ZP_SCRATCH_W2
                    lda  #>(${arrayVarName2}+$index2)
                    sta  P8ZP_SCRATCH_W2+1
-                    jsr  floats.swap_floats
+                    jsr  floats.func_swap_f
                """)
            }
            else -> throw AssemblyError("invalid aray elt type")
@@ -856,7 +1174,7 @@ internal class BuiltinFunctionsAsmGen(private val program: Program, private val
                    sta  P8ZP_SCRATCH_W2
                    bcc  +
                    inc  P8ZP_SCRATCH_W2+1
-+                   jsr  floats.swap_floats                                   
+                   jsr  floats.func_swap_f                                   
                """)
            }
            else -> throw AssemblyError("invalid aray elt type")
@@ -914,7 +1232,7 @@ internal class BuiltinFunctionsAsmGen(private val program: Program, private val
                    sta  P8ZP_SCRATCH_W1
                    bcc  +
                    inc  P8ZP_SCRATCH_W1+1
-+                   jsr  floats.swap_floats
+                   jsr  floats.func_swap_f
                """)
            }
            else -> throw AssemblyError("invalid aray elt type")
@@ -972,7 +1290,7 @@ internal class BuiltinFunctionsAsmGen(private val program: Program, private val
                    sta  P8ZP_SCRATCH_W2
                    lda  #>(${arrayVarName2}+$index2)
                    sta  P8ZP_SCRATCH_W2+1
-                    jsr  floats.swap_floats
+                    jsr  floats.func_swap_f
                """)
            }
            else -> throw AssemblyError("invalid aray elt type")
@@ -981,7 +1299,7 @@ internal class BuiltinFunctionsAsmGen(private val program: Program, private val

    private fun funcAbs(fcall: IFunctionCall, func: FSignature, resultToStack: Boolean, resultRegister: RegisterOrPair?, scope: Subroutine?) {
        translateArguments(fcall.args, func, scope)
-        val dt = fcall.args.single().inferType(program).typeOrElse(DataType.STRUCT)
+        val dt = fcall.args.single().inferType(program).getOr(DataType.UNDEFINED)
        if(resultToStack) {
            when (dt) {
                in ByteDatatypes -> asmgen.out("  jsr  prog8_lib.abs_b_stack")
@@ -993,15 +1311,15 @@ internal class BuiltinFunctionsAsmGen(private val program: Program, private val
            when (dt) {
                in ByteDatatypes -> {
                    asmgen.out("  jsr  prog8_lib.abs_b_into_A")
-                    assignAsmGen.assignRegisterByte(AsmAssignTarget.fromRegisters(resultRegister ?: RegisterOrPair.A, scope, program, asmgen), CpuRegister.A)
+                    assignAsmGen.assignRegisterByte(AsmAssignTarget.fromRegisters(resultRegister ?: RegisterOrPair.A, false, scope, program, asmgen), CpuRegister.A)
                }
                in WordDatatypes -> {
                    asmgen.out("  jsr  prog8_lib.abs_w_into_AY")
-                    assignAsmGen.assignRegisterpairWord(AsmAssignTarget.fromRegisters(resultRegister ?: RegisterOrPair.AY, scope, program, asmgen), RegisterOrPair.AY)
+                    assignAsmGen.assignRegisterpairWord(AsmAssignTarget.fromRegisters(resultRegister ?: RegisterOrPair.AY, false, scope, program, asmgen), RegisterOrPair.AY)
                }
                DataType.FLOAT -> {
                    asmgen.out("  jsr  floats.abs_f_fac1")
-                    assignAsmGen.assignFAC1float(AsmAssignTarget.fromRegisters(resultRegister ?: RegisterOrPair.FAC1, scope, program, asmgen))
+                    assignAsmGen.assignFAC1float(AsmAssignTarget.fromRegisters(resultRegister ?: RegisterOrPair.FAC1, true, scope, program, asmgen))
                }
                else -> throw AssemblyError("weird type")
            }
@@ -1010,20 +1328,12 @@ internal class BuiltinFunctionsAsmGen(private val program: Program, private val

    private fun funcRnd(func: FSignature, resultToStack: Boolean, resultRegister: RegisterOrPair?, scope: Subroutine?) {
        when(func.name) {
-            "fastrnd8" -> {
-                if(resultToStack)
-                    asmgen.out("  jsr  prog8_lib.func_fastrnd8_stack")
-                else {
-                    asmgen.out("  jsr  math.fast_randbyte")
-                    assignAsmGen.assignRegisterByte(AsmAssignTarget.fromRegisters(resultRegister ?: RegisterOrPair.A, scope, program, asmgen), CpuRegister.A)
-                }
-            }
            "rnd" -> {
                if(resultToStack)
                    asmgen.out("  jsr  prog8_lib.func_rnd_stack")
                else {
                    asmgen.out("  jsr  math.randbyte")
-                    assignAsmGen.assignRegisterByte(AsmAssignTarget.fromRegisters(resultRegister ?: RegisterOrPair.A, scope, program, asmgen), CpuRegister.A)
+                    assignAsmGen.assignRegisterByte(AsmAssignTarget.fromRegisters(resultRegister ?: RegisterOrPair.A, false, scope, program, asmgen), CpuRegister.A)
                }
            }
            "rndw" -> {
@@ -1031,7 +1341,7 @@ internal class BuiltinFunctionsAsmGen(private val program: Program, private val
                    asmgen.out("  jsr  prog8_lib.func_rndw_stack")
                else {
                    asmgen.out("  jsr  math.randword")
-                    assignAsmGen.assignRegisterpairWord(AsmAssignTarget.fromRegisters(resultRegister ?: RegisterOrPair.AY, scope, program, asmgen), RegisterOrPair.AY)
+                    assignAsmGen.assignRegisterpairWord(AsmAssignTarget.fromRegisters(resultRegister ?: RegisterOrPair.AY, false, scope, program, asmgen), RegisterOrPair.AY)
                }
            }
            else -> throw AssemblyError("wrong func")
@@ -1050,7 +1360,7 @@ internal class BuiltinFunctionsAsmGen(private val program: Program, private val
                val varname = asmgen.asmVariableName(addrExpr)
                if(asmgen.isZpVar(addrExpr)) {
                    // pointervar is already in the zero page, no need to copy
-                    asmgen.saveRegisterLocal(CpuRegister.X, (fcall as Node).definingSubroutine()!!)
+                    asmgen.saveRegisterLocal(CpuRegister.X, (fcall as Node).definingSubroutine!!)
                    asmgen.assignExpressionToRegister(fcall.args[1], RegisterOrPair.AX)
                    if (asmgen.isTargetCpu(CpuType.CPU65c02)) {
                        asmgen.out("""
@@ -1072,20 +1382,24 @@ internal class BuiltinFunctionsAsmGen(private val program: Program, private val
            }
            is BinaryExpression -> {
                if(addrExpr.operator=="+" && addrExpr.left is IdentifierReference && addrExpr.right is NumericLiteralValue) {
-                    asmgen.saveRegisterLocal(CpuRegister.X, (fcall as Node).definingSubroutine()!!)
-                    asmgen.assignExpressionToRegister(fcall.args[1], RegisterOrPair.AX)
                    val varname = asmgen.asmVariableName(addrExpr.left as IdentifierReference)
-                    val index = (addrExpr.right as NumericLiteralValue).number.toHex()
-                    asmgen.out("""
-                        ldy  #$index
-                        sta  ($varname),y
-                        txa
-                        iny
-                        sta  ($varname),y""")
-                    asmgen.restoreRegisterLocal(CpuRegister.X)
-                    return
+                    if(asmgen.isZpVar(addrExpr.left as IdentifierReference)) {
+                        // pointervar is already in the zero page, no need to copy
+                        asmgen.saveRegisterLocal(CpuRegister.X, (fcall as Node).definingSubroutine!!)
+                        asmgen.assignExpressionToRegister(fcall.args[1], RegisterOrPair.AX)
+                        val index = (addrExpr.right as NumericLiteralValue).number.toHex()
+                        asmgen.out("""
+                            ldy  #$index
+                            sta  ($varname),y
+                            txa
+                            iny
+                            sta  ($varname),y""")
+                        asmgen.restoreRegisterLocal(CpuRegister.X)
+                        return
+                    }
                }
            }
+            else -> throw AssemblyError("wrong pokew arg type")
        }

        asmgen.assignExpressionToVariable(fcall.args[0], "P8ZP_SCRATCH_W1", DataType.UWORD, null)
@@ -1127,15 +1441,21 @@ internal class BuiltinFunctionsAsmGen(private val program: Program, private val
            is BinaryExpression -> {
                if(addrExpr.operator=="+" && addrExpr.left is IdentifierReference && addrExpr.right is NumericLiteralValue) {
                    val varname = asmgen.asmVariableName(addrExpr.left as IdentifierReference)
-                    val index = (addrExpr.right as NumericLiteralValue).number.toHex()
-                    asmgen.out("""
-                        ldy  #$index
-                        lda  ($varname),y
-                        pha
-                        iny
-                        lda  ($varname),y
-                        tay
-                        pla""")
+                    if(asmgen.isZpVar(addrExpr.left as IdentifierReference)) {
+                        // pointervar is already in the zero page, no need to copy
+                        val index = (addrExpr.right as NumericLiteralValue).number.toHex()
+                        asmgen.out("""
+                            ldy  #$index
+                            lda  ($varname),y
+                            pha
+                            iny
+                            lda  ($varname),y
+                            tay
+                            pla""")
+                    }  else {
+                        asmgen.assignExpressionToRegister(fcall.args[0], RegisterOrPair.AY)
+                        asmgen.out("  jsr  prog8_lib.func_peekw")
+                    }
                } else {
                    asmgen.assignExpressionToRegister(fcall.args[0], RegisterOrPair.AY)
                    asmgen.out("  jsr  prog8_lib.func_peekw")
@@ -1154,7 +1474,10 @@ internal class BuiltinFunctionsAsmGen(private val program: Program, private val
                RegisterOrPair.AY -> {}
                RegisterOrPair.AX -> asmgen.out("  sty  P8ZP_SCRATCH_REG |  ldx  P8ZP_SCRATCH_REG")
                RegisterOrPair.XY -> asmgen.out("  tax")
-                in Cx16VirtualRegisters -> asmgen.out("  sta  cx16.${resultRegister.toString().toLowerCase()} |  sty  cx16.${resultRegister.toString().toLowerCase()}+1")
+                in Cx16VirtualRegisters -> asmgen.out(
+                    "  sta  cx16.${
+                        resultRegister.toString().lowercase()
+                    } |  sty  cx16.${resultRegister.toString().lowercase()}+1")
                else -> throw AssemblyError("invalid reg")
            }
        }
@@ -1204,9 +1527,9 @@ internal class BuiltinFunctionsAsmGen(private val program: Program, private val
                }
                in Cx16VirtualRegisters -> {
                    asmgen.assignExpressionToRegister(fcall.args[1], RegisterOrPair.A)      // lsb
-                    asmgen.out("  sta  cx16.${reg.toString().toLowerCase()}")
+                    asmgen.out("  sta  cx16.${reg.toString().lowercase()}")
                    asmgen.assignExpressionToRegister(fcall.args[0], RegisterOrPair.A)      // msb
-                    asmgen.out("  sta  cx16.${reg.toString().toLowerCase()}+1")
+                    asmgen.out("  sta  cx16.${reg.toString().lowercase()}+1")
                }
                else -> throw AssemblyError("invalid mkword target reg")
            }
@@ -1215,7 +1538,7 @@ internal class BuiltinFunctionsAsmGen(private val program: Program, private val

    private fun funcMsb(fcall: IFunctionCall, resultToStack: Boolean, resultRegister: RegisterOrPair?) {
        val arg = fcall.args.single()
-        if (arg.inferType(program).typeOrElse(DataType.STRUCT) !in WordDatatypes)
+        if (!arg.inferType(program).isWords)
            throw AssemblyError("msb required word argument")
        if (arg is NumericLiteralValue)
            throw AssemblyError("msb(const) should have been const-folded away")
@@ -1259,7 +1582,7 @@ internal class BuiltinFunctionsAsmGen(private val program: Program, private val

    private fun funcLsb(fcall: IFunctionCall, resultToStack: Boolean, resultRegister: RegisterOrPair?) {
        val arg = fcall.args.single()
-        if (arg.inferType(program).typeOrElse(DataType.STRUCT) !in WordDatatypes)
+        if (!arg.inferType(program).isWords)
            throw AssemblyError("lsb required word argument")
        if (arg is NumericLiteralValue)
            throw AssemblyError("lsb(const) should have been const-folded away")
@@ -1323,7 +1646,7 @@ internal class BuiltinFunctionsAsmGen(private val program: Program, private val
    }

    private fun translateArguments(args: MutableList<Expression>, signature: FSignature, scope: Subroutine?) {
-        val callConv = signature.callConvention(args.map { it.inferType(program).typeOrElse(DataType.STRUCT) })
+        val callConv = signature.callConvention(args.map { it.inferType(program).getOr(DataType.UNDEFINED) })

        fun getSourceForFloat(value: Expression): AsmAssignSource {
            return when (value) {
@@ -1382,7 +1705,7 @@ internal class BuiltinFunctionsAsmGen(private val program: Program, private val
                            AsmAssignSource.fromAstSource(value, program, asmgen)
                        }
                    }
-                    val tgt = AsmAssignTarget.fromRegisters(conv.reg, null, program, asmgen)
+                    val tgt = AsmAssignTarget.fromRegisters(conv.reg!!, false, null, program, asmgen)
                    val assign = AsmAssignment(src, tgt, false, program.memsizer, value.position)
                    asmgen.translateNormalAssignment(assign)
                }
@@ -0,0 +1,792 @@
+package prog8.compiler.target.cpu6502.codegen
+
+import prog8.ast.Program
+import prog8.ast.base.*
+import prog8.ast.expressions.*
+import prog8.ast.statements.BuiltinFunctionStatementPlaceholder
+import prog8.ast.statements.Subroutine
+import prog8.ast.toHex
+import prog8.compiler.target.AssemblyError
+import prog8.compilerinterface.BuiltinFunctions
+import prog8.compilerinterface.CpuType
+import kotlin.math.absoluteValue
+
+internal class ExpressionsAsmGen(private val program: Program, private val asmgen: AsmGen) {
+
+    @Deprecated("avoid calling this as it generates slow evalstack based code")
+    internal fun translateExpression(expression:Expression) {
+        if (this.asmgen.options.slowCodegenWarnings) {
+            asmgen.errors.warn("slow stack evaluation used for expression $expression", expression.position)
+        }
+        translateExpressionInternal(expression)
+    }
+
+
+    // the rest of the methods are all PRIVATE
+
+
+    private fun translateExpressionInternal(expression: Expression) {
+
+        when(expression) {
+            is PrefixExpression -> translateExpression(expression)
+            is BinaryExpression -> translateExpression(expression)
+            is ArrayIndexedExpression -> translateExpression(expression)
+            is TypecastExpression -> translateExpression(expression)
+            is AddressOf -> translateExpression(expression)
+            is DirectMemoryRead -> asmgen.translateDirectMemReadExpressionToRegAorStack(expression, true)
+            is NumericLiteralValue -> translateExpression(expression)
+            is IdentifierReference -> translateExpression(expression)
+            is FunctionCall -> translateFunctionCallResultOntoStack(expression)
+            is ArrayLiteralValue, is StringLiteralValue -> throw AssemblyError("no asm gen for string/array literal value assignment - should have been replaced by a variable")
+            is RangeExpr -> throw AssemblyError("range expression should have been changed into array values")
+            is CharLiteral -> throw AssemblyError("charliteral should have been replaced by ubyte using certain encoding")
+        }
+    }
+
+    private fun translateFunctionCallResultOntoStack(call: FunctionCall) {
+        // only for use in nested expression evaluation
+
+        val sub = call.target.targetStatement(program)
+        if(sub is BuiltinFunctionStatementPlaceholder) {
+            val builtinFunc = BuiltinFunctions.getValue(sub.name)
+            asmgen.translateBuiltinFunctionCallExpression(call, builtinFunc, true, null)
+        } else {
+            sub as Subroutine
+            asmgen.saveXbeforeCall(call)
+            asmgen.translateFunctionCall(call, true)
+            if(sub.regXasResult()) {
+                // store the return value in X somewhere that we can acces again below
+                asmgen.out("  stx  P8ZP_SCRATCH_REG")
+            }
+            asmgen.restoreXafterCall(call)
+
+            val returns = sub.returntypes.zip(sub.asmReturnvaluesRegisters)
+            for ((_, reg) in returns) {
+                // result value is in cpu or status registers, put it on the stack instead (as we're evaluating an expression tree)
+                if (reg.registerOrPair != null) {
+                    when (reg.registerOrPair!!) {
+                        RegisterOrPair.A -> asmgen.out("  sta  P8ESTACK_LO,x |  dex")
+                        RegisterOrPair.Y -> asmgen.out("  tya |  sta  P8ESTACK_LO,x |  dex")
+                        RegisterOrPair.AY -> asmgen.out("  sta  P8ESTACK_LO,x |  tya |  sta  P8ESTACK_HI,x |  dex")
+                        RegisterOrPair.X -> asmgen.out("  lda  P8ZP_SCRATCH_REG |  sta  P8ESTACK_LO,x |  dex")
+                        RegisterOrPair.AX -> asmgen.out("  sta  P8ESTACK_LO,x |  lda  P8ZP_SCRATCH_REG |  sta  P8ESTACK_HI,x |  dex")
+                        RegisterOrPair.XY -> asmgen.out("  tya |  sta  P8ESTACK_HI,x |  lda  P8ZP_SCRATCH_REG |  sta  P8ESTACK_LO,x |  dex")
+                        RegisterOrPair.FAC1 -> asmgen.out("  jsr  floats.push_fac1")
+                        RegisterOrPair.FAC2 -> asmgen.out("  jsr  floats.push_fac2")
+                        RegisterOrPair.R0,
+                        RegisterOrPair.R1,
+                        RegisterOrPair.R2,
+                        RegisterOrPair.R3,
+                        RegisterOrPair.R4,
+                        RegisterOrPair.R5,
+                        RegisterOrPair.R6,
+                        RegisterOrPair.R7,
+                        RegisterOrPair.R8,
+                        RegisterOrPair.R9,
+                        RegisterOrPair.R10,
+                        RegisterOrPair.R11,
+                        RegisterOrPair.R12,
+                        RegisterOrPair.R13,
+                        RegisterOrPair.R14,
+                        RegisterOrPair.R15 -> {
+                            asmgen.out(
+                                """
+                                lda  cx16.${reg.registerOrPair.toString().lowercase()}
+                                sta  P8ESTACK_LO,x
+                                lda  cx16.${reg.registerOrPair.toString().lowercase()}+1
+                                sta  P8ESTACK_HI,x
+                                dex
+                            """)
+                        }
+                    }
+                } else when(reg.statusflag) {
+                    Statusflag.Pc -> {
+                        asmgen.out("""
+                            lda  #0
+                            rol  a
+                            sta  P8ESTACK_LO,x
+                            dex""")
+                    }
+                    Statusflag.Pz -> {
+                        asmgen.out("""
+                            beq  +
+                            lda  #0
+                            beq  ++
+                           lda  #1
+                           sta  P8ESTACK_LO,x
+                            dex""")
+                    }
+                    Statusflag.Pv -> {
+                        asmgen.out("""
+                            bvs  +
+                            lda  #0
+                            beq  ++
+                           lda  #1
+                           sta  P8ESTACK_LO,x
+                            dex""")
+                    }
+                    Statusflag.Pn -> {
+                        asmgen.out("""
+                            bmi  +
+                            lda  #0
+                            beq  ++
+                           lda  #1
+                           sta  P8ESTACK_LO,x
+                            dex""")
+                    }
+                    null -> {}
+                }
+            }
+        }
+    }
+
+    private fun translateExpression(typecast: TypecastExpression) {
+        translateExpressionInternal(typecast.expression)
+        when(typecast.expression.inferType(program).getOr(DataType.UNDEFINED)) {
+            DataType.UBYTE -> {
+                when(typecast.type) {
+                    DataType.UBYTE, DataType.BYTE -> {}
+                    DataType.UWORD, DataType.WORD -> {
+                        if(asmgen.isTargetCpu(CpuType.CPU65c02))
+                            asmgen.out("  stz  P8ESTACK_HI+1,x")
+                        else
+                            asmgen.out("  lda  #0  |  sta  P8ESTACK_HI+1,x")
+                    }
+                    DataType.FLOAT -> asmgen.out(" jsr  floats.stack_ub2float")
+                    in PassByReferenceDatatypes -> throw AssemblyError("cannot cast to a pass-by-reference datatype")
+                    else -> throw AssemblyError("weird type")
+                }
+            }
+            DataType.BYTE -> {
+                when(typecast.type) {
+                    DataType.UBYTE, DataType.BYTE -> {}
+                    DataType.UWORD, DataType.WORD -> asmgen.signExtendStackLsb(DataType.BYTE)
+                    DataType.FLOAT -> asmgen.out(" jsr  floats.stack_b2float")
+                    in PassByReferenceDatatypes -> throw AssemblyError("cannot cast to a pass-by-reference datatype")
+                    else -> throw AssemblyError("weird type")
+                }
+            }
+            DataType.UWORD -> {
+                when(typecast.type) {
+                    DataType.BYTE, DataType.UBYTE -> {}
+                    DataType.WORD, DataType.UWORD -> {}
+                    DataType.FLOAT -> asmgen.out(" jsr  floats.stack_uw2float")
+                    in PassByReferenceDatatypes -> throw AssemblyError("cannot cast to a pass-by-reference datatype")
+                    else -> throw AssemblyError("weird type")
+                }
+            }
+            DataType.WORD -> {
+                when(typecast.type) {
+                    DataType.BYTE, DataType.UBYTE -> {}
+                    DataType.WORD, DataType.UWORD -> {}
+                    DataType.FLOAT -> asmgen.out(" jsr  floats.stack_w2float")
+                    in PassByReferenceDatatypes -> throw AssemblyError("cannot cast to a pass-by-reference datatype")
+                    else -> throw AssemblyError("weird type")
+                }
+            }
+            DataType.FLOAT -> {
+                when(typecast.type) {
+                    DataType.UBYTE -> asmgen.out(" jsr  floats.stack_float2uw")
+                    DataType.BYTE -> asmgen.out(" jsr  floats.stack_float2w")
+                    DataType.UWORD -> asmgen.out(" jsr  floats.stack_float2uw")
+                    DataType.WORD -> asmgen.out(" jsr  floats.stack_float2w")
+                    DataType.FLOAT -> {}
+                    in PassByReferenceDatatypes -> throw AssemblyError("cannot cast to a pass-by-reference datatype")
+                    else -> throw AssemblyError("weird type")
+                }
+            }
+            DataType.STR -> {
+                if (typecast.type != DataType.UWORD && typecast.type == DataType.STR)
+                    throw AssemblyError("cannot typecast a string into another incompatitble type")
+            }
+            in PassByReferenceDatatypes -> throw AssemblyError("cannot cast pass-by-reference value into another type")
+            else -> throw AssemblyError("weird type")
+        }
+    }
+
+    private fun translateExpression(expr: AddressOf) {
+        val name = asmgen.asmVariableName(expr.identifier)
+        asmgen.out("  lda  #<$name |  sta  P8ESTACK_LO,x |  lda  #>$name  |  sta  P8ESTACK_HI,x  | dex")
+    }
+
+    private fun translateExpression(expr: NumericLiteralValue) {
+        when(expr.type) {
+            DataType.UBYTE, DataType.BYTE -> asmgen.out(" lda  #${expr.number.toHex()}  | sta  P8ESTACK_LO,x  | dex")
+            DataType.UWORD, DataType.WORD -> asmgen.out("""
+                lda  #<${expr.number.toHex()}
+                sta  P8ESTACK_LO,x
+                lda  #>${expr.number.toHex()}
+                sta  P8ESTACK_HI,x
+                dex
+            """)
+            DataType.FLOAT -> {
+                val floatConst = asmgen.getFloatAsmConst(expr.number)
+                asmgen.out(" lda  #<$floatConst |  ldy  #>$floatConst |  jsr  floats.push_float")
+            }
+            else -> throw AssemblyError("weird type")
+        }
+    }
+
+    private fun translateExpression(expr: IdentifierReference) {
+        val varname = asmgen.asmVariableName(expr)
+        when(expr.inferType(program).getOr(DataType.UNDEFINED)) {
+            DataType.UBYTE, DataType.BYTE -> {
+                asmgen.out("  lda  $varname  |  sta  P8ESTACK_LO,x  |  dex")
+            }
+            DataType.UWORD, DataType.WORD -> {
+                asmgen.out("  lda  $varname  |  sta  P8ESTACK_LO,x  |  lda  $varname+1 |  sta  P8ESTACK_HI,x |  dex")
+            }
+            DataType.FLOAT -> {
+                asmgen.out(" lda  #<$varname |  ldy  #>$varname|  jsr  floats.push_float")
+            }
+            in IterableDatatypes -> {
+                asmgen.out("  lda  #<$varname  |  sta  P8ESTACK_LO,x  |  lda  #>$varname |  sta  P8ESTACK_HI,x |  dex")
+            }
+            else -> throw AssemblyError("stack push weird variable type $expr")
+        }
+    }
+
+    private fun translateExpression(expr: BinaryExpression) {
+        // Uses evalstack to evaluate the given expression.
+        // TODO we're slowly reducing the number of places where this is called and instead replace that by more efficient assignment-form code (using temp var or register for instance).
+        val leftIDt = expr.left.inferType(program)
+        val rightIDt = expr.right.inferType(program)
+        if(!leftIDt.isKnown || !rightIDt.isKnown)
+            throw AssemblyError("can't infer type of both expression operands")
+
+        val leftDt = leftIDt.getOr(DataType.UNDEFINED)
+        val rightDt = rightIDt.getOr(DataType.UNDEFINED)
+        // see if we can apply some optimized routines
+        when(expr.operator) {
+            "+" -> {
+                if(leftDt in IntegerDatatypes && rightDt in IntegerDatatypes) {
+                    val leftVal = expr.left.constValue(program)?.number?.toInt()
+                    val rightVal = expr.right.constValue(program)?.number?.toInt()
+                    if (leftVal!=null && leftVal in -4..4) {
+                        translateExpressionInternal(expr.right)
+                        if(rightDt in ByteDatatypes) {
+                            val incdec = if(leftVal<0) "dec" else "inc"
+                            repeat(leftVal.absoluteValue) {
+                                asmgen.out("  $incdec  P8ESTACK_LO+1,x")
+                            }
+                        } else {
+                            // word
+                            if(leftVal<0) {
+                                repeat(leftVal.absoluteValue) {
+                                    asmgen.out("""
+                                        lda  P8ESTACK_LO+1,x
+                                        bne  +
+                                        dec  P8ESTACK_HI+1,x
+                                       dec  P8ESTACK_LO+1,x""")
+                                }
+                            } else {
+                                repeat(leftVal) {
+                                    asmgen.out("""
+                                        inc  P8ESTACK_LO+1,x
+                                        bne  +
+                                        inc  P8ESTACK_HI+1,x
+""")
+                                }
+                            }
+                        }
+                        return
+                    }
+                    else if (rightVal!=null && rightVal in -4..4)
+                    {
+                        translateExpressionInternal(expr.left)
+                        if(leftDt in ByteDatatypes) {
+                            val incdec = if(rightVal<0) "dec" else "inc"
+                            repeat(rightVal.absoluteValue) {
+                                asmgen.out("  $incdec  P8ESTACK_LO+1,x")
+                            }
+                        } else {
+                            // word
+                            if(rightVal<0) {
+                                repeat(rightVal.absoluteValue) {
+                                    asmgen.out("""
+                                        lda  P8ESTACK_LO+1,x
+                                        bne  +
+                                        dec  P8ESTACK_HI+1,x
+                                       dec  P8ESTACK_LO+1,x""")
+                                }
+                            } else {
+                                repeat(rightVal) {
+                                    asmgen.out("""
+                                        inc  P8ESTACK_LO+1,x
+                                        bne  +
+                                        inc  P8ESTACK_HI+1,x
+""")
+                                }
+                            }
+                        }
+                        return
+                    }
+                }
+            }
+            "-" -> {
+                if(leftDt in IntegerDatatypes && rightDt in IntegerDatatypes) {
+                    val rightVal = expr.right.constValue(program)?.number?.toInt()
+                    if (rightVal!=null && rightVal in -4..4)
+                    {
+                        translateExpressionInternal(expr.left)
+                        if(leftDt in ByteDatatypes) {
+                            val incdec = if(rightVal<0) "inc" else "dec"
+                            repeat(rightVal.absoluteValue) {
+                                asmgen.out("  $incdec  P8ESTACK_LO+1,x")
+                            }
+                        } else {
+                            // word
+                            if(rightVal>0) {
+                                repeat(rightVal.absoluteValue) {
+                                    asmgen.out("""
+                                        lda  P8ESTACK_LO+1,x
+                                        bne  +
+                                        dec  P8ESTACK_HI+1,x
+                                       dec  P8ESTACK_LO+1,x""")
+                                }
+                            } else {
+                                repeat(rightVal) {
+                                    asmgen.out("""
+                                        inc  P8ESTACK_LO+1,x
+                                        bne  +
+                                        inc  P8ESTACK_HI+1,x
+""")
+                                }
+                            }
+                        }
+                        return
+                    }
+                }
+            }
+            ">>" -> {
+                val amount = expr.right.constValue(program)?.number?.toInt()
+                if(amount!=null) {
+                    translateExpressionInternal(expr.left)
+                    when (leftDt) {
+                        DataType.UBYTE -> {
+                            if (amount <= 2)
+                                repeat(amount) { asmgen.out(" lsr  P8ESTACK_LO+1,x") }
+                            else {
+                                asmgen.out(" lda  P8ESTACK_LO+1,x")
+                                repeat(amount) { asmgen.out(" lsr  a") }
+                                asmgen.out(" sta  P8ESTACK_LO+1,x")
+                            }
+                        }
+                        DataType.BYTE -> {
+                            if (amount <= 2)
+                                repeat(amount) { asmgen.out(" lda  P8ESTACK_LO+1,x |  asl  a |  ror  P8ESTACK_LO+1,x") }
+                            else {
+                                asmgen.out(" lda  P8ESTACK_LO+1,x |  sta  P8ZP_SCRATCH_B1")
+                                repeat(amount) { asmgen.out(" asl  a |  ror  P8ZP_SCRATCH_B1 |  lda  P8ZP_SCRATCH_B1") }
+                                asmgen.out(" sta  P8ESTACK_LO+1,x")
+                            }
+                        }
+                        DataType.UWORD -> {
+                            if(amount>=16) {
+                                if(asmgen.isTargetCpu(CpuType.CPU65c02))
+                                    asmgen.out("  stz  P8ESTACK_LO+1,x |  stz  P8ESTACK_HI+1,x")
+                                else
+                                    asmgen.out("  lda  #0 |  sta  P8ESTACK_LO+1,x |  sta  P8ESTACK_HI+1,x")
+                                return
+                            }
+                            var left = amount
+                            while (left >= 7) {
+                                asmgen.out(" jsr  math.shift_right_uw_7")
+                                left -= 7
+                            }
+                            if (left in 0..2)
+                                repeat(left) { asmgen.out(" lsr  P8ESTACK_HI+1,x |  ror  P8ESTACK_LO+1,x") }
+                            else
+                                asmgen.out(" jsr  math.shift_right_uw_$left")
+                        }
+                        DataType.WORD -> {
+                            if(amount>=16) {
+                                asmgen.out("""
+                                    lda  P8ESTACK_HI+1,x
+                                    bmi  +
+                                    lda  #0
+                                    sta  P8ESTACK_LO+1,x
+                                    sta  P8ESTACK_HI+1,x
+                                    beq  ++
+                                   lda  #255
+                                    sta  P8ESTACK_LO+1,x
+                                    sta  P8ESTACK_HI+1,x
+""")
+                                return
+                            }
+                            var left = amount
+                            while (left >= 7) {
+                                asmgen.out(" jsr  math.shift_right_w_7")
+                                left -= 7
+                            }
+                            if (left in 0..2)
+                                repeat(left) { asmgen.out(" lda  P8ESTACK_HI+1,x |  asl a  |  ror  P8ESTACK_HI+1,x |  ror  P8ESTACK_LO+1,x") }
+                            else
+                                asmgen.out(" jsr  math.shift_right_w_$left")
+                        }
+                        else -> throw AssemblyError("weird type")
+                    }
+                    return
+                }
+            }
+            "<<" -> {
+                val amount = expr.right.constValue(program)?.number?.toInt()
+                if(amount!=null) {
+                    translateExpressionInternal(expr.left)
+                    if (leftDt in ByteDatatypes) {
+                        if (amount <= 2)
+                            repeat(amount) { asmgen.out("  asl  P8ESTACK_LO+1,x") }
+                        else {
+                            asmgen.out("  lda  P8ESTACK_LO+1,x")
+                            repeat(amount) { asmgen.out("  asl  a") }
+                            asmgen.out("  sta  P8ESTACK_LO+1,x")
+                        }
+                    } else {
+                        var left = amount
+                        while (left >= 7) {
+                            asmgen.out(" jsr  math.shift_left_w_7")
+                            left -= 7
+                        }
+                        if (left in 0..2)
+                            repeat(left) { asmgen.out("  asl  P8ESTACK_LO+1,x |  rol  P8ESTACK_HI+1,x") }
+                        else
+                            asmgen.out(" jsr  math.shift_left_w_$left")
+                    }
+                    return
+                }
+            }
+            "*" -> {
+                if(leftDt in IntegerDatatypes && rightDt in IntegerDatatypes) {
+                    val leftVar = expr.left as? IdentifierReference
+                    val rightVar = expr.right as? IdentifierReference
+                    if(leftVar!=null && rightVar!=null && leftVar==rightVar)
+                        return translateSquared(leftVar, leftDt)
+                }
+
+                val value = expr.right.constValue(program)
+                if(value!=null) {
+                    if(rightDt in IntegerDatatypes) {
+                        val amount = value.number.toInt()
+                        if(amount==2) {
+                            // optimize x*2 common case
+                            translateExpressionInternal(expr.left)
+                            if(leftDt in ByteDatatypes) {
+                                asmgen.out("  asl  P8ESTACK_LO+1,x")
+                            } else {
+                                asmgen.out("  asl  P8ESTACK_LO+1,x |  rol  P8ESTACK_HI+1,x")
+                            }
+                            return
+                        }
+                        when(rightDt) {
+                            DataType.UBYTE -> {
+                                if(amount in asmgen.optimizedByteMultiplications) {
+                                    translateExpressionInternal(expr.left)
+                                    asmgen.out(" jsr  math.stack_mul_byte_$amount")
+                                    return
+                                }
+                            }
+                            DataType.BYTE -> {
+                                if(amount in asmgen.optimizedByteMultiplications) {
+                                    translateExpressionInternal(expr.left)
+                                    asmgen.out(" jsr  math.stack_mul_byte_$amount")
+                                    return
+                                }
+                                if(amount.absoluteValue in asmgen.optimizedByteMultiplications) {
+                                    translateExpressionInternal(expr.left)
+                                    asmgen.out(" jsr  prog8_lib.neg_b |  jsr  math.stack_mul_byte_${amount.absoluteValue}")
+                                    return
+                                }
+                            }
+                            DataType.UWORD -> {
+                                if(amount in asmgen.optimizedWordMultiplications) {
+                                    translateExpressionInternal(expr.left)
+                                    asmgen.out(" jsr  math.stack_mul_word_$amount")
+                                    return
+                                }
+                            }
+                            DataType.WORD -> {
+                                if(amount in asmgen.optimizedWordMultiplications) {
+                                    translateExpressionInternal(expr.left)
+                                    asmgen.out(" jsr  math.stack_mul_word_$amount")
+                                    return
+                                }
+                                if(amount.absoluteValue in asmgen.optimizedWordMultiplications) {
+                                    translateExpressionInternal(expr.left)
+                                    asmgen.out(" jsr  prog8_lib.neg_w |  jsr  math.stack_mul_word_${amount.absoluteValue}")
+                                    return
+                                }
+                            }
+                            else -> {}
+                        }
+                    }
+                }
+            }
+            "/" -> {
+                if(leftDt in IntegerDatatypes && rightDt in IntegerDatatypes) {
+                    val rightVal = expr.right.constValue(program)?.number?.toInt()
+                    if(rightVal!=null && rightVal==2) {
+                        translateExpressionInternal(expr.left)
+                        when(leftDt) {
+                            DataType.UBYTE -> asmgen.out("  lsr  P8ESTACK_LO+1,x")
+                            DataType.BYTE -> asmgen.out("  lda  P8ESTACK_LO+1,x |  asl  a |  ror  P8ESTACK_LO+1,x")
+                            DataType.UWORD -> asmgen.out("  lsr  P8ESTACK_HI+1,x |  ror  P8ESTACK_LO+1,x")
+                            DataType.WORD -> asmgen.out("  lda  P8ESTACK_HI+1,x |  asl  a |  ror  P8ESTACK_HI+1,x |  ror  P8ESTACK_LO+1,x")
+                            else -> throw AssemblyError("wrong dt")
+                        }
+                        return
+                    }
+                }
+            }
+        }
+
+        if((leftDt in ByteDatatypes && rightDt !in ByteDatatypes)
+                || (leftDt in WordDatatypes && rightDt !in WordDatatypes))
+            throw AssemblyError("binary operator ${expr.operator} left/right dt not identical")
+
+        if(leftDt==DataType.STR && rightDt==DataType.STR && expr.operator in comparisonOperators) {
+            translateCompareStrings(expr.left, expr.operator, expr.right)
+        }
+        else {
+            // the general, non-optimized cases  TODO optimize more cases.... (or one day just don't use the evalstack at all anymore)
+            translateExpressionInternal(expr.left)
+            translateExpressionInternal(expr.right)
+            when (leftDt) {
+                in ByteDatatypes -> translateBinaryOperatorBytes(expr.operator, leftDt)
+                in WordDatatypes -> translateBinaryOperatorWords(expr.operator, leftDt)
+                DataType.FLOAT -> translateBinaryOperatorFloats(expr.operator)
+                else -> throw AssemblyError("non-numerical datatype")
+            }
+        }
+    }
+
+    private fun translateSquared(variable: IdentifierReference, dt: DataType) {
+        val asmVar = asmgen.asmVariableName(variable)
+        when(dt) {
+            DataType.BYTE, DataType.UBYTE -> {
+                asmgen.out("  lda  $asmVar")
+                asmgen.signExtendAYlsb(dt)
+                asmgen.out("  jsr  math.square")
+            }
+            DataType.UWORD, DataType.WORD -> {
+                asmgen.out("  lda  $asmVar |  ldy  $asmVar+1 |  jsr  math.square")
+            }
+            else -> throw AssemblyError("require integer dt for square")
+        }
+        asmgen.out("  sta  P8ESTACK_LO,x |  tya |  sta  P8ESTACK_HI,x |  dex")
+    }
+
+    private fun translateExpression(expr: PrefixExpression) {
+        translateExpressionInternal(expr.expression)
+        val itype = expr.inferType(program)
+        if(!itype.isKnown)
+            throw AssemblyError("unknown dt")
+        val type = itype.getOr(DataType.UNDEFINED)
+        when(expr.operator) {
+            "+" -> {}
+            "-" -> {
+                when(type) {
+                    in ByteDatatypes -> asmgen.out("  jsr  prog8_lib.neg_b")
+                    in WordDatatypes -> asmgen.out("  jsr  prog8_lib.neg_w")
+                    DataType.FLOAT -> asmgen.out("  jsr  floats.neg_f")
+                    else -> throw AssemblyError("weird type")
+                }
+            }
+            "~" -> {
+                when(type) {
+                    in ByteDatatypes ->
+                        asmgen.out("""
+                            lda  P8ESTACK_LO+1,x
+                            eor  #255
+                            sta  P8ESTACK_LO+1,x
+                            """)
+                    in WordDatatypes -> asmgen.out("  jsr  prog8_lib.inv_word")
+                    else -> throw AssemblyError("weird type")
+                }
+            }
+            "not" -> {
+                when(type) {
+                    in ByteDatatypes -> asmgen.out("  jsr  prog8_lib.not_byte")
+                    in WordDatatypes -> asmgen.out("  jsr  prog8_lib.not_word")
+                    else -> throw AssemblyError("weird type")
+                }
+            }
+            else -> throw AssemblyError("invalid prefix operator ${expr.operator}")
+        }
+    }
+
+    private fun translateExpression(arrayExpr: ArrayIndexedExpression) {
+        val elementIDt = arrayExpr.inferType(program)
+        if(!elementIDt.isKnown)
+            throw AssemblyError("unknown dt")
+        val elementDt = elementIDt.getOr(DataType.UNDEFINED)
+        val arrayVarName = asmgen.asmVariableName(arrayExpr.arrayvar)
+        val constIndexNum = arrayExpr.indexer.constIndex()
+        if(constIndexNum!=null) {
+            val indexValue = constIndexNum * program.memsizer.memorySize(elementDt)
+            when(elementDt) {
+                in ByteDatatypes -> {
+                    asmgen.out("  lda  $arrayVarName+$indexValue |  sta  P8ESTACK_LO,x |  dex")
+                }
+                in WordDatatypes -> {
+                    asmgen.out("  lda  $arrayVarName+$indexValue |  sta  P8ESTACK_LO,x |  lda  $arrayVarName+$indexValue+1 |  sta  P8ESTACK_HI,x |  dex")
+                }
+                DataType.FLOAT -> {
+                    asmgen.out("  lda  #<$arrayVarName+$indexValue |  ldy  #>$arrayVarName+$indexValue |  jsr  floats.push_float")
+                }
+                else -> throw AssemblyError("weird element type")
+            }
+        } else {
+            when(elementDt) {
+                in ByteDatatypes -> {
+                    asmgen.loadScaledArrayIndexIntoRegister(arrayExpr, elementDt, CpuRegister.Y)
+                    asmgen.out(" lda  $arrayVarName,y |  sta  P8ESTACK_LO,x |  dex")
+                }
+                in WordDatatypes -> {
+                    asmgen.loadScaledArrayIndexIntoRegister(arrayExpr, elementDt, CpuRegister.Y)
+                    asmgen.out(" lda  $arrayVarName,y |  sta  P8ESTACK_LO,x |  lda  $arrayVarName+1,y |  sta  P8ESTACK_HI,x |  dex")
+                }
+                DataType.FLOAT -> {
+                    asmgen.loadScaledArrayIndexIntoRegister(arrayExpr, elementDt, CpuRegister.A)
+                    asmgen.out("""
+                        ldy  #>$arrayVarName
+                        clc
+                        adc  #<$arrayVarName
+                        bcc  +
+                        iny
+                       jsr  floats.push_float""")
+                }
+                else -> throw AssemblyError("weird dt")
+            }
+
+        }
+    }
+
+    private fun translateBinaryOperatorBytes(operator: String, types: DataType) {
+        when(operator) {
+            "**" -> throw AssemblyError("** operator requires floats")
+            "*" -> asmgen.out("  jsr  prog8_lib.mul_byte")  //  the optimized routines should have been checked earlier
+            "/" -> asmgen.out(if(types==DataType.UBYTE) "  jsr  prog8_lib.idiv_ub" else "  jsr  prog8_lib.idiv_b")
+            "%" -> {
+                if(types==DataType.BYTE)
+                    throw AssemblyError("remainder of signed integers is not properly defined/implemented, use unsigned instead")
+                asmgen.out("  jsr prog8_lib.remainder_ub")
+            }
+            "+" -> asmgen.out("""
+                lda  P8ESTACK_LO+2,x
+                clc
+                adc  P8ESTACK_LO+1,x
+                inx
+                sta  P8ESTACK_LO+1,x
+                """)
+            "-" -> asmgen.out("""
+                lda  P8ESTACK_LO+2,x
+                sec
+                sbc  P8ESTACK_LO+1,x
+                inx
+                sta  P8ESTACK_LO+1,x
+                """)
+            "<<" -> asmgen.out("  jsr  prog8_lib.shiftleft_b")
+            ">>" -> asmgen.out("  jsr  prog8_lib.shiftright_b")
+            "<" -> asmgen.out(if(types==DataType.UBYTE) "  jsr  prog8_lib.less_ub" else "  jsr  prog8_lib.less_b")
+            ">" -> asmgen.out(if(types==DataType.UBYTE) "  jsr  prog8_lib.greater_ub" else "  jsr  prog8_lib.greater_b")
+            "<=" -> asmgen.out(if(types==DataType.UBYTE) "  jsr  prog8_lib.lesseq_ub" else "  jsr  prog8_lib.lesseq_b")
+            ">=" -> asmgen.out(if(types==DataType.UBYTE) "  jsr  prog8_lib.greatereq_ub" else "  jsr  prog8_lib.greatereq_b")
+            "==" -> asmgen.out("  jsr  prog8_lib.equal_b")
+            "!=" -> asmgen.out("  jsr  prog8_lib.notequal_b")
+            "&" -> asmgen.out("  jsr  prog8_lib.bitand_b")
+            "^" -> asmgen.out("  jsr  prog8_lib.bitxor_b")
+            "|" -> asmgen.out("  jsr  prog8_lib.bitor_b")
+            "and" -> asmgen.out("  jsr  prog8_lib.and_b")
+            "or" -> asmgen.out("  jsr  prog8_lib.or_b")
+            "xor" -> asmgen.out("  jsr  prog8_lib.xor_b")
+            else -> throw AssemblyError("invalid operator $operator")
+        }
+    }
+
+    private fun translateBinaryOperatorWords(operator: String, dt: DataType) {
+        when(operator) {
+            "**" -> throw AssemblyError("** operator requires floats")
+            "*" -> asmgen.out("  jsr  prog8_lib.mul_word")
+            "/" -> asmgen.out(if(dt==DataType.UWORD) "  jsr  prog8_lib.idiv_uw" else "  jsr  prog8_lib.idiv_w")
+            "%" -> {
+                if(dt==DataType.WORD)
+                    throw AssemblyError("remainder of signed integers is not properly defined/implemented, use unsigned instead")
+                asmgen.out("  jsr prog8_lib.remainder_uw")
+            }
+            "+" -> asmgen.out("  jsr  prog8_lib.add_w")
+            "-" -> asmgen.out("  jsr  prog8_lib.sub_w")
+            "<<" -> asmgen.out("  jsr  math.shift_left_w")
+            ">>" -> {
+                if(dt==DataType.UWORD)
+                    asmgen.out("  jsr  math.shift_right_uw")
+                else
+                    asmgen.out("  jsr  math.shift_right_w")
+            }
+            "<" -> asmgen.out(if(dt==DataType.UWORD) "  jsr  prog8_lib.less_uw" else "  jsr  prog8_lib.less_w")
+            ">" -> asmgen.out(if(dt==DataType.UWORD) "  jsr  prog8_lib.greater_uw" else "  jsr  prog8_lib.greater_w")
+            "<=" -> asmgen.out(if(dt==DataType.UWORD) "  jsr  prog8_lib.lesseq_uw" else "  jsr  prog8_lib.lesseq_w")
+            ">=" -> asmgen.out(if(dt==DataType.UWORD) "  jsr  prog8_lib.greatereq_uw" else "  jsr  prog8_lib.greatereq_w")
+            "==" -> asmgen.out("  jsr  prog8_lib.equal_w")
+            "!=" -> asmgen.out("  jsr  prog8_lib.notequal_w")            "&" -> asmgen.out("  jsr  prog8_lib.bitand_w")
+            "^" -> asmgen.out("  jsr  prog8_lib.bitxor_w")
+            "|" -> asmgen.out("  jsr  prog8_lib.bitor_w")
+            "and" -> asmgen.out("  jsr  prog8_lib.and_w")
+            "or" -> asmgen.out("  jsr  prog8_lib.or_w")
+            "xor" -> asmgen.out("  jsr  prog8_lib.xor_w")
+            else -> throw AssemblyError("invalid operator $operator")
+        }
+    }
+
+    private fun translateBinaryOperatorFloats(operator: String) {
+        when(operator) {
+            "**" -> asmgen.out(" jsr  floats.pow_f")
+            "*" -> asmgen.out("  jsr  floats.mul_f")
+            "/" -> asmgen.out("  jsr  floats.div_f")
+            "+" -> asmgen.out("  jsr  floats.add_f")
+            "-" -> asmgen.out("  jsr  floats.sub_f")
+            "<" -> asmgen.out("  jsr  floats.less_f")
+            ">" -> asmgen.out("  jsr  floats.greater_f")
+            "<=" -> asmgen.out("  jsr  floats.lesseq_f")
+            ">=" -> asmgen.out("  jsr  floats.greatereq_f")
+            "==" -> asmgen.out("  jsr  floats.equal_f")
+            "!=" -> asmgen.out("  jsr  floats.notequal_f")
+            "%", "<<", ">>", "&", "^", "|", "and", "or", "xor" -> throw AssemblyError("requires integer datatype")
+            else -> throw AssemblyError("invalid operator $operator")
+        }
+    }
+
+    private fun translateCompareStrings(s1: Expression, operator: String, s2: Expression) {
+        asmgen.assignExpressionToVariable(s1, "prog8_lib.strcmp_expression._arg_s1", DataType.UWORD, null)
+        asmgen.assignExpressionToVariable(s2, "prog8_lib.strcmp_expression._arg_s2", DataType.UWORD, null)
+        asmgen.out(" jsr  prog8_lib.strcmp_expression")    // result  of compare is in A
+        when(operator) {
+            "==" -> asmgen.out(" and  #1 |  eor  #1 |  sta  P8ESTACK_LO,x")
+            "!=" -> asmgen.out(" and  #1 |  sta  P8ESTACK_LO,x")
+            "<=" -> asmgen.out("""
+                bpl  +
+                lda  #1
+                bne  ++
+               lda  #0
+               sta  P8ESTACK_LO,x""")
+            ">=" -> asmgen.out("""
+                bmi  +
+                lda  #1
+                bne  ++
+               lda  #0
+               sta  P8ESTACK_LO,x""")
+            "<" -> asmgen.out("""
+                bmi  +
+                lda  #0
+                beq  ++
+               lda  #1
+               sta  P8ESTACK_LO,x""")
+            ">" -> asmgen.out("""
+                bpl  +
+                lda  #0
+                beq  ++
+               lda  #1
+               sta  P8ESTACK_LO,x""")
+        }
+        asmgen.out("  dex")
+    }
+}
@@ -1,14 +1,15 @@
 package prog8.compiler.target.cpu6502.codegen

 import prog8.ast.Program
-import prog8.ast.base.ArrayElementTypes
+import prog8.ast.base.ArrayToElementTypes
 import prog8.ast.base.DataType
 import prog8.ast.base.RegisterOrPair
 import prog8.ast.expressions.IdentifierReference
 import prog8.ast.expressions.RangeExpr
 import prog8.ast.statements.ForLoop
 import prog8.ast.toHex
-import prog8.compiler.AssemblyError
+import prog8.compiler.target.AssemblyError
+import prog8.compilerinterface.toConstantIntegerRange
 import kotlin.math.absoluteValue

 internal class ForLoopsAsmGen(private val program: Program, private val asmgen: AsmGen) {
@@ -21,13 +22,13 @@ internal class ForLoopsAsmGen(private val program: Program, private val asmgen:
            is RangeExpr -> {
                val range = (stmt.iterable as RangeExpr).toConstantIntegerRange()
                if(range==null) {
-                    translateForOverNonconstRange(stmt, iterableDt.typeOrElse(DataType.STRUCT), stmt.iterable as RangeExpr)
+                    translateForOverNonconstRange(stmt, iterableDt.getOr(DataType.UNDEFINED), stmt.iterable as RangeExpr)
                } else {
-                    translateForOverConstRange(stmt, iterableDt.typeOrElse(DataType.STRUCT), range)
+                    translateForOverConstRange(stmt, iterableDt.getOr(DataType.UNDEFINED), range)
                }
            }
            is IdentifierReference -> {
-                translateForOverIterableVar(stmt, iterableDt.typeOrElse(DataType.STRUCT), stmt.iterable as IdentifierReference)
+                translateForOverIterableVar(stmt, iterableDt.getOr(DataType.UNDEFINED), stmt.iterable as IdentifierReference)
            }
            else -> throw AssemblyError("can't iterate over ${stmt.iterable.javaClass} - should have been replaced by a variable")
        }
@@ -40,6 +41,13 @@ internal class ForLoopsAsmGen(private val program: Program, private val asmgen:
        val modifiedLabel2 = asmgen.makeLabel("for_modifiedb")
        asmgen.loopEndLabels.push(endLabel)
        val stepsize=range.step.constValue(program)!!.number.toInt()
+
+        if(stepsize < -1) {
+            val limit = range.to.constValue(program)?.number
+            if(limit==0.0)
+                throw AssemblyError("for unsigned loop variable it's not possible to count down with step != -1 from a non-const value to exactly zero due to value wrapping")
+        }
+
        when(iterableDt) {
            DataType.ARRAY_B, DataType.ARRAY_UB -> {
                if (stepsize==1 || stepsize==-1) {
@@ -49,8 +57,8 @@ internal class ForLoopsAsmGen(private val program: Program, private val asmgen:
                    val incdec = if(stepsize==1) "inc" else "dec"
                    // loop over byte range via loopvar
                    val varname = asmgen.asmVariableName(stmt.loopVar)
-                    asmgen.assignExpressionToVariable(range.from, varname, ArrayElementTypes.getValue(iterableDt), null)
-                    asmgen.assignExpressionToVariable(range.to, "$modifiedLabel+1", ArrayElementTypes.getValue(iterableDt), null)
+                    asmgen.assignExpressionToVariable(range.from, varname, ArrayToElementTypes.getValue(iterableDt), null)
+                    asmgen.assignExpressionToVariable(range.to, "$modifiedLabel+1", ArrayToElementTypes.getValue(iterableDt), null)
                    asmgen.out(loopLabel)
                    asmgen.translate(stmt.body)
                    asmgen.out("""
@@ -67,8 +75,8 @@ $modifiedLabel          cmp  #0         ; modified

                    // loop over byte range via loopvar
                    val varname = asmgen.asmVariableName(stmt.loopVar)
-                    asmgen.assignExpressionToVariable(range.from, varname, ArrayElementTypes.getValue(iterableDt), null)
-                    asmgen.assignExpressionToVariable(range.to, "$modifiedLabel+1", ArrayElementTypes.getValue(iterableDt), null)
+                    asmgen.assignExpressionToVariable(range.from, varname, ArrayToElementTypes.getValue(iterableDt), null)
+                    asmgen.assignExpressionToVariable(range.to, "$modifiedLabel+1", ArrayToElementTypes.getValue(iterableDt), null)
                    asmgen.out(loopLabel)
                    asmgen.translate(stmt.body)
                    if(stepsize>0) {
@@ -281,7 +289,7 @@ $loopLabel          sty  $indexVar
                        bne  $loopLabel
                        beq  $endLabel""")
                }
-                if(length>=16 && asmgen.zeropage.available() > 0) {
+                if(length>=16 && asmgen.zeropage.hasByteAvailable()) {
                    // allocate index var on ZP
                    val zpAddr = asmgen.zeropage.allocate(indexVar, DataType.UBYTE, stmt.position, asmgen.errors)
                    asmgen.out("""$indexVar = $zpAddr  ; auto zp UBYTE""")
@@ -320,7 +328,7 @@ $loopLabel          sty  $indexVar
                        bne  $loopLabel
                        beq  $endLabel""")
                }
-                if(length>=16 && asmgen.zeropage.available() > 0) {
+                if(length>=16 && asmgen.zeropage.hasByteAvailable()) {
                    // allocate index var on ZP
                    val zpAddr = asmgen.zeropage.allocate(indexVar, DataType.UBYTE, stmt.position, asmgen.errors)
                    asmgen.out("""$indexVar = $zpAddr  ; auto zp UBYTE""")
@@ -581,5 +589,5 @@ $loopLabel""")
    }

    private fun assignLoopvar(stmt: ForLoop, range: RangeExpr) =
-        asmgen.assignExpressionToVariable(range.from, asmgen.asmVariableName(stmt.loopVar), stmt.loopVarDt(program).typeOrElse(DataType.STRUCT), stmt.definingSubroutine())
+        asmgen.assignExpressionToVariable(range.from, asmgen.asmVariableName(stmt.loopVar), stmt.loopVarDt(program).getOr(DataType.UNDEFINED), stmt.definingSubroutine)
 }
@@ -6,19 +6,19 @@ import prog8.ast.Program
 import prog8.ast.base.*
 import prog8.ast.expressions.*
 import prog8.ast.statements.*
-import prog8.compiler.AssemblyError
-import prog8.compiler.target.CpuType
+import prog8.compiler.target.AssemblyError
 import prog8.compiler.target.cpu6502.codegen.assignment.AsmAssignSource
 import prog8.compiler.target.cpu6502.codegen.assignment.AsmAssignTarget
 import prog8.compiler.target.cpu6502.codegen.assignment.AsmAssignment
 import prog8.compiler.target.cpu6502.codegen.assignment.TargetStorageKind
+import prog8.compilerinterface.CpuType


 internal class FunctionCallAsmGen(private val program: Program, private val asmgen: AsmGen) {

    internal fun translateFunctionCallStatement(stmt: IFunctionCall) {
        saveXbeforeCall(stmt)
-        translateFunctionCall(stmt)
+        translateFunctionCall(stmt, false)
        restoreXafterCall(stmt)
        // just ignore any result values from the function call.
    }
@@ -27,11 +27,21 @@ internal class FunctionCallAsmGen(private val program: Program, private val asmg
        val sub = stmt.target.targetSubroutine(program) ?: throw AssemblyError("undefined subroutine ${stmt.target}")
        if(sub.shouldSaveX()) {
            val regSaveOnStack = sub.asmAddress==null       // rom-routines don't require registers to be saved on stack, normal subroutines do because they can contain nested calls
-            val (keepAonEntry: Boolean, keepAonReturn: Boolean) = sub.shouldKeepA()
            if(regSaveOnStack)
-                asmgen.saveRegisterStack(CpuRegister.X, keepAonEntry)
+                asmgen.saveRegisterStack(CpuRegister.X, sub.shouldKeepA().saveOnEntry)
            else
-                asmgen.saveRegisterLocal(CpuRegister.X, (stmt as Node).definingSubroutine()!!)
+                asmgen.saveRegisterLocal(CpuRegister.X, (stmt as Node).definingSubroutine!!)
+        }
+    }
+
+    internal fun saveXbeforeCall(gosub: GoSub) {
+        val sub = gosub.identifier?.targetSubroutine(program)
+        if(sub?.shouldSaveX()==true) {
+            val regSaveOnStack = sub.asmAddress==null       // rom-routines don't require registers to be saved on stack, normal subroutines do because they can contain nested calls
+            if(regSaveOnStack)
+                asmgen.saveRegisterStack(CpuRegister.X, sub.shouldKeepA().saveOnEntry)
+            else
+                asmgen.saveRegisterLocal(CpuRegister.X, gosub.definingSubroutine!!)
        }
    }

@@ -39,105 +49,105 @@ internal class FunctionCallAsmGen(private val program: Program, private val asmg
        val sub = stmt.target.targetSubroutine(program) ?: throw AssemblyError("undefined subroutine ${stmt.target}")
        if(sub.shouldSaveX()) {
            val regSaveOnStack = sub.asmAddress==null       // rom-routines don't require registers to be saved on stack, normal subroutines do because they can contain nested calls
-            val (keepAonEntry: Boolean, keepAonReturn: Boolean) = sub.shouldKeepA()
-
            if(regSaveOnStack)
-                asmgen.restoreRegisterStack(CpuRegister.X, keepAonReturn)
+                asmgen.restoreRegisterStack(CpuRegister.X, sub.shouldKeepA().saveOnReturn)
            else
                asmgen.restoreRegisterLocal(CpuRegister.X)
        }
    }

-    internal fun translateFunctionCall(stmt: IFunctionCall) {
-        // Output only the code to setup the parameters and perform the actual call
+    internal fun restoreXafterCall(gosub: GoSub) {
+        val sub = gosub.identifier?.targetSubroutine(program)
+        if(sub?.shouldSaveX()==true) {
+            val regSaveOnStack = sub.asmAddress==null       // rom-routines don't require registers to be saved on stack, normal subroutines do because they can contain nested calls
+            if(regSaveOnStack)
+                asmgen.restoreRegisterStack(CpuRegister.X, sub.shouldKeepA().saveOnReturn)
+            else
+                asmgen.restoreRegisterLocal(CpuRegister.X)
+        }
+    }
+
+    internal fun translateFunctionCall(call: IFunctionCall, isExpression: Boolean) {
+        // Output only the code to set up the parameters and perform the actual call
        // NOTE: does NOT output the code to deal with the result values!
        // NOTE: does NOT output code to save/restore the X register for this call! Every caller should deal with this in their own way!!
        //       (you can use subroutine.shouldSaveX() and saveX()/restoreX() routines as a help for this)

-        val sub = stmt.target.targetSubroutine(program) ?: throw AssemblyError("undefined subroutine ${stmt.target}")
-        val subName = asmgen.asmSymbolName(stmt.target)
-        if(stmt.args.isNotEmpty()) {
+        val sub = call.target.targetSubroutine(program) ?: throw AssemblyError("undefined subroutine ${call.target}")
+        val subAsmName = asmgen.asmSymbolName(call.target)

-            if(sub.asmParameterRegisters.isEmpty()) {
-                // via variables
-                for(arg in sub.parameters.withIndex().zip(stmt.args)) {
-                    argumentViaVariable(sub, arg.first, arg.second)
-                }
+        if(!isExpression && !sub.isAsmSubroutine)
+            throw AssemblyError("functioncall statements to non-asmsub should have been replaced by GoSub $call")
+
+        if(sub.isAsmSubroutine) {
+            argumentsViaRegisters(sub, call)
+            if (sub.inline && asmgen.options.optimize) {
+                // inline the subroutine.
+                // we do this by copying the subroutine's statements at the call site.
+                // NOTE: *if* there is a return statement, it will be the only one, and the very last statement of the subroutine
+                // (this condition has been enforced by an ast check earlier)
+                asmgen.out("  \t; inlined routine follows: ${sub.name}")
+                val assembly = sub.statements.single() as InlineAssembly
+                asmgen.translate(assembly)
+                asmgen.out("  \t; inlined routine end: ${sub.name}")
            } else {
-                // via registers
-                if(sub.parameters.size==1) {
-                    // just a single parameter, no risk of clobbering registers
-                    argumentViaRegister(sub, IndexedValue(0, sub.parameters.single()), stmt.args[0])
-                } else {
-
-                    fun isNoClobberRisk(expr: Expression): Boolean {
-                        if(expr is AddressOf ||
-                                expr is NumericLiteralValue ||
-                                expr is StringLiteralValue ||
-                                expr is ArrayLiteralValue ||
-                                expr is IdentifierReference)
-                            return true
-
-                        if(expr is FunctionCall) {
-                            if(expr.target.nameInSource==listOf("lsb") || expr.target.nameInSource==listOf("msb"))
-                                return isNoClobberRisk(expr.args[0])
-                            if(expr.target.nameInSource==listOf("mkword"))
-                                return isNoClobberRisk(expr.args[0]) && isNoClobberRisk(expr.args[1])
-                        }
-
-                        return false
-                    }
-
-                    when {
-                        stmt.args.all {isNoClobberRisk(it)} -> {
-                            // There's no risk of clobbering for these simple argument types. Optimize the register loading directly from these values.
-                            // register assignment order: 1) cx16 virtual word registers, 2) actual CPU registers, 3) CPU Carry status flag.
-                            val argsInfo = sub.parameters.withIndex().zip(stmt.args).zip(sub.asmParameterRegisters)
-                            val (cx16virtualRegs, args2) = argsInfo.partition { it.second.registerOrPair in Cx16VirtualRegisters }
-                            val (cpuRegs, statusRegs) = args2.partition { it.second.registerOrPair!=null }
-                            for(arg in cx16virtualRegs)
-                                argumentViaRegister(sub, arg.first.first, arg.first.second)
-                            for(arg in cpuRegs)
-                                argumentViaRegister(sub, arg.first.first, arg.first.second)
-                            for(arg in statusRegs)
-                                argumentViaRegister(sub, arg.first.first, arg.first.second)
-                        }
-                        else -> {
-                            // Risk of clobbering due to complex expression args. Evaluate first, then assign registers.
-                            registerArgsViaStackEvaluation(stmt, sub)
-                        }
-                    }
-                }
+                asmgen.out("  jsr  $subAsmName")
            }
        }
-
-        if(sub.inline && asmgen.options.optimize) {
-            if(sub.containsDefinedVariables())
-                throw AssemblyError("can't inline sub with vars")
-            if(!sub.isAsmSubroutine && sub.parameters.isNotEmpty())
-                throw AssemblyError("can't inline a non-asm subroutine with parameters")
-            asmgen.out("  \t; inlined routine follows: ${sub.name} from ${sub.position}")
-            val statements = sub.statements.filter { it !is ParameterVarDecl && it !is Directive }
-            statements.forEach { asmgen.translate(it) }
-        }
        else {
-            asmgen.out("  jsr  $subName")
+            if(sub.inline)
+                throw AssemblyError("can only reliably inline asmsub routines at this time")
+
+            argumentsViaVariables(sub, call)
+            asmgen.out("  jsr  $subAsmName")
        }

        // remember: dealing with the X register and/or dealing with return values is the responsibility of the caller
    }

+    private fun argumentsViaVariables(sub: Subroutine, call: IFunctionCall) {
+        for(arg in sub.parameters.withIndex().zip(call.args))
+            argumentViaVariable(sub, arg.first, arg.second)
+    }
+
+    private fun argumentsViaRegisters(sub: Subroutine, call: IFunctionCall) {
+        if(sub.parameters.size==1) {
+            argumentViaRegister(sub, IndexedValue(0, sub.parameters.single()), call.args[0])
+        } else {
+            if(asmgen.asmsubArgsHaveRegisterClobberRisk(call.args, sub.asmParameterRegisters)) {
+                registerArgsViaStackEvaluation(call, sub)
+            } else {
+                asmgen.asmsubArgsEvalOrder(sub).forEach {
+                    val param = sub.parameters[it]
+                    val arg = call.args[it]
+                    argumentViaRegister(sub, IndexedValue(it, param), arg)
+                }
+            }
+        }
+    }
+
    private fun registerArgsViaStackEvaluation(stmt: IFunctionCall, sub: Subroutine) {
        // this is called when one or more of the arguments are 'complex' and
        // cannot be assigned to a register easily or risk clobbering other registers.
+        // TODO find another way to prepare the arguments, without using the eval stack

        if(sub.parameters.isEmpty())
            return

+
        // 1. load all arguments reversed onto the stack: first arg goes last (is on top).
+
        for (arg in stmt.args.reversed())
            asmgen.translateExpression(arg)

+        // TODO here's an alternative to the above, but for now generates bigger code due to intermediate register steps:
+//        for (arg in stmt.args.reversed()) {
+//            // note this stuff below is needed to (eventually) avoid calling asmgen.translateExpression()
+//            // TODO also This STILL requires the translateNormalAssignment() to be fixed to avoid stack eval for expressions...
+//            val dt = arg.inferType(program).getOr(DataType.UNDEFINED)
+//            asmgen.assignExpressionTo(arg, AsmAssignTarget(TargetStorageKind.STACK, program, asmgen, dt, sub))
+//        }
+
        var argForCarry: IndexedValue<Pair<Expression, RegisterOrStatusflag>>? = null
        var argForXregister: IndexedValue<Pair<Expression, RegisterOrStatusflag>>? = null
        var argForAregister: IndexedValue<Pair<Expression, RegisterOrStatusflag>>? = null
@@ -152,11 +162,11 @@ internal class FunctionCallAsmGen(private val program: Program, private val asmg
                    argForCarry = argi
                }
                argi.value.second.statusflag != null -> throw AssemblyError("can only use Carry as status flag parameter")
-                argi.value.second.registerOrPair in setOf(RegisterOrPair.X, RegisterOrPair.AX, RegisterOrPair.XY) -> {
+                argi.value.second.registerOrPair in arrayOf(RegisterOrPair.X, RegisterOrPair.AX, RegisterOrPair.XY) -> {
                    require(argForXregister==null)
                    argForXregister = argi
                }
-                argi.value.second.registerOrPair in setOf(RegisterOrPair.A, RegisterOrPair.AY) -> {
+                argi.value.second.registerOrPair in arrayOf(RegisterOrPair.A, RegisterOrPair.AY) -> {
                    require(argForAregister == null)
                    argForAregister = argi
                }
@@ -168,21 +178,31 @@ internal class FunctionCallAsmGen(private val program: Program, private val asmg
                    when (sub.parameters[argi.index].type) {
                        in ByteDatatypes -> {
                            // only load the lsb of the virtual register
-                            asmgen.out("""
+                            asmgen.out(
+                                """
                                lda  P8ESTACK_LO$plusIdxStr,x
-                                sta  cx16.${argi.value.second.registerOrPair.toString().toLowerCase()}
+                                sta  cx16.${argi.value.second.registerOrPair.toString().lowercase()}
                            """)
                            if (asmgen.isTargetCpu(CpuType.CPU65c02))
-                                asmgen.out("  stz  cx16.${argi.value.second.registerOrPair.toString().toLowerCase()}+1")
+                                asmgen.out(
+                                    "  stz  cx16.${
+                                        argi.value.second.registerOrPair.toString().lowercase()
+                                    }+1")
                            else
-                                asmgen.out("  lda  #0 |  sta  cx16.${argi.value.second.registerOrPair.toString().toLowerCase()}+1")
+                                asmgen.out(
+                                    "  lda  #0 |  sta  cx16.${
+                                        argi.value.second.registerOrPair.toString().lowercase()
+                                    }+1")
                        }
                        in WordDatatypes, in IterableDatatypes ->
-                            asmgen.out("""
+                            asmgen.out(
+                                """
                                lda  P8ESTACK_LO$plusIdxStr,x
-                                sta  cx16.${argi.value.second.registerOrPair.toString().toLowerCase()}
+                                sta  cx16.${argi.value.second.registerOrPair.toString().lowercase()}
                                lda  P8ESTACK_HI$plusIdxStr,x
-                                sta  cx16.${argi.value.second.registerOrPair.toString().toLowerCase()}+1
+                                sta  cx16.${
+                                    argi.value.second.registerOrPair.toString().lowercase()
+                                }+1
                            """)
                        else -> throw AssemblyError("weird dt")
                    }
@@ -194,11 +214,10 @@ internal class FunctionCallAsmGen(private val program: Program, private val asmg
        if(argForCarry!=null) {
            val plusIdxStr = if(argForCarry.index==0) "" else "+${argForCarry.index}"
            asmgen.out("""
+                clc
                lda  P8ESTACK_LO$plusIdxStr,x
                beq  +
                sec
-                bcs  ++
-+               clc
 +               php""")             // push the status flags
        }

@@ -237,11 +256,11 @@ internal class FunctionCallAsmGen(private val program: Program, private val asmg
        val valueIDt = value.inferType(program)
        if(!valueIDt.isKnown)
            throw AssemblyError("unknown dt")
-        val valueDt = valueIDt.typeOrElse(DataType.STRUCT)
+        val valueDt = valueIDt.getOr(DataType.UNDEFINED)
        if(!isArgumentTypeCompatible(valueDt, parameter.value.type))
            throw AssemblyError("argument type incompatible")

-        val varName = asmgen.asmVariableName(sub.scopedname+"."+parameter.value.name)
+        val varName = asmgen.asmVariableName(sub.scopedName + parameter.value.name)
        asmgen.assignExpressionToVariable(value, varName, parameter.value.type, sub)
    }

@@ -250,7 +269,7 @@ internal class FunctionCallAsmGen(private val program: Program, private val asmg
        val valueIDt = value.inferType(program)
        if(!valueIDt.isKnown)
            throw AssemblyError("unknown dt")
-        val valueDt = valueIDt.typeOrElse(DataType.STRUCT)
+        val valueDt = valueIDt.getOr(DataType.UNDEFINED)
        if(!isArgumentTypeCompatible(valueDt, parameter.value.type))
            throw AssemblyError("argument type incompatible")

@@ -277,11 +296,10 @@ internal class FunctionCallAsmGen(private val program: Program, private val asmg
                        val sourceName = asmgen.asmVariableName(value)
                        asmgen.out("""
                pha
+                clc
                lda  $sourceName
                beq  +
                sec  
-                bcs  ++
-    +           clc
    +           pla
    """)
                    }
@@ -302,16 +320,17 @@ internal class FunctionCallAsmGen(private val program: Program, private val asmg
            register!!
            if(requiredDt largerThan valueDt) {
                // we need to sign extend the source, do this via temporary word variable
-                val scratchVar = asmgen.asmVariableName("P8ZP_SCRATCH_W1")
-                asmgen.assignExpressionToVariable(value, scratchVar, DataType.UBYTE, sub)
-                asmgen.signExtendVariableLsb(scratchVar, valueDt)
-                asmgen.assignVariableToRegister(scratchVar, register)
+                asmgen.assignExpressionToVariable(value, "P8ZP_SCRATCH_W1", DataType.UBYTE, sub)
+                asmgen.signExtendVariableLsb("P8ZP_SCRATCH_W1", valueDt)
+                asmgen.assignVariableToRegister("P8ZP_SCRATCH_W1", register)
            } else {
                val target: AsmAssignTarget =
                    if(parameter.value.type in ByteDatatypes && (register==RegisterOrPair.AX || register == RegisterOrPair.AY || register==RegisterOrPair.XY || register in Cx16VirtualRegisters))
                        AsmAssignTarget(TargetStorageKind.REGISTER, program, asmgen, parameter.value.type, sub, register = register)
-                    else
-                        AsmAssignTarget.fromRegisters(register, sub, program, asmgen)
+                    else {
+                        val signed = parameter.value.type == DataType.BYTE || parameter.value.type == DataType.WORD
+                        AsmAssignTarget.fromRegisters(register, signed, sub, program, asmgen)
+                    }
                val src = if(valueDt in PassByReferenceDatatypes) {
                    if(value is IdentifierReference) {
                        val addr = AddressOf(value, Position.DUMMY)
@@ -6,7 +6,7 @@ import prog8.ast.expressions.IdentifierReference
 import prog8.ast.expressions.NumericLiteralValue
 import prog8.ast.statements.PostIncrDecr
 import prog8.ast.toHex
-import prog8.compiler.AssemblyError
+import prog8.compiler.target.AssemblyError


 internal class PostIncrDecrAsmGen(private val program: Program, private val asmgen: AsmGen) {
@@ -15,11 +15,11 @@ internal class PostIncrDecrAsmGen(private val program: Program, private val asmg
        val targetIdent = stmt.target.identifier
        val targetMemory = stmt.target.memoryAddress
        val targetArrayIdx = stmt.target.arrayindexed
-        val scope = stmt.definingSubroutine()
+        val scope = stmt.definingSubroutine
        when {
            targetIdent!=null -> {
                val what = asmgen.asmVariableName(targetIdent)
-                when (stmt.target.inferType(program).typeOrElse(DataType.STRUCT)) {
+                when (stmt.target.inferType(program).getOr(DataType.UNDEFINED)) {
                    in ByteDatatypes -> asmgen.out(if (incr) "  inc  $what" else "  dec  $what")
                    in WordDatatypes -> {
                        if(incr)
@@ -65,7 +65,7 @@ internal class PostIncrDecrAsmGen(private val program: Program, private val asmg
            }
            targetArrayIdx!=null -> {
                val asmArrayvarname = asmgen.asmVariableName(targetArrayIdx.arrayvar)
-                val elementDt = targetArrayIdx.inferType(program).typeOrElse(DataType.STRUCT)
+                val elementDt = targetArrayIdx.inferType(program).getOr(DataType.UNDEFINED)
                val constIndex = targetArrayIdx.indexer.constIndex()
                if(constIndex!=null) {
                    val indexValue = constIndex * program.memsizer.memorySize(elementDt)
@@ -1,11 +1,11 @@
 package prog8.compiler.target.cpu6502.codegen.assignment

-import prog8.ast.IMemSizer
 import prog8.ast.Program
 import prog8.ast.base.*
 import prog8.ast.expressions.*
 import prog8.ast.statements.*
-import prog8.compiler.AssemblyError
+import prog8.compilerinterface.IMemSizer
+import prog8.compiler.target.AssemblyError
 import prog8.compiler.target.cpu6502.codegen.AsmGen


@@ -39,13 +39,14 @@ internal class AsmAssignTarget(val kind: TargetStorageKind,
                               val origAstTarget: AssignTarget? = null
                               )
 {
-    val constMemoryAddress by lazy { memory?.addressExpression?.constValue(program)?.number?.toInt() ?: 0}
-    val constArrayIndexValue by lazy { array?.indexer?.constIndex() }
-    val asmVarname: String
-        get() = if(array==null)
+    val constMemoryAddress by lazy { memory?.addressExpression?.constValue(program)?.number?.toUInt() ?: 0u}
+    val constArrayIndexValue by lazy { array?.indexer?.constIndex()?.toUInt() }
+    val asmVarname: String by lazy {
+        if (array == null)
            variableAsmName!!
        else
            asmgen.asmVariableName(array.arrayvar)
+    }

    lateinit var origAssign: AsmAssignment

@@ -55,27 +56,42 @@ internal class AsmAssignTarget(val kind: TargetStorageKind,
    }

    companion object {
-        fun fromAstAssignment(assign: Assignment, program: Program, asmgen: AsmGen): AsmAssignTarget = with(assign.target) {
-            val idt = inferType(program)
-            if(!idt.isKnown)
-                throw AssemblyError("unknown dt")
-            val dt = idt.typeOrElse(DataType.STRUCT)
-            when {
-                identifier != null -> AsmAssignTarget(TargetStorageKind.VARIABLE, program, asmgen, dt, assign.definingSubroutine(), variableAsmName = asmgen.asmVariableName(identifier!!), origAstTarget =  this)
-                arrayindexed != null -> AsmAssignTarget(TargetStorageKind.ARRAY, program, asmgen, dt, assign.definingSubroutine(), array = arrayindexed, origAstTarget =  this)
-                memoryAddress != null -> AsmAssignTarget(TargetStorageKind.MEMORY, program, asmgen, dt, assign.definingSubroutine(), memory =  memoryAddress, origAstTarget =  this)
-                else -> throw AssemblyError("weird target")
+        fun fromAstAssignment(assign: Assignment, program: Program, asmgen: AsmGen): AsmAssignTarget {
+            with(assign.target) {
+                val idt = inferType(program)
+                if(!idt.isKnown)
+                    throw AssemblyError("unknown dt")
+                val dt = idt.getOr(DataType.UNDEFINED)
+                when {
+                    identifier != null -> {
+                        val parameter = identifier!!.targetVarDecl(program)?.subroutineParameter
+                        if (parameter!=null) {
+                            val sub = parameter.definingSubroutine!!
+                            if (sub.isAsmSubroutine) {
+                                val reg = sub.asmParameterRegisters[sub.parameters.indexOf(parameter)]
+                                if(reg.statusflag!=null)
+                                    throw AssemblyError("can't assign value to processor statusflag directly")
+                                else
+                                    return AsmAssignTarget(TargetStorageKind.REGISTER, program, asmgen, dt, assign.definingSubroutine, register=reg.registerOrPair, origAstTarget = this)
+                            }
+                        }
+                        return AsmAssignTarget(TargetStorageKind.VARIABLE, program, asmgen, dt, assign.definingSubroutine, variableAsmName = asmgen.asmVariableName(identifier!!), origAstTarget =  this)
+                    }
+                    arrayindexed != null -> return AsmAssignTarget(TargetStorageKind.ARRAY, program, asmgen, dt, assign.definingSubroutine, array = arrayindexed, origAstTarget =  this)
+                    memoryAddress != null -> return AsmAssignTarget(TargetStorageKind.MEMORY, program, asmgen, dt, assign.definingSubroutine, memory =  memoryAddress, origAstTarget =  this)
+                    else -> throw AssemblyError("weird target")
+                }
            }
        }

-        fun fromRegisters(registers: RegisterOrPair, scope: Subroutine?, program: Program, asmgen: AsmGen): AsmAssignTarget =
+        fun fromRegisters(registers: RegisterOrPair, signed: Boolean, scope: Subroutine?, program: Program, asmgen: AsmGen): AsmAssignTarget =
                when(registers) {
                    RegisterOrPair.A,
                    RegisterOrPair.X,
-                    RegisterOrPair.Y -> AsmAssignTarget(TargetStorageKind.REGISTER, program, asmgen, DataType.UBYTE, scope, register = registers)
+                    RegisterOrPair.Y -> AsmAssignTarget(TargetStorageKind.REGISTER, program, asmgen, if(signed) DataType.BYTE else DataType.UBYTE, scope, register = registers)
                    RegisterOrPair.AX,
                    RegisterOrPair.AY,
-                    RegisterOrPair.XY -> AsmAssignTarget(TargetStorageKind.REGISTER, program, asmgen, DataType.UWORD, scope, register = registers)
+                    RegisterOrPair.XY -> AsmAssignTarget(TargetStorageKind.REGISTER, program, asmgen, if(signed) DataType.WORD else DataType.UWORD, scope, register = registers)
                    RegisterOrPair.FAC1,
                    RegisterOrPair.FAC2 -> AsmAssignTarget(TargetStorageKind.REGISTER, program, asmgen, DataType.FLOAT, scope, register = registers)
                    RegisterOrPair.R0,
@@ -93,7 +109,7 @@ internal class AsmAssignTarget(val kind: TargetStorageKind,
                    RegisterOrPair.R12,
                    RegisterOrPair.R13,
                    RegisterOrPair.R14,
-                    RegisterOrPair.R15 -> AsmAssignTarget(TargetStorageKind.REGISTER, program, asmgen, DataType.UWORD, scope, register = registers)
+                    RegisterOrPair.R15 -> AsmAssignTarget(TargetStorageKind.REGISTER, program, asmgen, if(signed) DataType.WORD else DataType.UWORD, scope, register = registers)
                }
    }
 }
@@ -110,8 +126,8 @@ internal class AsmAssignSource(val kind: SourceStorageKind,
                               val expression: Expression? = null
 )
 {
-    val constMemoryAddress by lazy { memory?.addressExpression?.constValue(program)?.number?.toInt() ?: 0}
-    val constArrayIndexValue by lazy { array?.indexer?.constIndex() }
+    val constMemoryAddress by lazy { memory?.addressExpression?.constValue(program)?.number?.toUInt() ?: 0u}
+    val constArrayIndexValue by lazy { array?.indexer?.constIndex()?.toUInt() }

    val asmVarname: String
        get() = if(array==null)
@@ -132,12 +148,15 @@ internal class AsmAssignSource(val kind: SourceStorageKind,
                is StringLiteralValue -> throw AssemblyError("string literal value should not occur anymore for asm generation")
                is ArrayLiteralValue -> throw AssemblyError("array literal value should not occur anymore for asm generation")
                is IdentifierReference -> {
-                    val dt = value.inferType(program).typeOrElse(DataType.STRUCT)
+                    val parameter = value.targetVarDecl(program)?.subroutineParameter
+                    if(parameter!=null && parameter.definingSubroutine!!.isAsmSubroutine)
+                        throw AssemblyError("can't assign from a asmsub register parameter $value ${value.position}")
+                    val dt = value.inferType(program).getOr(DataType.UNDEFINED)
                    val varName=asmgen.asmVariableName(value)
                    // special case: "cx16.r[0-15]" are 16-bits virtual registers of the commander X16 system
-                    if(dt==DataType.UWORD && varName.toLowerCase().startsWith("cx16.r")) {
-                        val regStr = varName.toLowerCase().substring(5)
-                        val reg = RegisterOrPair.valueOf(regStr.toUpperCase())
+                    if(dt == DataType.UWORD && varName.lowercase().startsWith("cx16.r")) {
+                        val regStr = varName.lowercase().substring(5)
+                        val reg = RegisterOrPair.valueOf(regStr.uppercase())
                        AsmAssignSource(SourceStorageKind.REGISTER, program, asmgen, dt, register = reg)
                    } else {
                        AsmAssignSource(SourceStorageKind.VARIABLE, program, asmgen, dt, variableAsmName = varName)
@@ -147,7 +166,7 @@ internal class AsmAssignSource(val kind: SourceStorageKind,
                    AsmAssignSource(SourceStorageKind.MEMORY, program, asmgen, DataType.UBYTE, memory = value)
                }
                is ArrayIndexedExpression -> {
-                    val dt = value.inferType(program).typeOrElse(DataType.STRUCT)
+                    val dt = value.inferType(program).getOr(DataType.UNDEFINED)
                    AsmAssignSource(SourceStorageKind.ARRAY, program, asmgen, dt, array = value)
                }
                is FunctionCall -> {
@@ -162,7 +181,7 @@ internal class AsmAssignSource(val kind: SourceStorageKind,
                            val returnType = value.inferType(program)
                            if(!returnType.isKnown)
                                throw AssemblyError("unknown dt")
-                            AsmAssignSource(SourceStorageKind.EXPRESSION, program, asmgen, returnType.typeOrElse(DataType.STRUCT), expression = value)
+                            AsmAssignSource(SourceStorageKind.EXPRESSION, program, asmgen, returnType.getOr(DataType.UNDEFINED), expression = value)
                        }
                        else -> {
                            throw AssemblyError("weird call")
@@ -173,7 +192,7 @@ internal class AsmAssignSource(val kind: SourceStorageKind,
                    val dt = value.inferType(program)
                    if(!dt.isKnown)
                        throw AssemblyError("unknown dt")
-                    AsmAssignSource(SourceStorageKind.EXPRESSION, program, asmgen, dt.typeOrElse(DataType.STRUCT), expression = value)
+                    AsmAssignSource(SourceStorageKind.EXPRESSION, program, asmgen, dt.getOr(DataType.UNDEFINED), expression = value)
                }
            }
        }
@@ -205,10 +224,10 @@ internal class AsmAssignment(val source: AsmAssignSource,
                             val position: Position) {

    init {
-        if(target.register !in setOf(RegisterOrPair.XY, RegisterOrPair.AX, RegisterOrPair.AY))
-            require(source.datatype != DataType.STRUCT) { "must not be placeholder datatype" }
+        if(target.register !in arrayOf(RegisterOrPair.XY, RegisterOrPair.AX, RegisterOrPair.AY))
+            require(source.datatype != DataType.UNDEFINED) { "must not be placeholder/undefined datatype" }
            require(memsizer.memorySize(source.datatype) <= memsizer.memorySize(target.datatype)) {
-                "source storage size must be less or equal to target datatype storage size"
+                "source dt size must be less or equal to target dt size at $position"
            }
    }
 }
@@ -5,19 +5,16 @@ import prog8.ast.base.*
 import prog8.ast.expressions.*
 import prog8.ast.statements.*
 import prog8.ast.toHex
-import prog8.compiler.AssemblyError
-import prog8.compiler.functions.BuiltinFunctions
-import prog8.compiler.functions.builtinFunctionReturnType
-import prog8.compiler.target.CpuType
+import prog8.compiler.target.AssemblyError
 import prog8.compiler.target.cpu6502.codegen.AsmGen
-import prog8.compiler.target.cpu6502.codegen.ExpressionsAsmGen
+import prog8.compilerinterface.BuiltinFunctions
+import prog8.compilerinterface.CpuType
+import prog8.compilerinterface.builtinFunctionReturnType


-internal class AssignmentAsmGen(private val program: Program, private val asmgen: AsmGen,
-                                private val exprAsmgen: ExpressionsAsmGen
-) {
+internal class AssignmentAsmGen(private val program: Program, private val asmgen: AsmGen) {

-    private val augmentableAsmGen = AugmentableAssignmentAsmGen(program, this, exprAsmgen, asmgen)
+    private val augmentableAsmGen = AugmentableAssignmentAsmGen(program, this, asmgen)

    fun translate(assignment: Assignment) {
        val target = AsmAssignTarget.fromAstAssignment(assignment, program, asmgen)
@@ -32,15 +29,27 @@ internal class AssignmentAsmGen(private val program: Program, private val asmgen
            translateNormalAssignment(assign)
    }

+    internal fun virtualRegsToVariables(origtarget: AsmAssignTarget): AsmAssignTarget {
+        return if(origtarget.kind==TargetStorageKind.REGISTER && origtarget.register in Cx16VirtualRegisters) {
+            AsmAssignTarget(TargetStorageKind.VARIABLE, program, asmgen, origtarget.datatype, origtarget.scope,
+                variableAsmName = "cx16.${origtarget.register!!.name.lowercase()}", origAstTarget = origtarget.origAstTarget)
+        } else origtarget
+    }
+
    fun translateNormalAssignment(assign: AsmAssignment) {
+        if(assign.isAugmentable) {
+            augmentableAsmGen.translate(assign)
+            return
+        }
+
        when(assign.source.kind) {
            SourceStorageKind.LITERALNUMBER -> {
                // simple case: assign a constant number
                val num = assign.source.number!!.number
                when (assign.target.datatype) {
-                    DataType.UBYTE, DataType.BYTE -> assignConstantByte(assign.target, num.toShort())
+                    DataType.UBYTE, DataType.BYTE -> assignConstantByte(assign.target, num.toInt())
                    DataType.UWORD, DataType.WORD -> assignConstantWord(assign.target, num.toInt())
-                    DataType.FLOAT -> assignConstantFloat(assign.target, num.toDouble())
+                    DataType.FLOAT -> assignConstantFloat(assign.target, num)
                    else -> throw AssemblyError("weird numval type")
                }
            }
@@ -115,7 +124,7 @@ internal class AssignmentAsmGen(private val program: Program, private val asmgen
            }
            SourceStorageKind.MEMORY -> {
                fun assignViaExprEval(expression: Expression) {
-                    assignExpressionToVariable(expression, asmgen.asmVariableName("P8ZP_SCRATCH_W2"), DataType.UWORD, assign.target.scope)
+                    assignExpressionToVariable(expression, "P8ZP_SCRATCH_W2", DataType.UWORD, assign.target.scope)
                    if (asmgen.isTargetCpu(CpuType.CPU65c02))
                        asmgen.out("  lda  (P8ZP_SCRATCH_W2)")
                    else
@@ -126,7 +135,7 @@ internal class AssignmentAsmGen(private val program: Program, private val asmgen
                val value = assign.source.memory!!
                when (value.addressExpression) {
                    is NumericLiteralValue -> {
-                        val address = (value.addressExpression as NumericLiteralValue).number.toInt()
+                        val address = (value.addressExpression as NumericLiteralValue).number.toUInt()
                        assignMemoryByte(assign.target, address, null)
                    }
                    is IdentifierReference -> {
@@ -145,7 +154,7 @@ internal class AssignmentAsmGen(private val program: Program, private val asmgen
            SourceStorageKind.EXPRESSION -> {
                when(val value = assign.source.expression!!) {
                    is AddressOf -> {
-                        val sourceName = value.identifier.firstStructVarName(program) ?: asmgen.asmVariableName(value.identifier)
+                        val sourceName = asmgen.asmSymbolName(value.identifier)
                        assignAddressOf(assign.target, sourceName)
                    }
                    is NumericLiteralValue -> throw AssemblyError("source kind should have been literalnumber")
@@ -157,7 +166,7 @@ internal class AssignmentAsmGen(private val program: Program, private val asmgen
                        when (val sub = value.target.targetStatement(program)) {
                            is Subroutine -> {
                                asmgen.saveXbeforeCall(value)
-                                asmgen.translateFunctionCall(value)
+                                asmgen.translateFunctionCall(value, true)
                                val returnValue = sub.returntypes.zip(sub.asmReturnvaluesRegisters).singleOrNull { it.second.registerOrPair!=null } ?:
                                    sub.returntypes.zip(sub.asmReturnvaluesRegisters).single { it.second.statusflag!=null }
                                when (returnValue.first) {
@@ -171,13 +180,13 @@ internal class AssignmentAsmGen(private val program: Program, private val asmgen
                                            DataType.STR, DataType.ARRAY_UB, DataType.ARRAY_B -> {
                                                // copy the actual string result into the target string variable
                                                asmgen.out("""
-                                                                        pha
-                                                                        lda  #<${assign.target.asmVarname}
-                                                                        sta  P8ZP_SCRATCH_W1
-                                                                        lda  #>${assign.target.asmVarname}
-                                                                        sta  P8ZP_SCRATCH_W1+1
-                                                                        pla
-                                                                        jsr  prog8_lib.strcpy""")
+                                                    pha
+                                                    lda  #<${assign.target.asmVarname}
+                                                    sta  P8ZP_SCRATCH_W1
+                                                    lda  #>${assign.target.asmVarname}
+                                                    sta  P8ZP_SCRATCH_W1+1
+                                                    pla
+                                                    jsr  prog8_lib.strcpy""")
                                            }
                                            else -> throw AssemblyError("weird target dt")
                                        }
@@ -217,7 +226,7 @@ internal class AssignmentAsmGen(private val program: Program, private val asmgen
                                    val returntype = builtinFunctionReturnType(sub.name, value.args, program)
                                    if(!returntype.isKnown)
                                        throw AssemblyError("unknown dt")
-                                    when(returntype.typeOrElse(DataType.STRUCT)) {
+                                    when(returntype.getOr(DataType.UNDEFINED)) {
                                        in ByteDatatypes -> assignRegisterByte(assign.target, CpuRegister.A)            // function's byte result is in A
                                        in WordDatatypes -> assignRegisterpairWord(assign.target, RegisterOrPair.AY)    // function's word result is in AY
                                        DataType.STR -> {
@@ -249,30 +258,41 @@ internal class AssignmentAsmGen(private val program: Program, private val asmgen
                            }
                        }
                    }
+                    is PrefixExpression -> {
+                        // first assign the value to the target then apply the operator in place on the target.
+                        translateNormalAssignment(AsmAssignment(
+                            AsmAssignSource.fromAstSource(value.expression, program, asmgen),
+                            assign.target,
+                            false, program.memsizer, assign.position
+                        ))
+                        val target = virtualRegsToVariables(assign.target)
+                        when(value.operator) {
+                            "+" -> {}
+                            "-" -> augmentableAsmGen.inplaceNegate(target, target.datatype)
+                            "~" -> augmentableAsmGen.inplaceInvert(target, target.datatype)
+                            "not" -> augmentableAsmGen.inplaceBooleanNot(target, target.datatype)
+                            else -> throw AssemblyError("invalid prefix operator")
+                        }
+                    }
                    else -> {
                        // Everything else just evaluate via the stack.
-                        // (we can't use the assignment helper functions to do it via registers here,
+                        // (we can't use the assignment helper functions (assignExpressionTo...) to do it via registers here,
                        // because the code here is the implementation of exactly that...)
-                        if (value.parent is Return) {
-                            if (this.asmgen.options.slowCodegenWarnings)
-                                println("warning: slow stack evaluation used for return: $value  target=${assign.target.kind} at ${value.position}")
-                        }
-                        exprAsmgen.translateExpression(value)
+                        // TODO DON'T STACK-EVAL THIS... by using a temp var? so that it becomes augmentable assignment expression?
+                        asmgen.translateExpression(value)
                        if (assign.target.datatype in WordDatatypes && assign.source.datatype in ByteDatatypes)
                            asmgen.signExtendStackLsb(assign.source.datatype)
-                        assignStackValue(assign.target)
+                        if(assign.target.kind!=TargetStorageKind.STACK || assign.target.datatype != assign.source.datatype)
+                            assignStackValue(assign.target)
                    }
                }
            }
            SourceStorageKind.REGISTER -> {
-                when(assign.source.datatype) {
-                    DataType.UBYTE -> assignRegisterByte(assign.target, assign.source.register!!.asCpuRegister())
-                    DataType.UWORD -> assignRegisterpairWord(assign.target, assign.source.register!!)
-                    else -> throw AssemblyError("invalid register dt")
-                }
+                asmgen.assignRegister(assign.source.register!!, assign.target)
            }
            SourceStorageKind.STACK -> {
-                assignStackValue(assign.target)
+                if(assign.target.kind!=TargetStorageKind.STACK || assign.target.datatype != assign.source.datatype)
+                    assignStackValue(assign.target)
            }
        }
    }
@@ -299,7 +319,7 @@ internal class AssignmentAsmGen(private val program: Program, private val asmgen
        val valueIDt = value.inferType(program)
        if(!valueIDt.isKnown)
            throw AssemblyError("unknown dt")
-        val valueDt = valueIDt.typeOrElse(DataType.STRUCT)
+        val valueDt = valueIDt.getOr(DataType.UNDEFINED)
        if(valueDt==targetDt)
            throw AssemblyError("type cast to identical dt should have been removed")

@@ -320,7 +340,7 @@ internal class AssignmentAsmGen(private val program: Program, private val asmgen
                if(targetDt in WordDatatypes) {

                    fun assignViaExprEval(addressExpression: Expression) {
-                        asmgen.assignExpressionToVariable(addressExpression, asmgen.asmVariableName("P8ZP_SCRATCH_W2"), DataType.UWORD, null)
+                        asmgen.assignExpressionToVariable(addressExpression, "P8ZP_SCRATCH_W2", DataType.UWORD, null)
                        if (asmgen.isTargetCpu(CpuType.CPU65c02))
                            asmgen.out("  lda  (P8ZP_SCRATCH_W2)")
                        else
@@ -330,7 +350,7 @@ internal class AssignmentAsmGen(private val program: Program, private val asmgen

                    when (value.addressExpression) {
                        is NumericLiteralValue -> {
-                            val address = (value.addressExpression as NumericLiteralValue).number.toInt()
+                            val address = (value.addressExpression as NumericLiteralValue).number.toUInt()
                            assignMemoryByteIntoWord(target, address, null)
                            return
                        }
@@ -359,21 +379,21 @@ internal class AssignmentAsmGen(private val program: Program, private val asmgen

        // special case optimizations
        if(target.kind== TargetStorageKind.VARIABLE) {
-            if(value is IdentifierReference && valueDt != DataType.STRUCT)
+            if(value is IdentifierReference && valueDt != DataType.UNDEFINED)
                return assignTypeCastedIdentifier(target.asmVarname, targetDt, asmgen.asmVariableName(value), valueDt)

            when (valueDt) {
                in ByteDatatypes -> {
-                    assignExpressionToRegister(value, RegisterOrPair.A)
+                    assignExpressionToRegister(value, RegisterOrPair.A, valueDt==DataType.BYTE)
                    assignTypeCastedRegisters(target.asmVarname, targetDt, RegisterOrPair.A, valueDt)
                }
                in WordDatatypes -> {
-                    assignExpressionToRegister(value, RegisterOrPair.AY)
+                    assignExpressionToRegister(value, RegisterOrPair.AY, valueDt==DataType.WORD)
                    assignTypeCastedRegisters(target.asmVarname, targetDt, RegisterOrPair.AY, valueDt)
                }
                DataType.FLOAT -> {
-                    assignExpressionToRegister(value, RegisterOrPair.FAC1)
-                    assignTypecastedFloatFAC1(target.asmVarname, targetDt)
+                    assignExpressionToRegister(value, RegisterOrPair.FAC1, true)
+                    assignTypeCastedFloatFAC1(target.asmVarname, targetDt)
                }
                in PassByReferenceDatatypes -> {
                    // str/array value cast (most likely to UWORD, take address-of)
@@ -398,15 +418,15 @@ internal class AssignmentAsmGen(private val program: Program, private val asmgen
                RegisterOrPair.A,
                RegisterOrPair.X,
                RegisterOrPair.Y -> {
-                    // 'cast' a ubyte value to a byte register; no cast needed at all
-                    return assignExpressionToRegister(value, target.register)
+                    // 'cast' an ubyte value to a byte register; no cast needed at all
+                    return assignExpressionToRegister(value, target.register, false)
                }
                RegisterOrPair.AX,
                RegisterOrPair.AY,
                RegisterOrPair.XY,
                in Cx16VirtualRegisters -> {
                    // cast an ubyte value to a 16 bits register, just assign it and make use of the value extension
-                    return assignExpressionToRegister(value, target.register!!)
+                    return assignExpressionToRegister(value, target.register!!, false)
                }
                else -> {}
            }
@@ -424,19 +444,41 @@ internal class AssignmentAsmGen(private val program: Program, private val asmgen
                RegisterOrPair.XY,
                in Cx16VirtualRegisters -> {
                    // 'cast' uword into a 16 bits register, just assign it
-                    return assignExpressionToRegister(value, target.register!!)
+                    return assignExpressionToRegister(value, target.register!!, false)
                }
                else -> {}
            }
        }

-        // give up, do it via eval stack
-        // TODO optimize typecasts for more special cases?
-        // note: cannot use assignTypeCastedValue because that is ourselves :P
-        if(this.asmgen.options.slowCodegenWarnings)
-            println("warning: slow stack evaluation used for typecast: $value into $targetDt (target=${target.kind} at ${value.position}")
-        asmgen.translateExpression(origTypeCastExpression)      // this performs the actual type cast in translateExpression(Typecast)
-        assignStackValue(target)
+        if(targetDt==DataType.FLOAT && (target.register==RegisterOrPair.FAC1 || target.register==RegisterOrPair.FAC2)) {
+            when(valueDt) {
+                DataType.UBYTE -> {
+                    assignExpressionToRegister(value, RegisterOrPair.Y, false)
+                    asmgen.out("  jsr  floats.FREADUY")
+                }
+                DataType.BYTE -> {
+                    assignExpressionToRegister(value, RegisterOrPair.A, true)
+                    asmgen.out("  jsr  floats.FREADSA")
+                }
+                DataType.UWORD -> {
+                    assignExpressionToRegister(value, RegisterOrPair.AY, false)
+                    asmgen.out("  jsr  floats.GIVUAYFAY")
+                }
+                DataType.WORD -> {
+                    assignExpressionToRegister(value, RegisterOrPair.AY, true)
+                    asmgen.out("  jsr  floats.GIVAYFAY")
+                }
+                else -> throw AssemblyError("invalid dt")
+            }
+            if(target.register==RegisterOrPair.FAC2) {
+                asmgen.out("  jsr floats.MOVEF")
+            }
+        } else {
+            // No more special optmized cases yet. Do the rest via more complex evaluation
+            // note: cannot use assignTypeCastedValue because that is ourselves :P
+            // NOTE: THIS MAY TURN INTO A STACK OVERFLOW ERROR IF IT CAN'T SIMPLIFY THE TYPECAST..... :-/
+            asmgen.assignExpressionTo(origTypeCastExpression, target)
+        }
    }

    private fun assignCastViaLsbFunc(value: Expression, target: AsmAssignTarget) {
@@ -447,7 +489,7 @@ internal class AssignmentAsmGen(private val program: Program, private val asmgen
        translateNormalAssignment(assign)
    }

-    private fun assignTypecastedFloatFAC1(targetAsmVarName: String, targetDt: DataType) {
+    private fun assignTypeCastedFloatFAC1(targetAsmVarName: String, targetDt: DataType) {

        if(targetDt==DataType.FLOAT)
            throw AssemblyError("typecast to identical type")
@@ -587,13 +629,19 @@ internal class AssignmentAsmGen(private val program: Program, private val asmgen
            DataType.UBYTE -> {
                when(targetDt) {
                    DataType.UBYTE, DataType.BYTE -> {
-                        asmgen.out("  st${regs.toString().toLowerCase()}  $targetAsmVarName")
+                        asmgen.out("  st${regs.toString().lowercase()}  $targetAsmVarName")
                    }
                    DataType.UWORD, DataType.WORD -> {
                        if(asmgen.isTargetCpu(CpuType.CPU65c02))
-                            asmgen.out("  st${regs.toString().toLowerCase()}  $targetAsmVarName |  stz  $targetAsmVarName+1")
+                            asmgen.out(
+                                "  st${
+                                    regs.toString().lowercase()
+                                }  $targetAsmVarName |  stz  $targetAsmVarName+1")
                        else
-                            asmgen.out("  st${regs.toString().toLowerCase()}  $targetAsmVarName |  lda  #0  |  sta  $targetAsmVarName+1")
+                            asmgen.out(
+                                "  st${
+                                    regs.toString().lowercase()
+                                }  $targetAsmVarName |  lda  #0  |  sta  $targetAsmVarName+1")
                    }
                    DataType.FLOAT -> {
                        when(regs) {
@@ -615,13 +663,19 @@ internal class AssignmentAsmGen(private val program: Program, private val asmgen
            DataType.BYTE -> {
                when(targetDt) {
                    DataType.UBYTE, DataType.BYTE -> {
-                        asmgen.out("  st${regs.toString().toLowerCase()}  $targetAsmVarName")
+                        asmgen.out("  st${regs.toString().lowercase()}  $targetAsmVarName")
                    }
                    DataType.UWORD -> {
                        if(asmgen.isTargetCpu(CpuType.CPU65c02))
-                            asmgen.out("  st${regs.toString().toLowerCase()}  $targetAsmVarName |  stz  $targetAsmVarName+1")
+                            asmgen.out(
+                                "  st${
+                                    regs.toString().lowercase()
+                                }  $targetAsmVarName |  stz  $targetAsmVarName+1")
                        else
-                            asmgen.out("  st${regs.toString().toLowerCase()}  $targetAsmVarName |  lda  #0  |  sta  $targetAsmVarName+1")
+                            asmgen.out(
+                                "  st${
+                                    regs.toString().lowercase()
+                                }  $targetAsmVarName |  lda  #0  |  sta  $targetAsmVarName+1")
                    }
                    DataType.WORD -> {
                        when(regs) {
@@ -653,7 +707,7 @@ internal class AssignmentAsmGen(private val program: Program, private val asmgen
            DataType.UWORD -> {
                when(targetDt) {
                    DataType.BYTE, DataType.UBYTE -> {
-                        asmgen.out("  st${regs.toString().toLowerCase().first()}  $targetAsmVarName")
+                        asmgen.out("  st${regs.toString().lowercase().first()}  $targetAsmVarName")
                    }
                    DataType.WORD, DataType.UWORD -> {
                        when(regs) {
@@ -681,7 +735,7 @@ internal class AssignmentAsmGen(private val program: Program, private val asmgen
            DataType.WORD -> {
                when(targetDt) {
                    DataType.BYTE, DataType.UBYTE -> {
-                        asmgen.out("  st${regs.toString().toLowerCase().first()}  $targetAsmVarName")
+                        asmgen.out("  st${regs.toString().lowercase().first()}  $targetAsmVarName")
                    }
                    DataType.WORD, DataType.UWORD -> {
                        when(regs) {
@@ -756,7 +810,7 @@ internal class AssignmentAsmGen(private val program: Program, private val asmgen
            }
            TargetStorageKind.ARRAY -> {
                if(target.constArrayIndexValue!=null) {
-                    val scaledIdx = target.constArrayIndexValue!! * program.memsizer.memorySize(target.datatype)
+                    val scaledIdx = target.constArrayIndexValue!! * program.memsizer.memorySize(target.datatype).toUInt()
                    when(target.datatype) {
                        in ByteDatatypes -> {
                            asmgen.out(" inx | lda  P8ESTACK_LO,x  | sta  ${target.asmVarname}+$scaledIdx")
@@ -822,12 +876,13 @@ internal class AssignmentAsmGen(private val program: Program, private val asmgen
                            RegisterOrPair.AX -> asmgen.out(" inx |  txy |  ldx  #0 |  lda  P8ESTACK_LO,y")
                            RegisterOrPair.AY -> asmgen.out(" inx |  ldy  #0 |  lda  P8ESTACK_LO,x")
                            in Cx16VirtualRegisters -> {
-                                asmgen.out("""
+                                asmgen.out(
+                                    """
                                    inx
                                    lda  P8ESTACK_LO,x
-                                    sta  cx16.${target.register.toString().toLowerCase()}
+                                    sta  cx16.${target.register.toString().lowercase()}
                                    lda  #0
-                                    sta  cx16.${target.register.toString().toLowerCase()}+1
+                                    sta  cx16.${target.register.toString().lowercase()}+1
                                """)
                            }
                            else -> throw AssemblyError("can't assign byte from stack to register pair XY")
@@ -839,12 +894,13 @@ internal class AssignmentAsmGen(private val program: Program, private val asmgen
                            RegisterOrPair.AY-> asmgen.out(" inx |  ldy  P8ESTACK_HI,x |  lda  P8ESTACK_LO,x")
                            RegisterOrPair.XY-> throw AssemblyError("can't load X from stack here - use intermediary var? ${target.origAstTarget?.position}")
                            in Cx16VirtualRegisters -> {
-                                asmgen.out("""
+                                asmgen.out(
+                                    """
                                    inx
                                    lda  P8ESTACK_LO,x
-                                    sta  cx16.${target.register.toString().toLowerCase()}
+                                    sta  cx16.${target.register.toString().lowercase()}
                                    lda  P8ESTACK_HI,x
-                                    sta  cx16.${target.register.toString().toLowerCase()}+1
+                                    sta  cx16.${target.register.toString().lowercase()}+1
                                """)
                            }
                            else -> throw AssemblyError("can't assign word to single byte register")
@@ -888,11 +944,12 @@ internal class AssignmentAsmGen(private val program: Program, private val asmgen
                    RegisterOrPair.AY -> asmgen.out("  ldy  #>$sourceName |  lda  #<$sourceName")
                    RegisterOrPair.XY -> asmgen.out("  ldy  #>$sourceName |  ldx  #<$sourceName")
                    in Cx16VirtualRegisters -> {
-                        asmgen.out("""
+                        asmgen.out(
+                            """
                            lda  #<$sourceName
-                            sta  cx16.${target.register.toString().toLowerCase()}
+                            sta  cx16.${target.register.toString().lowercase()}
                            lda  #>$sourceName
-                            sta  cx16.${target.register.toString().toLowerCase()}+1
+                            sta  cx16.${target.register.toString().lowercase()}+1
                        """)
                    }
                    else -> throw AssemblyError("can't load address in a single 8-bit register")
@@ -939,7 +996,8 @@ internal class AssignmentAsmGen(private val program: Program, private val asmgen
                    lda  #<$sourceName
                    ldy  #>$sourceName+1
                    sta  P8ESTACK_LO,x
-                    sty  P8ESTACK_HI,x
+                    tya
+                    sta  P8ESTACK_HI,x
                    dex""")
            }
            else -> throw AssemblyError("string-assign to weird target")
@@ -962,7 +1020,7 @@ internal class AssignmentAsmGen(private val program: Program, private val asmgen
            TargetStorageKind.ARRAY -> {
                target.array!!
                if(target.constArrayIndexValue!=null) {
-                    val scaledIdx = target.constArrayIndexValue!! * program.memsizer.memorySize(target.datatype)
+                    val scaledIdx = target.constArrayIndexValue!! * program.memsizer.memorySize(target.datatype).toUInt()
                    when(target.datatype) {
                        in ByteDatatypes -> {
                            asmgen.out(" lda  $sourceName  | sta  ${target.asmVarname}+$scaledIdx")
@@ -1017,7 +1075,7 @@ internal class AssignmentAsmGen(private val program: Program, private val asmgen
                                adc  #<${target.asmVarname}
                                bcc  +
                                iny
-+                                   jsr  floats.copy_float""")
+                               jsr  floats.copy_float""")
                        }
                        else -> throw AssemblyError("weird dt")
                    }
@@ -1029,11 +1087,12 @@ internal class AssignmentAsmGen(private val program: Program, private val asmgen
                    RegisterOrPair.AY -> asmgen.out("  ldy  $sourceName+1 |  lda  $sourceName")
                    RegisterOrPair.XY -> asmgen.out("  ldy  $sourceName+1 |  ldx  $sourceName")
                    in Cx16VirtualRegisters -> {
-                        asmgen.out("""
+                        asmgen.out(
+                            """
                            lda  $sourceName
-                            sta  cx16.${target.register.toString().toLowerCase()}
+                            sta  cx16.${target.register.toString().lowercase()}
                            lda  $sourceName+1
-                            sta  cx16.${target.register.toString().toLowerCase()}+1
+                            sta  cx16.${target.register.toString().lowercase()}+1
                        """)
                    }
                    else -> throw AssemblyError("can't load word in a single 8-bit register")
@@ -1050,6 +1109,11 @@ internal class AssignmentAsmGen(private val program: Program, private val asmgen
        }
    }

+    internal fun assignFAC2float(target: AsmAssignTarget) {
+        asmgen.out("  jsr  floats.MOVFA")       // fac2 -> fac1
+        assignFAC1float(target)
+    }
+
    internal fun assignFAC1float(target: AsmAssignTarget) {
        when(target.kind) {
            TargetStorageKind.VARIABLE -> {
@@ -1185,7 +1249,7 @@ internal class AssignmentAsmGen(private val program: Program, private val asmgen
            }
            TargetStorageKind.ARRAY -> {
                if (target.constArrayIndexValue!=null) {
-                    val scaledIdx = target.constArrayIndexValue!! * program.memsizer.memorySize(target.datatype)
+                    val scaledIdx = target.constArrayIndexValue!! * program.memsizer.memorySize(target.datatype).toUInt()
                    asmgen.out(" lda  $sourceName  | sta  ${target.asmVarname}+$scaledIdx")
                }
                else {
@@ -1203,11 +1267,12 @@ internal class AssignmentAsmGen(private val program: Program, private val asmgen
                    RegisterOrPair.XY -> asmgen.out("  ldy  #0 |  ldx  $sourceName")
                    RegisterOrPair.FAC1, RegisterOrPair.FAC2 -> throw AssemblyError("expected typecasted byte to float")
                    in Cx16VirtualRegisters -> {
-                        asmgen.out("""
+                        asmgen.out(
+                            """
                            lda  $sourceName
-                            sta  cx16.${target.register.toString().toLowerCase()}
+                            sta  cx16.${target.register.toString().lowercase()}
                            lda  #0
-                            sta  cx16.${target.register.toString().toLowerCase()}+1
+                            sta  cx16.${target.register.toString().lowercase()}+1
                            """)
                    }
                    else -> throw AssemblyError("weird register")
@@ -1236,11 +1301,20 @@ internal class AssignmentAsmGen(private val program: Program, private val asmgen
                    """)
            }
            TargetStorageKind.ARRAY -> {
-                // TODO optimize slow stack evaluation for this case, see assignVariableUByteIntoWord
-                if(this.asmgen.options.slowCodegenWarnings)
-                    println("warning: slow stack evaluation used for sign-extend byte typecast at ${bytevar.position}")
-                asmgen.translateExpression(wordtarget.origAssign.source.expression!!)
-                assignStackValue(wordtarget)
+                if (wordtarget.constArrayIndexValue!=null) {
+                    val scaledIdx = wordtarget.constArrayIndexValue!! * 2u
+                    asmgen.out("  lda  $sourceName")
+                    asmgen.signExtendAYlsb(DataType.BYTE)
+                    asmgen.out("  sta  ${wordtarget.asmVarname}+$scaledIdx |  sty  ${wordtarget.asmVarname}+$scaledIdx+1")
+                }
+                else {
+                    asmgen.saveRegisterLocal(CpuRegister.X, wordtarget.scope!!)
+                    asmgen.loadScaledArrayIndexIntoRegister(wordtarget.array!!, wordtarget.datatype, CpuRegister.X)
+                    asmgen.out("  lda  $sourceName")
+                    asmgen.signExtendAYlsb(DataType.BYTE)
+                    asmgen.out("  sta  ${wordtarget.asmVarname},x |  inx |  tya |  sta  ${wordtarget.asmVarname},x")
+                    asmgen.restoreRegisterLocal(CpuRegister.X)
+                }
            }
            TargetStorageKind.REGISTER -> {
                when(wordtarget.register!!) {
@@ -1296,7 +1370,7 @@ internal class AssignmentAsmGen(private val program: Program, private val asmgen
            }
            TargetStorageKind.ARRAY -> {
                if (wordtarget.constArrayIndexValue!=null) {
-                    val scaledIdx = wordtarget.constArrayIndexValue!! * 2
+                    val scaledIdx = wordtarget.constArrayIndexValue!! * 2u
                    asmgen.out("  lda  $sourceName  | sta  ${wordtarget.asmVarname}+$scaledIdx")
                    if(asmgen.isTargetCpu(CpuType.CPU65c02))
                        asmgen.out("  stz  ${wordtarget.asmVarname}+$scaledIdx+1")
@@ -1333,9 +1407,11 @@ internal class AssignmentAsmGen(private val program: Program, private val asmgen
    }

    internal fun assignRegisterByte(target: AsmAssignTarget, register: CpuRegister) {
-        // we make an exception in the type check for assigning something to a cx16 virtual register
-        if(target.register !in Cx16VirtualRegisters) {
-            if(target.kind==TargetStorageKind.VARIABLE) {
+        // we make an exception in the type check for assigning something to a cx16 virtual register, or a register pair
+        // these will be correctly typecasted from a byte to a word value
+        if(target.register !in Cx16VirtualRegisters &&
+            target.register!=RegisterOrPair.AX && target.register!=RegisterOrPair.AY && target.register!=RegisterOrPair.XY) {
+            if(target.kind== TargetStorageKind.VARIABLE) {
                val parts = target.asmVarname.split('.')
                if (parts.size != 2 || parts[0] != "cx16")
                    require(target.datatype in ByteDatatypes)
@@ -1346,7 +1422,7 @@ internal class AssignmentAsmGen(private val program: Program, private val asmgen

        when(target.kind) {
            TargetStorageKind.VARIABLE -> {
-                asmgen.out("  st${register.name.toLowerCase()}  ${target.asmVarname}")
+                asmgen.out("  st${register.name.lowercase()}  ${target.asmVarname}")
            }
            TargetStorageKind.MEMORY -> {
                when(register) {
@@ -1386,7 +1462,7 @@ internal class AssignmentAsmGen(private val program: Program, private val asmgen
                        RegisterOrPair.FAC1, RegisterOrPair.FAC2 -> throw AssemblyError("expected type cast to float")
                        in Cx16VirtualRegisters -> {
                            // only assign a single byte to the virtual register's Lsb
-                            asmgen.out("  sta  cx16.${target.register.toString().toLowerCase()}")
+                            asmgen.out("  sta  cx16.${target.register.toString().lowercase()}")
                        }
                        else -> throw AssemblyError("weird register")
                    }
@@ -1400,7 +1476,7 @@ internal class AssignmentAsmGen(private val program: Program, private val asmgen
                        RegisterOrPair.FAC1, RegisterOrPair.FAC2 -> throw AssemblyError("expected type cast to float")
                        in Cx16VirtualRegisters -> {
                            // only assign a single byte to the virtual register's Lsb
-                            asmgen.out("  stx  cx16.${target.register.toString().toLowerCase()}")
+                            asmgen.out("  stx  cx16.${target.register.toString().lowercase()}")
                        }
                        else -> throw AssemblyError("weird register")
                    }
@@ -1414,7 +1490,7 @@ internal class AssignmentAsmGen(private val program: Program, private val asmgen
                        RegisterOrPair.FAC1, RegisterOrPair.FAC2 -> throw AssemblyError("expected type cast to float")
                        in Cx16VirtualRegisters -> {
                            // only assign a single byte to the virtual register's Lsb
-                            asmgen.out("  sty  cx16.${target.register.toString().toLowerCase()}")
+                            asmgen.out("  sty  cx16.${target.register.toString().lowercase()}")
                        }
                        else -> throw AssemblyError("weird register")
                    }
@@ -1431,7 +1507,7 @@ internal class AssignmentAsmGen(private val program: Program, private val asmgen
    }

    internal fun assignRegisterpairWord(target: AsmAssignTarget, regs: RegisterOrPair) {
-        require(target.datatype in NumericDatatypes)
+        require(target.datatype in NumericDatatypes || target.datatype in PassByReferenceDatatypes)
        if(target.datatype==DataType.FLOAT)
            throw AssemblyError("float value should be from FAC1 not from registerpair memory pointer")

@@ -1454,7 +1530,7 @@ internal class AssignmentAsmGen(private val program: Program, private val asmgen
            }
            TargetStorageKind.ARRAY -> {
                if (target.constArrayIndexValue!=null) {
-                    val idx = target.constArrayIndexValue!! * 2
+                    val idx = target.constArrayIndexValue!! * 2u
                    when (regs) {
                        RegisterOrPair.AX -> asmgen.out("  sta  ${target.asmVarname}+$idx |  stx  ${target.asmVarname}+$idx+1")
                        RegisterOrPair.AY -> asmgen.out("  sta  ${target.asmVarname}+$idx |  sty  ${target.asmVarname}+$idx+1")
@@ -1504,9 +1580,10 @@ internal class AssignmentAsmGen(private val program: Program, private val asmgen
                        RegisterOrPair.AX -> { }
                        RegisterOrPair.XY -> { asmgen.out("  stx  P8ZP_SCRATCH_REG |  ldy  P8ZP_SCRATCH_REG |  tax") }
                        in Cx16VirtualRegisters -> {
-                            asmgen.out("""
-                                    sta  cx16.${target.register.toString().toLowerCase()}
-                                    stx  cx16.${target.register.toString().toLowerCase()}+1
+                            asmgen.out(
+                                """
+                                    sta  cx16.${target.register.toString().lowercase()}
+                                    stx  cx16.${target.register.toString().lowercase()}+1
                                """)
                        }
                        else -> throw AssemblyError("expected reg pair or cx16 virtual 16-bit register")
@@ -1516,9 +1593,10 @@ internal class AssignmentAsmGen(private val program: Program, private val asmgen
                        RegisterOrPair.AX -> { asmgen.out("  sty  P8ZP_SCRATCH_REG |  ldx  P8ZP_SCRATCH_REG") }
                        RegisterOrPair.XY -> { asmgen.out("  tax") }
                        in Cx16VirtualRegisters -> {
-                            asmgen.out("""
-                                    sta  cx16.${target.register.toString().toLowerCase()}
-                                    sty  cx16.${target.register.toString().toLowerCase()}+1
+                            asmgen.out(
+                                """
+                                    sta  cx16.${target.register.toString().lowercase()}
+                                    sty  cx16.${target.register.toString().lowercase()}+1
                                """)
                        }
                        else -> throw AssemblyError("expected reg pair or cx16 virtual 16-bit register")
@@ -1528,9 +1606,10 @@ internal class AssignmentAsmGen(private val program: Program, private val asmgen
                        RegisterOrPair.AX -> { asmgen.out("  txa |  sty  P8ZP_SCRATCH_REG |  ldx  P8ZP_SCRATCH_REG") }
                        RegisterOrPair.XY -> { }
                        in Cx16VirtualRegisters -> {
-                            asmgen.out("""
-                                    stx  cx16.${target.register.toString().toLowerCase()}
-                                    sty  cx16.${target.register.toString().toLowerCase()}+1
+                            asmgen.out(
+                                """
+                                    stx  cx16.${target.register.toString().lowercase()}
+                                    sty  cx16.${target.register.toString().lowercase()}+1
                                """)
                        }
                        else -> throw AssemblyError("expected reg pair or cx16 virtual 16-bit register")
@@ -1555,7 +1634,7 @@ internal class AssignmentAsmGen(private val program: Program, private val asmgen
            }
            TargetStorageKind.STACK -> {
                when(regs) {
-                    RegisterOrPair.AY -> asmgen.out("  sta  P8ESTACK_LO,x |  sty  P8ESTACK_HI,x |  dex")
+                    RegisterOrPair.AY -> asmgen.out("  sta  P8ESTACK_LO,x |  tya |  sta  P8ESTACK_HI,x |  dex")
                    RegisterOrPair.AX, RegisterOrPair.XY -> throw AssemblyError("can't use X here")
                    in Cx16VirtualRegisters -> {
                        val srcReg = asmgen.asmSymbolName(regs)
@@ -1597,7 +1676,10 @@ internal class AssignmentAsmGen(private val program: Program, private val asmgen
                        RegisterOrPair.AY -> asmgen.out("  lda  #0 |  tay")
                        RegisterOrPair.XY -> asmgen.out("  ldx  #0 |  ldy  #0")
                        in Cx16VirtualRegisters -> {
-                            asmgen.out("  stz  cx16.${target.register.toString().toLowerCase()} |  stz  cx16.${target.register.toString().toLowerCase()}+1")
+                            asmgen.out(
+                                "  stz  cx16.${
+                                    target.register.toString().lowercase()
+                                } |  stz  cx16.${target.register.toString().lowercase()}+1")
                        }
                        else -> throw AssemblyError("invalid register for word value")
                    }
@@ -1647,11 +1729,12 @@ internal class AssignmentAsmGen(private val program: Program, private val asmgen
                    RegisterOrPair.AY -> asmgen.out("  ldy  #>${word.toHex()} |  lda  #<${word.toHex()}")
                    RegisterOrPair.XY -> asmgen.out("  ldy  #>${word.toHex()} |  ldx  #<${word.toHex()}")
                    in Cx16VirtualRegisters -> {
-                        asmgen.out("""
+                        asmgen.out(
+                            """
                            lda  #<${word.toHex()}
-                            sta  cx16.${target.register.toString().toLowerCase()}
+                            sta  cx16.${target.register.toString().lowercase()}
                            lda  #>${word.toHex()}
-                            sta  cx16.${target.register.toString().toLowerCase()}+1
+                            sta  cx16.${target.register.toString().lowercase()}+1
                            """)
                    }
                    else -> throw AssemblyError("invalid register for word value")
@@ -1668,8 +1751,8 @@ internal class AssignmentAsmGen(private val program: Program, private val asmgen
        }
    }

-    private fun assignConstantByte(target: AsmAssignTarget, byte: Short) {
-        if(byte==0.toShort() && asmgen.isTargetCpu(CpuType.CPU65c02)) {
+    private fun assignConstantByte(target: AsmAssignTarget, byte: Int) {
+        if(byte==0 && asmgen.isTargetCpu(CpuType.CPU65c02)) {
            // optimize setting zero value for this cpu
            when(target.kind) {
                TargetStorageKind.VARIABLE -> {
@@ -1698,7 +1781,10 @@ internal class AssignmentAsmGen(private val program: Program, private val asmgen
                    RegisterOrPair.XY -> asmgen.out("  ldx  #0 |  ldy  #0")
                    RegisterOrPair.FAC1, RegisterOrPair.FAC2 -> throw AssemblyError("expected typecasted byte to float")
                    in Cx16VirtualRegisters -> {
-                        asmgen.out("  stz  cx16.${target.register.toString().toLowerCase()} |  stz  cx16.${target.register.toString().toLowerCase()}+1")
+                        asmgen.out(
+                            "  stz  cx16.${
+                                target.register.toString().lowercase()
+                            } |  stz  cx16.${target.register.toString().lowercase()}+1")
                    }
                    else -> throw AssemblyError("weird register")
                }
@@ -1738,11 +1824,17 @@ internal class AssignmentAsmGen(private val program: Program, private val asmgen
                RegisterOrPair.XY -> asmgen.out("  ldy  #0 |  ldx  #${byte.toHex()}")
                RegisterOrPair.FAC1, RegisterOrPair.FAC2 -> throw AssemblyError("expected typecasted byte to float")
                in Cx16VirtualRegisters -> {
-                    asmgen.out("  lda  #${byte.toHex()} |  sta  cx16.${target.register.toString().toLowerCase()}")
+                    asmgen.out(
+                        "  lda  #${byte.toHex()} |  sta  cx16.${
+                            target.register.toString().lowercase()
+                        }")
                    if(asmgen.isTargetCpu(CpuType.CPU65c02))
-                        asmgen.out("  stz  cx16.${target.register.toString().toLowerCase()}+1\n")
+                        asmgen.out("  stz  cx16.${target.register.toString().lowercase()}+1\n")
                    else
-                        asmgen.out("  lda  #0 |  sta  cx16.${target.register.toString().toLowerCase()}+1\n")
+                        asmgen.out(
+                            "  lda  #0 |  sta  cx16.${
+                                target.register.toString().lowercase()
+                            }+1\n")
                }
                else -> throw AssemblyError("weird register")
            }
@@ -1893,7 +1985,7 @@ internal class AssignmentAsmGen(private val program: Program, private val asmgen
        }
    }

-    private fun assignMemoryByte(target: AsmAssignTarget, address: Int?, identifier: IdentifierReference?) {
+    private fun assignMemoryByte(target: AsmAssignTarget, address: UInt?, identifier: IdentifierReference?) {
        if (address != null) {
            when(target.kind) {
                TargetStorageKind.VARIABLE -> {
@@ -1918,11 +2010,12 @@ internal class AssignmentAsmGen(private val program: Program, private val asmgen
                    RegisterOrPair.XY -> asmgen.out("  ldy  #0 |  ldy  ${address.toHex()}")
                    RegisterOrPair.FAC1, RegisterOrPair.FAC2 -> throw AssemblyError("expected typecasted byte to float")
                    in Cx16VirtualRegisters -> {
-                        asmgen.out("""
+                        asmgen.out(
+                            """
                            lda  ${address.toHex()}
-                            sta  cx16.${target.register.toString().toLowerCase()}
+                            sta  cx16.${target.register.toString().lowercase()}
                            lda  #0
-                            sta  cx16.${target.register.toString().toLowerCase()}+1
+                            sta  cx16.${target.register.toString().lowercase()}+1
                        """)
                    }
                    else -> throw AssemblyError("weird register")
@@ -1958,10 +2051,11 @@ internal class AssignmentAsmGen(private val program: Program, private val asmgen
                        RegisterOrPair.XY -> asmgen.out("  tax |  ldy  #0")
                        RegisterOrPair.FAC1, RegisterOrPair.FAC2 -> throw AssemblyError("expected typecasted byte to float")
                        in Cx16VirtualRegisters -> {
-                            asmgen.out("""
-                                sta  cx16.${target.register.toString().toLowerCase()}
+                            asmgen.out(
+                                """
+                                sta  cx16.${target.register.toString().lowercase()}
                                lda  #0
-                                sta  cx16.${target.register.toString().toLowerCase()}+1
+                                sta  cx16.${target.register.toString().lowercase()}+1
                            """)
                        }
                        else -> throw AssemblyError("weird register")
@@ -1975,7 +2069,7 @@ internal class AssignmentAsmGen(private val program: Program, private val asmgen
        }
    }

-    private fun assignMemoryByteIntoWord(wordtarget: AsmAssignTarget, address: Int?, identifier: IdentifierReference?) {
+    private fun assignMemoryByteIntoWord(wordtarget: AsmAssignTarget, address: UInt?, identifier: IdentifierReference?) {
        if (address != null) {
            when(wordtarget.kind) {
                TargetStorageKind.VARIABLE -> {
@@ -2045,7 +2139,7 @@ internal class AssignmentAsmGen(private val program: Program, private val asmgen
        fun storeViaExprEval() {
            when(addressExpr) {
                is NumericLiteralValue, is IdentifierReference -> {
-                    assignExpressionToVariable(addressExpr, asmgen.asmVariableName("P8ZP_SCRATCH_W2"), DataType.UWORD, null)
+                    assignExpressionToVariable(addressExpr, "P8ZP_SCRATCH_W2", DataType.UWORD, null)
                    if (asmgen.isTargetCpu(CpuType.CPU65c02))
                        asmgen.out("  sta  (P8ZP_SCRATCH_W2)")
                    else
@@ -2054,7 +2148,7 @@ internal class AssignmentAsmGen(private val program: Program, private val asmgen
                else -> {
                    // same as above but we need to save the A register
                    asmgen.out("  pha")
-                    assignExpressionToVariable(addressExpr, asmgen.asmVariableName("P8ZP_SCRATCH_W2"), DataType.UWORD, null)
+                    assignExpressionToVariable(addressExpr, "P8ZP_SCRATCH_W2", DataType.UWORD, null)
                    asmgen.out("  pla")
                    if (asmgen.isTargetCpu(CpuType.CPU65c02))
                        asmgen.out("  sta  (P8ZP_SCRATCH_W2)")
@@ -2067,7 +2161,7 @@ internal class AssignmentAsmGen(private val program: Program, private val asmgen
        fun storeAIntoPointerVar(pointervar: IdentifierReference) {
            val sourceName = asmgen.asmVariableName(pointervar)
            val vardecl = pointervar.targetVarDecl(program)!!
-            val scopedName = vardecl.makeScopedName(vardecl.name)
+            val scopedName = vardecl.scopedName.joinToString(".")
            if (asmgen.isTargetCpu(CpuType.CPU65c02)) {
                if (asmgen.isZpVar(scopedName)) {
                    // pointervar is already in the zero page, no need to copy
@@ -2111,9 +2205,9 @@ internal class AssignmentAsmGen(private val program: Program, private val asmgen
        }
    }

-    internal fun assignExpressionToRegister(expr: Expression, register: RegisterOrPair) {
+    internal fun assignExpressionToRegister(expr: Expression, register: RegisterOrPair, signed: Boolean) {
        val src = AsmAssignSource.fromAstSource(expr, program, asmgen)
-        val tgt = AsmAssignTarget.fromRegisters(register, null, program, asmgen)
+        val tgt = AsmAssignTarget.fromRegisters(register, signed, null, program, asmgen)
        val assign = AsmAssignment(src, tgt, false, program.memsizer, expr.position)
        translateNormalAssignment(assign)
    }
@@ -2125,8 +2219,8 @@ internal class AssignmentAsmGen(private val program: Program, private val asmgen
        translateNormalAssignment(assign)
    }

-    internal fun assignVariableToRegister(asmVarName: String, register: RegisterOrPair) {
-        val tgt = AsmAssignTarget.fromRegisters(register, null, program, asmgen)
+    internal fun assignVariableToRegister(asmVarName: String, register: RegisterOrPair, signed: Boolean) {
+        val tgt = AsmAssignTarget.fromRegisters(register, signed, null, program, asmgen)
        val src = AsmAssignSource(SourceStorageKind.VARIABLE, program, asmgen, tgt.datatype, variableAsmName = asmVarName)
        val assign = AsmAssignment(src, tgt, false, program.memsizer, Position.DUMMY)
        translateNormalAssignment(assign)
@@ -5,14 +5,13 @@ import prog8.ast.base.*
 import prog8.ast.expressions.*
 import prog8.ast.statements.Subroutine
 import prog8.ast.toHex
-import prog8.compiler.AssemblyError
-import prog8.compiler.target.CpuType
+import prog8.compiler.target.AssemblyError
 import prog8.compiler.target.cpu6502.codegen.AsmGen
-import prog8.compiler.target.cpu6502.codegen.ExpressionsAsmGen
+import prog8.compilerinterface.CpuType
+

 internal class AugmentableAssignmentAsmGen(private val program: Program,
                                           private val assignmentAsmGen: AssignmentAsmGen,
-                                           private val exprAsmGen: ExpressionsAsmGen,
                                           private val asmgen: AsmGen
 ) {
    fun translate(assign: AsmAssignment) {
@@ -22,15 +21,16 @@ internal class AugmentableAssignmentAsmGen(private val program: Program,
        when (val value = assign.source.expression!!) {
            is PrefixExpression -> {
                // A = -A , A = +A, A = ~A, A = not A
+                val target = assignmentAsmGen.virtualRegsToVariables(assign.target)
                val itype = value.inferType(program)
                if(!itype.isKnown)
                    throw AssemblyError("unknown dt")
-                val type = itype.typeOrElse(DataType.STRUCT)
+                val type = itype.getOr(DataType.UNDEFINED)
                when (value.operator) {
                    "+" -> {}
-                    "-" -> inplaceNegate(assign.target, type)
-                    "~" -> inplaceInvert(assign.target, type)
-                    "not" -> inplaceBooleanNot(assign.target, type)
+                    "-" -> inplaceNegate(target, type)
+                    "~" -> inplaceInvert(target, type)
+                    "not" -> inplaceBooleanNot(target, type)
                    else -> throw AssemblyError("invalid prefix operator")
                }
            }
@@ -102,15 +102,71 @@ internal class AugmentableAssignmentAsmGen(private val program: Program,
            }
        }

-        throw FatalAstException("assignment should be augmentable $binExpr")
+        val leftBinExpr = binExpr.left as? BinaryExpression
+        val rightBinExpr = binExpr.right as? BinaryExpression
+        if(leftBinExpr!=null && rightBinExpr==null) {
+            if(leftBinExpr.left isSameAs astTarget) {
+                // X = (X <oper> Right) <oper> Something
+                inplaceModification(target, leftBinExpr.operator, leftBinExpr.right)
+                inplaceModification(target, binExpr.operator, binExpr.right)
+                return
+            }
+            if(leftBinExpr.right isSameAs astTarget) {
+                // X = (Left <oper> X) <oper> Something
+                if(leftBinExpr.operator in associativeOperators) {
+                    inplaceModification(target, leftBinExpr.operator, leftBinExpr.left)
+                    inplaceModification(target, binExpr.operator, binExpr.right)
+                    return
+                } else {
+                    throw AssemblyError("operands in wrong order for non-associative operator")
+                }
+            }
+        }
+        if(leftBinExpr==null && rightBinExpr!=null) {
+            if(rightBinExpr.left isSameAs astTarget) {
+                // X = Something <oper> (X <oper> Right)
+                if(binExpr.operator in associativeOperators) {
+                    inplaceModification(target, rightBinExpr.operator, rightBinExpr.right)
+                    inplaceModification(target, binExpr.operator, binExpr.left)
+                    return
+                } else {
+                    throw AssemblyError("operands in wrong order for non-associative operator")
+                }
+            }
+            if(rightBinExpr.right isSameAs astTarget) {
+                // X = Something <oper> (Left <oper> X)
+                if(binExpr.operator in associativeOperators && rightBinExpr.operator in associativeOperators) {
+                    inplaceModification(target, rightBinExpr.operator, rightBinExpr.left)
+                    inplaceModification(target, binExpr.operator, binExpr.left)
+                    return
+                } else {
+                    throw AssemblyError("operands in wrong order for non-associative operator")
+                }
+            }
+        }
+
+        throw FatalAstException("assignment should follow augmentable rules $binExpr")
    }

-    private fun inplaceModification(target: AsmAssignTarget, operator: String, value: Expression) {
+    private fun inplaceModification(target: AsmAssignTarget, operator: String, origValue: Expression) {
+
+        // the asm-gen code can deal with situations where you want to assign a byte into a word.
+        // it will create the most optimized code to do this (so it type-extends for us).
+        // But we can't deal with writing a word into a byte - explicit typeconversion is required
+        val value = if(program.memsizer.memorySize(origValue.inferType(program).getOr(DataType.UNDEFINED)) > program.memsizer.memorySize(target.datatype)) {
+            val typecast = TypecastExpression(origValue, target.datatype, true, origValue.position)
+            typecast.linkParents(origValue.parent)
+            typecast
+        }
+        else {
+            origValue
+        }
+
        val valueLv = (value as? NumericLiteralValue)?.number
        val ident = value as? IdentifierReference
        val memread = value as? DirectMemoryRead

-        when(target.kind) {
+        when (target.kind) {
            TargetStorageKind.VARIABLE -> {
                when (target.datatype) {
                    in ByteDatatypes -> {
@@ -160,7 +216,7 @@ internal class AugmentableAssignmentAsmGen(private val program: Program,
                        when {
                            valueLv != null -> inplaceModification_byte_litval_to_variable(addr.toHex(), DataType.UBYTE, operator, valueLv.toInt())
                            ident != null -> inplaceModification_byte_variable_to_variable(addr.toHex(), DataType.UBYTE, operator, ident)
-                            // TODO more specialized code for types such as memory read etc.  -> inplaceModification_byte_memread_to_variable()
+                            memread != null -> inplaceModification_byte_memread_to_variable(addr.toHex(), DataType.UBYTE, operator, value)
                            value is TypecastExpression -> {
                                if (tryRemoveRedundantCast(value, target, operator)) return
                                inplaceModification_byte_value_to_variable(addr.toHex(), DataType.UBYTE, operator, value)
@@ -181,7 +237,8 @@ internal class AugmentableAssignmentAsmGen(private val program: Program,
                        }
                    }
                    else -> {
-                        asmgen.translateExpression(memory.addressExpression)
+                        // TODO OTHER EVALUATION HERE, don't use the estack to transfer the address to read/write from
+                        asmgen.assignExpressionTo(memory.addressExpression, AsmAssignTarget(TargetStorageKind.STACK, program, asmgen, DataType.UWORD, memory.definingSubroutine))
                        asmgen.out("  jsr  prog8_lib.read_byte_from_address_on_stack |  sta  P8ZP_SCRATCH_B1")
                        when {
                            valueLv != null -> inplaceModification_byte_litval_to_variable("P8ZP_SCRATCH_B1", DataType.UBYTE, operator, valueLv.toInt())
@@ -204,7 +261,7 @@ internal class AugmentableAssignmentAsmGen(private val program: Program,
                    when {
                        indexNum!=null -> {
                            val targetVarName = "${target.asmVarname} + ${indexNum.number.toInt()*program.memsizer.memorySize(target.datatype)}"
-                            when(target.datatype) {
+                            when (target.datatype) {
                                in ByteDatatypes -> {
                                    when {
                                        valueLv != null -> inplaceModification_byte_litval_to_variable(targetVarName, target.datatype, operator, valueLv.toInt())
@@ -244,21 +301,39 @@ internal class AugmentableAssignmentAsmGen(private val program: Program,
                            }
                        }
                        indexVar!=null -> {
-                            when(target.datatype) {
+                            when (target.datatype) {
                                in ByteDatatypes -> {
-                                    val tgt = AsmAssignTarget.fromRegisters(RegisterOrPair.A, null, program, asmgen)
+                                    val tgt =
+                                        AsmAssignTarget.fromRegisters(
+                                            RegisterOrPair.A,
+                                            target.datatype == DataType.BYTE, null,
+                                            program,
+                                            asmgen
+                                        )
                                    val assign = AsmAssignment(target.origAssign.source, tgt, false, program.memsizer, value.position)
                                    assignmentAsmGen.translateNormalAssignment(assign)
                                    assignmentAsmGen.assignRegisterByte(target, CpuRegister.A)
                                }
                                in WordDatatypes -> {
-                                    val tgt = AsmAssignTarget.fromRegisters(RegisterOrPair.AY, null, program, asmgen)
+                                    val tgt =
+                                        AsmAssignTarget.fromRegisters(
+                                            RegisterOrPair.AY,
+                                            target.datatype == DataType.WORD, null,
+                                            program,
+                                            asmgen
+                                        )
                                    val assign = AsmAssignment(target.origAssign.source, tgt, false, program.memsizer, value.position)
                                    assignmentAsmGen.translateNormalAssignment(assign)
                                    assignmentAsmGen.assignRegisterpairWord(target, RegisterOrPair.AY)
                                }
                                DataType.FLOAT -> {
-                                    val tgt = AsmAssignTarget.fromRegisters(RegisterOrPair.FAC1, null, program, asmgen)
+                                    val tgt =
+                                        AsmAssignTarget.fromRegisters(
+                                            RegisterOrPair.FAC1,
+                                            true, null,
+                                            program,
+                                            asmgen
+                                        )
                                    val assign = AsmAssignment(target.origAssign.source, tgt, false, program.memsizer, value.position)
                                    assignmentAsmGen.translateNormalAssignment(assign)
                                    assignmentAsmGen.assignFAC1float(target)
@@ -270,8 +345,8 @@ internal class AugmentableAssignmentAsmGen(private val program: Program,
                    }
                }
            }
-            TargetStorageKind.REGISTER -> throw AssemblyError("missing codegen for reg in-place modification")
-            TargetStorageKind.STACK -> throw AssemblyError("missing codegen for stack in-place modification")
+            TargetStorageKind.REGISTER -> throw AssemblyError("no asm gen for reg in-place modification")
+            TargetStorageKind.STACK -> throw AssemblyError("no asm gen for stack in-place modification")
        }
    }

@@ -280,7 +355,7 @@ internal class AugmentableAssignmentAsmGen(private val program: Program,
            val childIDt = value.expression.inferType(program)
            if(!childIDt.isKnown)
                throw AssemblyError("unknown dt")
-            val childDt = childIDt.typeOrElse(DataType.STRUCT)
+            val childDt = childIDt.getOr(DataType.UNDEFINED)
            if (value.type!=DataType.FLOAT && (value.type.equalsSize(childDt) || value.type.largerThan(childDt))) {
                // this typecast is redundant here; the rest of the code knows how to deal with the uncasted value.
                // (works for integer types, not for float.)
@@ -293,7 +368,6 @@ internal class AugmentableAssignmentAsmGen(private val program: Program,

    private fun inplaceModification_byte_value_to_pointer(pointervar: IdentifierReference, operator: String, value: Expression) {
        asmgen.assignExpressionToVariable(value, "P8ZP_SCRATCH_B1", DataType.UBYTE, null)
-        val (ptrOnZp, sourceName) = asmgen.loadByteFromPointerIntoA(pointervar)
        when (operator) {
            // note: ** (power) operator requires floats.
            "+" -> asmgen.out("  clc |  adc  P8ZP_SCRATCH_B1")
@@ -324,15 +398,13 @@ internal class AugmentableAssignmentAsmGen(private val program: Program,
            "^", "xor" -> asmgen.out(" eor  P8ZP_SCRATCH_B1")
            else -> throw AssemblyError("invalid operator for in-place modification $operator")
        }
-        if(ptrOnZp)
-            asmgen.out("  sta  ($sourceName),y")
-        else
-            asmgen.out("  sta  (P8ZP_SCRATCH_W1),y")
+        val sourceName = asmgen.loadByteFromPointerIntoA(pointervar)
+        asmgen.out("  sta  ($sourceName),y")
    }

    private fun inplaceModification_byte_variable_to_pointer(pointervar: IdentifierReference, operator: String, value: IdentifierReference) {
        val otherName = asmgen.asmVariableName(value)
-        val (ptrOnZp, sourceName) = asmgen.loadByteFromPointerIntoA(pointervar)
+        val sourceName = asmgen.loadByteFromPointerIntoA(pointervar)

        when (operator) {
            // note: ** (power) operator requires floats.
@@ -364,105 +436,72 @@ internal class AugmentableAssignmentAsmGen(private val program: Program,
            "^", "xor" -> asmgen.out(" eor  $otherName")
            else -> throw AssemblyError("invalid operator for in-place modification $operator")
        }
-        if(ptrOnZp)
-            asmgen.out("  sta  ($sourceName),y")
-        else
-            asmgen.out("  sta  (P8ZP_SCRATCH_W1),y")
+        asmgen.out("  sta  ($sourceName),y")
    }

    private fun inplaceModification_byte_litval_to_pointer(pointervar: IdentifierReference, operator: String, value: Int) {
        when (operator) {
            // note: ** (power) operator requires floats.
            "+" -> {
-                val (ptrOnZp, sourceName) = asmgen.loadByteFromPointerIntoA(pointervar)
-                asmgen.out(" clc |  adc  #$value")
-                if(ptrOnZp)
-                    asmgen.out("  sta  ($sourceName),y")
-                else
-                    asmgen.out("  sta  (P8ZP_SCRATCH_W1),y")
+                val sourceName = asmgen.loadByteFromPointerIntoA(pointervar)
+                asmgen.out("  clc |  adc  #$value")
+                asmgen.out("  sta  ($sourceName),y")
            }
            "-" -> {
-                val (ptrOnZp, sourceName) = asmgen.loadByteFromPointerIntoA(pointervar)
-                asmgen.out(" sec |  sbc  #$value")
-                if(ptrOnZp)
-                    asmgen.out("  sta  ($sourceName),y")
-                else
-                    asmgen.out("  sta  (P8ZP_SCRATCH_W1),y")
+                val sourceName = asmgen.loadByteFromPointerIntoA(pointervar)
+                asmgen.out("  sec |  sbc  #$value")
+                asmgen.out("  sta  ($sourceName),y")
            }
            "*" -> {
-                val (ptrOnZp, sourceName) = asmgen.loadByteFromPointerIntoA(pointervar)
+                val sourceName = asmgen.loadByteFromPointerIntoA(pointervar)
                if(value in asmgen.optimizedByteMultiplications)
                    asmgen.out("  jsr  math.mul_byte_${value}")
                else
                    asmgen.out("  ldy  #$value |  jsr  math.multiply_bytes |  ldy  #0")
-                if(ptrOnZp)
-                    asmgen.out("  sta  ($sourceName),y")
-                else
-                    asmgen.out("  sta  (P8ZP_SCRATCH_W1),y")
+                asmgen.out("  sta  ($sourceName),y")
            }
            "/" -> {
-                val (ptrOnZp, sourceName) = asmgen.loadByteFromPointerIntoA(pointervar)
+                val sourceName = asmgen.loadByteFromPointerIntoA(pointervar)
                if(value==0)
                    throw AssemblyError("division by zero")
                asmgen.out("  ldy  #$value |  jsr  math.divmod_ub_asm |  tya |  ldy  #0")
-                if(ptrOnZp)
-                    asmgen.out("  sta  ($sourceName),y")
-                else
-                    asmgen.out("  sta  (P8ZP_SCRATCH_W1),y")
+                asmgen.out("  sta  ($sourceName),y")
            }
            "%" -> {
-                val (ptrOnZp, sourceName) = asmgen.loadByteFromPointerIntoA(pointervar)
+                val sourceName = asmgen.loadByteFromPointerIntoA(pointervar)
                if(value==0)
                    throw AssemblyError("division by zero")
                asmgen.out("  ldy  #$value |  jsr  math.divmod_ub_asm |  ldy  #0")
-                if(ptrOnZp)
-                    asmgen.out("  sta  ($sourceName),y")
-                else
-                    asmgen.out("  sta  (P8ZP_SCRATCH_W1),y")
+                asmgen.out("  sta  ($sourceName),y")
            }
            "<<" -> {
                if (value > 0) {
-                    val (ptrOnZp, sourceName) = asmgen.loadByteFromPointerIntoA(pointervar)
+                    val sourceName = asmgen.loadByteFromPointerIntoA(pointervar)
                    repeat(value) { asmgen.out(" asl  a") }
-                    if(ptrOnZp)
-                        asmgen.out("  sta  ($sourceName),y")
-                    else
-                        asmgen.out("  sta  (P8ZP_SCRATCH_W1),y")
+                    asmgen.out("  sta  ($sourceName),y")
                }
            }
            ">>" -> {
                if (value > 0) {
-                    val (ptrOnZp, sourceName) = asmgen.loadByteFromPointerIntoA(pointervar)
+                    val sourceName = asmgen.loadByteFromPointerIntoA(pointervar)
                    repeat(value) { asmgen.out(" lsr  a") }
-                    if(ptrOnZp)
-                        asmgen.out("  sta  ($sourceName),y")
-                    else
-                        asmgen.out("  sta  (P8ZP_SCRATCH_W1),y")
+                    asmgen.out("  sta  ($sourceName),y")
                }
            }
            "&", "and" -> {
-                val (ptrOnZp, sourceName) = asmgen.loadByteFromPointerIntoA(pointervar)
-                asmgen.out(" and  #$value")
-                if(ptrOnZp)
-                    asmgen.out("  sta  ($sourceName),y")
-                else
-                    asmgen.out("  sta  (P8ZP_SCRATCH_W1),y")
+                val sourceName = asmgen.loadByteFromPointerIntoA(pointervar)
+                asmgen.out("  and  #$value")
+                asmgen.out("  sta  ($sourceName),y")
            }
            "|", "or" -> {
-                val (ptrOnZp, sourceName) = asmgen.loadByteFromPointerIntoA(pointervar)
-                asmgen.out(" ora  #$value")
-                if(ptrOnZp)
-                    asmgen.out("  sta  ($sourceName),y")
-                else
-                    asmgen.out("  sta  (P8ZP_SCRATCH_W1),y")
+                val sourceName = asmgen.loadByteFromPointerIntoA(pointervar)
+                asmgen.out("  ora  #$value")
+                asmgen.out("  sta  ($sourceName),y")
            }
            "^", "xor" -> {
-                val (ptrOnZp, sourceName) = asmgen.loadByteFromPointerIntoA(pointervar)
-                asmgen.out(" eor  #$value")
-                if(ptrOnZp)
-                    asmgen.out("  sta  ($sourceName),y")
-                else
-                    asmgen.out("  sta  (P8ZP_SCRATCH_W1),y")
+                val sourceName = asmgen.loadByteFromPointerIntoA(pointervar)
+                asmgen.out("  eor  #$value")
+                asmgen.out("  sta  ($sourceName),y")
            }
            else -> throw AssemblyError("invalid operator for in-place modification $operator")
        }
@@ -672,24 +711,36 @@ internal class AugmentableAssignmentAsmGen(private val program: Program,
    }

    private fun inplaceModification_byte_memread_to_variable(name: String, dt: DataType, operator: String, memread: DirectMemoryRead) {
-        when(operator) {
+        when (operator) {
            "+" -> {
-                exprAsmGen.translateDirectMemReadExpression(memread, false)
+                asmgen.translateDirectMemReadExpressionToRegAorStack(memread, false)
                asmgen.out("""
                    clc
                    adc  $name
                    sta  $name""")
            }
            "-" -> {
-                exprAsmGen.translateDirectMemReadExpression(memread, false)
+                asmgen.translateDirectMemReadExpressionToRegAorStack(memread, false)
                asmgen.out("""
                    sta  P8ZP_SCRATCH_B1
                    lda  $name
                    sec
                    sbc  P8ZP_SCRATCH_B1
                    sta  $name""")
-                // TODO: tuned code for more operators
            }
+            "|", "or" -> {
+                asmgen.translateDirectMemReadExpressionToRegAorStack(memread, false)
+                asmgen.out("  ora  $name  |  sta  $name")
+            }
+            "&", "and" -> {
+                asmgen.translateDirectMemReadExpressionToRegAorStack(memread, false)
+                asmgen.out("  and  $name  |  sta  $name")
+            }
+            "^", "xor" -> {
+                asmgen.translateDirectMemReadExpressionToRegAorStack(memread, false)
+                asmgen.out("  eor  $name  |  sta  $name")
+            }
+            // TODO: tuned code for more operators
            else -> {
                inplaceModification_byte_value_to_variable(name, dt, operator, memread)
            }
@@ -697,9 +748,9 @@ internal class AugmentableAssignmentAsmGen(private val program: Program,
    }

    private fun inplaceModification_word_memread_to_variable(name: String, dt: DataType, operator: String, memread: DirectMemoryRead) {
-        when(operator) {
+        when (operator) {
            "+" -> {
-                exprAsmGen.translateDirectMemReadExpression(memread, false)
+                asmgen.translateDirectMemReadExpressionToRegAorStack(memread, false)
                asmgen.out("""
                    clc
                    adc  $name
@@ -709,7 +760,7 @@ internal class AugmentableAssignmentAsmGen(private val program: Program,
 +""")
            }
            "-" -> {
-                exprAsmGen.translateDirectMemReadExpression(memread, false)
+                asmgen.translateDirectMemReadExpressionToRegAorStack(memread, false)
                asmgen.out("""
                    sta  P8ZP_SCRATCH_B1
                    lda  $name
@@ -719,8 +770,26 @@ internal class AugmentableAssignmentAsmGen(private val program: Program,
                    bcc  +
                    dec  $name+1
 +""")
-                // TODO: tuned code for more operators
            }
+            "|", "or" -> {
+                asmgen.translateDirectMemReadExpressionToRegAorStack(memread, false)
+                asmgen.out("  ora  $name  |  sta  $name")
+            }
+            "&", "and" -> {
+                asmgen.translateDirectMemReadExpressionToRegAorStack(memread, false)
+                asmgen.out("  and  $name  |  sta  $name")
+                if(dt in WordDatatypes) {
+                    if(asmgen.isTargetCpu(CpuType.CPU65c02))
+                        asmgen.out("  stz  $name+1")
+                    else
+                        asmgen.out("  lda  #0 |  sta  $name+1")
+                }
+            }
+            "^", "xor" -> {
+                asmgen.translateDirectMemReadExpressionToRegAorStack(memread, false)
+                asmgen.out("  eor  $name  |  sta  $name")
+            }
+            // TODO: tuned code for more operators
            else -> {
                inplaceModification_word_value_to_variable(name, dt, operator, memread)
            }
@@ -980,8 +1049,7 @@ internal class AugmentableAssignmentAsmGen(private val program: Program,

    private fun inplaceModification_word_variable_to_variable(name: String, dt: DataType, operator: String, ident: IdentifierReference) {
        val otherName = asmgen.asmVariableName(ident)
-        val valueDt = ident.targetVarDecl(program)!!.datatype
-        when (valueDt) {
+        when (val valueDt = ident.targetVarDecl(program)!!.datatype) {
            in ByteDatatypes -> {
                // the other variable is a BYTE type so optimize for that
                when (operator) {
@@ -1091,7 +1159,8 @@ internal class AugmentableAssignmentAsmGen(private val program: Program,
                            sta  $name
                            lda  P8ZP_SCRATCH_W2+1
                            sta  $name+1
-                        """)                    }
+                        """)
+                    }
                    "<<" -> {
                        asmgen.out("""
                        ldy  $otherName
@@ -1225,7 +1294,7 @@ internal class AugmentableAssignmentAsmGen(private val program: Program,
        val valueiDt = value.inferType(program)
        if(!valueiDt.isKnown)
            throw AssemblyError("unknown dt")
-        val valueDt = valueiDt.typeOrElse(DataType.STRUCT)
+        val valueDt = valueiDt.getOr(DataType.UNDEFINED)

        fun multiplyVarByWordInAY() {
            asmgen.out("""
@@ -1274,7 +1343,7 @@ internal class AugmentableAssignmentAsmGen(private val program: Program,
            """)
        }

-        when(valueDt) {
+        when (valueDt) {
            in ByteDatatypes -> {
                // the other variable is a BYTE type so optimize for that
                when (operator) {
@@ -1331,21 +1400,21 @@ internal class AugmentableAssignmentAsmGen(private val program: Program,
                    }
                    "*" -> {
                        // stack contains (u) byte value, sign extend that and proceed with regular 16 bit operation
-                        // TODO use an optimized word * byte multiplication routine
+                        // TODO use an optimized word * byte multiplication routine?
                        asmgen.assignExpressionToRegister(value, RegisterOrPair.A)
                        asmgen.signExtendAYlsb(valueDt)
                        multiplyVarByWordInAY()
                    }
                    "/" -> {
                        // stack contains (u) byte value, sign extend that and proceed with regular 16 bit operation
-                        // TODO use an optimized word / byte divmod routine
+                        // TODO use an optimized word / byte divmod routine?
                        asmgen.assignExpressionToRegister(value, RegisterOrPair.A)
                        asmgen.signExtendAYlsb(valueDt)
                        divideVarByWordInAY()
                    }
                    "%" -> {
                        // stack contains (u) byte value, sign extend that and proceed with regular 16 bit operation
-                        // TODO use an optimized word / byte divmod routine
+                        // TODO use an optimized word / byte divmod routine?
                        asmgen.assignExpressionToRegister(value, RegisterOrPair.A)
                        asmgen.signExtendAYlsb(valueDt)
                        remainderVarByWordInAY()
@@ -1667,11 +1736,11 @@ internal class AugmentableAssignmentAsmGen(private val program: Program,
        if (innerCastDt == null) {
            // simple typecast where the value is the target
            when (target.datatype) {
-                DataType.UBYTE, DataType.BYTE -> { /* byte target can't be casted to anything else at all */ }
+                DataType.UBYTE, DataType.BYTE -> { /* byte target can't be typecasted to anything else at all */ }
                DataType.UWORD, DataType.WORD -> {
                    when (outerCastDt) {
                        DataType.UBYTE, DataType.BYTE -> {
-                            when(target.kind) {
+                            when (target.kind) {
                                TargetStorageKind.VARIABLE -> {
                                    if(asmgen.isTargetCpu(CpuType.CPU65c02))
                                        asmgen.out(" stz  ${target.asmVarname}+1")
@@ -1712,10 +1781,10 @@ internal class AugmentableAssignmentAsmGen(private val program: Program,
        }
    }

-    private fun inplaceBooleanNot(target: AsmAssignTarget, dt: DataType) {
+    internal fun inplaceBooleanNot(target: AsmAssignTarget, dt: DataType) {
        when (dt) {
            DataType.UBYTE -> {
-                when(target.kind) {
+                when (target.kind) {
                    TargetStorageKind.VARIABLE -> {
                        asmgen.out("""
                            lda  ${target.asmVarname}
@@ -1737,18 +1806,15 @@ internal class AugmentableAssignmentAsmGen(private val program: Program,
                                    sta  $addr""")
                            }
                            is IdentifierReference -> {
-                                val (ptrOnZp, sourceName) = asmgen.loadByteFromPointerIntoA(mem.addressExpression as IdentifierReference)
+                                val sourceName = asmgen.loadByteFromPointerIntoA(mem.addressExpression as IdentifierReference)
                                asmgen.out("""
                                    beq  +
                                    lda  #1
 +                                   eor  #1""")
-                                if(ptrOnZp)
-                                    asmgen.out("  sta  ($sourceName),y")
-                                else
-                                    asmgen.out("  sta  (P8ZP_SCRATCH_W1),y")
+                                asmgen.out("  sta  ($sourceName),y")
                            }
                            else -> {
-                                asmgen.assignExpressionToVariable(mem.addressExpression, asmgen.asmVariableName("P8ZP_SCRATCH_W2"), DataType.UWORD, target.scope)
+                                asmgen.assignExpressionToVariable(mem.addressExpression, "P8ZP_SCRATCH_W2", DataType.UWORD, target.scope)
                                asmgen.out("""
                                    ldy  #0
                                    lda  (P8ZP_SCRATCH_W2),y
@@ -1759,13 +1825,34 @@ internal class AugmentableAssignmentAsmGen(private val program: Program,
                            }
                        }
                    }
-                    TargetStorageKind.ARRAY -> throw AssemblyError("missing codegen for in-place not of ubyte array")
-                    TargetStorageKind.REGISTER -> throw AssemblyError("missing codegen for reg not")
-                    TargetStorageKind.STACK -> throw AssemblyError("missing codegen for stack not")
+                    TargetStorageKind.REGISTER -> {
+                        when(target.register!!) {
+                            RegisterOrPair.A -> asmgen.out("""
+                                cmp  #0
+                                beq  +
+                                lda  #1
+    +                           eor  #1""")
+                            RegisterOrPair.X -> asmgen.out("""
+                                txa
+                                beq  +
+                                lda  #1
+    +                           eor  #1
+                                tax""")
+                            RegisterOrPair.Y -> asmgen.out("""
+                                tya
+                                beq  +
+                                lda  #1
+    +                           eor  #1
+                                tay""")
+                            else -> throw AssemblyError("invalid reg dt for byte not")
+                        }
+                    }
+                    TargetStorageKind.STACK -> TODO("no asm gen for byte stack not")
+                    else -> throw AssemblyError("no asm gen for in-place not of ubyte ${target.kind}")
                }
            }
            DataType.UWORD -> {
-                when(target.kind) {
+                when (target.kind) {
                    TargetStorageKind.VARIABLE -> {
                        asmgen.out("""
                            lda  ${target.asmVarname}
@@ -1777,20 +1864,58 @@ internal class AugmentableAssignmentAsmGen(private val program: Program,
                            lsr  a
                            sta  ${target.asmVarname}+1""")
                    }
-                    TargetStorageKind.MEMORY -> throw AssemblyError("no asm gen for uword-memory not")
-                    TargetStorageKind.ARRAY -> throw AssemblyError("missing codegen for in-place not of uword array")
-                    TargetStorageKind.REGISTER -> throw AssemblyError("missing codegen for reg not")
-                    TargetStorageKind.STACK -> throw AssemblyError("missing codegen for stack not")
+                    TargetStorageKind.REGISTER -> {
+                        when(target.register!!) {
+                            RegisterOrPair.AX -> {
+                                asmgen.out("""
+                                    stx  P8ZP_SCRATCH_REG
+                                    ora  P8ZP_SCRATCH_REG
+                                    beq  +
+                                    lda  #0
+                                    tax
+                                    beq  ++
+        +                           lda  #1
+        +""")
+                            }
+                            RegisterOrPair.AY -> {
+                                asmgen.out("""
+                                    sty  P8ZP_SCRATCH_REG
+                                    ora  P8ZP_SCRATCH_REG
+                                    beq  +
+                                    lda  #0
+                                    tay
+                                    beq  ++
+        +                           lda  #1
+        +""")
+                            }
+                            RegisterOrPair.XY -> {
+                                asmgen.out("""
+                                    stx  P8ZP_SCRATCH_REG
+                                    tya
+                                    ora  P8ZP_SCRATCH_REG
+                                    beq  +
+                                    ldy  #0
+                                    ldx  #0
+                                    beq  ++
+        +                           ldx  #1
+        +""")
+                            }
+                            in Cx16VirtualRegisters -> throw AssemblyError("cx16 virtual regs should be variables, not real registers")
+                            else -> throw AssemblyError("invalid reg dt for word not")
+                        }
+                    }
+                    TargetStorageKind.STACK -> TODO("no asm gen for word stack not")
+                    else -> throw AssemblyError("no asm gen for in-place not of uword for ${target.kind}")
                }
            }
            else -> throw AssemblyError("boolean-not of invalid type")
        }
    }

-    private fun inplaceInvert(target: AsmAssignTarget, dt: DataType) {
+    internal fun inplaceInvert(target: AsmAssignTarget, dt: DataType) {
        when (dt) {
            DataType.UBYTE -> {
-                when(target.kind) {
+                when (target.kind) {
                    TargetStorageKind.VARIABLE -> {
                        asmgen.out("""
                            lda  ${target.asmVarname}
@@ -1808,15 +1933,12 @@ internal class AugmentableAssignmentAsmGen(private val program: Program,
                                    sta  $addr""")
                            }
                            is IdentifierReference -> {
-                                val (ptrOnZp, sourceName) = asmgen.loadByteFromPointerIntoA(memory.addressExpression as IdentifierReference)
+                                val sourceName = asmgen.loadByteFromPointerIntoA(memory.addressExpression as IdentifierReference)
                                asmgen.out("  eor  #255")
-                                if(ptrOnZp)
-                                    asmgen.out("  sta  ($sourceName),y")
-                                else
-                                    asmgen.out("  sta  (P8ZP_SCRATCH_W1),y")
+                                asmgen.out("  sta  ($sourceName),y")
                            }
                            else -> {
-                                asmgen.assignExpressionToVariable(memory.addressExpression, asmgen.asmVariableName("P8ZP_SCRATCH_W2"), DataType.UWORD, target.scope)
+                                asmgen.assignExpressionToVariable(memory.addressExpression, "P8ZP_SCRATCH_W2", DataType.UWORD, target.scope)
                                asmgen.out("""
                                    ldy  #0
                                    lda  (P8ZP_SCRATCH_W2),y
@@ -1825,13 +1947,20 @@ internal class AugmentableAssignmentAsmGen(private val program: Program,
                            }
                        }
                    }
-                    TargetStorageKind.ARRAY -> throw AssemblyError("missing codegen for in-place invert ubyte array")
-                    TargetStorageKind.REGISTER -> throw AssemblyError("missing codegen for reg invert")
-                    TargetStorageKind.STACK -> throw AssemblyError("missing codegen for stack invert")
+                    TargetStorageKind.REGISTER -> {
+                        when(target.register!!) {
+                            RegisterOrPair.A -> asmgen.out("  eor  #255")
+                            RegisterOrPair.X -> asmgen.out("  txa |  eor  #255 |  tax")
+                            RegisterOrPair.Y -> asmgen.out("  tya |  eor  #255 |  tay")
+                            else -> throw AssemblyError("invalid reg dt for byte invert")
+                        }
+                    }
+                    TargetStorageKind.STACK -> TODO("no asm gen for byte stack invert")
+                    else -> throw AssemblyError("no asm gen for in-place invert ubyte for ${target.kind}")
                }
            }
            DataType.UWORD -> {
-                when(target.kind) {
+                when (target.kind) {
                    TargetStorageKind.VARIABLE -> {
                        asmgen.out("""
                            lda  ${target.asmVarname}
@@ -1841,17 +1970,24 @@ internal class AugmentableAssignmentAsmGen(private val program: Program,
                            eor  #255
                            sta  ${target.asmVarname}+1""")
                    }
-                    TargetStorageKind.MEMORY -> throw AssemblyError("no asm gen for uword-memory invert")
-                    TargetStorageKind.ARRAY -> throw AssemblyError("missing codegen for in-place invert uword array")
-                    TargetStorageKind.REGISTER -> throw AssemblyError("missing codegen for reg invert")
-                    TargetStorageKind.STACK -> throw AssemblyError("missing codegen for stack invert")
+                    TargetStorageKind.REGISTER -> {
+                        when(target.register!!) {
+                            RegisterOrPair.AX -> asmgen.out("  pha |  txa |  eor  #255 |  tax |  pla |  eor  #255")
+                            RegisterOrPair.AY -> asmgen.out("  pha |  tya |  eor  #255 |  tay |  pla |  eor  #255")
+                            RegisterOrPair.XY -> asmgen.out("  txa |  eor  #255 |  tax |  tya |  eor  #255 |  tay")
+                            in Cx16VirtualRegisters -> throw AssemblyError("cx16 virtual regs should be variables, not real registers")
+                            else -> throw AssemblyError("invalid reg dt for word invert")
+                        }
+                    }
+                    TargetStorageKind.STACK -> TODO("no asm gen for word stack invert")
+                    else -> throw AssemblyError("no asm gen for in-place invert uword for ${target.kind}")
                }
            }
            else -> throw AssemblyError("invert of invalid type")
        }
    }

-    private fun inplaceNegate(target: AsmAssignTarget, dt: DataType) {
+    internal fun inplaceNegate(target: AsmAssignTarget, dt: DataType) {
        when (dt) {
            DataType.BYTE -> {
                when (target.kind) {
@@ -1862,14 +1998,27 @@ internal class AugmentableAssignmentAsmGen(private val program: Program,
                            sbc  ${target.asmVarname}
                            sta  ${target.asmVarname}""")
                    }
-                    TargetStorageKind.MEMORY -> throw AssemblyError("can't in-place negate memory ubyte")
-                    TargetStorageKind.ARRAY -> throw AssemblyError("missing codegen for in-place negate byte array")
-                    TargetStorageKind.REGISTER -> throw AssemblyError("missing codegen for reg negate")
-                    TargetStorageKind.STACK -> throw AssemblyError("missing codegen for stack negate")
+                    TargetStorageKind.REGISTER -> {
+                        when(target.register!!) {
+                            RegisterOrPair.A -> {
+                                if(asmgen.isTargetCpu(CpuType.CPU65c02))
+                                    asmgen.out("  eor  #255 |  ina")
+                                else
+                                    asmgen.out("  eor  #255 |  clc |  adc  #1")
+
+                            }
+                            RegisterOrPair.X -> asmgen.out("  txa |  eor  #255 |  tax |  inx")
+                            RegisterOrPair.Y -> asmgen.out("  tya |  eor  #255 |  tay |  iny")
+                            else -> throw AssemblyError("invalid reg dt for byte negate")
+                        }
+                    }
+                    TargetStorageKind.MEMORY -> throw AssemblyError("memory is ubyte, can't in-place negate")
+                    TargetStorageKind.STACK -> TODO("no asm gen for byte stack negate")
+                    else -> throw AssemblyError("no asm gen for in-place negate byte")
                }
            }
            DataType.WORD -> {
-                when(target.kind) {
+                when (target.kind) {
                    TargetStorageKind.VARIABLE -> {
                        asmgen.out("""
                            lda  #0
@@ -1880,14 +2029,56 @@ internal class AugmentableAssignmentAsmGen(private val program: Program,
                            sbc  ${target.asmVarname}+1
                            sta  ${target.asmVarname}+1""")
                    }
-                    TargetStorageKind.ARRAY -> throw AssemblyError("missing codegen for in-place negate word array")
-                    TargetStorageKind.MEMORY -> throw AssemblyError("no asm gen for word memory negate")
-                    TargetStorageKind.REGISTER -> throw AssemblyError("missing codegen for reg negate")
-                    TargetStorageKind.STACK -> throw AssemblyError("missing codegen for stack negate")
+                    TargetStorageKind.REGISTER -> {
+                        when(target.register!!) { //P8ZP_SCRATCH_REG
+                            RegisterOrPair.AX -> {
+                                asmgen.out("""
+                                    sta  P8ZP_SCRATCH_REG
+                                    stx  P8ZP_SCRATCH_REG+1
+                                    lda  #0
+                                    sec
+                                    sbc  P8ZP_SCRATCH_REG
+                                    pha
+                                    lda  #0
+                                    sbc  P8ZP_SCRATCH_REG+1
+                                    tax
+                                    pla""")
+                            }
+                            RegisterOrPair.AY -> {
+                                asmgen.out("""
+                                    sta  P8ZP_SCRATCH_REG
+                                    sty  P8ZP_SCRATCH_REG+1
+                                    lda  #0
+                                    sec
+                                    sbc  P8ZP_SCRATCH_REG
+                                    pha
+                                    lda  #0
+                                    sbc  P8ZP_SCRATCH_REG+1
+                                    tay
+                                    pla""")
+                            }
+                            RegisterOrPair.XY -> {
+                                asmgen.out("""
+                                    stx  P8ZP_SCRATCH_REG
+                                    sty  P8ZP_SCRATCH_REG+1
+                                    lda  #0
+                                    sec
+                                    sbc  P8ZP_SCRATCH_REG
+                                    tax
+                                    lda  #0
+                                    sbc  P8ZP_SCRATCH_REG+1
+                                    tay""")
+                            }
+                            in Cx16VirtualRegisters -> throw AssemblyError("cx16 virtual regs should be variables, not real registers")
+                            else -> throw AssemblyError("invalid reg dt for word neg")
+                        }
+                    }
+                    TargetStorageKind.STACK -> TODO("no asm gen for word stack negate")
+                    else -> throw AssemblyError("no asm gen for in-place negate word")
                }
            }
            DataType.FLOAT -> {
-                when(target.kind) {
+                when (target.kind) {
                    TargetStorageKind.VARIABLE -> {
                        // simply flip the sign bit in the float
                        asmgen.out("""
@@ -1896,12 +2087,11 @@ internal class AugmentableAssignmentAsmGen(private val program: Program,
                            sta  ${target.asmVarname}+1
                        """)
                    }
-                    TargetStorageKind.ARRAY -> throw AssemblyError("missing codegen for in-place negate float array")
-                    TargetStorageKind.STACK -> throw AssemblyError("missing codegen for stack float negate")
-                    else -> throw AssemblyError("weird target kind for float")
+                    TargetStorageKind.STACK -> TODO("no asm gen for stack float negate")
+                    else -> throw AssemblyError("weird target kind for inplace negate float ${target.kind}")
                }
            }
-            else -> throw AssemblyError("negate of invalid type")
+            else -> throw AssemblyError("negate of invalid type $dt")
        }
    }

@@ -1,12 +1,13 @@
 package prog8.compiler.target.cx16

-import prog8.compiler.*
-import prog8.compiler.target.CpuType
-import prog8.compiler.target.IMachineDefinition
 import prog8.compiler.target.c64.C64MachineDefinition
+import prog8.compiler.target.cbm.viceMonListPostfix
+import prog8.compilerinterface.*
 import java.io.IOException
+import java.nio.file.Path

-internal object CX16MachineDefinition: IMachineDefinition {
+
+object CX16MachineDefinition: IMachineDefinition {

    override val cpu = CpuType.CPU65c02

@@ -15,12 +16,12 @@ internal object CX16MachineDefinition: IMachineDefinition {
    override val FLOAT_MAX_NEGATIVE = -1.7014118345e+38        // bytes: 255,255,255,255,255
    override val FLOAT_MEM_SIZE = 5
    override val POINTER_MEM_SIZE = 2
-    override val BASIC_LOAD_ADDRESS = 0x0801
-    override val RAW_LOAD_ADDRESS = 0x8000
+    override val BASIC_LOAD_ADDRESS = 0x0801u
+    override val RAW_LOAD_ADDRESS = 0x8000u

    // the 2*256 byte evaluation stack (on which bytes, words, and even floats are stored during calculations)
-    override val ESTACK_LO = 0x0400        //  $0400-$04ff inclusive
-    override val ESTACK_HI = 0x0500        //  $0500-$05ff inclusive
+    override val ESTACK_LO = 0x0400u        //  $0400-$04ff inclusive
+    override val ESTACK_HI = 0x0500u        //  $0500-$05ff inclusive

    override lateinit var zeropage: Zeropage

@@ -32,10 +33,28 @@ internal object CX16MachineDefinition: IMachineDefinition {
            emptyList()
    }

-    override fun launchEmulator(programName: String) {
-        for(emulator in listOf("x16emu")) {
+    override fun launchEmulator(selectedEmulator: Int, programNameWithPath: Path) {
+        val emulatorName: String
+        val extraArgs: List<String>
+
+        when(selectedEmulator) {
+            1 -> {
+                emulatorName = "x16emu"
+                extraArgs = emptyList()
+            }
+            2 -> {
+                emulatorName = "box16"
+                extraArgs = listOf("-sym", "${programNameWithPath}.$viceMonListPostfix")
+            }
+            else -> {
+                System.err.println("Cx16 target only supports x16emu and box16 emulators.")
+                return
+            }
+        }
+
+        for(emulator in listOf(emulatorName)) {
            println("\nStarting Commander X16 emulator $emulator...")
-            val cmdline = listOf(emulator, "-scale", "2", "-run", "-prg", "$programName.prg")
+            val cmdline = listOf(emulator, "-scale", "2", "-run", "-prg", "${programNameWithPath}.prg") + extraArgs
            val processb = ProcessBuilder(cmdline).inheritIO()
            val process: Process
            try {
@@ -48,7 +67,7 @@ internal object CX16MachineDefinition: IMachineDefinition {
        }
    }

-    override fun isRegularRAMaddress(address: Int): Boolean = address < 0x9f00 || address in 0xa000..0xbfff
+    override fun isIOAddress(address: UInt): Boolean = address==0u || address==1u || address in 0x9f00u..0x9fffu

    override fun initializeZeropage(compilerOptions: CompilationOptions) {
        zeropage = CX16Zeropage(compilerOptions)
@@ -68,47 +87,38 @@ internal object CX16MachineDefinition: IMachineDefinition {
            "rmb", "smb", "stp", "wai")


-    internal class CX16Zeropage(options: CompilationOptions) : Zeropage(options) {
+    class CX16Zeropage(options: CompilationOptions) : Zeropage(options) {

-        override val SCRATCH_B1 = 0x7a      // temp storage for a single byte
-        override val SCRATCH_REG = 0x7b     // temp storage for a register, must be B1+1
-        override val SCRATCH_W1 = 0x7c      // temp storage 1 for a word  $7c+$7d
-        override val SCRATCH_W2 = 0x7e      // temp storage 2 for a word  $7e+$7f
+        override val SCRATCH_B1 = 0x7au      // temp storage for a single byte
+        override val SCRATCH_REG = 0x7bu     // temp storage for a register, must be B1+1
+        override val SCRATCH_W1 = 0x7cu      // temp storage 1 for a word  $7c+$7d
+        override val SCRATCH_W2 = 0x7eu      // temp storage 2 for a word  $7e+$7f


        init {
-            if (options.floats && options.zeropage !in setOf(ZeropageType.BASICSAFE, ZeropageType.DONTUSE ))
-                throw CompilerException("when floats are enabled, zero page type should be 'basicsafe' or 'dontuse'")
+            if (options.floats && options.zeropage !in arrayOf(ZeropageType.BASICSAFE, ZeropageType.DONTUSE ))
+                throw InternalCompilerException("when floats are enabled, zero page type should be 'basicsafe' or 'dontuse'")

            // the addresses 0x02 to 0x21 (inclusive) are taken for sixteen virtual 16-bit api registers.

            when (options.zeropage) {
                ZeropageType.FULL -> {
-                    free.addAll(0x22..0xff)
-                    free.removeAll(listOf(SCRATCH_B1, SCRATCH_REG, SCRATCH_W1, SCRATCH_W1 + 1, SCRATCH_W2, SCRATCH_W2 + 1))
+                    free.addAll(0x22u..0xffu)
                }
                ZeropageType.KERNALSAFE -> {
-                    free.addAll(0x22..0x7f)
-                    free.addAll(0xa9..0xff)
-                    free.removeAll(listOf(SCRATCH_B1, SCRATCH_REG, SCRATCH_W1, SCRATCH_W1 + 1, SCRATCH_W2, SCRATCH_W2 + 1))
+                    free.addAll(0x22u..0x7fu)
+                    free.addAll(0xa9u..0xffu)
                }
                ZeropageType.BASICSAFE -> {
-                    free.addAll(0x22..0x7f)
-                    free.removeAll(listOf(SCRATCH_B1, SCRATCH_REG, SCRATCH_W1, SCRATCH_W1 + 1, SCRATCH_W2, SCRATCH_W2 + 1))
+                    free.addAll(0x22u..0x7fu)
                }
                ZeropageType.DONTUSE -> {
                    free.clear() // don't use zeropage at all
                }
-                else -> throw CompilerException("for this machine target, zero page type 'floatsafe' is not available. ${options.zeropage}")
+                else -> throw InternalCompilerException("for this machine target, zero page type 'floatsafe' is not available. ${options.zeropage}")
            }

-            require(SCRATCH_B1 !in free)
-            require(SCRATCH_REG !in free)
-            require(SCRATCH_W1 !in free)
-            require(SCRATCH_W2 !in free)
-
-            for (reserved in options.zpReserved)
-                reserve(reserved)
+            removeReservedFromFreePool()
        }
    }
 }
@@ -0,0 +1,172 @@
+package prog8tests.asmgen
+
+import io.kotest.assertions.withClue
+import io.kotest.core.spec.style.StringSpec
+import io.kotest.matchers.shouldBe
+import prog8.ast.Module
+import prog8.ast.Program
+import prog8.ast.base.*
+import prog8.ast.expressions.AddressOf
+import prog8.ast.expressions.IdentifierReference
+import prog8.ast.expressions.NumericLiteralValue
+import prog8.ast.statements.*
+import prog8.compiler.target.C64Target
+import prog8.compiler.target.c64.C64MachineDefinition
+import prog8.compiler.target.cpu6502.codegen.AsmGen
+import prog8.compilerinterface.*
+import prog8.parser.SourceCode
+import prog8tests.asmgen.helpers.DummyFunctions
+import prog8tests.asmgen.helpers.DummyMemsizer
+import prog8tests.asmgen.helpers.DummyStringEncoder
+import prog8tests.asmgen.helpers.ErrorReporterForTests
+import java.nio.file.Path
+
+class AsmGenSymbolsTests: StringSpec({
+    fun createTestProgram(): Program {
+        /*
+    main  {
+
+    label_outside:
+    uword var_outside
+
+    sub start () {
+        uword localvar = 1234
+        uword tgt
+
+    locallabel:
+        tgt = localvar
+        tgt = &locallabel
+        tgt = &var_outside
+        tgt = &label_outside
+        tgt = &main.start.localvar
+        tgt = &main.start.locallabel
+        tgt = &main.var_outside
+        tgt = &main.label_outside
+    }
+    }
+
+         */
+        val varInSub = VarDecl(VarDeclType.VAR, DataType.UWORD, ZeropageWish.DONTCARE, null, "localvar", NumericLiteralValue.optimalInteger(1234, Position.DUMMY), false, false, false, null, Position.DUMMY)
+        val var2InSub = VarDecl(VarDeclType.VAR, DataType.UWORD, ZeropageWish.DONTCARE, null, "tgt", null, false, false, false, null, Position.DUMMY)
+        val labelInSub = Label("locallabel", Position.DUMMY)
+
+        val tgt = AssignTarget(IdentifierReference(listOf("tgt"), Position.DUMMY), null, null, Position.DUMMY)
+        val assign1 = Assignment(tgt, IdentifierReference(listOf("localvar"), Position.DUMMY), Position.DUMMY)
+        val assign2 = Assignment(tgt, AddressOf(IdentifierReference(listOf("locallabel"), Position.DUMMY), Position.DUMMY), Position.DUMMY)
+        val assign3 = Assignment(tgt, AddressOf(IdentifierReference(listOf("var_outside"), Position.DUMMY), Position.DUMMY), Position.DUMMY)
+        val assign4 = Assignment(tgt, AddressOf(IdentifierReference(listOf("label_outside"), Position.DUMMY), Position.DUMMY), Position.DUMMY)
+        val assign5 = Assignment(tgt, AddressOf(IdentifierReference(listOf("main","start","localvar"), Position.DUMMY), Position.DUMMY), Position.DUMMY)
+        val assign6 = Assignment(tgt, AddressOf(IdentifierReference(listOf("main","start","locallabel"), Position.DUMMY), Position.DUMMY), Position.DUMMY)
+        val assign7 = Assignment(tgt, AddressOf(IdentifierReference(listOf("main","var_outside"), Position.DUMMY), Position.DUMMY), Position.DUMMY)
+        val assign8 = Assignment(tgt, AddressOf(IdentifierReference(listOf("main","label_outside"), Position.DUMMY), Position.DUMMY), Position.DUMMY)
+
+        val statements = mutableListOf(varInSub, var2InSub, labelInSub, assign1, assign2, assign3, assign4, assign5, assign6, assign7, assign8)
+        val subroutine = Subroutine("start", mutableListOf(), emptyList(), emptyList(), emptyList(), emptySet(), null, false, false, statements, Position.DUMMY)
+        val labelInBlock = Label("label_outside", Position.DUMMY)
+        val varInBlock = VarDecl(VarDeclType.VAR, DataType.UWORD, ZeropageWish.DONTCARE, null, "var_outside", null, false, false, false, null, Position.DUMMY)
+        val block = Block("main", null, mutableListOf(labelInBlock, varInBlock, subroutine), false, Position.DUMMY)
+
+        val module = Module(mutableListOf(block), Position.DUMMY, SourceCode.Generated("test"))
+        val program = Program("test", DummyFunctions, DummyMemsizer, DummyStringEncoder)
+            .addModule(module)
+        return program
+    }
+
+    fun createTestAsmGen(program: Program): AsmGen {
+        val errors = ErrorReporterForTests()
+        val options = CompilationOptions(OutputType.RAW, LauncherType.NONE, ZeropageType.FULL, emptyList(), false, true, C64Target)
+        val zp = C64MachineDefinition.C64Zeropage(options)
+        val asmgen = AsmGen(program, errors, zp, options, C64Target, Path.of(""))
+        return asmgen
+    }
+
+    "symbol and variable names from strings" {
+        val program = createTestProgram()
+        val asmgen = createTestAsmGen(program)
+        asmgen.asmSymbolName("name") shouldBe "name"
+        asmgen.asmSymbolName("name") shouldBe "name"
+        asmgen.asmSymbolName("<name>") shouldBe "prog8_name"
+        asmgen.asmSymbolName(RegisterOrPair.R15) shouldBe "cx16.r15"
+        asmgen.asmSymbolName(listOf("a", "b", "name")) shouldBe "a.b.name"
+        asmgen.asmVariableName("name") shouldBe "name"
+        asmgen.asmVariableName("<name>") shouldBe "prog8_name"
+        asmgen.asmVariableName(listOf("a", "b", "name")) shouldBe "a.b.name"
+    }
+
+    "symbol and variable names from variable identifiers" {
+        val program = createTestProgram()
+        val asmgen = createTestAsmGen(program)
+        val sub = program.entrypoint
+
+        // local variable
+        val localvarIdent = sub.statements.filterIsInstance<Assignment>().first { it.value is IdentifierReference }.value as IdentifierReference
+        asmgen.asmSymbolName(localvarIdent) shouldBe "localvar"
+        asmgen.asmVariableName(localvarIdent) shouldBe "localvar"
+        val localvarIdentScoped = (sub.statements.filterIsInstance<Assignment>().first { (it.value as? AddressOf)?.identifier?.nameInSource==listOf("main", "start", "localvar") }.value as AddressOf).identifier
+        asmgen.asmSymbolName(localvarIdentScoped) shouldBe "main.start.localvar"
+        asmgen.asmVariableName(localvarIdentScoped) shouldBe "main.start.localvar"
+
+        // variable from outer scope (note that for Variables, no scoping prefix symbols are required,
+        //   because they're not outputted as locally scoped symbols for the assembler
+        val scopedVarIdent = (sub.statements.filterIsInstance<Assignment>().first { (it.value as? AddressOf)?.identifier?.nameInSource==listOf("var_outside") }.value as AddressOf).identifier
+        asmgen.asmSymbolName(scopedVarIdent) shouldBe "main.var_outside"
+        asmgen.asmVariableName(scopedVarIdent) shouldBe "var_outside"
+        val scopedVarIdentScoped = (sub.statements.filterIsInstance<Assignment>().first { (it.value as? AddressOf)?.identifier?.nameInSource==listOf("main", "var_outside") }.value as AddressOf).identifier
+        asmgen.asmSymbolName(scopedVarIdentScoped) shouldBe "main.var_outside"
+        asmgen.asmVariableName(scopedVarIdentScoped) shouldBe "main.var_outside"
+    }
+
+    "symbol and variable names from label identifiers" {
+        val program = createTestProgram()
+        val asmgen = createTestAsmGen(program)
+        val sub = program.entrypoint
+
+        // local label
+        val localLabelIdent = (sub.statements.filterIsInstance<Assignment>().first { (it.value as? AddressOf)?.identifier?.nameInSource==listOf("locallabel") }.value as AddressOf).identifier
+        asmgen.asmSymbolName(localLabelIdent) shouldBe "_locallabel"
+        withClue("as a variable it uses different naming rules (no underscore prefix)") {
+            asmgen.asmVariableName(localLabelIdent) shouldBe "locallabel"
+        }
+        val localLabelIdentScoped = (sub.statements.filterIsInstance<Assignment>().first { (it.value as? AddressOf)?.identifier?.nameInSource==listOf("main","start","locallabel") }.value as AddressOf).identifier
+        asmgen.asmSymbolName(localLabelIdentScoped) shouldBe "main.start._locallabel"
+        withClue("as a variable it uses different naming rules (no underscore prefix)") {
+            asmgen.asmVariableName(localLabelIdentScoped) shouldBe "main.start.locallabel"
+        }
+
+        // label from outer scope needs sope prefixes because it is outputted as a locally scoped symbol for the assembler
+        val scopedLabelIdent = (sub.statements.filterIsInstance<Assignment>().first { (it.value as? AddressOf)?.identifier?.nameInSource==listOf("label_outside") }.value as AddressOf).identifier
+        asmgen.asmSymbolName(scopedLabelIdent) shouldBe "main._label_outside"
+        withClue("as a variable it uses different naming rules (no underscore prefix)") {
+            asmgen.asmVariableName(scopedLabelIdent) shouldBe "label_outside"
+        }
+        val scopedLabelIdentScoped = (sub.statements.filterIsInstance<Assignment>().first { (it.value as? AddressOf)?.identifier?.nameInSource==listOf("main","label_outside") }.value as AddressOf).identifier
+        asmgen.asmSymbolName(scopedLabelIdentScoped) shouldBe "main._label_outside"
+        withClue("as a variable it uses different naming rules (no underscore prefix)") {
+            asmgen.asmVariableName(scopedLabelIdentScoped) shouldBe "main.label_outside"
+        }
+    }
+
+    "asm names for hooks to zp temp vars" {
+        /*
+main {
+
+    sub start() {
+        prog8_lib.P8ZP_SCRATCH_REG = 1
+        prog8_lib.P8ZP_SCRATCH_B1 = 1
+        prog8_lib.P8ZP_SCRATCH_W1 = 1
+        prog8_lib.P8ZP_SCRATCH_W2 = 1
+         */
+        val program = createTestProgram()
+        val asmgen = createTestAsmGen(program)
+        asmgen.asmSymbolName("prog8_lib.P8ZP_SCRATCH_REG") shouldBe "P8ZP_SCRATCH_REG"
+        asmgen.asmSymbolName("prog8_lib.P8ZP_SCRATCH_W2") shouldBe "P8ZP_SCRATCH_W2"
+        asmgen.asmSymbolName(listOf("prog8_lib","P8ZP_SCRATCH_REG")) shouldBe "P8ZP_SCRATCH_REG"
+        asmgen.asmSymbolName(listOf("prog8_lib","P8ZP_SCRATCH_W2")) shouldBe "P8ZP_SCRATCH_W2"
+        val id1 = IdentifierReference(listOf("prog8_lib","P8ZP_SCRATCH_REG"), Position.DUMMY)
+        id1.linkParents(program.toplevelModule)
+        val id2 = IdentifierReference(listOf("prog8_lib","P8ZP_SCRATCH_W2"), Position.DUMMY)
+        id2.linkParents(program.toplevelModule)
+        asmgen.asmSymbolName(id1) shouldBe "P8ZP_SCRATCH_REG"
+        asmgen.asmSymbolName(id2) shouldBe "P8ZP_SCRATCH_W2"
+    }
+})
@@ -0,0 +1,8 @@
+package prog8tests.asmgen
+
+import io.kotest.core.config.AbstractProjectConfig
+import kotlin.math.max
+
+object ProjectConfig : AbstractProjectConfig() {
+    override val parallelism = max(2, Runtime.getRuntime().availableProcessors() / 2)
+}
@@ -0,0 +1,37 @@
+package prog8tests.asmgen.helpers
+
+import prog8.ast.IBuiltinFunctions
+import prog8.ast.base.Position
+import prog8.ast.expressions.Expression
+import prog8.ast.expressions.InferredTypes
+import prog8.ast.expressions.NumericLiteralValue
+import prog8.compilerinterface.IMemSizer
+import prog8.ast.base.DataType
+import prog8.compilerinterface.IStringEncoding
+
+
+internal val DummyFunctions = object : IBuiltinFunctions {
+    override val names: Set<String> = emptySet()
+    override val purefunctionNames: Set<String> = emptySet()
+    override fun constValue(
+        name: String,
+        args: List<Expression>,
+        position: Position,
+    ): NumericLiteralValue? = null
+
+    override fun returnType(name: String, args: MutableList<Expression>) = InferredTypes.InferredType.unknown()
+}
+
+internal val DummyMemsizer = object : IMemSizer {
+    override fun memorySize(dt: DataType) = 0
+}
+
+internal val DummyStringEncoder = object : IStringEncoding {
+    override fun encodeString(str: String, altEncoding: Boolean): List<UByte> {
+        return emptyList()
+    }
+
+    override fun decodeString(bytes: List<UByte>, altEncoding: Boolean): String {
+        return ""
+    }
+}
@@ -0,0 +1,30 @@
+package prog8tests.asmgen.helpers
+
+import prog8.ast.base.Position
+import prog8.compilerinterface.IErrorReporter
+
+internal class ErrorReporterForTests(private val throwExceptionAtReportIfErrors: Boolean=true): IErrorReporter {
+
+
+    val errors = mutableListOf<String>()
+    val warnings = mutableListOf<String>()
+
+    override fun err(msg: String, position: Position) {
+        errors.add("${position.toClickableStr()} $msg")
+    }
+
+    override fun warn(msg: String, position: Position) {
+        warnings.add("${position.toClickableStr()} $msg")
+    }
+
+    override fun noErrors(): Boolean  = errors.isEmpty()
+
+    override fun report() {
+        warnings.forEach { println("UNITTEST COMPILATION REPORT: WARNING: $it") }
+        errors.forEach { println("UNITTEST COMPILATION REPORT: ERROR: $it") }
+        if(throwExceptionAtReportIfErrors)
+            finalizeNumErrors(errors.size, warnings.size)
+        errors.clear()
+        warnings.clear()
+    }
+}
@@ -0,0 +1,32 @@
+
+plugins {
+    id 'java'
+    id 'application'
+    id "org.jetbrains.kotlin.jvm"
+}
+
+java {
+    toolchain {
+        languageVersion = JavaLanguageVersion.of(javaVersion)
+    }
+}
+
+dependencies {
+    implementation project(':compilerInterfaces')
+    implementation project(':compilerAst')
+    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk8"
+    // implementation "org.jetbrains.kotlin:kotlin-reflect"
+}
+
+sourceSets {
+    main {
+        java {
+            srcDirs = ["${project.projectDir}/src"]
+        }
+        resources {
+            srcDirs = ["${project.projectDir}/res"]
+        }
+    }
+}
+
+// note: there are no unit tests in this module!
@@ -0,0 +1,16 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<module type="JAVA_MODULE" version="4">
+  <component name="NewModuleRootManager" inherit-compiler-output="true">
+    <exclude-output />
+    <content url="file://$MODULE_DIR$">
+      <sourceFolder url="file://$MODULE_DIR$/src" isTestSource="false" />
+      <sourceFolder url="file://$MODULE_DIR$/test" isTestSource="true" />
+      <excludeFolder url="file://$MODULE_DIR$/build" />
+    </content>
+    <orderEntry type="jdk" jdkName="openjdk-11" jdkType="JavaSDK" />
+    <orderEntry type="sourceFolder" forTests="false" />
+    <orderEntry type="library" name="KotlinJavaRuntime" level="project" />
+    <orderEntry type="module" module-name="compilerInterfaces" />
+    <orderEntry type="module" module-name="compilerAst" />
+  </component>
+</module>
@@ -0,0 +1,2 @@
+Unittests for things in this module are located in the Compiler module instead,
+for convenience sake, and to not spread the test cases around too much.
@@ -0,0 +1,128 @@
+package prog8.optimizer
+
+import prog8.ast.IStatementContainer
+import prog8.ast.Node
+import prog8.ast.Program
+import prog8.ast.base.DataType
+import prog8.ast.base.FatalAstException
+import prog8.ast.expressions.BinaryExpression
+import prog8.ast.expressions.IdentifierReference
+import prog8.ast.expressions.TypecastExpression
+import prog8.ast.expressions.augmentAssignmentOperators
+import prog8.ast.statements.AssignTarget
+import prog8.ast.statements.Assignment
+import prog8.ast.walk.AstWalker
+import prog8.ast.walk.IAstModification
+import prog8.compilerinterface.CompilationOptions
+import prog8.compilerinterface.ICompilationTarget
+import prog8.compilerinterface.isIOAddress
+
+
+class BinExprSplitter(private val program: Program, private val options: CompilationOptions, private val compTarget: ICompilationTarget) : AstWalker() {
+
+    override fun after(assignment: Assignment, parent: Node): Iterable<IAstModification> {
+
+        if(assignment.value.inferType(program).istype(DataType.FLOAT) && !options.optimizeFloatExpressions)
+            return noModifications
+
+        val binExpr = assignment.value as? BinaryExpression
+        if (binExpr != null) {
+
+/*
+
+Reduce the complexity of a (binary) expression that has to be evaluated on the eval stack,
+by attempting to splitting it up into individual simple steps.
+We only consider a binary expression *one* level deep (so the operands must not be a combined expression)
+
+
+X =      BinExpr                                    X   =   LeftExpr
+        <operator>                                     followed by
+          /   \             IF 'X' not used         X   =   BinExpr
+         /     \             IN expression ==>             <operator>
+        /       \                                           /   \
+    LeftExpr.  RightExpr.                                  /     \
+                                                          X     RightExpr.
+
+
+ */
+            if(binExpr.operator in augmentAssignmentOperators && isSimpleTarget(assignment.target)) {
+                if(assignment.target isSameAs binExpr.right)
+                    return noModifications
+                if(assignment.target isSameAs binExpr.left) {
+                    if(binExpr.right.isSimple)
+                        return noModifications
+                    val leftBx = binExpr.left as? BinaryExpression
+                    if(leftBx!=null && (!leftBx.left.isSimple || !leftBx.right.isSimple))
+                        return noModifications
+                    val rightBx = binExpr.right as? BinaryExpression
+                    if(rightBx!=null && (!rightBx.left.isSimple || !rightBx.right.isSimple))
+                        return noModifications
+
+                      // TODO below attempts to remove stack-based evaluated expressions, but often the resulting code is BIGGER, and SLOWER.
+//                    val dt = assignment.target.inferType(program)
+//                    if(!dt.isInteger)
+//                        return noModifications
+//                    val tempVar = IdentifierReference(getTempVarName(dt), binExpr.right.position)
+//                    val assignTempVar = Assignment(
+//                        AssignTarget(tempVar, null, null, binExpr.right.position),
+//                        binExpr.right, binExpr.right.position
+//                    )
+//                    return listOf(
+//                        IAstModification.InsertBefore(assignment, assignTempVar, assignment.parent as IStatementContainer),
+//                        IAstModification.ReplaceNode(binExpr.right, tempVar.copy(), binExpr)
+//                    )
+                }
+
+                if(binExpr.right.isSimple) {
+                    val firstAssign = Assignment(assignment.target.copy(), binExpr.left, binExpr.left.position)
+                    val targetExpr = assignment.target.toExpression()
+                    val augExpr = BinaryExpression(targetExpr, binExpr.operator, binExpr.right, binExpr.right.position)
+                    return listOf(
+                        IAstModification.ReplaceNode(binExpr, augExpr, assignment),
+                        IAstModification.InsertBefore(assignment, firstAssign, assignment.parent as IStatementContainer)
+                    )
+                }
+            }
+
+            // TODO further unraveling of binary expression trees into flat statements.
+            // however this should probably be done in a more generic way to also work on
+            // the expressiontrees that are not used in an assignment statement...
+        }
+
+        val typecast = assignment.value as? TypecastExpression
+        if(typecast!=null) {
+            val origExpr = typecast.expression as? BinaryExpression
+            if(origExpr!=null) {
+                // it's a typecast of a binary expression.
+                // we can see if we can unwrap the binary expression by working on a new temporary variable
+                // (that has the type of the expression), and then finally doing the typecast.
+                // Once it's outside the typecast, the regular splitting can commence.
+                val tempVar = when(val tempDt = origExpr.inferType(program).getOr(DataType.UNDEFINED)) {
+                    DataType.UBYTE -> listOf("prog8_lib", "retval_interm_ub")
+                    DataType.BYTE -> listOf("prog8_lib", "retval_interm_b")
+                    DataType.UWORD -> listOf("prog8_lib", "retval_interm_uw")
+                    DataType.WORD -> listOf("prog8_lib", "retval_interm_w")
+                    DataType.FLOAT -> listOf("floats", "tempvar_swap_float")
+                    else -> throw FatalAstException("invalid dt $tempDt")
+                }
+                val assignTempVar = Assignment(
+                    AssignTarget(IdentifierReference(tempVar, typecast.position), null, null, typecast.position),
+                    typecast.expression, typecast.position
+                )
+                return listOf(
+                    IAstModification.InsertBefore(assignment, assignTempVar, parent as IStatementContainer),
+                    IAstModification.ReplaceNode(typecast.expression, IdentifierReference(tempVar, typecast.position), typecast)
+                )
+            }
+        }
+
+        return noModifications
+    }
+
+    private fun isSimpleTarget(target: AssignTarget) =
+            if (target.identifier!=null || target.memoryAddress!=null)
+                !target.isIOAddress(compTarget.machine)
+            else
+                false
+
+}
@@ -46,14 +46,14 @@ class ConstExprEvaluator {
                    left.number.toInt().ushr(amount.number.toInt())
                else
                    left.number.toInt().shr(amount.number.toInt())
-        return NumericLiteralValue(left.type, result, left.position)
+        return NumericLiteralValue(left.type, result.toDouble(), left.position)
    }

    private fun shiftedleft(left: NumericLiteralValue, amount: NumericLiteralValue): Expression {
        if(left.type !in IntegerDatatypes || amount.type !in IntegerDatatypes)
            throw ExpressionError("cannot compute $left << $amount", left.position)
        val result = left.number.toInt().shl(amount.number.toInt())
-        return NumericLiteralValue(left.type, result, left.position)
+        return NumericLiteralValue(left.type, result.toDouble(), left.position)
    }

    private fun logicalxor(left: NumericLiteralValue, right: NumericLiteralValue): NumericLiteralValue {
@@ -61,12 +61,12 @@ class ConstExprEvaluator {
        return when (left.type) {
            in IntegerDatatypes -> when (right.type) {
                in IntegerDatatypes -> NumericLiteralValue.fromBoolean((left.number.toInt() != 0) xor (right.number.toInt() != 0), left.position)
-                DataType.FLOAT -> NumericLiteralValue.fromBoolean((left.number.toInt() != 0) xor (right.number.toDouble() != 0.0), left.position)
+                DataType.FLOAT -> NumericLiteralValue.fromBoolean((left.number.toInt() != 0) xor (right.number != 0.0), left.position)
                else -> throw ExpressionError(error, left.position)
            }
            DataType.FLOAT -> when (right.type) {
-                in IntegerDatatypes -> NumericLiteralValue.fromBoolean((left.number.toDouble() != 0.0) xor (right.number.toInt() != 0), left.position)
-                DataType.FLOAT -> NumericLiteralValue.fromBoolean((left.number.toDouble() != 0.0) xor (right.number.toDouble() != 0.0), left.position)
+                in IntegerDatatypes -> NumericLiteralValue.fromBoolean((left.number != 0.0) xor (right.number.toInt() != 0), left.position)
+                DataType.FLOAT -> NumericLiteralValue.fromBoolean((left.number != 0.0) xor (right.number != 0.0), left.position)
                else -> throw ExpressionError(error, left.position)
            }
            else -> throw ExpressionError(error, left.position)
@@ -78,12 +78,12 @@ class ConstExprEvaluator {
        return when (left.type) {
            in IntegerDatatypes -> when (right.type) {
                in IntegerDatatypes -> NumericLiteralValue.fromBoolean(left.number.toInt() != 0 || right.number.toInt() != 0, left.position)
-                DataType.FLOAT -> NumericLiteralValue.fromBoolean(left.number.toInt() != 0 || right.number.toDouble() != 0.0, left.position)
+                DataType.FLOAT -> NumericLiteralValue.fromBoolean(left.number.toInt() != 0 || right.number != 0.0, left.position)
                else -> throw ExpressionError(error, left.position)
            }
            DataType.FLOAT -> when (right.type) {
-                in IntegerDatatypes -> NumericLiteralValue.fromBoolean(left.number.toDouble() != 0.0 || right.number.toInt() != 0, left.position)
-                DataType.FLOAT -> NumericLiteralValue.fromBoolean(left.number.toDouble() != 0.0 || right.number.toDouble() != 0.0, left.position)
+                in IntegerDatatypes -> NumericLiteralValue.fromBoolean(left.number != 0.0 || right.number.toInt() != 0, left.position)
+                DataType.FLOAT -> NumericLiteralValue.fromBoolean(left.number != 0.0 || right.number != 0.0, left.position)
                else -> throw ExpressionError(error, left.position)
            }
            else -> throw ExpressionError(error, left.position)
@@ -95,12 +95,12 @@ class ConstExprEvaluator {
        return when (left.type) {
            in IntegerDatatypes -> when (right.type) {
                in IntegerDatatypes -> NumericLiteralValue.fromBoolean(left.number.toInt() != 0 && right.number.toInt() != 0, left.position)
-                DataType.FLOAT -> NumericLiteralValue.fromBoolean(left.number.toInt() != 0 && right.number.toDouble() != 0.0, left.position)
+                DataType.FLOAT -> NumericLiteralValue.fromBoolean(left.number.toInt() != 0 && right.number != 0.0, left.position)
                else -> throw ExpressionError(error, left.position)
            }
            DataType.FLOAT -> when (right.type) {
-                in IntegerDatatypes -> NumericLiteralValue.fromBoolean(left.number.toDouble() != 0.0 && right.number.toInt() != 0, left.position)
-                DataType.FLOAT -> NumericLiteralValue.fromBoolean(left.number.toDouble() != 0.0 && right.number.toDouble() != 0.0, left.position)
+                in IntegerDatatypes -> NumericLiteralValue.fromBoolean(left.number != 0.0 && right.number.toInt() != 0, left.position)
+                DataType.FLOAT -> NumericLiteralValue.fromBoolean(left.number != 0.0 && right.number != 0.0, left.position)
                else -> throw ExpressionError(error, left.position)
            }
            else -> throw ExpressionError(error, left.position)
@@ -110,11 +110,11 @@ class ConstExprEvaluator {
    private fun bitwisexor(left: NumericLiteralValue, right: NumericLiteralValue): NumericLiteralValue {
        if(left.type== DataType.UBYTE) {
            if(right.type in IntegerDatatypes) {
-                return NumericLiteralValue(DataType.UBYTE, (left.number.toInt() xor (right.number.toInt() and 255)).toShort(), left.position)
+                return NumericLiteralValue(DataType.UBYTE, (left.number.toInt() xor (right.number.toInt() and 255)).toDouble(), left.position)
            }
        } else if(left.type== DataType.UWORD) {
            if(right.type in IntegerDatatypes) {
-                return NumericLiteralValue(DataType.UWORD, left.number.toInt() xor right.number.toInt(), left.position)
+                return NumericLiteralValue(DataType.UWORD, (left.number.toInt() xor right.number.toInt()).toDouble(), left.position)
            }
        }
        throw ExpressionError("cannot calculate $left ^ $right", left.position)
@@ -123,11 +123,11 @@ class ConstExprEvaluator {
    private fun bitwiseor(left: NumericLiteralValue, right: NumericLiteralValue): NumericLiteralValue {
        if(left.type== DataType.UBYTE) {
            if(right.type in IntegerDatatypes) {
-                return NumericLiteralValue(DataType.UBYTE, (left.number.toInt() or (right.number.toInt() and 255)).toShort(), left.position)
+                return NumericLiteralValue(DataType.UBYTE, (left.number.toInt() or (right.number.toInt() and 255)).toDouble(), left.position)
            }
        } else if(left.type== DataType.UWORD) {
            if(right.type in IntegerDatatypes) {
-                return NumericLiteralValue(DataType.UWORD, left.number.toInt() or right.number.toInt(), left.position)
+                return NumericLiteralValue(DataType.UWORD, (left.number.toInt() or right.number.toInt()).toDouble(), left.position)
            }
        }
        throw ExpressionError("cannot calculate $left | $right", left.position)
@@ -136,11 +136,11 @@ class ConstExprEvaluator {
    private fun bitwiseand(left: NumericLiteralValue, right: NumericLiteralValue): NumericLiteralValue {
        if(left.type== DataType.UBYTE) {
            if(right.type in IntegerDatatypes) {
-                return NumericLiteralValue(DataType.UBYTE, (left.number.toInt() and (right.number.toInt() and 255)).toShort(), left.position)
+                return NumericLiteralValue(DataType.UBYTE, (left.number.toInt() and (right.number.toInt() and 255)).toDouble(), left.position)
            }
        } else if(left.type== DataType.UWORD) {
            if(right.type in IntegerDatatypes) {
-                return NumericLiteralValue(DataType.UWORD, left.number.toInt() and right.number.toInt(), left.position)
+                return NumericLiteralValue(DataType.UWORD, (left.number.toInt() and right.number.toInt()).toDouble(), left.position)
            }
        }
        throw ExpressionError("cannot calculate $left & $right", left.position)
@@ -151,12 +151,12 @@ class ConstExprEvaluator {
        return when (left.type) {
            in IntegerDatatypes -> when (right.type) {
                in IntegerDatatypes -> NumericLiteralValue.optimalNumeric(left.number.toInt().toDouble().pow(right.number.toInt()), left.position)
-                DataType.FLOAT -> NumericLiteralValue(DataType.FLOAT, left.number.toInt().toDouble().pow(right.number.toDouble()), left.position)
+                DataType.FLOAT -> NumericLiteralValue(DataType.FLOAT, left.number.toInt().toDouble().pow(right.number), left.position)
                else -> throw ExpressionError(error, left.position)
            }
            DataType.FLOAT -> when (right.type) {
-                in IntegerDatatypes -> NumericLiteralValue(DataType.FLOAT, left.number.toDouble().pow(right.number.toInt()), left.position)
-                DataType.FLOAT -> NumericLiteralValue(DataType.FLOAT, left.number.toDouble().pow(right.number.toDouble()), left.position)
+                in IntegerDatatypes -> NumericLiteralValue(DataType.FLOAT, left.number.pow(right.number.toInt()), left.position)
+                DataType.FLOAT -> NumericLiteralValue(DataType.FLOAT, left.number.pow(right.number), left.position)
                else -> throw ExpressionError(error, left.position)
            }
            else -> throw ExpressionError(error, left.position)
@@ -168,12 +168,12 @@ class ConstExprEvaluator {
        return when (left.type) {
            in IntegerDatatypes -> when (right.type) {
                in IntegerDatatypes -> NumericLiteralValue.optimalInteger(left.number.toInt() + right.number.toInt(), left.position)
-                DataType.FLOAT -> NumericLiteralValue(DataType.FLOAT, left.number.toInt() + right.number.toDouble(), left.position)
+                DataType.FLOAT -> NumericLiteralValue(DataType.FLOAT, left.number.toInt() + right.number, left.position)
                else -> throw ExpressionError(error, left.position)
            }
            DataType.FLOAT -> when (right.type) {
-                in IntegerDatatypes -> NumericLiteralValue(DataType.FLOAT, left.number.toDouble() + right.number.toInt(), left.position)
-                DataType.FLOAT -> NumericLiteralValue(DataType.FLOAT, left.number.toDouble() + right.number.toDouble(), left.position)
+                in IntegerDatatypes -> NumericLiteralValue(DataType.FLOAT, left.number + right.number.toInt(), left.position)
+                DataType.FLOAT -> NumericLiteralValue(DataType.FLOAT, left.number + right.number, left.position)
                else -> throw ExpressionError(error, left.position)
            }
            else -> throw ExpressionError(error, left.position)
@@ -185,12 +185,12 @@ class ConstExprEvaluator {
        return when (left.type) {
            in IntegerDatatypes -> when (right.type) {
                in IntegerDatatypes -> NumericLiteralValue.optimalInteger(left.number.toInt() - right.number.toInt(), left.position)
-                DataType.FLOAT -> NumericLiteralValue(DataType.FLOAT, left.number.toInt() - right.number.toDouble(), left.position)
+                DataType.FLOAT -> NumericLiteralValue(DataType.FLOAT, left.number.toInt() - right.number, left.position)
                else -> throw ExpressionError(error, left.position)
            }
            DataType.FLOAT -> when (right.type) {
-                in IntegerDatatypes -> NumericLiteralValue(DataType.FLOAT, left.number.toDouble() - right.number.toInt(), left.position)
-                DataType.FLOAT -> NumericLiteralValue(DataType.FLOAT, left.number.toDouble() - right.number.toDouble(), left.position)
+                in IntegerDatatypes -> NumericLiteralValue(DataType.FLOAT, left.number - right.number.toInt(), left.position)
+                DataType.FLOAT -> NumericLiteralValue(DataType.FLOAT, left.number - right.number, left.position)
                else -> throw ExpressionError(error, left.position)
            }
            else -> throw ExpressionError(error, left.position)
@@ -202,12 +202,12 @@ class ConstExprEvaluator {
        return when (left.type) {
            in IntegerDatatypes -> when (right.type) {
                in IntegerDatatypes -> NumericLiteralValue.optimalInteger(left.number.toInt() * right.number.toInt(), left.position)
-                DataType.FLOAT -> NumericLiteralValue(DataType.FLOAT, left.number.toInt() * right.number.toDouble(), left.position)
+                DataType.FLOAT -> NumericLiteralValue(DataType.FLOAT, left.number.toInt() * right.number, left.position)
                else -> throw ExpressionError(error, left.position)
            }
            DataType.FLOAT -> when (right.type) {
-                in IntegerDatatypes -> NumericLiteralValue(DataType.FLOAT, left.number.toDouble() * right.number.toInt(), left.position)
-                DataType.FLOAT -> NumericLiteralValue(DataType.FLOAT, left.number.toDouble() * right.number.toDouble(), left.position)
+                in IntegerDatatypes -> NumericLiteralValue(DataType.FLOAT, left.number * right.number.toInt(), left.position)
+                DataType.FLOAT -> NumericLiteralValue(DataType.FLOAT, left.number * right.number, left.position)
                else -> throw ExpressionError(error, left.position)
            }
            else -> throw ExpressionError(error, left.position)
@@ -227,19 +227,19 @@ class ConstExprEvaluator {
                    NumericLiteralValue.optimalInteger(result, left.position)
                }
                DataType.FLOAT -> {
-                    if(right.number.toDouble()==0.0) divideByZeroError(right.position)
-                    NumericLiteralValue(DataType.FLOAT, left.number.toInt() / right.number.toDouble(), left.position)
+                    if(right.number==0.0) divideByZeroError(right.position)
+                    NumericLiteralValue(DataType.FLOAT, left.number.toInt() / right.number, left.position)
                }
                else -> throw ExpressionError(error, left.position)
            }
            DataType.FLOAT -> when (right.type) {
                in IntegerDatatypes -> {
                    if(right.number.toInt()==0) divideByZeroError(right.position)
-                    NumericLiteralValue(DataType.FLOAT, left.number.toDouble() / right.number.toInt(), left.position)
+                    NumericLiteralValue(DataType.FLOAT, left.number / right.number.toInt(), left.position)
                }
                DataType.FLOAT -> {
-                    if(right.number.toDouble()==0.0) divideByZeroError(right.position)
-                    NumericLiteralValue(DataType.FLOAT, left.number.toDouble() / right.number.toDouble(), left.position)
+                    if(right.number ==0.0) divideByZeroError(right.position)
+                    NumericLiteralValue(DataType.FLOAT, left.number / right.number, left.position)
                }
                else -> throw ExpressionError(error, left.position)
            }
@@ -256,19 +256,19 @@ class ConstExprEvaluator {
                    NumericLiteralValue.optimalNumeric(left.number.toInt().toDouble() % right.number.toInt().toDouble(), left.position)
                }
                DataType.FLOAT -> {
-                    if(right.number.toDouble()==0.0) divideByZeroError(right.position)
-                    NumericLiteralValue(DataType.FLOAT, left.number.toInt() % right.number.toDouble(), left.position)
+                    if(right.number ==0.0) divideByZeroError(right.position)
+                    NumericLiteralValue(DataType.FLOAT, left.number.toInt() % right.number, left.position)
                }
                else -> throw ExpressionError(error, left.position)
            }
            DataType.FLOAT -> when (right.type) {
                in IntegerDatatypes -> {
                    if(right.number.toInt()==0) divideByZeroError(right.position)
-                    NumericLiteralValue(DataType.FLOAT, left.number.toDouble() % right.number.toInt(), left.position)
+                    NumericLiteralValue(DataType.FLOAT, left.number % right.number.toInt(), left.position)
                }
                DataType.FLOAT -> {
-                    if(right.number.toDouble()==0.0) divideByZeroError(right.position)
-                    NumericLiteralValue(DataType.FLOAT, left.number.toDouble() % right.number.toDouble(), left.position)
+                    if(right.number ==0.0) divideByZeroError(right.position)
+                    NumericLiteralValue(DataType.FLOAT, left.number % right.number, left.position)
                }
                else -> throw ExpressionError(error, left.position)
            }
@@ -9,12 +9,10 @@ import prog8.ast.statements.ForLoop
 import prog8.ast.statements.VarDecl
 import prog8.ast.walk.AstWalker
 import prog8.ast.walk.IAstModification
-import prog8.compiler.target.ICompilationTarget
 import kotlin.math.pow


-internal class ConstantFoldingOptimizer(private val program: Program, private val compTarget: ICompilationTarget) : AstWalker() {
-    private val noModifications = emptyList<IAstModification>()
+class ConstantFoldingOptimizer(private val program: Program) : AstWalker() {

    override fun before(memread: DirectMemoryRead, parent: Node): Iterable<IAstModification> {
        // @( &thing )  -->  thing
@@ -42,7 +40,7 @@ internal class ConstantFoldingOptimizer(private val program: Program, private va
                    }
                    DataType.FLOAT -> {
                        listOf(IAstModification.ReplaceNode(expr,
-                                NumericLiteralValue(DataType.FLOAT, -subexpr.number.toDouble(), subexpr.position),
+                                NumericLiteralValue(DataType.FLOAT, -subexpr.number, subexpr.position),
                                parent))
                    }
                    else -> throw ExpressionError("can only take negative of int or float", subexpr.position)
@@ -50,29 +48,29 @@ internal class ConstantFoldingOptimizer(private val program: Program, private va
                "~" -> when (subexpr.type) {
                    DataType.BYTE -> {
                        listOf(IAstModification.ReplaceNode(expr,
-                                NumericLiteralValue(DataType.BYTE, subexpr.number.toInt().inv(), subexpr.position),
+                                NumericLiteralValue(DataType.BYTE, subexpr.number.toInt().inv().toDouble(), subexpr.position),
                                parent))
                    }
                    DataType.UBYTE -> {
                        listOf(IAstModification.ReplaceNode(expr,
-                                NumericLiteralValue(DataType.UBYTE, subexpr.number.toInt().inv() and 255, subexpr.position),
+                                NumericLiteralValue(DataType.UBYTE, (subexpr.number.toInt().inv() and 255).toDouble(), subexpr.position),
                                parent))
                    }
                    DataType.WORD -> {
                        listOf(IAstModification.ReplaceNode(expr,
-                                NumericLiteralValue(DataType.WORD, subexpr.number.toInt().inv(), subexpr.position),
+                                NumericLiteralValue(DataType.WORD, subexpr.number.toInt().inv().toDouble(), subexpr.position),
                                parent))
                    }
                    DataType.UWORD -> {
                        listOf(IAstModification.ReplaceNode(expr,
-                                NumericLiteralValue(DataType.UWORD, subexpr.number.toInt().inv() and 65535, subexpr.position),
+                                NumericLiteralValue(DataType.UWORD, (subexpr.number.toInt().inv() and 65535).toDouble(), subexpr.position),
                                parent))
                    }
                    else -> throw ExpressionError("can only take bitwise inversion of int", subexpr.position)
                }
                "not" -> {
                    listOf(IAstModification.ReplaceNode(expr,
-                            NumericLiteralValue.fromBoolean(subexpr.number.toDouble() == 0.0, subexpr.position),
+                            NumericLiteralValue.fromBoolean(subexpr.number == 0.0, subexpr.position),
                            parent))
                }
                else -> throw ExpressionError(expr.operator, subexpr.position)
@@ -81,7 +79,7 @@ internal class ConstantFoldingOptimizer(private val program: Program, private va
        return noModifications
    }

-    /**
+    /*
     * Try to constfold a binary expression.
     * Compile-time constant sub expressions will be evaluated on the spot.
     * For instance, "9 * (4 + 2)" will be optimized into the integer literal 54.
@@ -103,34 +101,61 @@ internal class ConstantFoldingOptimizer(private val program: Program, private va
        val rightconst = expr.right.constValue(program)
        val modifications = mutableListOf<IAstModification>()

+        if(expr.operator=="==" && rightconst!=null) {
+            val leftExpr = expr.left as? BinaryExpression
+            if(leftExpr!=null) {
+                val leftRightConst = leftExpr.right.constValue(program)
+                if(leftRightConst!=null) {
+                    when (leftExpr.operator) {
+                        "+" -> {
+                            // X + С1 == C2  -->  X == C2 - C1
+                            val newRightConst = NumericLiteralValue(rightconst.type, rightconst.number - leftRightConst.number, rightconst.position)
+                            return listOf(
+                                IAstModification.ReplaceNode(leftExpr, leftExpr.left, expr),
+                                IAstModification.ReplaceNode(expr.right, newRightConst, expr)
+                            )
+                        }
+                        "-" -> {
+                            // X - С1 == C2  -->  X == C2 + C1
+                            val newRightConst = NumericLiteralValue(rightconst.type, rightconst.number + leftRightConst.number, rightconst.position)
+                            return listOf(
+                                IAstModification.ReplaceNode(leftExpr, leftExpr.left, expr),
+                                IAstModification.ReplaceNode(expr.right, newRightConst, expr)
+                            )
+                        }
+                    }
+                }
+            }
+        }
+
        if(expr.operator == "**" && leftconst!=null) {
            // optimize various simple cases of ** :
            //  optimize away 1 ** x into just 1 and 0 ** x into just 0
            //  optimize 2 ** x into (1<<x)  if both operands are integer.
-            val leftDt = leftconst.inferType(program).typeOrElse(DataType.STRUCT)
-            when (leftconst.number.toDouble()) {
+            val leftDt = leftconst.inferType(program).getOr(DataType.UNDEFINED)
+            when (leftconst.number) {
                0.0 -> {
-                    val value = NumericLiteralValue(leftDt, 0, expr.position)
+                    val value = NumericLiteralValue(leftDt, 0.0, expr.position)
                    modifications += IAstModification.ReplaceNode(expr, value, parent)
                }
                1.0 -> {
-                    val value = NumericLiteralValue(leftDt, 1, expr.position)
+                    val value = NumericLiteralValue(leftDt, 1.0, expr.position)
                    modifications += IAstModification.ReplaceNode(expr, value, parent)
                }
                2.0 -> {
                    if(rightconst!=null) {
-                        val value = NumericLiteralValue(leftDt, 2.0.pow(rightconst.number.toDouble()), expr.position)
+                        val value = NumericLiteralValue(leftDt, 2.0.pow(rightconst.number), expr.position)
                        modifications += IAstModification.ReplaceNode(expr, value, parent)
                    } else {
-                        val rightDt = expr.right.inferType(program).typeOrElse(DataType.STRUCT)
+                        val rightDt = expr.right.inferType(program).getOr(DataType.UNDEFINED)
                        if(leftDt in IntegerDatatypes && rightDt in IntegerDatatypes) {
                            val targetDt =
                                when (parent) {
-                                    is Assignment -> parent.target.inferType(program).typeOrElse(DataType.STRUCT)
+                                    is Assignment -> parent.target.inferType(program).getOr(DataType.UNDEFINED)
                                    is VarDecl -> parent.datatype
                                    else -> leftDt
                                }
-                            val one = NumericLiteralValue(targetDt, 1, expr.position)
+                            val one = NumericLiteralValue(targetDt, 1.0, expr.position)
                            val shift = BinaryExpression(one, "<<", expr.right, expr.position)
                            modifications += IAstModification.ReplaceNode(expr, shift, parent)
                        }
@@ -139,7 +164,7 @@ internal class ConstantFoldingOptimizer(private val program: Program, private va
            }
        }

-        if(expr.inferType(program).istype(DataType.FLOAT)) {
+        if(expr.inferType(program) istype DataType.FLOAT) {
            val subExpr: BinaryExpression? = when {
                leftconst != null -> expr.right as? BinaryExpression
                rightconst != null -> expr.left as? BinaryExpression
@@ -161,13 +186,52 @@ internal class ConstantFoldingOptimizer(private val program: Program, private va
            }
        }

+        val evaluator = ConstExprEvaluator()
+
        // const fold when both operands are a const
        if(leftconst != null && rightconst != null) {
-            val evaluator = ConstExprEvaluator()
            val result = evaluator.evaluate(leftconst, expr.operator, rightconst)
            modifications += IAstModification.ReplaceNode(expr, result, parent)
        }

+
+        val leftBinExpr = expr.left as? BinaryExpression
+        val rightBinExpr = expr.right as? BinaryExpression
+        if(expr.operator=="+" || expr.operator=="-") {
+            if(leftBinExpr!=null && rightBinExpr!=null) {
+                val c1 = leftBinExpr.right.constValue(program)
+                val c2 = rightBinExpr.right.constValue(program)
+                if(leftBinExpr.operator=="+" && rightBinExpr.operator=="+") {
+                    if (c1 != null && c2 != null) {
+                        // (X + C1) <plusmin> (Y + C2)  =>  (X <plusmin> Y) + (C1 <plusmin> C2)
+                        val c3 = evaluator.evaluate(c1, expr.operator, c2)
+                        val xwithy = BinaryExpression(leftBinExpr.left, expr.operator, rightBinExpr.left, expr.position)
+                        val newExpr = BinaryExpression(xwithy, "+", c3, expr.position)
+                        modifications += IAstModification.ReplaceNode(expr, newExpr, parent)
+                    }
+                }
+                else if(leftBinExpr.operator=="-" && rightBinExpr.operator=="-") {
+                    if (c1 != null && c2 != null) {
+                        // (X - C1) <plusmin> (Y - C2)  =>  (X <plusmin> Y) - (C1 <plusmin> C2)
+                        val c3 = evaluator.evaluate(c1, expr.operator, c2)
+                        val xwithy = BinaryExpression(leftBinExpr.left, expr.operator, rightBinExpr.left, expr.position)
+                        val newExpr = BinaryExpression(xwithy, "-", c3, expr.position)
+                        modifications += IAstModification.ReplaceNode(expr, newExpr, parent)
+                    }
+                }
+                else if(leftBinExpr.operator=="*" && rightBinExpr.operator=="*"){
+                    if (c1 != null && c2 != null && c1==c2) {
+                        //(X * C) <plusmin> (Y * C)  =>  (X <plusmin> Y) * C
+                        val xwithy = BinaryExpression(leftBinExpr.left, expr.operator, rightBinExpr.left, expr.position)
+                        val newExpr = BinaryExpression(xwithy, "*", c1, expr.position)
+                        modifications += IAstModification.ReplaceNode(expr, newExpr, parent)
+                    }
+                }
+            }
+        }
+
+
+
        return modifications
    }

@@ -188,7 +252,7 @@ internal class ConstantFoldingOptimizer(private val program: Program, private va
        } else {
            val arrayDt = array.guessDatatype(program)
            if (arrayDt.isKnown) {
-                val newArray = array.cast(arrayDt.typeOrElse(DataType.STRUCT))
+                val newArray = array.cast(arrayDt.getOr(DataType.UNDEFINED))
                if (newArray != null && newArray != array)
                    return listOf(IAstModification.ReplaceNode(array, newArray, parent))
            }
@@ -224,7 +288,7 @@ internal class ConstantFoldingOptimizer(private val program: Program, private va
                    range.step
                }

-            return RangeExpr(fromCast.valueOrZero(), toCast.valueOrZero(), newStep, compTarget, range.position)
+            return RangeExpr(fromCast.valueOrZero(), toCast.valueOrZero(), newStep, range.position)
        }

        // adjust the datatype of a range expression in for loops to the loop variable.
@@ -279,7 +343,7 @@ internal class ConstantFoldingOptimizer(private val program: Program, private va
        val numval = decl.value as? NumericLiteralValue
        if(decl.type== VarDeclType.CONST && numval!=null) {
            val valueDt = numval.inferType(program)
-            if(!valueDt.istype(decl.datatype)) {
+            if(valueDt isnot decl.datatype) {
                val cast = numval.cast(decl.datatype)
                if(cast.isValid)
                    return listOf(IAstModification.ReplaceNode(numval, cast.valueOrZero(), decl))
@@ -4,28 +4,36 @@ import prog8.ast.Node
 import prog8.ast.Program
 import prog8.ast.base.*
 import prog8.ast.expressions.*
-import prog8.ast.statements.ArrayIndex
-import prog8.ast.statements.AssignTarget
-import prog8.ast.statements.ForLoop
-import prog8.ast.statements.VarDecl
+import prog8.ast.statements.*
 import prog8.ast.walk.AstWalker
 import prog8.ast.walk.IAstModification
-import prog8.compiler.IErrorReporter
-import prog8.compiler.target.ICompilationTarget
+import prog8.compilerinterface.ICompilationTarget
+import prog8.compilerinterface.IErrorReporter
+import prog8.compilerinterface.size
+import prog8.compilerinterface.toConstantIntegerRange

 // Fix up the literal value's type to match that of the vardecl
-internal class VarConstantValueTypeAdjuster(private val program: Program, private val errors: IErrorReporter) : AstWalker() {
-    private val noModifications = emptyList<IAstModification>()
+//   (also check range literal operands types before they get expanded into arrays for instance)
+class VarConstantValueTypeAdjuster(private val program: Program, private val errors: IErrorReporter) : AstWalker() {

    override fun after(decl: VarDecl, parent: Node): Iterable<IAstModification> {
+
+        if(decl.parent is AnonymousScope)
+            throw FatalAstException("vardecl may no longer occur in anonymousscope")
+
        try {
            val declConstValue = decl.value?.constValue(program)
            if(declConstValue!=null && (decl.type==VarDeclType.VAR || decl.type==VarDeclType.CONST)
-                && !declConstValue.inferType(program).istype(decl.datatype)) {
-                // cast the numeric literal to the appropriate datatype of the variable
-                val cast = declConstValue.cast(decl.datatype)
-                if(cast.isValid)
-                    return listOf(IAstModification.ReplaceNode(decl.value!!, cast.valueOrZero(), decl))
+                && declConstValue.type != decl.datatype) {
+                // avoid silent float roundings
+                if(decl.datatype in IntegerDatatypes && declConstValue.type==DataType.FLOAT) {
+                    errors.err("refused silent rounding of float to avoid loss of precision", decl.value!!.position)
+                } else {
+                    // cast the numeric literal to the appropriate datatype of the variable
+                    val cast = declConstValue.cast(decl.datatype)
+                    if (cast.isValid)
+                        return listOf(IAstModification.ReplaceNode(decl.value!!, cast.valueOrZero(), decl))
+                }
            }
        } catch (x: UndefinedSymbolError) {
            errors.err(x.message, x.position)
@@ -33,6 +41,35 @@ internal class VarConstantValueTypeAdjuster(private val program: Program, privat

        return noModifications
    }
+
+    override fun after(range: RangeExpr, parent: Node): Iterable<IAstModification> {
+        val from = range.from.constValue(program)?.number
+        val to = range.to.constValue(program)?.number
+        val step = range.step.constValue(program)?.number
+
+        if(from==null) {
+            if(!range.from.inferType(program).isInteger)
+                errors.err("range expression from value must be integer", range.from.position)
+        } else if(from-from.toInt()>0) {
+            errors.err("range expression from value must be integer", range.from.position)
+        }
+
+        if(to==null) {
+            if(!range.to.inferType(program).isInteger)
+                errors.err("range expression to value must be integer", range.to.position)
+        } else if(to-to.toInt()>0) {
+            errors.err("range expression to value must be integer", range.to.position)
+        }
+
+        if(step==null) {
+            if(!range.step.inferType(program).isInteger)
+                errors.err("range expression step value must be integer", range.step.position)
+        } else if(step-step.toInt()>0) {
+            errors.err("range expression step value must be integer", range.step.position)
+        }
+
+        return noModifications
+    }
 }


@@ -40,7 +77,6 @@ internal class VarConstantValueTypeAdjuster(private val program: Program, privat
 // and the array var initializer values and sizes.
 // This is needed because further constant optimizations depend on those.
 internal class ConstantIdentifierReplacer(private val program: Program, private val errors: IErrorReporter, private val compTarget: ICompilationTarget) : AstWalker() {
-    private val noModifications = emptyList<IAstModification>()

    override fun after(identifier: IdentifierReference, parent: Node): Iterable<IAstModification> {
        // replace identifiers that refer to const value, with the value itself
@@ -74,8 +110,7 @@ internal class ConstantIdentifierReplacer(private val program: Program, private

    override fun before(decl: VarDecl, parent: Node): Iterable<IAstModification> {
        // the initializer value can't refer to the variable itself (recursive definition)
-        // TODO: use call graph for this?
-        if(decl.value?.referencesIdentifier(decl.name) == true || decl.arraysize?.indexExpr?.referencesIdentifier(decl.name) == true) {
+        if(decl.value?.referencesIdentifier(listOf(decl.name)) == true || decl.arraysize?.indexExpr?.referencesIdentifier(listOf(decl.name)) == true) {
            errors.err("recursive var declaration", decl.position)
            return noModifications
        }
@@ -101,33 +136,33 @@ internal class ConstantIdentifierReplacer(private val program: Program, private
                    // vardecl: for scalar float vars, promote constant integer initialization values to floats
                    val litval = decl.value as? NumericLiteralValue
                    if (litval!=null && litval.type in IntegerDatatypes) {
-                        val newValue = NumericLiteralValue(DataType.FLOAT, litval.number.toDouble(), litval.position)
+                        val newValue = NumericLiteralValue(DataType.FLOAT, litval.number, litval.position)
                        return listOf(IAstModification.ReplaceNode(decl.value!!, newValue, decl))
                    }
                }
                DataType.ARRAY_UB, DataType.ARRAY_B, DataType.ARRAY_UW, DataType.ARRAY_W -> {
-                    val numericLv = decl.value as? NumericLiteralValue
                    val rangeExpr = decl.value as? RangeExpr
                    if(rangeExpr!=null) {
                        // convert the initializer range expression to an actual array
                        val declArraySize = decl.arraysize?.constIndex()
                        if(declArraySize!=null && declArraySize!=rangeExpr.size())
-                            errors.err("range expression size doesn't match declared array size", decl.value?.position!!)
+                            errors.err("range expression size (${rangeExpr.size()}) doesn't match declared array size ($declArraySize)", decl.value?.position!!)
                        val constRange = rangeExpr.toConstantIntegerRange()
                        if(constRange!=null) {
-                            val eltType = rangeExpr.inferType(program).typeOrElse(DataType.UBYTE)
+                            val eltType = rangeExpr.inferType(program).getOr(DataType.UBYTE)
                            val newValue = if(eltType in ByteDatatypes) {
                                ArrayLiteralValue(InferredTypes.InferredType.known(decl.datatype),
-                                        constRange.map { NumericLiteralValue(eltType, it.toShort(), decl.value!!.position) }.toTypedArray(),
+                                        constRange.map { NumericLiteralValue(eltType, it.toDouble(), decl.value!!.position) }.toTypedArray(),
                                        position = decl.value!!.position)
                            } else {
                                ArrayLiteralValue(InferredTypes.InferredType.known(decl.datatype),
-                                        constRange.map { NumericLiteralValue(eltType, it, decl.value!!.position) }.toTypedArray(),
+                                        constRange.map { NumericLiteralValue(eltType, it.toDouble(), decl.value!!.position) }.toTypedArray(),
                                        position = decl.value!!.position)
                            }
                            return listOf(IAstModification.ReplaceNode(decl.value!!, newValue, decl))
                        }
                    }
+                    val numericLv = decl.value as? NumericLiteralValue
                    if(numericLv!=null && numericLv.type== DataType.FLOAT)
                        errors.err("arraysize requires only integers here", numericLv.position)
                    val size = decl.arraysize?.constIndex() ?: return noModifications
@@ -154,20 +189,18 @@ internal class ConstantIdentifierReplacer(private val program: Program, private
                            else -> {}
                        }
                        // create the array itself, filled with the fillvalue.
-                        val array = Array(size) {fillvalue}.map { NumericLiteralValue(ArrayElementTypes.getValue(decl.datatype), it, numericLv.position) }.toTypedArray<Expression>()
+                        val array = Array(size) {fillvalue}.map { NumericLiteralValue(ArrayToElementTypes.getValue(decl.datatype), it.toDouble(), numericLv.position) }.toTypedArray<Expression>()
                        val refValue = ArrayLiteralValue(InferredTypes.InferredType.known(decl.datatype), array, position = numericLv.position)
                        return listOf(IAstModification.ReplaceNode(decl.value!!, refValue, decl))
                    }
                }
                DataType.ARRAY_F -> {
-                    val size = decl.arraysize?.constIndex() ?: return noModifications
-                    val litval = decl.value as? NumericLiteralValue
                    val rangeExpr = decl.value as? RangeExpr
                    if(rangeExpr!=null) {
                        // convert the initializer range expression to an actual array of floats
                        val declArraySize = decl.arraysize?.constIndex()
                        if(declArraySize!=null && declArraySize!=rangeExpr.size())
-                            errors.err("range expression size doesn't match declared array size", decl.value?.position!!)
+                            errors.err("range expression size (${rangeExpr.size()}) doesn't match declared array size ($declArraySize)", decl.value?.position!!)
                        val constRange = rangeExpr.toConstantIntegerRange()
                        if(constRange!=null) {
                            val newValue = ArrayLiteralValue(InferredTypes.InferredType.known(DataType.ARRAY_F),
@@ -176,22 +209,24 @@ internal class ConstantIdentifierReplacer(private val program: Program, private
                            return listOf(IAstModification.ReplaceNode(decl.value!!, newValue, decl))
                        }
                    }
-                    if(rangeExpr==null && litval!=null) {
+
+                    val numericLv = decl.value as? NumericLiteralValue
+                    val size = decl.arraysize?.constIndex() ?: return noModifications
+                    if(rangeExpr==null && numericLv!=null) {
                        // arraysize initializer is a single int, and we know the size.
-                        val fillvalue = litval.number.toDouble()
+                        val fillvalue = numericLv.number
                        if (fillvalue < compTarget.machine.FLOAT_MAX_NEGATIVE || fillvalue > compTarget.machine.FLOAT_MAX_POSITIVE)
-                            errors.err("float value overflow", litval.position)
+                            errors.err("float value overflow", numericLv.position)
                        else {
                            // create the array itself, filled with the fillvalue.
-                            val array = Array(size) {fillvalue}.map { NumericLiteralValue(DataType.FLOAT, it, litval.position) }.toTypedArray<Expression>()
-                            val refValue = ArrayLiteralValue(InferredTypes.InferredType.known(DataType.ARRAY_F), array, position = litval.position)
+                            val array = Array(size) {fillvalue}.map { NumericLiteralValue(DataType.FLOAT, it, numericLv.position) }.toTypedArray<Expression>()
+                            val refValue = ArrayLiteralValue(InferredTypes.InferredType.known(DataType.ARRAY_F), array, position = numericLv.position)
                            return listOf(IAstModification.ReplaceNode(decl.value!!, refValue, decl))
                        }
                    }
                }
                else -> {
                    // nothing to do for this type
-                    // this includes strings and structs
                }
            }
        }
@@ -15,17 +15,16 @@ import kotlin.math.log2
 import kotlin.math.pow

 /*
-    todo add more expression optimizations
+    todo add more peephole expression optimizations

    Investigate what optimizations binaryen has, also see  https://egorbo.com/peephole-optimizations.html

 */


-internal class ExpressionSimplifier(private val program: Program) : AstWalker() {
+class ExpressionSimplifier(private val program: Program) : AstWalker() {
    private val powersOfTwo = (1..16).map { (2.0).pow(it) }.toSet()
    private val negativePowersOfTwo = powersOfTwo.map { -it }.toSet()
-    private val noModifications = emptyList<IAstModification>()

    override fun after(typecast: TypecastExpression, parent: Node): Iterable<IAstModification> {
        val mods = mutableListOf<IAstModification>()
@@ -46,7 +45,7 @@ internal class ExpressionSimplifier(private val program: Program) : AstWalker()
                mods += IAstModification.ReplaceNode(typecast.expression, subTypecast.expression, typecast)
            }
        } else {
-            if (typecast.expression.inferType(program).istype(typecast.type)) {
+            if (typecast.expression.inferType(program) istype typecast.type) {
                // remove duplicate cast
                mods += IAstModification.ReplaceNode(typecast, typecast.expression, parent)
            }
@@ -135,8 +134,8 @@ internal class ExpressionSimplifier(private val program: Program) : AstWalker()
            ))
        }

-        val leftDt = leftIDt.typeOrElse(DataType.STRUCT)
-        val rightDt = rightIDt.typeOrElse(DataType.STRUCT)
+        val leftDt = leftIDt.getOr(DataType.UNDEFINED)
+        val rightDt = rightIDt.getOr(DataType.UNDEFINED)

        if (expr.operator == "+" || expr.operator == "-"
                && leftVal == null && rightVal == null
@@ -150,7 +149,7 @@ internal class ExpressionSimplifier(private val program: Program) : AstWalker()
                    val x = expr.right
                    val y = determineY(x, leftBinExpr)
                    if (y != null) {
-                        val yPlus1 = BinaryExpression(y, "+", NumericLiteralValue(leftDt, 1, y.position), y.position)
+                        val yPlus1 = BinaryExpression(y, "+", NumericLiteralValue(leftDt, 1.0, y.position), y.position)
                        val newExpr = BinaryExpression(x, "*", yPlus1, x.position)
                        return listOf(IAstModification.ReplaceNode(expr, newExpr, parent))
                    }
@@ -160,7 +159,7 @@ internal class ExpressionSimplifier(private val program: Program) : AstWalker()
                    val x = expr.right
                    val y = determineY(x, leftBinExpr)
                    if (y != null) {
-                        val yMinus1 = BinaryExpression(y, "-", NumericLiteralValue(leftDt, 1, y.position), y.position)
+                        val yMinus1 = BinaryExpression(y, "-", NumericLiteralValue(leftDt, 1.0, y.position), y.position)
                        val newExpr = BinaryExpression(x, "*", yMinus1, x.position)
                        return listOf(IAstModification.ReplaceNode(expr, newExpr, parent))
                    }
@@ -180,14 +179,26 @@ internal class ExpressionSimplifier(private val program: Program) : AstWalker()
            }
        }

-        if(expr.operator == ">=" && rightVal?.number == 0) {
+        if(leftDt!=DataType.FLOAT && expr.operator == ">=" && rightVal?.number == 1.0) {
+            // for integers: x >= 1  -->  x > 0
+            expr.operator = ">"
+            return listOf(IAstModification.ReplaceNode(expr.right, NumericLiteralValue.optimalInteger(0, expr.right.position), expr))
+        }
+
+        if(expr.operator == ">=" && rightVal?.number == 0.0) {
            if (leftDt == DataType.UBYTE || leftDt == DataType.UWORD) {
                // unsigned >= 0 --> true
                return listOf(IAstModification.ReplaceNode(expr, NumericLiteralValue.fromBoolean(true, expr.position), parent))
            }
        }

-        if(expr.operator == "<" && rightVal?.number == 0) {
+        if(leftDt!=DataType.FLOAT && expr.operator == "<" && rightVal?.number == 1.0) {
+            // for integers: x < 1  -->  x <= 0
+            expr.operator = "<="
+            return listOf(IAstModification.ReplaceNode(expr.right, NumericLiteralValue.optimalInteger(0, expr.right.position), expr))
+        }
+
+        if(expr.operator == "<" && rightVal?.number == 0.0) {
            if (leftDt == DataType.UBYTE || leftDt == DataType.UWORD) {
                // unsigned < 0 --> false
                return listOf(IAstModification.ReplaceNode(expr, NumericLiteralValue.fromBoolean(false, expr.position), parent))
@@ -221,52 +232,62 @@ internal class ExpressionSimplifier(private val program: Program) : AstWalker()
        val constFalse = NumericLiteralValue.fromBoolean(false, expr.position)
        val newExpr: Expression? = when (expr.operator) {
            "or" -> {
-                if ((leftVal != null && leftVal.asBooleanValue) || (rightVal != null && rightVal.asBooleanValue))
-                    constTrue
-                else if (leftVal != null && !leftVal.asBooleanValue)
-                    expr.right
-                else if (rightVal != null && !rightVal.asBooleanValue)
-                    expr.left
-                else
-                    null
+                when {
+                    leftVal != null && leftVal.asBooleanValue || rightVal != null && rightVal.asBooleanValue -> constTrue
+                    leftVal != null && !leftVal.asBooleanValue -> expr.right
+                    rightVal != null && !rightVal.asBooleanValue -> expr.left
+                    else -> null
+                }
            }
            "and" -> {
-                if ((leftVal != null && !leftVal.asBooleanValue) || (rightVal != null && !rightVal.asBooleanValue))
-                    constFalse
-                else if (leftVal != null && leftVal.asBooleanValue)
-                    expr.right
-                else if (rightVal != null && rightVal.asBooleanValue)
-                    expr.left
-                else
-                    null
+                when {
+                    leftVal != null && !leftVal.asBooleanValue || rightVal != null && !rightVal.asBooleanValue -> constFalse
+                    leftVal != null && leftVal.asBooleanValue -> expr.right
+                    rightVal != null && rightVal.asBooleanValue -> expr.left
+                    else -> null
+                }
            }
            "xor" -> {
-                if (leftVal != null && !leftVal.asBooleanValue)
-                    expr.right
-                else if (rightVal != null && !rightVal.asBooleanValue)
-                    expr.left
-                else if (leftVal != null && leftVal.asBooleanValue)
-                    PrefixExpression("not", expr.right, expr.right.position)
-                else if (rightVal != null && rightVal.asBooleanValue)
-                    PrefixExpression("not", expr.left, expr.left.position)
-                else
-                    null
+                when {
+                    leftVal != null && !leftVal.asBooleanValue -> expr.right
+                    rightVal != null && !rightVal.asBooleanValue -> expr.left
+                    leftVal != null && leftVal.asBooleanValue -> PrefixExpression("not", expr.right, expr.right.position)
+                    rightVal != null && rightVal.asBooleanValue -> PrefixExpression("not", expr.left, expr.left.position)
+                    else -> null
+                }
            }
-            "|", "^" -> {
-                if (leftVal != null && !leftVal.asBooleanValue)
-                    expr.right
-                else if (rightVal != null && !rightVal.asBooleanValue)
-                    expr.left
-                else
-                    null
+            "|" -> {
+                when {
+                    leftVal?.number==0.0 -> expr.right
+                    rightVal?.number==0.0 -> expr.left
+                    rightIDt.isBytes && rightVal?.number==255.0 -> NumericLiteralValue(DataType.UBYTE, 255.0, rightVal.position)
+                    rightIDt.isWords && rightVal?.number==65535.0 -> NumericLiteralValue(DataType.UWORD, 65535.0, rightVal.position)
+                    leftIDt.isBytes && leftVal?.number==255.0 -> NumericLiteralValue(DataType.UBYTE, 255.0, leftVal.position)
+                    leftIDt.isWords && leftVal?.number==65535.0 -> NumericLiteralValue(DataType.UWORD, 65535.0, leftVal.position)
+                    else -> null
+                }
+            }
+            "^" -> {
+                when {
+                    leftVal?.number==0.0 -> expr.right
+                    rightVal?.number==0.0 -> expr.left
+                    rightIDt.isBytes && rightVal?.number==255.0 -> PrefixExpression("~", expr.left, expr.left.position)
+                    rightIDt.isWords && rightVal?.number==65535.0 -> PrefixExpression("~", expr.left, expr.left.position)
+                    leftIDt.isBytes && leftVal?.number==255.0 -> PrefixExpression("~", expr.right, expr.right.position)
+                    leftIDt.isWords && leftVal?.number==65535.0 -> PrefixExpression("~", expr.right, expr.right.position)
+                    else -> null
+                }
            }
            "&" -> {
-                if (leftVal != null && !leftVal.asBooleanValue)
-                    constFalse
-                else if (rightVal != null && !rightVal.asBooleanValue)
-                    constFalse
-                else
-                    null
+                when {
+                    leftVal?.number==0.0  -> constFalse
+                    rightVal?.number==0.0 -> constFalse
+                    rightIDt.isBytes && rightVal?.number==255.0 -> expr.left
+                    rightIDt.isWords && rightVal?.number==65535.0 -> expr.left
+                    leftIDt.isBytes && leftVal?.number==255.0 -> expr.right
+                    leftIDt.isWords && leftVal?.number==65535.0 -> expr.right
+                    else -> null
+                }
            }
            "*" -> optimizeMultiplication(expr, leftVal, rightVal)
            "/" -> optimizeDivision(expr, leftVal, rightVal)
@@ -290,13 +311,13 @@ internal class ExpressionSimplifier(private val program: Program) : AstWalker()
            val arg = functionCall.args[0]
            if(arg is TypecastExpression) {
                val valueDt = arg.expression.inferType(program)
-                if (valueDt.istype(DataType.BYTE) || valueDt.istype(DataType.UBYTE)) {
-                    // useless lsb() of byte value that was casted to word
+                if (valueDt istype DataType.BYTE || valueDt istype DataType.UBYTE) {
+                    // useless lsb() of byte value that was typecasted to word
                    return listOf(IAstModification.ReplaceNode(functionCall, arg.expression, parent))
                }
            } else {
                val argDt = arg.inferType(program)
-                if (argDt.istype(DataType.BYTE) || argDt.istype(DataType.UBYTE)) {
+                if (argDt istype DataType.BYTE || argDt istype DataType.UBYTE) {
                    // useless lsb() of byte value
                    return listOf(IAstModification.ReplaceNode(functionCall, arg, parent))
                }
@@ -306,20 +327,20 @@ internal class ExpressionSimplifier(private val program: Program) : AstWalker()
            val arg = functionCall.args[0]
            if(arg is TypecastExpression) {
                val valueDt = arg.expression.inferType(program)
-                if (valueDt.istype(DataType.BYTE) || valueDt.istype(DataType.UBYTE)) {
-                    // useless msb() of byte value that was casted to word, replace with 0
+                if (valueDt istype DataType.BYTE || valueDt istype DataType.UBYTE) {
+                    // useless msb() of byte value that was typecasted to word, replace with 0
                    return listOf(IAstModification.ReplaceNode(
                            functionCall,
-                            NumericLiteralValue(valueDt.typeOrElse(DataType.UBYTE), 0, arg.expression.position),
+                            NumericLiteralValue(valueDt.getOr(DataType.UBYTE), 0.0, arg.expression.position),
                            parent))
                }
            } else {
                val argDt = arg.inferType(program)
-                if (argDt.istype(DataType.BYTE) || argDt.istype(DataType.UBYTE)) {
+                if (argDt istype DataType.BYTE || argDt istype DataType.UBYTE) {
                    // useless msb() of byte value, replace with 0
                    return listOf(IAstModification.ReplaceNode(
                            functionCall,
-                            NumericLiteralValue(argDt.typeOrElse(DataType.UBYTE), 0, arg.position),
+                            NumericLiteralValue(argDt.getOr(DataType.UBYTE), 0.0, arg.position),
                            parent))
                }
            }
@@ -352,7 +373,7 @@ internal class ExpressionSimplifier(private val program: Program) : AstWalker()
        if (rightVal2 != null) {
            // right value is a constant, see if we can optimize
            val rightConst: NumericLiteralValue = rightVal2
-            when (rightConst.number.toDouble()) {
+            when (rightConst.number) {
                0.0 -> {
                    // left
                    return expr2.left
@@ -361,7 +382,7 @@ internal class ExpressionSimplifier(private val program: Program) : AstWalker()
        }
        // no need to check for left val constant (because of associativity)

-        val rnum = rightVal?.number?.toDouble()
+        val rnum = rightVal?.number
        if(rnum!=null && rnum<0.0) {
            expr.operator = "-"
            expr.right = NumericLiteralValue(rightVal.type, -rnum, rightVal.position)
@@ -382,7 +403,7 @@ internal class ExpressionSimplifier(private val program: Program) : AstWalker()

        if (rightVal != null) {
            // right value is a constant, see if we can optimize
-            val rnum = rightVal.number.toDouble()
+            val rnum = rightVal.number
            if (rnum == 0.0) {
                // left
                return expr.left
@@ -396,7 +417,7 @@ internal class ExpressionSimplifier(private val program: Program) : AstWalker()
        }
        if (leftVal != null) {
            // left value is a constant, see if we can optimize
-            when (leftVal.number.toDouble()) {
+            when (leftVal.number) {
                0.0 -> {
                    // -right
                    return PrefixExpression("-", expr.right, expr.position)
@@ -415,7 +436,7 @@ internal class ExpressionSimplifier(private val program: Program) : AstWalker()
        if (rightVal != null) {
            // right value is a constant, see if we can optimize
            val rightConst: NumericLiteralValue = rightVal
-            when (rightConst.number.toDouble()) {
+            when (rightConst.number) {
                -3.0 -> {
                    // -1/(left*left*left)
                    return BinaryExpression(NumericLiteralValue(DataType.FLOAT, -1.0, expr.position), "/",
@@ -435,7 +456,7 @@ internal class ExpressionSimplifier(private val program: Program) : AstWalker()
                }
                0.0 -> {
                    // 1
-                    return NumericLiteralValue(rightConst.type, 1, expr.position)
+                    return NumericLiteralValue(rightConst.type, 1.0, expr.position)
                }
                0.5 -> {
                    // sqrt(left)
@@ -457,18 +478,18 @@ internal class ExpressionSimplifier(private val program: Program) : AstWalker()
        }
        if (leftVal != null) {
            // left value is a constant, see if we can optimize
-            when (leftVal.number.toDouble()) {
+            when (leftVal.number) {
                -1.0 -> {
                    // -1
                    return NumericLiteralValue(DataType.FLOAT, -1.0, expr.position)
                }
                0.0 -> {
                    // 0
-                    return NumericLiteralValue(leftVal.type, 0, expr.position)
+                    return NumericLiteralValue(leftVal.type, 0.0, expr.position)
                }
                1.0 -> {
                    //1
-                    return NumericLiteralValue(leftVal.type, 1, expr.position)
+                    return NumericLiteralValue(leftVal.type, 1.0, expr.position)
                }

            }
@@ -490,10 +511,10 @@ internal class ExpressionSimplifier(private val program: Program) : AstWalker()
                    val idt = expr.inferType(program)
                    if(!idt.isKnown)
                        throw FatalAstException("unknown dt")
-                    return NumericLiteralValue(idt.typeOrElse(DataType.STRUCT), 0, expr.position)
-                } else if (cv == 2.0) {
+                    return NumericLiteralValue(idt.getOr(DataType.UNDEFINED), 0.0, expr.position)
+                } else if (cv in powersOfTwo) {
                    expr.operator = "&"
-                    expr.right = NumericLiteralValue.optimalInteger(1, expr.position)
+                    expr.right = NumericLiteralValue.optimalInteger(cv!!.toInt()-1, expr.position)
                    return null
                }
            }
@@ -510,11 +531,11 @@ internal class ExpressionSimplifier(private val program: Program) : AstWalker()
        if (rightVal != null) {
            // right value is a constant, see if we can optimize
            val rightConst: NumericLiteralValue = rightVal
-            val cv = rightConst.number.toDouble()
+            val cv = rightConst.number
            val leftIDt = expr.left.inferType(program)
            if (!leftIDt.isKnown)
                return null
-            val leftDt = leftIDt.typeOrElse(DataType.STRUCT)
+            val leftDt = leftIDt.getOr(DataType.UNDEFINED)
            when (cv) {
                -1.0 -> {
                    //  '/' -> -left
@@ -545,22 +566,22 @@ internal class ExpressionSimplifier(private val program: Program) : AstWalker()
            }

            if (leftDt == DataType.UBYTE) {
-                if (abs(rightConst.number.toDouble()) >= 256.0) {
-                    return NumericLiteralValue(DataType.UBYTE, 0, expr.position)
+                if (abs(rightConst.number) >= 256.0) {
+                    return NumericLiteralValue(DataType.UBYTE, 0.0, expr.position)
                }
            } else if (leftDt == DataType.UWORD) {
-                if (abs(rightConst.number.toDouble()) >= 65536.0) {
-                    return NumericLiteralValue(DataType.UBYTE, 0, expr.position)
+                if (abs(rightConst.number) >= 65536.0) {
+                    return NumericLiteralValue(DataType.UBYTE, 0.0, expr.position)
                }
            }
        }

        if (leftVal != null) {
            // left value is a constant, see if we can optimize
-            when (leftVal.number.toDouble()) {
+            when (leftVal.number) {
                0.0 -> {
                    // 0
-                    return NumericLiteralValue(leftVal.type, 0, expr.position)
+                    return NumericLiteralValue(leftVal.type, 0.0, expr.position)
                }
            }
        }
@@ -577,28 +598,28 @@ internal class ExpressionSimplifier(private val program: Program) : AstWalker()
            // right value is a constant, see if we can optimize
            val leftValue: Expression = expr2.left
            val rightConst: NumericLiteralValue = rightVal2
-            when (val cv = rightConst.number.toDouble()) {
+            when (val cv = rightConst.number) {
                -1.0 -> {
                    // -left
                    return PrefixExpression("-", leftValue, expr.position)
                }
                0.0 -> {
                    // 0
-                    return NumericLiteralValue(rightConst.type, 0, expr.position)
+                    return NumericLiteralValue(rightConst.type, 0.0, expr.position)
                }
                1.0 -> {
                    // left
                    return expr2.left
                }
                in powersOfTwo -> {
-                    if (leftValue.inferType(program).typeOrElse(DataType.STRUCT) in IntegerDatatypes) {
+                    if (leftValue.inferType(program).isInteger) {
                        // times a power of two => shift left
                        val numshifts = log2(cv).toInt()
                        return BinaryExpression(expr2.left, "<<", NumericLiteralValue.optimalInteger(numshifts, expr.position), expr.position)
                    }
                }
                in negativePowersOfTwo -> {
-                    if (leftValue.inferType(program).typeOrElse(DataType.STRUCT) in IntegerDatatypes) {
+                    if (leftValue.inferType(program).isInteger) {
                        // times a negative power of two => negate, then shift left
                        val numshifts = log2(-cv).toInt()
                        return BinaryExpression(PrefixExpression("-", expr2.left, expr.position), "<<", NumericLiteralValue.optimalInteger(numshifts, expr.position), expr.position)
@@ -622,15 +643,15 @@ internal class ExpressionSimplifier(private val program: Program) : AstWalker()
        val targetIDt = expr.left.inferType(program)
        if(!targetIDt.isKnown)
            throw FatalAstException("unknown dt")
-        when (val targetDt = targetIDt.typeOrElse(DataType.STRUCT)) {
+        when (val targetDt = targetIDt.getOr(DataType.UNDEFINED)) {
            DataType.UBYTE, DataType.BYTE -> {
                if (amount >= 8) {
-                    return NumericLiteralValue(targetDt, 0, expr.position)
+                    return NumericLiteralValue(targetDt, 0.0, expr.position)
                }
            }
            DataType.UWORD, DataType.WORD -> {
                if (amount >= 16) {
-                    return NumericLiteralValue(targetDt, 0, expr.position)
+                    return NumericLiteralValue(targetDt, 0.0, expr.position)
                } else if (amount >= 8) {
                    val lsb = FunctionCall(IdentifierReference(listOf("lsb"), expr.position), mutableListOf(expr.left), expr.position)
                    if (amount == 8) {
@@ -657,7 +678,7 @@ internal class ExpressionSimplifier(private val program: Program) : AstWalker()
        val idt = expr.left.inferType(program)
        if(!idt.isKnown)
            throw FatalAstException("unknown dt")
-        when (idt.typeOrElse(DataType.STRUCT)) {
+        when (idt.getOr(DataType.UNDEFINED)) {
            DataType.UBYTE -> {
                if (amount >= 8) {
                    return NumericLiteralValue.optimalInteger(0, expr.position)
@@ -677,7 +698,7 @@ internal class ExpressionSimplifier(private val program: Program) : AstWalker()
                    val msb = FunctionCall(IdentifierReference(listOf("msb"), expr.position), mutableListOf(expr.left), expr.position)
                    if (amount == 8) {
                        // mkword(0, msb(v))
-                        val zero = NumericLiteralValue(DataType.UBYTE, 0, expr.position)
+                        val zero = NumericLiteralValue(DataType.UBYTE, 0.0, expr.position)
                        return FunctionCall(IdentifierReference(listOf("mkword"), expr.position), mutableListOf(zero, msb), expr.position)
                    }
                    return TypecastExpression(BinaryExpression(msb, ">>", NumericLiteralValue.optimalInteger(amount - 8, expr.position), expr.position), DataType.UWORD, true, expr.position)
@@ -0,0 +1,82 @@
+package prog8.optimizer
+
+import prog8.ast.IBuiltinFunctions
+import prog8.ast.Program
+import prog8.ast.base.DataType
+import prog8.ast.base.FatalAstException
+import prog8.ast.expressions.InferredTypes
+import prog8.compilerinterface.CompilationOptions
+import prog8.compilerinterface.ICompilationTarget
+import prog8.compilerinterface.IErrorReporter
+
+
+fun Program.constantFold(errors: IErrorReporter, compTarget: ICompilationTarget) {
+    val valuetypefixer = VarConstantValueTypeAdjuster(this, errors)
+    valuetypefixer.visit(this)
+    if(errors.noErrors()) {
+        valuetypefixer.applyModifications()
+
+        val replacer = ConstantIdentifierReplacer(this, errors, compTarget)
+        replacer.visit(this)
+        if (errors.noErrors()) {
+            replacer.applyModifications()
+
+            valuetypefixer.visit(this)
+            if(errors.noErrors()) {
+                valuetypefixer.applyModifications()
+
+                val optimizer = ConstantFoldingOptimizer(this)
+                optimizer.visit(this)
+                while (errors.noErrors() && optimizer.applyModifications() > 0) {
+                    optimizer.visit(this)
+                }
+
+                if (errors.noErrors()) {
+                    replacer.visit(this)
+                    replacer.applyModifications()
+                }
+            }
+        }
+    }
+
+    if(errors.noErrors())
+        modules.forEach { it.linkParents(namespace) }   // re-link in final configuration
+}
+
+
+fun Program.optimizeStatements(errors: IErrorReporter,
+                               functions: IBuiltinFunctions,
+                               compTarget: ICompilationTarget
+): Int {
+    val optimizer = StatementOptimizer(this, errors, functions, compTarget)
+    optimizer.visit(this)
+    val optimizationCount = optimizer.applyModifications()
+
+    modules.forEach { it.linkParents(this.namespace) }   // re-link in final configuration
+
+    return optimizationCount
+}
+
+fun Program.simplifyExpressions() : Int {
+    val opti = ExpressionSimplifier(this)
+    opti.visit(this)
+    return opti.applyModifications()
+}
+
+fun Program.splitBinaryExpressions(options: CompilationOptions, compTarget: ICompilationTarget) : Int {
+    val opti = BinExprSplitter(this, options, compTarget)
+    opti.visit(this)
+    return opti.applyModifications()
+}
+
+fun getTempVarName(dt: InferredTypes.InferredType): List<String> {
+    return when {
+        // TODO assume (hope) cx16.r9 isn't used for anything else...
+        dt.istype(DataType.UBYTE) -> listOf("cx16", "r9L")
+        dt.istype(DataType.BYTE) -> listOf("cx16", "r9sL")
+        dt.istype(DataType.UWORD) -> listOf("cx16", "r9")
+        dt.istype(DataType.WORD) -> listOf("cx16", "r9s")
+        dt.isPassByReference -> listOf("cx16", "r9")
+        else -> throw FatalAstException("invalid dt $dt")
+    }
+}
@@ -1,92 +1,72 @@
 package prog8.optimizer

-import prog8.ast.IBuiltinFunctions
-import prog8.ast.INameScope
-import prog8.ast.Node
-import prog8.ast.Program
+import prog8.ast.*
 import prog8.ast.base.*
 import prog8.ast.expressions.*
 import prog8.ast.statements.*
 import prog8.ast.walk.AstWalker
 import prog8.ast.walk.IAstModification
 import prog8.ast.walk.IAstVisitor
-import prog8.compiler.IErrorReporter
-import prog8.compiler.target.ICompilationTarget
-import java.nio.file.Path
+import prog8.compilerinterface.ICompilationTarget
+import prog8.compilerinterface.IErrorReporter
+import prog8.compilerinterface.size
 import kotlin.math.floor


-internal class StatementOptimizer(private val program: Program,
+class StatementOptimizer(private val program: Program,
                                  private val errors: IErrorReporter,
                                  private val functions: IBuiltinFunctions,
-                                  private val compTarget: ICompilationTarget,
-                                  asmFileLoader: (filename: String, source: Path)->String
+                                  private val compTarget: ICompilationTarget
 ) : AstWalker() {

-    private val noModifications = emptyList<IAstModification>()
-    private val callgraph = CallGraph(program, asmFileLoader)
+    override fun before(functionCall: FunctionCall, parent: Node): Iterable<IAstModification> {
+        // if the first instruction in the called subroutine is a return statement with a simple value,
+        // remove the jump altogeter and inline the returnvalue directly.

-    override fun after(block: Block, parent: Node): Iterable<IAstModification> {
-        if("force_output" !in block.options()) {
-            if (block.containsNoCodeNorVars()) {
-                if(block.name != program.internedStringsModuleName)
-                    errors.warn("removing empty block '${block.name}'", block.position)
-                return listOf(IAstModification.Remove(block, parent as INameScope))
-            }
+        fun scopePrefix(variable: IdentifierReference): IdentifierReference {
+            val target = variable.targetStatement(program) as INamedStatement
+            return IdentifierReference(target.scopedName, variable.position)
+        }

-            if (block !in callgraph.usedSymbols) {
-                errors.warn("removing unused block '${block.name}'", block.position)
-                return listOf(IAstModification.Remove(block, parent as INameScope))
+        val subroutine = functionCall.target.targetSubroutine(program)
+        if(subroutine!=null) {
+            val first = subroutine.statements.asSequence().filterNot { it is VarDecl || it is Directive }.firstOrNull()
+            if(first is Return && first.value?.isSimple==true) {
+                val copy = when(val orig = first.value!!) {
+                    is AddressOf -> {
+                        val scoped = scopePrefix(orig.identifier)
+                        AddressOf(scoped, orig.position)
+                    }
+                    is DirectMemoryRead -> {
+                        when(val expr = orig.addressExpression) {
+                            is NumericLiteralValue -> DirectMemoryRead(expr.copy(), orig.position)
+                            else -> return noModifications
+                        }
+                    }
+                    is IdentifierReference -> scopePrefix(orig)
+                    is NumericLiteralValue -> orig.copy()
+                    is StringLiteralValue -> orig.copy()
+                    else -> return noModifications
+                }
+                return listOf(IAstModification.ReplaceNode(functionCall, copy, parent))
            }
        }
        return noModifications
    }

-    override fun after(subroutine: Subroutine, parent: Node): Iterable<IAstModification> {
-        val forceOutput = "force_output" in subroutine.definingBlock().options()
-        if(subroutine.asmAddress==null && !forceOutput) {
-            if(subroutine.containsNoCodeNorVars() && !subroutine.inline) {
-                errors.warn("removing empty subroutine '${subroutine.name}'", subroutine.position)
-                val removals = callgraph.calledBy.getValue(subroutine).map {
-                    IAstModification.Remove(it, it.definingScope())
-                }.toMutableList()
-                removals += IAstModification.Remove(subroutine, subroutine.definingScope())
-                return removals
-            }
-        }

-        if(subroutine !in callgraph.usedSymbols && !forceOutput) {
-            if(!subroutine.isAsmSubroutine) {
-                errors.warn("removing unused subroutine '${subroutine.name}'", subroutine.position)
-                return listOf(IAstModification.Remove(subroutine, subroutine.definingScope()))
-            }
-        }
-
-        return noModifications
-    }
-
-    override fun after(decl: VarDecl, parent: Node): Iterable<IAstModification> {
-        val forceOutput = "force_output" in decl.definingBlock().options()
-        if(decl !in callgraph.usedSymbols && !forceOutput) {
-            if(decl.type == VarDeclType.VAR)
-                errors.warn("removing unused variable '${decl.name}'", decl.position)
-
-            return listOf(IAstModification.Remove(decl, decl.definingScope()))
-        }
-
-        return noModifications
-    }

    override fun after(functionCallStatement: FunctionCallStatement, parent: Node): Iterable<IAstModification> {
-        if(functionCallStatement.target.nameInSource.size==1 && functionCallStatement.target.nameInSource[0] in functions.names) {
+        if(functionCallStatement.target.targetStatement(program) is BuiltinFunctionStatementPlaceholder) {
            val functionName = functionCallStatement.target.nameInSource[0]
            if (functionName in functions.purefunctionNames) {
                errors.warn("statement has no effect (function return value is discarded)", functionCallStatement.position)
-                return listOf(IAstModification.Remove(functionCallStatement, functionCallStatement.definingScope()))
+                return listOf(IAstModification.Remove(functionCallStatement, parent as IStatementContainer))
            }
        }

        // printing a literal string of just 2 or 1 characters is replaced by directly outputting those characters
+        // only do this optimization if the arg is a known-constant string literal instead of a user defined variable.
        if(functionCallStatement.target.nameInSource==listOf("txt", "print")) {
            val arg = functionCallStatement.args.single()
            val stringVar: IdentifierReference? = if(arg is AddressOf) {
@@ -94,33 +74,32 @@ internal class StatementOptimizer(private val program: Program,
            } else {
                arg as? IdentifierReference
            }
-            if(stringVar!=null) {
-                val vardecl = stringVar.targetVarDecl(program)!!
-                val string = vardecl.value as? StringLiteralValue
+            if(stringVar!=null && stringVar.wasStringLiteral(program)) {
+                val string = stringVar.targetVarDecl(program)?.value as? StringLiteralValue
                if(string!=null) {
                    val pos = functionCallStatement.position
                    if (string.value.length == 1) {
                        val firstCharEncoded = compTarget.encodeString(string.value, string.altEncoding)[0]
                        val chrout = FunctionCallStatement(
-                                IdentifierReference(listOf("txt", "chrout"), pos),
-                                mutableListOf(NumericLiteralValue(DataType.UBYTE, firstCharEncoded.toInt(), pos)),
-                                functionCallStatement.void, pos
+                            IdentifierReference(listOf("txt", "chrout"), pos),
+                            mutableListOf(NumericLiteralValue(DataType.UBYTE, firstCharEncoded.toDouble(), pos)),
+                            functionCallStatement.void, pos
                        )
                        return listOf(IAstModification.ReplaceNode(functionCallStatement, chrout, parent))
                    } else if (string.value.length == 2) {
                        val firstTwoCharsEncoded = compTarget.encodeString(string.value.take(2), string.altEncoding)
                        val chrout1 = FunctionCallStatement(
-                                IdentifierReference(listOf("txt", "chrout"), pos),
-                                mutableListOf(NumericLiteralValue(DataType.UBYTE, firstTwoCharsEncoded[0].toInt(), pos)),
-                                functionCallStatement.void, pos
+                            IdentifierReference(listOf("txt", "chrout"), pos),
+                            mutableListOf(NumericLiteralValue(DataType.UBYTE, firstTwoCharsEncoded[0].toDouble(), pos)),
+                            functionCallStatement.void, pos
                        )
                        val chrout2 = FunctionCallStatement(
-                                IdentifierReference(listOf("txt", "chrout"), pos),
-                                mutableListOf(NumericLiteralValue(DataType.UBYTE, firstTwoCharsEncoded[1].toInt(), pos)),
-                                functionCallStatement.void, pos
+                            IdentifierReference(listOf("txt", "chrout"), pos),
+                            mutableListOf(NumericLiteralValue(DataType.UBYTE, firstTwoCharsEncoded[1].toDouble(), pos)),
+                            functionCallStatement.void, pos
                        )
                        return listOf(
-                            IAstModification.InsertBefore(functionCallStatement, chrout1, parent as INameScope),
+                            IAstModification.InsertBefore(functionCallStatement, chrout1, parent as IStatementContainer),
                            IAstModification.ReplaceNode(functionCallStatement, chrout2, parent)
                        )
                    }
@@ -133,33 +112,35 @@ internal class StatementOptimizer(private val program: Program,
        if(subroutine!=null) {
            val first = subroutine.statements.asSequence().filterNot { it is VarDecl || it is Directive }.firstOrNull()
            if(first is Return)
-                return listOf(IAstModification.Remove(functionCallStatement, functionCallStatement.definingScope()))
+                return listOf(IAstModification.Remove(functionCallStatement, parent as IStatementContainer))
        }

-        return noModifications
-    }
-
-    override fun before(functionCall: FunctionCall, parent: Node): Iterable<IAstModification> {
-        // if the first instruction in the called subroutine is a return statement with constant value, replace with the constant value
-        val subroutine = functionCall.target.targetSubroutine(program)
-        if(subroutine!=null) {
-            val first = subroutine.statements.asSequence().filterNot { it is VarDecl || it is Directive }.firstOrNull()
-            if(first is Return && first.value!=null) {
-                val constval = first.value?.constValue(program)
-                if(constval!=null)
-                    return listOf(IAstModification.ReplaceNode(functionCall, constval, parent))
+        // see if we can optimize any complex arguments
+        // TODO for now, only works for single-argument functions because we use just 1 temp var: R9
+        if(functionCallStatement.target.nameInSource !in listOf(listOf("pop"), listOf("popw")) && functionCallStatement.args.size==1) {
+            val arg = functionCallStatement.args[0]
+            if(!arg.isSimple && arg !is TypecastExpression && arg !is IFunctionCall) {
+                val name = getTempVarName(arg.inferType(program))
+                val tempvar = IdentifierReference(name, functionCallStatement.position)
+                val assignTempvar = Assignment(AssignTarget(tempvar.copy(), null, null, functionCallStatement.position), arg, functionCallStatement.position)
+                return listOf(
+                    IAstModification.InsertBefore(functionCallStatement, assignTempvar, parent as IStatementContainer),
+                    IAstModification.ReplaceNode(arg, tempvar, functionCallStatement)
+                )
            }
        }
+
+
        return noModifications
    }

    override fun after(ifStatement: IfStatement, parent: Node): Iterable<IAstModification> {
        // remove empty if statements
-        if(ifStatement.truepart.containsNoCodeNorVars() && ifStatement.elsepart.containsNoCodeNorVars())
-            return listOf(IAstModification.Remove(ifStatement, ifStatement.definingScope()))
+        if(ifStatement.truepart.isEmpty() && ifStatement.elsepart.isEmpty())
+            return listOf(IAstModification.Remove(ifStatement, parent as IStatementContainer))

        // empty true part? switch with the else part
-        if(ifStatement.truepart.containsNoCodeNorVars() && ifStatement.elsepart.containsCodeOrVars()) {
+        if(ifStatement.truepart.isEmpty() && ifStatement.elsepart.isNotEmpty()) {
            val invertedCondition = PrefixExpression("not", ifStatement.condition, ifStatement.condition.position)
            val emptyscope = AnonymousScope(mutableListOf(), ifStatement.elsepart.position)
            val truepart = AnonymousScope(ifStatement.elsepart.statements, ifStatement.truepart.position)
@@ -187,20 +168,20 @@ internal class StatementOptimizer(private val program: Program,
    }

    override fun after(forLoop: ForLoop, parent: Node): Iterable<IAstModification> {
-        if(forLoop.body.containsNoCodeNorVars()) {
+        if(forLoop.body.isEmpty()) {
            errors.warn("removing empty for loop", forLoop.position)
-            return listOf(IAstModification.Remove(forLoop, forLoop.definingScope()))
+            return listOf(IAstModification.Remove(forLoop, parent as IStatementContainer))
        } else if(forLoop.body.statements.size==1) {
            val loopvar = forLoop.body.statements[0] as? VarDecl
            if(loopvar!=null && loopvar.name==forLoop.loopVar.nameInSource.singleOrNull()) {
                // remove empty for loop (only loopvar decl in it)
-                return listOf(IAstModification.Remove(forLoop, forLoop.definingScope()))
+                return listOf(IAstModification.Remove(forLoop, parent as IStatementContainer))
            }
        }

        val range = forLoop.iterable as? RangeExpr
        if(range!=null) {
-            if(range.size()==1) {
+            if (range.size() == 1) {
                // for loop over a (constant) range of just a single value-- optimize the loop away
                // loopvar/reg = range value , follow by block
                val scope = AnonymousScope(mutableListOf(), forLoop.position)
@@ -217,7 +198,7 @@ internal class StatementOptimizer(private val program: Program,
                if(size==1) {
                    // loop over string of length 1 -> just assign the single character
                    val character = compTarget.encodeString(sv.value, sv.altEncoding)[0]
-                    val byte = NumericLiteralValue(DataType.UBYTE, character, iterable.position)
+                    val byte = NumericLiteralValue(DataType.UBYTE, character.toDouble(), iterable.position)
                    val scope = AnonymousScope(mutableListOf(), forLoop.position)
                    scope.statements.add(Assignment(AssignTarget(forLoop.loopVar, null, null, forLoop.position), byte, forLoop.position))
                    scope.statements.addAll(forLoop.body.statements)
@@ -271,7 +252,7 @@ internal class StatementOptimizer(private val program: Program,
            } else {
                // always false -> remove the while statement altogether
                errors.warn("condition is always false", whileLoop.condition.position)
-                listOf(IAstModification.Remove(whileLoop, whileLoop.definingScope()))
+                listOf(IAstModification.Remove(whileLoop, parent as IStatementContainer))
            }
        }
        return noModifications
@@ -280,14 +261,14 @@ internal class StatementOptimizer(private val program: Program,
    override fun after(repeatLoop: RepeatLoop, parent: Node): Iterable<IAstModification> {
        val iter = repeatLoop.iterations
        if(iter!=null) {
-            if(repeatLoop.body.containsNoCodeNorVars()) {
+            if(repeatLoop.body.isEmpty()) {
                errors.warn("empty loop removed", repeatLoop.position)
-                return listOf(IAstModification.Remove(repeatLoop, repeatLoop.definingScope()))
+                return listOf(IAstModification.Remove(repeatLoop, parent as IStatementContainer))
            }
            val iterations = iter.constValue(program)?.number?.toInt()
            if (iterations == 0) {
                errors.warn("iterations is always 0, removed loop", iter.position)
-                return listOf(IAstModification.Remove(repeatLoop, repeatLoop.definingScope()))
+                return listOf(IAstModification.Remove(repeatLoop, parent as IStatementContainer))
            }
            if (iterations == 1) {
                errors.warn("iterations is always 1", iter.position)
@@ -298,12 +279,13 @@ internal class StatementOptimizer(private val program: Program,
    }

    override fun after(jump: Jump, parent: Node): Iterable<IAstModification> {
-        // if the jump is to the next statement, remove the jump
-        val scope = jump.definingScope()
-        val label = jump.identifier?.targetStatement(program)
-        if(label!=null && scope.statements.indexOf(label) == scope.statements.indexOf(jump)+1)
-            return listOf(IAstModification.Remove(jump, jump.definingScope()))
-
+        if(!jump.isGosub) {
+            // if the jump is to the next statement, remove the jump
+            val scope = jump.parent as IStatementContainer
+            val label = jump.identifier?.targetStatement(program)
+            if (label != null && scope.statements.indexOf(label) == scope.statements.indexOf(jump) + 1)
+                return listOf(IAstModification.Remove(jump, scope))
+        }
        return noModifications
    }

@@ -326,27 +308,27 @@ internal class StatementOptimizer(private val program: Program,
                    if(rNum!=null) {
                        if (op1 == "+" || op1 == "-") {
                            if (op2 == "+") {
-                                // A = A +/- B + N
+                                // A = A +/- B + N  --->  A = A +/- B  ;  A = A + N
                                val expr2 = BinaryExpression(binExpr.left, binExpr.operator, rExpr.left, binExpr.position)
                                val addConstant = Assignment(
-                                        assignment.target,
-                                        BinaryExpression(binExpr.left, "+", rExpr.right, rExpr.position),
+                                        assignment.target.copy(),
+                                        BinaryExpression(binExpr.left.copy(), "+", rExpr.right, rExpr.position),
                                        assignment.position
                                )
                                return listOf(
                                        IAstModification.ReplaceNode(binExpr, expr2, binExpr.parent),
-                                        IAstModification.InsertAfter(assignment, addConstant, assignment.definingScope()))
+                                        IAstModification.InsertAfter(assignment, addConstant, parent as IStatementContainer))
                            } else if (op2 == "-") {
-                                // A = A +/- B - N
+                                // A = A +/- B - N  --->  A = A +/- B  ;  A = A - N
                                val expr2 = BinaryExpression(binExpr.left, binExpr.operator, rExpr.left, binExpr.position)
                                val subConstant = Assignment(
-                                        assignment.target,
-                                        BinaryExpression(binExpr.left, "-", rExpr.right, rExpr.position),
+                                        assignment.target.copy(),
+                                        BinaryExpression(binExpr.left.copy(), "-", rExpr.right, rExpr.position),
                                        assignment.position
                                )
                                return listOf(
                                        IAstModification.ReplaceNode(binExpr, expr2, binExpr.parent),
-                                        IAstModification.InsertAfter(assignment, subConstant, assignment.definingScope()))
+                                        IAstModification.InsertAfter(assignment, subConstant, parent as IStatementContainer))
                            }
                        }
                    }
@@ -368,7 +350,7 @@ internal class StatementOptimizer(private val program: Program,
    override fun after(assignment: Assignment, parent: Node): Iterable<IAstModification> {
        if(assignment.target isSameAs assignment.value) {
            // remove assignment to self
-            return listOf(IAstModification.Remove(assignment, assignment.definingScope()))
+            return listOf(IAstModification.Remove(assignment, parent as IStatementContainer))
        }

        val targetIDt = assignment.target.inferType(program)
@@ -376,56 +358,68 @@ internal class StatementOptimizer(private val program: Program,
            throw FatalAstException("can't infer type of assignment target")

        // optimize binary expressions a bit
-        val targetDt = targetIDt.typeOrElse(DataType.STRUCT)
        val bexpr=assignment.value as? BinaryExpression
        if(bexpr!=null) {
-            val rightCv = bexpr.right.constValue(program)?.number?.toDouble()
+            val rightCv = bexpr.right.constValue(program)?.number
+            if(bexpr.operator=="-" && rightCv==null) {
+                if(bexpr.right isSameAs assignment.target) {
+                    // X = value - X  -->  X = -X ; X += value  (to avoid need of stack-evaluation)
+                    val negation = PrefixExpression("-", bexpr.right.copy(), bexpr.position)
+                    val addValue = Assignment(assignment.target.copy(), BinaryExpression(bexpr.right, "+", bexpr.left, bexpr.position), assignment.position)
+                    return listOf(
+                        IAstModification.ReplaceNode(bexpr, negation, assignment),
+                        IAstModification.InsertAfter(assignment, addValue, parent as IStatementContainer)
+                    )
+                }
+            }
+
            if (rightCv != null && assignment.target isSameAs bexpr.left) {
                // assignments of the form:  X = X <operator> <expr>
                // remove assignments that have no effect (such as X=X+0)
                // optimize/rewrite some other expressions
+                val targetDt = targetIDt.getOr(DataType.UNDEFINED)
                val vardeclDt = (assignment.target.identifier?.targetVarDecl(program))?.type
                when (bexpr.operator) {
                    "+" -> {
                        if (rightCv == 0.0) {
-                            return listOf(IAstModification.Remove(assignment, assignment.definingScope()))
+                            return listOf(IAstModification.Remove(assignment, parent as IStatementContainer))
                        } else if (targetDt in IntegerDatatypes && floor(rightCv) == rightCv) {
                            if (vardeclDt != VarDeclType.MEMORY && rightCv in 1.0..4.0) {
                                // replace by several INCs if it's not a memory address (inc on a memory mapped register doesn't work very well)
                                val incs = AnonymousScope(mutableListOf(), assignment.position)
                                repeat(rightCv.toInt()) {
-                                    incs.statements.add(PostIncrDecr(assignment.target, "++", assignment.position))
+                                    incs.statements.add(PostIncrDecr(assignment.target.copy(), "++", assignment.position))
                                }
-                                return listOf(IAstModification.ReplaceNode(assignment, incs, parent))
+                                listOf(IAstModification.ReplaceNode(assignment, if(incs.statements.size==1) incs.statements[0] else incs, parent))
                            }
                        }
                    }
                    "-" -> {
                        if (rightCv == 0.0) {
-                            return listOf(IAstModification.Remove(assignment, assignment.definingScope()))
+                            return listOf(IAstModification.Remove(assignment, parent as IStatementContainer))
                        } else if (targetDt in IntegerDatatypes && floor(rightCv) == rightCv) {
                            if (vardeclDt != VarDeclType.MEMORY && rightCv in 1.0..4.0) {
                                // replace by several DECs if it's not a memory address (dec on a memory mapped register doesn't work very well)
                                val decs = AnonymousScope(mutableListOf(), assignment.position)
                                repeat(rightCv.toInt()) {
-                                    decs.statements.add(PostIncrDecr(assignment.target, "--", assignment.position))
+                                    decs.statements.add(PostIncrDecr(assignment.target.copy(), "--", assignment.position))
                                }
                                return listOf(IAstModification.ReplaceNode(assignment, decs, parent))
                            }
                        }
                    }
-                    "*" -> if (rightCv == 1.0) return listOf(IAstModification.Remove(assignment, assignment.definingScope()))
-                    "/" -> if (rightCv == 1.0) return listOf(IAstModification.Remove(assignment, assignment.definingScope()))
-                    "**" -> if (rightCv == 1.0) return listOf(IAstModification.Remove(assignment, assignment.definingScope()))
-                    "|" -> if (rightCv == 0.0) return listOf(IAstModification.Remove(assignment, assignment.definingScope()))
-                    "^" -> if (rightCv == 0.0) return listOf(IAstModification.Remove(assignment, assignment.definingScope()))
+                    "*" -> if (rightCv == 1.0) return listOf(IAstModification.Remove(assignment, parent as IStatementContainer))
+                    "/" -> if (rightCv == 1.0) return listOf(IAstModification.Remove(assignment, parent as IStatementContainer))
+                    "**" -> if (rightCv == 1.0) return listOf(IAstModification.Remove(assignment, parent as IStatementContainer))
+                    "|" -> if (rightCv == 0.0) return listOf(IAstModification.Remove(assignment, parent as IStatementContainer))
+                    "^" -> if (rightCv == 0.0) return listOf(IAstModification.Remove(assignment, parent as IStatementContainer))
                    "<<" -> {
                        if (rightCv == 0.0)
-                            return listOf(IAstModification.Remove(assignment, assignment.definingScope()))
+                            return listOf(IAstModification.Remove(assignment, parent as IStatementContainer))
                    }
                    ">>" -> {
                        if (rightCv == 0.0)
-                            return listOf(IAstModification.Remove(assignment, assignment.definingScope()))
+                            return listOf(IAstModification.Remove(assignment, parent as IStatementContainer))
                    }
                }

@@ -436,23 +430,24 @@ internal class StatementOptimizer(private val program: Program,
    }

    override fun after(returnStmt: Return, parent: Node): Iterable<IAstModification> {
-        fun returnViaIntermediary(value: Expression): Iterable<IAstModification>? {
-            val returnDt = returnStmt.definingSubroutine()!!.returntypes.single()
+        fun returnViaIntermediaryVar(value: Expression): Iterable<IAstModification>? {
+            val subr = returnStmt.definingSubroutine!!
+            val returnDt = subr.returntypes.single()
            if (returnDt in IntegerDatatypes) {
-                // first assign to intermediary, then return that register
-                val returnValueIntermediary =
-                    when(returnDt) {
-                        DataType.UBYTE -> IdentifierReference(listOf("prog8_lib", "retval_interm_ub"), returnStmt.position)
-                        DataType.BYTE -> IdentifierReference(listOf("prog8_lib", "retval_interm_b"), returnStmt.position)
-                        DataType.UWORD -> IdentifierReference(listOf("prog8_lib", "retval_interm_uw"), returnStmt.position)
-                        DataType.WORD -> IdentifierReference(listOf("prog8_lib", "retval_interm_w"), returnStmt.position)
-                        else -> throw FatalAstException("weird return dt")
-                    }
+                // first assign to intermediary variable, then return that
+                val returnVarName = "retval_interm_" + when(returnDt) {
+                    DataType.UBYTE -> "ub"
+                    DataType.BYTE -> "b"
+                    DataType.UWORD -> "uw"
+                    DataType.WORD -> "w"
+                    else -> "<undefined>"
+                }
+                val returnValueIntermediary = IdentifierReference(listOf("prog8_lib", returnVarName), returnStmt.position)
                val tgt = AssignTarget(returnValueIntermediary, null, null, returnStmt.position)
                val assign = Assignment(tgt, value, returnStmt.position)
-                val returnReplacement = Return(returnValueIntermediary, returnStmt.position)
+                val returnReplacement = Return(returnValueIntermediary.copy(), returnStmt.position)
                return listOf(
-                    IAstModification.InsertBefore(returnStmt, assign, parent as INameScope),
+                    IAstModification.InsertBefore(returnStmt, assign, parent as IStatementContainer),
                    IAstModification.ReplaceNode(returnStmt, returnReplacement, parent)
                )
            }
@@ -461,12 +456,12 @@ internal class StatementOptimizer(private val program: Program,

        when(returnStmt.value) {
            is PrefixExpression -> {
-                val mod = returnViaIntermediary(returnStmt.value!!)
+                val mod = returnViaIntermediaryVar(returnStmt.value!!)
                if(mod!=null)
                    return mod
            }
            is BinaryExpression -> {
-                val mod = returnViaIntermediary(returnStmt.value!!)
+                val mod = returnViaIntermediaryVar(returnStmt.value!!)
                if(mod!=null)
                    return mod
            }
@@ -476,7 +471,7 @@ internal class StatementOptimizer(private val program: Program,
        return super.after(returnStmt, parent)
    }

-    private fun hasBreak(scope: INameScope): Boolean {
+    private fun hasBreak(scope: IStatementContainer): Boolean {

        class Searcher: IAstVisitor
        {
@@ -0,0 +1,247 @@
+package prog8.optimizer
+
+import prog8.ast.*
+import prog8.ast.base.DataType
+import prog8.ast.base.VarDeclType
+import prog8.ast.expressions.*
+import prog8.ast.statements.*
+import prog8.ast.walk.AstWalker
+import prog8.ast.walk.IAstModification
+import prog8.compilerinterface.CallGraph
+import prog8.compilerinterface.ICompilationTarget
+import prog8.compilerinterface.IErrorReporter
+import prog8.compilerinterface.isIOAddress
+
+
+class UnusedCodeRemover(private val program: Program,
+                        private val errors: IErrorReporter,
+                        private val compTarget: ICompilationTarget
+): AstWalker() {
+
+    private val callgraph = CallGraph(program)
+
+    override fun before(module: Module, parent: Node): Iterable<IAstModification> {
+        return if (!module.isLibrary && (module.containsNoCodeNorVars || callgraph.unused(module)))
+            listOf(IAstModification.Remove(module, parent as IStatementContainer))
+        else
+            noModifications
+    }
+
+    override fun before(breakStmt: Break, parent: Node): Iterable<IAstModification> {
+        reportUnreachable(breakStmt)
+        return emptyList()
+    }
+
+    override fun before(jump: Jump, parent: Node): Iterable<IAstModification> {
+        if(!jump.isGosub)
+            reportUnreachable(jump)
+        return emptyList()
+    }
+
+    override fun before(returnStmt: Return, parent: Node): Iterable<IAstModification> {
+        reportUnreachable(returnStmt)
+        return emptyList()
+    }
+
+    override fun before(functionCallStatement: FunctionCallStatement, parent: Node): Iterable<IAstModification> {
+        if(functionCallStatement.target.nameInSource.last() == "exit")
+            reportUnreachable(functionCallStatement)
+        return emptyList()
+    }
+
+    private fun reportUnreachable(stmt: Statement) {
+        when(val next = stmt.nextSibling()) {
+            null, is Label, is Directive, is VarDecl, is InlineAssembly, is Subroutine -> {}
+            else -> errors.warn("unreachable code", next.position)
+        }
+    }
+
+    override fun after(scope: AnonymousScope, parent: Node): Iterable<IAstModification> {
+        return deduplicateAssignments(scope.statements, scope)
+    }
+
+    override fun after(block: Block, parent: Node): Iterable<IAstModification> {
+        if("force_output" !in block.options()) {
+            if (block.containsNoCodeNorVars) {
+                if(block.name != internedStringsModuleName)
+                    errors.warn("removing unused block '${block.name}'", block.position)
+                return listOf(IAstModification.Remove(block, parent as IStatementContainer))
+            }
+            if(callgraph.unused(block)) {
+                errors.warn("removing unused block '${block.name}'", block.position)
+                return listOf(IAstModification.Remove(block, parent as IStatementContainer))
+            }
+        }
+
+        return deduplicateAssignments(block.statements, block)
+    }
+
+    override fun after(subroutine: Subroutine, parent: Node): Iterable<IAstModification> {
+        val forceOutput = "force_output" in subroutine.definingBlock.options()
+        if (subroutine !== program.entrypoint && !forceOutput && !subroutine.inline && !subroutine.isAsmSubroutine) {
+            if(callgraph.unused(subroutine)) {
+                if(subroutine.containsNoCodeNorVars) {
+                    if(!subroutine.definingModule.isLibrary)
+                        errors.warn("removing empty subroutine '${subroutine.name}'", subroutine.position)
+                    val removals = mutableListOf(IAstModification.Remove(subroutine, parent as IStatementContainer))
+                    callgraph.calledBy[subroutine]?.let {
+                        for(node in it)
+                            removals.add(IAstModification.Remove(node, node.parent as IStatementContainer))
+                    }
+                    return removals
+                }
+                if(!subroutine.definingModule.isLibrary)
+                    errors.warn("removing unused subroutine '${subroutine.name}'", subroutine.position)
+                return listOf(IAstModification.Remove(subroutine, parent as IStatementContainer))
+            }
+        }
+
+        return deduplicateAssignments(subroutine.statements, subroutine)
+    }
+
+    override fun after(decl: VarDecl, parent: Node): Iterable<IAstModification> {
+        if(decl.type==VarDeclType.VAR) {
+            val forceOutput = "force_output" in decl.definingBlock.options()
+            if (!forceOutput && !decl.autogeneratedDontRemove && !decl.sharedWithAsm && !decl.definingBlock.isInLibrary) {
+                val usages = callgraph.usages(decl)
+                if (usages.isEmpty()) {
+                    errors.warn("removing unused variable '${decl.name}'", decl.position)
+                    return listOf(IAstModification.Remove(decl, parent as IStatementContainer))
+                } else {
+                    // if all usages are just an assignment to this vardecl,
+                    // and it is in regular RAM, then remove the var as well including all assignments
+                    val assignTargets = usages.mapNotNull {
+                        it.parent as? AssignTarget
+                    }.filter {
+                        !it.isIOAddress(compTarget.machine)
+                    }
+                    if(assignTargets.size==usages.size) {
+                        errors.warn("removing unused variable '${decl.name}'", decl.position)
+                        val assignmentsToRemove = assignTargets.map { it.parent to it.parent.parent as IStatementContainer}.toSet()
+                        return assignmentsToRemove.map {
+                            IAstModification.Remove(it.first, it.second)
+                        } + listOf(
+                            IAstModification.Remove(decl, parent as IStatementContainer)
+                        )
+                    }
+                }
+            }
+        }
+
+        return noModifications
+    }
+
+    private fun deduplicateAssignments(statements: List<Statement>, scope: IStatementContainer): List<IAstModification> {
+        // removes 'duplicate' assignments that assign the same target directly after another
+        val linesToRemove = mutableListOf<Assignment>()
+        val modifications = mutableListOf<IAstModification>()
+
+        fun substituteZeroInBinexpr(expr: BinaryExpression, zero: NumericLiteralValue, assign1: Assignment, assign2: Assignment) {
+            if(expr.left isSameAs assign2.target) {
+                // X = X <oper> Right
+                linesToRemove.add(assign1)
+                modifications.add(IAstModification.ReplaceNode(
+                    expr.left, zero, expr
+                ))
+            }
+            if(expr.right isSameAs assign2.target) {
+                // X = Left <oper> X
+                linesToRemove.add(assign1)
+                modifications.add(IAstModification.ReplaceNode(
+                    expr.right, zero, expr
+                ))
+            }
+            val leftBinExpr = expr.left as? BinaryExpression
+            val rightBinExpr = expr.right as? BinaryExpression
+            if(leftBinExpr!=null && rightBinExpr==null) {
+                if(leftBinExpr.left isSameAs assign2.target) {
+                    // X = (X <oper> Right) <oper> Something
+                    linesToRemove.add(assign1)
+                    modifications.add(IAstModification.ReplaceNode(
+                        leftBinExpr.left, zero, leftBinExpr
+                    ))
+                }
+                if(leftBinExpr.right isSameAs assign2.target) {
+                    // X = (Left <oper> X) <oper> Something
+                    linesToRemove.add(assign1)
+                    modifications.add(IAstModification.ReplaceNode(
+                        leftBinExpr.right, zero, leftBinExpr
+                    ))
+                }
+            }
+            if(leftBinExpr==null && rightBinExpr!=null) {
+                if(rightBinExpr.left isSameAs assign2.target) {
+                    // X = Something <oper> (X <oper> Right)
+                    linesToRemove.add(assign1)
+                    modifications.add(IAstModification.ReplaceNode(
+                        rightBinExpr.left, zero, rightBinExpr
+                    ))
+                }
+                if(rightBinExpr.right isSameAs assign2.target) {
+                    // X = Something <oper> (Left <oper> X)
+                    linesToRemove.add(assign1)
+                    modifications.add(IAstModification.ReplaceNode(
+                        rightBinExpr.right, zero, rightBinExpr
+                    ))
+                }
+            }
+        }
+
+        fun substituteZeroInPrefixexpr(expr: PrefixExpression, zero: NumericLiteralValue, assign1: Assignment, assign2: Assignment) {
+            if(expr.expression isSameAs assign2.target) {
+                linesToRemove.add(assign1)
+                modifications.add(IAstModification.ReplaceNode(
+                    expr.expression, zero, expr
+                ))
+            }
+        }
+
+        fun substituteZeroInTypecast(expr: TypecastExpression, zero: NumericLiteralValue, assign1: Assignment, assign2: Assignment) {
+            if(expr.expression isSameAs assign2.target) {
+                linesToRemove.add(assign1)
+                modifications.add(IAstModification.ReplaceNode(
+                    expr.expression, zero, expr
+                ))
+            }
+            val subCast = expr.expression as? TypecastExpression
+            if(subCast!=null && subCast.expression isSameAs assign2.target) {
+                linesToRemove.add(assign1)
+                modifications.add(IAstModification.ReplaceNode(
+                    subCast.expression, zero, subCast
+                ))
+            }
+        }
+
+        for (stmtPairs in statements.windowed(2, step = 1)) {
+            val assign1 = stmtPairs[0] as? Assignment
+            val assign2 = stmtPairs[1] as? Assignment
+            if (assign1 != null && assign2 != null) {
+                val cvalue1 = assign1.value.constValue(program)
+                if(cvalue1!=null && cvalue1.number==0.0 && assign2.target.isSameAs(assign1.target, program) && assign2.isAugmentable) {
+                    val value2 = assign2.value
+                    val zero = VarDecl.defaultZero(value2.inferType(program).getOr(DataType.UNDEFINED), value2.position)
+                    when(value2) {
+                        is BinaryExpression -> substituteZeroInBinexpr(value2, zero, assign1, assign2)
+                        is PrefixExpression -> substituteZeroInPrefixexpr(value2, zero, assign1, assign2)
+                        is TypecastExpression -> substituteZeroInTypecast(value2, zero, assign1, assign2)
+                        else -> {}
+                    }
+                } else {
+                    if (assign1.target.isSameAs(assign2.target, program) && !assign1.target.isIOAddress(compTarget.machine))  {
+                        if(assign2.target.identifier==null || !assign2.value.referencesIdentifier(assign2.target.identifier!!.nameInSource))
+                            // only remove the second assignment if its value is a simple expression!
+                            when(assign2.value) {
+                                is PrefixExpression,
+                                is BinaryExpression,
+                                is TypecastExpression,
+                                is FunctionCall -> { /* don't remove */ }
+                                else -> linesToRemove.add(assign1)
+                            }
+                    }
+                }
+            }
+        }
+
+        return modifications + linesToRemove.map { IAstModification.Remove(it, scope) }
+    }
+}
@@ -1,51 +1,45 @@
 plugins {
    id 'java'
    id 'application'
-    id "org.jetbrains.kotlin.jvm" version "1.4.30"
-    id 'org.jetbrains.dokka' version "0.9.18"
-    id 'com.github.johnrengelman.shadow' version '6.1.0'
+    id "org.jetbrains.kotlin.jvm"
+    id 'com.github.johnrengelman.shadow' version '7.1.0'
+    id "io.kotest" version "0.3.8"
 }

-targetCompatibility = 11
-sourceCompatibility = 11
-
-repositories {
-    mavenLocal()
-    mavenCentral()
-    maven { url "https://kotlin.bintray.com/kotlinx" }
+java {
+    toolchain {
+        languageVersion = JavaLanguageVersion.of(javaVersion)
+    }
 }

 def prog8version = rootProject.file('compiler/res/version.txt').text.trim()

 dependencies {
+    implementation project(':compilerInterfaces')
+    implementation project(':codeOptimizers')
    implementation project(':compilerAst')
+    implementation project(':codeGeneration')
    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk8"
    // implementation "org.jetbrains.kotlin:kotlin-reflect"
-    implementation 'org.jetbrains.kotlinx:kotlinx-cli:0.3.1'
-    // implementation 'net.razorvine:ksim65:1.8'
-    // implementation "com.github.hypfvieh:dbus-java:3.2.4"
+    implementation 'org.jetbrains.kotlinx:kotlinx-cli:0.3.3'
+    implementation "com.michael-bull.kotlin-result:kotlin-result-jvm:1.1.12"

-    testImplementation "org.jetbrains.kotlin:kotlin-test-junit5"
-    testImplementation 'org.junit.jupiter:junit-jupiter-api:5.3.2'
-    testImplementation 'org.hamcrest:hamcrest-junit:2.0.0.0'
-    testRuntimeOnly 'org.junit.jupiter:junit-jupiter-engine:5.3.2'
+    testImplementation 'io.kotest:kotest-runner-junit5-jvm:4.6.3'
 }

-compileKotlin {
-    kotlinOptions {
-        jvmTarget = "11"
-        useIR = true
-        // verbose = true
-        // freeCompilerArgs += "-XXLanguage:+NewInference"
+configurations.all {
+    exclude group: 'com.ibm.icu', module: 'icu4j'
+    exclude group: "org.antlr", module: "antlr4"
+}
+
+configurations {
+    // strange antlr plugin issue, see https://github.com/gradle/gradle/issues/820
+    // this avoids linking in the complete antlr binary jar
+    compile {
+        extendsFrom = extendsFrom.findAll { it != configurations.antlr }
    }
 }

-compileTestKotlin {
-    kotlinOptions {
-        jvmTarget = "11"
-        useIR = true
-    }
-}

 sourceSets {
    main {
@@ -58,7 +52,8 @@ sourceSets {
    }
    test {
        java {
-            srcDirs = ["${project.projectDir}/test"]
+            srcDir "${project.projectDir}/test"
+            srcDir "${project(':compilerAst').projectDir}/test/helpers"
        }
    }
 }
@@ -67,15 +62,9 @@ startScripts.enabled = true

 application {
    mainClass = 'prog8.CompilerMainKt'
-    mainClassName = 'prog8.CompilerMainKt'  // deprecated
    applicationName = 'p8compile'
 }

-artifacts {
-    archives shadowJar
-}
-
-
 shadowJar {
    archiveBaseName = 'prog8compiler'
    archiveVersion = prog8version
@@ -96,12 +85,4 @@ test {
    }
 }

-
-dokka {
-    outputFormat = 'html'
-    outputDirectory = "$buildDir/kdoc"
-}
-
-task wrapper(type: Wrapper) {
-    gradleVersion = '6.7'
-}
+build.finalizedBy installDist, installShadowDist
@@ -1,10 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <module type="JAVA_MODULE" version="4">
-  <component name="FacetManager">
-    <facet type="Python" name="Python">
-      <configuration sdkName="Python 3.9" />
-    </facet>
-  </component>
  <component name="NewModuleRootManager" inherit-compiler-output="true">
    <exclude-output />
    <content url="file://$MODULE_DIR$">
@@ -13,12 +8,16 @@
      <sourceFolder url="file://$MODULE_DIR$/test" isTestSource="true" />
      <excludeFolder url="file://$MODULE_DIR$/build" />
    </content>
-    <orderEntry type="jdk" jdkName="11" jdkType="JavaSDK" />
+    <orderEntry type="jdk" jdkName="openjdk-11" jdkType="JavaSDK" />
    <orderEntry type="sourceFolder" forTests="false" />
    <orderEntry type="library" name="KotlinJavaRuntime" level="project" />
-    <orderEntry type="library" name="unittest-libs" level="project" />
-    <orderEntry type="library" name="kotlinx-cli-jvm" level="project" />
    <orderEntry type="module" module-name="compilerAst" />
-    <orderEntry type="library" name="Python 3.9 interpreter library" level="application" />
+    <orderEntry type="library" name="jetbrains.kotlinx.cli.jvm" level="project" />
+    <orderEntry type="library" name="michael.bull.kotlin.result.jvm" level="project" />
+    <orderEntry type="module" module-name="codeOptimizers" />
+    <orderEntry type="module" module-name="compilerInterfaces" />
+    <orderEntry type="module" module-name="codeGeneration" />
+    <orderEntry type="library" name="io.kotest.assertions.core.jvm" level="project" />
+    <orderEntry type="library" name="io.kotest.runner.junit5.jvm" level="project" />
  </component>
 </module>
@@ -4,7 +4,6 @@
 ;
 ; indent format: TABS, size=8

-%target c64
 %option enable_floats

 floats {
@@ -13,6 +12,7 @@ floats {
        const float  PI     = 3.141592653589793
        const float  TWOPI  = 6.283185307179586

+        float  tempvar_swap_float     ; used for some swap() operations

 ; ---- C64 basic and kernal ROM float constants and functions ----

@@ -83,7 +83,7 @@ romsub $bc58 = ABS()                                        ; fac1 = ABS(fac1)
 romsub $bf71 = SQR() clobbers(A,X,Y)                        ; fac1 = SQRT(fac1)
 romsub $bf74 = SQRA() clobbers(A,X,Y)                       ; fac1 = SQRT(fac2)
 romsub $bfed = EXP() clobbers(A,X,Y)                        ; fac1 = EXP(fac1)  (e ** fac1)
-romsub $bfb4 = NEGOP() clobbers(A)                          ; switch the sign of fac1
+romsub $bfb4 = NEGOP() clobbers(A)                          ; switch the sign of fac1 (fac1 = -fac1)
 romsub $e097 = RND() clobbers(A,X,Y)                        ; fac1 = RND(fac1) float random number generator
 romsub $e264 = COS() clobbers(A,X,Y)                        ; fac1 = COS(fac1)
 romsub $e26b = SIN() clobbers(A,X,Y)                        ; fac1 = SIN(fac1)
@@ -195,7 +195,7 @@ sub  print_f  (float value) {
 	}}
 }

-%asminclude "library:c64/floats.asm", ""
-%asminclude "library:c64/floats_funcs.asm", ""
+%asminclude "library:c64/floats.asm"
+%asminclude "library:c64/floats_funcs.asm"

 }
@@ -1,4 +1,3 @@
-%target c64
 %import textio

 ; bitmap pixel graphics module for the C64
@@ -34,6 +33,9 @@ graphics {
    sub line(uword @zp x1, ubyte @zp y1, uword @zp x2, ubyte @zp y2) {
        ; Bresenham algorithm.
        ; This code special-cases various quadrant loops to allow simple ++ and -- operations.
+        ; TODO implement this as optimized assembly, for instance https://github.com/EgonOlsen71/bresenham/blob/main/src/asm/graphics.asm  ??
+        ;      or from here https://retro64.altervista.org/blog/an-introduction-to-vector-based-graphics-the-commodore-64-rotating-simple-3d-objects/
+
        if y1>y2 {
            ; make sure dy is always positive to have only 4 instead of 8 special cases
            swap(x1, x2)
@@ -5,8 +5,6 @@
 ;
 ; indent format: TABS, size=8

-%target c64
-
 c64 {
        &ubyte  TIME_HI         = $a0       ; software jiffy clock, hi byte
        &ubyte  TIME_MID        = $a1       ;  .. mid byte
@@ -214,7 +212,7 @@ romsub $FFD2 = CHROUT(ubyte char @ A)                           ; (via 806 ($326
 romsub $FFD5 = LOAD(ubyte verify @ A, uword address @ XY) -> ubyte @Pc, ubyte @ A, uword @ XY     ; (via 816 ($330)) load from device
 romsub $FFD8 = SAVE(ubyte zp_startaddr @ A, uword endaddr @ XY) -> ubyte @ Pc, ubyte @ A          ; (via 818 ($332)) save to a device
 romsub $FFDB = SETTIM(ubyte low @ A, ubyte middle @ X, ubyte high @ Y)      ; set the software clock
-romsub $FFDE = RDTIM() -> ubyte @ A, ubyte @ X, ubyte @ Y       ; read the software clock
+romsub $FFDE = RDTIM() -> ubyte @ A, ubyte @ X, ubyte @ Y       ; read the software clock (A=lo,X=mid,Y=high)
 romsub $FFE1 = STOP() clobbers(X) -> ubyte @ Pz, ubyte @ A      ; (via 808 ($328)) check the STOP key (and some others in A)
 romsub $FFE4 = GETIN() clobbers(X,Y) -> ubyte @Pc, ubyte @ A    ; (via 810 ($32A)) get a character
 romsub $FFE7 = CLALL() clobbers(A,X)                            ; (via 812 ($32C)) close all files
@@ -246,7 +244,7 @@ asmsub STOP2() -> ubyte @A  {
 }

 asmsub RDTIM16() -> uword @AY {
-    ; --  like RDTIM() but only returning the lower 16 bits for convenience
+    ; --  like RDTIM() but only returning the lower 16 bits in AY for convenience
    %asm {{
        stx  P8ZP_SCRATCH_REG
        jsr  c64.RDTIM
@@ -478,7 +476,7 @@ sys {


    asmsub  reset_system()  {
-        ; Soft-reset the system back to Basic prompt.
+        ; Soft-reset the system back to initial power-on Basic prompt.
        %asm {{
            sei
            lda  #14
@@ -489,6 +487,7 @@ sys {

    sub wait(uword jiffies) {
        ; --- wait approximately the given number of jiffies (1/60th seconds)
+        ;     note: the system irq handler has to be active for this to work as it depends on the system jiffy clock
        repeat jiffies {
            ubyte jiff = lsb(c64.RDTIM16())
            while jiff==lsb(c64.RDTIM16()) {
@@ -497,6 +496,27 @@ sys {
        }
    }

+    asmsub waitvsync() clobbers(A) {
+        ; --- busy wait till the next vsync has occurred (approximately), without depending on custom irq handling.
+        ;     note: a more accurate way to wait for vsync is to set up a vsync irq handler instead.
+        %asm {{
+-           bit  c64.SCROLY
+            bpl  -
+-           bit  c64.SCROLY
+            bmi  -
+            rts
+        }}
+    }
+
+    inline asmsub waitrastborder() {
+        ; --- busy wait till the raster position has reached the bottom screen border (approximately)
+        ;     note: a more accurate way to do this is by using a raster irq handler instead.
+        %asm {{
+-           bit  c64.SCROLY
+            bpl  -
+        }}
+    }
+
    asmsub memcopy(uword source @R0, uword target @R1, uword count @AY) clobbers(A,X,Y) {
        %asm {{
            ldx  cx16.r0
@@ -577,62 +597,34 @@ _longcopy
        }}
    }

-
-    inline asmsub rsave() {
-        ; save cpu status flag and all registers A, X, Y.
-        ; see http://6502.org/tutorials/register_preservation.html
-        %asm {{
-            php
-            sta  P8ZP_SCRATCH_REG
-            pha
-            txa
-            pha
-            tya
-            pha
-            lda  P8ZP_SCRATCH_REG
-        }}
-    }
-
-    inline asmsub rrestore() {
-        ; restore all registers and cpu status flag
-        %asm {{
-            pla
-            tay
-            pla
-            tax
-            pla
-            plp
-        }}
-    }
-
    inline asmsub read_flags() -> ubyte @A {
        %asm {{
-            php
-            pla
+        php
+        pla
        }}
    }

    inline asmsub clear_carry() {
        %asm {{
-            clc
+        clc
        }}
    }

    inline asmsub set_carry() {
        %asm {{
-            sec
+        sec
        }}
    }

    inline asmsub clear_irqd() {
        %asm {{
-            cli
+        cli
        }}
    }

    inline asmsub set_irqd() {
        %asm {{
-            sei
+        sei
        }}
    }

@@ -679,4 +671,88 @@ cx16 {
    &uword r14 = $cf1c
    &uword r15 = $cf1e

+    &word r0s  = $cf00
+    &word r1s  = $cf02
+    &word r2s  = $cf04
+    &word r3s  = $cf06
+    &word r4s  = $cf08
+    &word r5s  = $cf0a
+    &word r6s  = $cf0c
+    &word r7s  = $cf0e
+    &word r8s  = $cf10
+    &word r9s  = $cf12
+    &word r10s = $cf14
+    &word r11s = $cf16
+    &word r12s = $cf18
+    &word r13s = $cf1a
+    &word r14s = $cf1c
+    &word r15s = $cf1e
+
+    &ubyte r0L  = $cf00
+    &ubyte r1L  = $cf02
+    &ubyte r2L  = $cf04
+    &ubyte r3L  = $cf06
+    &ubyte r4L  = $cf08
+    &ubyte r5L  = $cf0a
+    &ubyte r6L  = $cf0c
+    &ubyte r7L  = $cf0e
+    &ubyte r8L  = $cf10
+    &ubyte r9L  = $cf12
+    &ubyte r10L = $cf14
+    &ubyte r11L = $cf16
+    &ubyte r12L = $cf18
+    &ubyte r13L = $cf1a
+    &ubyte r14L = $cf1c
+    &ubyte r15L = $cf1e
+
+    &ubyte r0H  = $cf01
+    &ubyte r1H  = $cf03
+    &ubyte r2H  = $cf05
+    &ubyte r3H  = $cf07
+    &ubyte r4H  = $cf09
+    &ubyte r5H  = $cf0b
+    &ubyte r6H  = $cf0d
+    &ubyte r7H  = $cf0f
+    &ubyte r8H  = $cf11
+    &ubyte r9H  = $cf13
+    &ubyte r10H = $cf15
+    &ubyte r11H = $cf17
+    &ubyte r12H = $cf19
+    &ubyte r13H = $cf1b
+    &ubyte r14H = $cf1d
+    &ubyte r15H = $cf1f
+
+    &byte r0sL  = $cf00
+    &byte r1sL  = $cf02
+    &byte r2sL  = $cf04
+    &byte r3sL  = $cf06
+    &byte r4sL  = $cf08
+    &byte r5sL  = $cf0a
+    &byte r6sL  = $cf0c
+    &byte r7sL  = $cf0e
+    &byte r8sL  = $cf10
+    &byte r9sL  = $cf12
+    &byte r10sL = $cf14
+    &byte r11sL = $cf16
+    &byte r12sL = $cf18
+    &byte r13sL = $cf1a
+    &byte r14sL = $cf1c
+    &byte r15sL = $cf1e
+
+    &byte r0sH  = $cf01
+    &byte r1sH  = $cf03
+    &byte r2sH  = $cf05
+    &byte r3sH  = $cf07
+    &byte r4sH  = $cf09
+    &byte r5sH  = $cf0b
+    &byte r6sH  = $cf0d
+    &byte r7sH  = $cf0f
+    &byte r8sH  = $cf11
+    &byte r9sH  = $cf13
+    &byte r10sH = $cf15
+    &byte r11sH = $cf17
+    &byte r12sH = $cf19
+    &byte r13sH = $cf1b
+    &byte r14sH = $cf1d
+    &byte r15sH = $cf1f
 }
@@ -4,7 +4,6 @@
 ;
 ; indent format: TABS, size=8

-%target c64
 %import syslib
 %import conv

@@ -12,14 +12,14 @@ conv {
 asmsub  str_ub0  (ubyte value @ A) clobbers(A,Y)  {
 	; ---- convert the ubyte in A in decimal string form, with left padding 0s (3 positions total)
 	%asm {{
-            phx
+            stx  P8ZP_SCRATCH_REG
            jsr  conv.ubyte2decimal
            sty  string_out
            sta  string_out+1
            stx  string_out+2
            lda  #0
            sta  string_out+3
-            plx
+            ldx  P8ZP_SCRATCH_REG
            rts
 	}}
 }
@@ -27,7 +27,7 @@ asmsub  str_ub0  (ubyte value @ A) clobbers(A,Y)  {
 asmsub  str_ub  (ubyte value @ A) clobbers(A,Y)  {
 	; ---- convert the ubyte in A in decimal string form, without left padding 0s
 	%asm {{
-		phx
+		stx  P8ZP_SCRATCH_REG
 		ldy  #0
 		sty  P8ZP_SCRATCH_B1
 		jsr  conv.ubyte2decimal
@@ -53,7 +53,7 @@ _output_byte_digits
                iny
                lda  #0
                sta  string_out,y
-                plx
+                ldx  P8ZP_SCRATCH_REG
                rts
 	}}
 }
@@ -61,7 +61,7 @@ _output_byte_digits
 asmsub  str_b  (byte value @ A) clobbers(A,Y)  {
 	; ---- convert the byte in A in decimal string form, without left padding 0s
 	%asm {{
-            phx
+            stx  P8ZP_SCRATCH_REG
            ldy  #0
            sty  P8ZP_SCRATCH_B1
            cmp  #0
@@ -149,7 +149,7 @@ asmsub  str_uwhex  (uword value @ AY) clobbers(A,Y)  {
 asmsub  str_uw0  (uword value @ AY) clobbers(A,Y)  {
 	; ---- convert the uword in A/Y in decimal string form, with left padding 0s (5 positions total)
 	%asm {{
-	    phx
+	    stx  P8ZP_SCRATCH_REG
 	    jsr  conv.uword2decimal
 	    ldy  #0
 -           lda  conv.uword2decimal.decTenThousands,y
@@ -157,7 +157,7 @@ asmsub  str_uw0  (uword value @ AY) clobbers(A,Y)  {
            beq  +
            iny
            bne  -
-+           plx
+           ldx  P8ZP_SCRATCH_REG
 	    rts
 	}}
 }
@@ -165,7 +165,7 @@ asmsub  str_uw0  (uword value @ AY) clobbers(A,Y)  {
 asmsub  str_uw  (uword value @ AY) clobbers(A,Y)  {
 	; ---- convert the uword in A/Y in decimal string form, without left padding 0s
 	%asm {{
-	    phx
+	    stx  P8ZP_SCRATCH_REG
 	    jsr  conv.uword2decimal
 	    ldx  #0
 _output_digits
@@ -183,7 +183,7 @@ _gotdigit   sta  string_out,x
            bne  _gotdigit
 _end        lda  #0
            sta  string_out,x
-            plx
+            ldx  P8ZP_SCRATCH_REG
            rts

 _allzero    lda  #'0'
@@ -198,7 +198,7 @@ asmsub  str_w  (word value @ AY) clobbers(A,Y)  {
 	%asm {{
 	    cpy  #0
 	    bpl  str_uw
-	    phx
+	    stx  P8ZP_SCRATCH_REG
 	    pha
 	    lda  #'-'
 	    sta  string_out
@@ -516,7 +516,7 @@ asmsub  uword2decimal  (uword value @AY) -> ubyte @Y, ubyte @A, ubyte @X  {

 ;Convert 16 bit Hex to Decimal (0-65535) Rev 2
 ;By Omegamatrix    Further optimizations by tepples
-; routine from http://forums.nesdev.com/viewtopic.php?f=2&t=11341&start=15
+; routine from https://forums.nesdev.org/viewtopic.php?f=2&t=11341&start=15

 ;HexToDec99
 ; start in A
@@ -4,15 +4,17 @@
 ;
 ; indent format: TABS, size=8

-%target cx16
 %option enable_floats

 floats {
-	; ---- this block contains C-64 floating point related functions ----
+	; ---- this block contains C-64 compatible floating point related functions ----
+	;      the addresses are from cx16 V39 emulator and roms! they won't work on older versions.

        const float  PI     = 3.141592653589793
        const float  TWOPI  = 6.283185307179586

+        float  tempvar_swap_float     ; used for some swap() operations
+

 ; ---- ROM float functions ----

@@ -43,36 +45,34 @@ romsub $fe1e = NORMAL() clobbers(A,X,Y)                     ; normalize fac1 (?)
 romsub $fe24 = LOG() clobbers(A,X,Y)                        ; fac1 = LN(fac1)  (natural log)
 romsub $fe27 = FMULT(uword mflpt @ AY) clobbers(A,X,Y)      ; fac1 *= mflpt value from A/Y
 romsub $fe2a = FMULTT() clobbers(A,X,Y)                     ; fac1 *= fac2
-romsub $fe33 = CONUPK(uword mflpt @ AY) clobbers(A,Y)       ; load mflpt value from memory  in A/Y into fac2
-romsub $fe36 = MUL10() clobbers(A,X,Y)                      ; fac1 *= 10
-romsub $fe3c = DIV10() clobbers(A,X,Y)                      ; fac1 /= 10 , CAUTION: result is always positive!
-romsub $fe3f = FDIV(uword mflpt @ AY) clobbers(A,X,Y)       ; fac1 = mflpt in A/Y / fac1  (remainder in fac2)
-romsub $fe42 = FDIVT() clobbers(A,X,Y)                      ; fac1 = fac2/fac1  (remainder in fac2)  mind the order of the operands
+romsub $fe30 = CONUPK(uword mflpt @ AY) clobbers(A,X,Y)     ; load mflpt value from memory  in A/Y into fac2
+romsub $fe33 = MUL10() clobbers(A,X,Y)                      ; fac1 *= 10
+romsub $fe36 = DIV10() clobbers(A,X,Y)                      ; fac1 /= 10 , CAUTION: result is always positive!
+romsub $fe39 = FDIV(uword mflpt @ AY) clobbers(A,X,Y)       ; fac1 = mflpt in A/Y / fac1  (remainder in fac2)
+romsub $fe3c = FDIVT() clobbers(A,X,Y)                      ; fac1 = fac2/fac1  (remainder in fac2)  mind the order of the operands

-romsub $fe48 = MOVFM(uword mflpt @ AY) clobbers(A,Y)        ; load mflpt value from memory  in A/Y into fac1
-romsub $fe4b = MOVMF(uword mflpt @ XY) clobbers(A,Y)        ; store fac1 to memory  X/Y as 5-byte mflpt
-romsub $fe4e = MOVFA() clobbers(A,X)                        ; copy fac2 to fac1
-romsub $fe51 = MOVAF() clobbers(A,X)                        ; copy fac1 to fac2  (rounded)
-romsub $fe54 = MOVEF() clobbers(A,X)                        ; copy fac1 to fac2
-romsub $fe5a = SIGN() -> ubyte @ A                          ; SIGN(fac1) to A, $ff, $0, $1 for negative, zero, positive
-romsub $fe5d = SGN() clobbers(A,X,Y)                        ; fac1 = SGN(fac1), result of SIGN (-1, 0 or 1)
-romsub $fe60 = FREADSA(byte value @ A) clobbers(A,X,Y)      ; 8 bit signed A -> float in fac1
-romsub $fe6c = ABS()                                        ; fac1 = ABS(fac1)
-romsub $fe6f = FCOMP(uword mflpt @ AY) clobbers(X,Y) -> ubyte @ A   ; A = compare fac1 to mflpt in A/Y, 0=equal 1=fac1 is greater, 255=fac1 is less than
-romsub $fe78 = INT() clobbers(A,X,Y)                        ; INT() truncates, use FADDH first to round instead of trunc
-romsub $fe7e = FINLOG(byte value @A) clobbers (A, X, Y)           ; fac1 += signed byte in A
-romsub $fe81 = FOUT() clobbers(X) -> uword @ AY             ; fac1 -> string, address returned in AY
-romsub $fe8a = SQR() clobbers(A,X,Y)                        ; fac1 = SQRT(fac1)
-romsub $fe8d = FPWRT() clobbers(A,X,Y)                      ; fac1 = fac2 ** fac1
-; note: there is no FPWR() on the Cx16
-romsub $fe93 = NEGOP() clobbers(A)                          ; switch the sign of fac1
-romsub $fe96 = EXP() clobbers(A,X,Y)                        ; fac1 = EXP(fac1)  (e ** fac1)
-romsub $fe9f = RND2(byte value @A) clobbers(A,X,Y)                ; fac1 = RND(A) float random number generator
-romsub $fea2 = RND() clobbers(A,X,Y)                        ; fac1 = RND(fac1) float random number generator
-romsub $fea5 = COS() clobbers(A,X,Y)                        ; fac1 = COS(fac1)
-romsub $fea8 = SIN() clobbers(A,X,Y)                        ; fac1 = SIN(fac1)
-romsub $feab = TAN() clobbers(A,X,Y)                        ; fac1 = TAN(fac1)
-romsub $feae = ATN() clobbers(A,X,Y)                        ; fac1 = ATN(fac1)
+romsub $fe42 = MOVFM(uword mflpt @ AY) clobbers(A,X,Y)      ; load mflpt value from memory  in A/Y into fac1
+romsub $fe45 = MOVMF(uword mflpt @ XY) clobbers(A,X,Y)      ; store fac1 to memory  X/Y as 5-byte mflpt
+romsub $fe48 = MOVFA() clobbers(A,X)                        ; copy fac2 to fac1
+romsub $fe4b = MOVAF() clobbers(A,X)                        ; copy fac1 to fac2  (rounded)
+romsub $fe4e = MOVEF() clobbers(A,X)                        ; copy fac1 to fac2
+romsub $fe54 = SIGN() clobbers(X,Y) -> ubyte @ A            ; SIGN(fac1) to A, $ff, $0, $1 for negative, zero, positive
+romsub $fe57 = SGN() clobbers(A,X,Y)                        ; fac1 = SGN(fac1), result of SIGN (-1, 0 or 1)
+romsub $fe5a = FREADSA(byte value @ A) clobbers(A,X,Y)      ; 8 bit signed A -> float in fac1
+romsub $fe66 = ABS() clobbers(A,X,Y)                        ; fac1 = ABS(fac1)
+romsub $fe69 = FCOMP(uword mflpt @ AY) clobbers(X,Y) -> ubyte @ A   ; A = compare fac1 to mflpt in A/Y, 0=equal 1=fac1 is greater, 255=fac1 is less than
+romsub $fe72 = INT() clobbers(A,X,Y)                        ; INT() truncates, use FADDH first to round instead of trunc
+romsub $fe78 = FINLOG(byte value @A) clobbers (A, X, Y)           ; fac1 += signed byte in A
+romsub $fe7b = FOUT() clobbers(X) -> uword @ AY             ; fac1 -> string, address returned in AY
+romsub $fe81 = SQR() clobbers(A,X,Y)                        ; fac1 = SQRT(fac1)
+romsub $fe84 = FPWRT() clobbers(A,X,Y)                      ; fac1 = fac2 ** fac1
+romsub $fe8a = NEGOP() clobbers(A)                          ; switch the sign of fac1 (fac1 = -fac1)
+romsub $fe8d = EXP() clobbers(A,X,Y)                        ; fac1 = EXP(fac1)  (e ** fac1)
+romsub $fe96 = RND() clobbers(A,X,Y)                        ; fac1 = RND(fac1) float random number generator
+romsub $fe99 = COS() clobbers(A,X,Y)                        ; fac1 = COS(fac1)
+romsub $fe9c = SIN() clobbers(A,X,Y)                        ; fac1 = SIN(fac1)
+romsub $fe9f = TAN() clobbers(A,X,Y)                        ; fac1 = TAN(fac1)
+romsub $fea2 = ATN() clobbers(A,X,Y)                        ; fac1 = ATN(fac1)


 asmsub  GIVUAYFAY  (uword value @ AY) clobbers(A,X,Y)  {
@@ -158,7 +158,7 @@ sub  print_f  (float value) {
 	}}
 }

-%asminclude "library:c64/floats.asm", ""
-%asminclude "library:c64/floats_funcs.asm", ""
+%asminclude "library:c64/floats.asm"
+%asminclude "library:c64/floats_funcs.asm"

 }
@@ -1,5 +1,3 @@
-%target cx16
-
 ; Bitmap pixel graphics routines for the CommanderX16
 ; Custom routines to use the full-screen 640x480 and 320x240 screen modes.
 ; (These modes are not supported by the documented GRAPH_xxxx kernal routines)
@@ -22,6 +20,7 @@
 ;   mode 6 = bitmap 640 x 480 x 4c
 ;   higher color dephts in highres are not supported due to lack of VRAM

+
 ; TODO can we make a FB vector table and emulation routines for the Cx16s' GRAPH_init() call? to replace the builtin 320x200 fb driver?

 gfx2 {
@@ -274,9 +273,9 @@ _done
                        ora  colorbits,y
                        sta  cx16.VERA_DATA0
                        cpy  #%00000011         ; next vera byte?
-                        bne  +
+                        bne  ++
                        inc  cx16.VERA_ADDR_L
-                        bne  +
+                        bne  ++
                        inc  cx16.VERA_ADDR_M
 +                       bne  +
                        inc  cx16.VERA_ADDR_H
@@ -292,92 +291,56 @@ _done
    }

    sub vertical_line(uword x, uword y, uword height, ubyte color) {
-        position(x,y)
        when active_mode {
            1, 5 -> {
-                ; monochrome, either resolution
-                ; note for the 1 bpp modes we can't use vera's auto increment mode because we have to 'or' the pixel data in place.
-                ; TODO use TWO vera adress pointers simultaneously one for reading, one for writing, so auto-increment IS possible
-                cx16.VERA_ADDR_H &= %00000111   ; no auto advance
-                cx16.r15 = gfx2.plot.bits[x as ubyte & 7]           ; bitmask
-                if active_mode>=5
-                    cx16.r14 = 640/8
-                else
-                    cx16.r14 = 320/8
+                ; monochrome, lo-res
+                cx16.r15L = gfx2.plot.bits[x as ubyte & 7]           ; bitmask
                if color {
                    if monochrome_dont_stipple_flag {
+                        ; draw continuous line.
+                        position2(x,y,true)
+                        if active_mode==1
+                            set_both_strides(11)    ; 40 increment = 1 line in 320 px monochrome
+                        else
+                            set_both_strides(12)    ; 80 increment = 1 line in 640 px monochrome
                        repeat height {
                            %asm {{
                                lda  cx16.VERA_DATA0
-                                ora  cx16.r15
-                                sta  cx16.VERA_DATA0
-                                lda  cx16.VERA_ADDR_L
-                                clc
-                                adc  cx16.r14                 ; advance vera ptr to go to the next line
-                                sta  cx16.VERA_ADDR_L
-                                lda  cx16.VERA_ADDR_M
-                                adc  #0
-                                sta  cx16.VERA_ADDR_M
-                                ; lda  cx16.VERA_ADDR_H     ; the bitmap size is small enough to not have to deal with the _H part.
-                                ; adc  #0
-                                ; sta  cx16.VERA_ADDR_H
+                                ora  cx16.r15L
+                                sta  cx16.VERA_DATA1
                            }}
                        }
                    } else {
-                        ; stippling.
-                        height = (height+1)/2       ; TODO is the line sometimes 1 pixel too long now because of rounding?
-                        %asm {{
-                            lda x
-                            eor y
-                            and #1
-                            bne +
-                            lda  cx16.VERA_ADDR_L
-                            clc
-                            adc  cx16.r14                ; advance vera ptr to go to the next line for correct stipple pattern
-                            sta  cx16.VERA_ADDR_L
-                            lda  cx16.VERA_ADDR_M
-                            adc  #0
-                            sta  cx16.VERA_ADDR_M
-        +
-                            asl  cx16.r14
-                            ldy  height
-                            beq  +
-        -                   lda  cx16.VERA_DATA0
-                            ora  cx16.r15
-                            sta  cx16.VERA_DATA0
-                            lda  cx16.VERA_ADDR_L
-                            clc
-                            adc  cx16.r14               ; advance vera data ptr to go to the next-next line
-                            sta  cx16.VERA_ADDR_L
-                            lda  cx16.VERA_ADDR_M
-                            adc  #0
-                            sta  cx16.VERA_ADDR_M
-                            ; lda  cx16.VERA_ADDR_H      ; the bitmap size is small enough to not have to deal with the _H part.
-                            ; adc  #0
-                            ; sta  cx16.VERA_ADDR_H
-                            dey
-                            bne  -
-        +
-                        }}
+                        ; draw stippled line.
+                        if x&1 {
+                            y++
+                            height--
+                        }
+                        position2(x,y,true)
+                        if active_mode==1
+                            set_both_strides(12)    ; 80 increment = 2 line in 320 px monochrome
+                        else
+                            set_both_strides(13)    ; 160 increment = 2 line in 640 px monochrome
+                        repeat height/2 {
+                            %asm {{
+                                lda  cx16.VERA_DATA0
+                                ora  cx16.r15L
+                                sta  cx16.VERA_DATA1
+                            }}
+                        }
                    }
                } else {
-                    cx16.r15 = ~cx16.r15
+                    position2(x,y,true)
+                    cx16.r15 = ~cx16.r15    ; erase pixels
+                    if active_mode==1
+                        set_both_strides(11)    ; 40 increment = 1 line in 320 px monochrome
+                    else
+                        set_both_strides(12)    ; 80 increment = 1 line in 640 px monochrome
                    repeat height {
                        %asm {{
                            lda  cx16.VERA_DATA0
-                            and  cx16.r15
-                            sta  cx16.VERA_DATA0
-                            lda  cx16.VERA_ADDR_L
-                            clc
-                            adc  cx16.r14             ; advance vera data ptr to go to the next line
-                            sta  cx16.VERA_ADDR_L
-                            lda  cx16.VERA_ADDR_M
-                            adc  #0
-                            sta  cx16.VERA_ADDR_M
-                            ; the bitmap size is small enough to not have to deal with the _H part:
-                            ; lda  cx16.VERA_ADDR_H
-                            ; adc  #0
-                            ; sta  cx16.VERA_ADDR_H
+                            and  cx16.r15L
+                            sta  cx16.VERA_DATA1
                        }}
                    }
                }
@@ -385,6 +348,7 @@ _done
            4 -> {
                ; lores 256c
                ; set vera auto-increment to 320 pixel increment (=next line)
+                position(x,y)
                cx16.VERA_ADDR_H = cx16.VERA_ADDR_H & %00000111 | (14<<4)
                %asm {{
                    ldy  height
@@ -398,36 +362,33 @@ _done
            }
            6 -> {
                ; highres 4c
-                ; note for this mode we can't use vera's auto increment mode because we have to 'or' the pixel data in place.
-                ; TODO use TWO vera adress pointers simultaneously one for reading, one for writing, so auto-increment IS possible
-                cx16.VERA_ADDR_H &= %00000111   ; no auto advance
-                ; TODO also mostly usable for lores 4c?
-                void addr_mul_24_for_highres_4c(y, x)      ; 24 bits result is in r0 and r1L (highest byte)
-
-                ; TODO optimize this vertical line loop in pure assembly
+                ; use TWO vera adress pointers simultaneously one for reading, one for writing, so auto-increment is possible
+                if height==0
+                    return
+                position2(x,y,true)
+                set_both_strides(13)    ; 160 increment = 1 line in 640 px 4c mode
                color &= 3
                color <<= gfx2.plot.shift4c[lsb(x) & 3]
                ubyte mask = gfx2.plot.mask4c[lsb(x) & 3]
                repeat height {
-                    ubyte value = cx16.vpeek(lsb(cx16.r1), cx16.r0) & mask | color
-                    cx16.vpoke(lsb(cx16.r1), cx16.r0, value)
                    %asm {{
-                        ; 24 bits add 160 (640/4)
-                        clc
-                        lda  cx16.r0
-                        adc  #640/4
-                        sta  cx16.r0
-                        lda  cx16.r0+1
-                        adc  #0
-                        sta  cx16.r0+1
-                        bcc  +
-                        inc  cx16.r1
-+
+                        lda  cx16.VERA_DATA0
+                        and  mask
+                        ora  color
+                        sta  cx16.VERA_DATA1
                    }}
                }
            }
        }

+        sub set_both_strides(ubyte stride) {
+            stride <<= 4
+            cx16.VERA_CTRL = 0
+            cx16.VERA_ADDR_H = cx16.VERA_ADDR_H & %00000111 | stride
+            cx16.VERA_CTRL = 1
+            cx16.VERA_ADDR_H = cx16.VERA_ADDR_H & %00000111 | stride
+        }
+
    }

    sub line(uword @zp x1, uword @zp y1, uword @zp x2, uword @zp y2, ubyte color) {
@@ -587,8 +548,6 @@ _done
        ubyte[8] bits = [128, 64, 32, 16, 8, 4, 2, 1]
        ubyte[4] mask4c = [%00111111, %11001111, %11110011, %11111100]
        ubyte[4] shift4c = [6,4,2,0]
-        uword addr
-        ubyte value

        when active_mode {
            1 -> {
@@ -600,23 +559,43 @@ _done
                    and  #1
                }}
                if_nz {
-                    addr = x/8 + y*(320/8)
-                    value = bits[lsb(x)&7]
-                    if color
-                        cx16.vpoke_or(0, addr, value)
-                    else {
-                        value = ~value
-                        cx16.vpoke_and(0, addr, value)
-                    }
+                    cx16.r0L = lsb(x) & 7       ; xbits
+                    x /= 8
+                    x += y*(320/8)
+                    %asm {{
+                        stz  cx16.VERA_CTRL
+                        stz  cx16.VERA_ADDR_H
+                        lda  x+1
+                        sta  cx16.VERA_ADDR_M
+                        lda  x
+                        sta  cx16.VERA_ADDR_L
+                        ldy  cx16.r0L       ; xbits
+                        lda  bits,y
+                        ldy  color
+                        beq  +
+                        tsb  cx16.VERA_DATA0
+                        bra  ++
+                       trb  cx16.VERA_DATA0
+
+                    }}
                }
            }
+            ; TODO mode 2,3
            4 -> {
                ; lores 256c
                void addr_mul_24_for_lores_256c(y, x)      ; 24 bits result is in r0 and r1L (highest byte)
-                cx16.vpoke(lsb(cx16.r1), cx16.r0, color)
-                ; activate vera auto-increment mode so next_pixel() can be used after this
-                cx16.VERA_ADDR_H = cx16.VERA_ADDR_H & %00000111 | %00010000
-                color = cx16.VERA_DATA0
+                %asm {{
+                    stz  cx16.VERA_CTRL
+                    lda  cx16.r1
+                    ora  #%00010000     ; enable auto-increment so next_pixel() can be used after this
+                    sta  cx16.VERA_ADDR_H
+                    lda  cx16.r0+1
+                    sta  cx16.VERA_ADDR_M
+                    lda  cx16.r0
+                    sta  cx16.VERA_ADDR_L
+                    lda  color
+                    sta  cx16.VERA_DATA0
+                }}
            }
            5 -> {
                ; highres monochrome
@@ -627,26 +606,48 @@ _done
                    and  #1
                }}
                if_nz {
-                    addr = x/8 + y*(640/8)
-                    value = bits[lsb(x)&7]
-                    if color
-                        cx16.vpoke_or(0, addr, value)
-                    else {
-                        value = ~value
-                        cx16.vpoke_and(0, addr, value)
-                    }
+                    cx16.r0L = lsb(x) & 7       ; xbits
+                    x /= 8
+                    x += y*(640/8)
+                    %asm {{
+                        stz  cx16.VERA_CTRL
+                        stz  cx16.VERA_ADDR_H
+                        lda  x+1
+                        sta  cx16.VERA_ADDR_M
+                        lda  x
+                        sta  cx16.VERA_ADDR_L
+                        ldy  cx16.r0L           ; xbits
+                        lda  bits,y
+                        ldy  color
+                        beq  +
+                        tsb  cx16.VERA_DATA0
+                        bra  ++
+                       trb  cx16.VERA_DATA0
+
+                    }}
                }
            }
            6 -> {
                ; highres 4c
                ; TODO also mostly usable for lores 4c?
                void addr_mul_24_for_highres_4c(y, x)      ; 24 bits result is in r0 and r1L (highest byte)
+                cx16.r2L = lsb(x) & 3       ; xbits
                color &= 3
-                color <<= shift4c[lsb(x) & 3]
-                ; TODO optimize the vera memory manipulation in pure assembly
-                cx16.VERA_ADDR_H &= %00000111   ; no auto advance
-                value = cx16.vpeek(lsb(cx16.r1), cx16.r0) & mask4c[lsb(x) & 3] | color
-                cx16.vpoke(lsb(cx16.r1), cx16.r0, value)
+                color <<= shift4c[cx16.r2L]
+                %asm {{
+                    stz  cx16.VERA_CTRL
+                    lda  cx16.r1L
+                    sta  cx16.VERA_ADDR_H
+                    lda  cx16.r0H
+                    sta  cx16.VERA_ADDR_M
+                    lda  cx16.r0L
+                    sta  cx16.VERA_ADDR_L
+                    ldy  cx16.r2L           ; xbits
+                    lda  mask4c,y
+                    and  cx16.VERA_DATA0
+                    ora  color
+                    sta  cx16.VERA_DATA0
+                }}
            }
        }
    }
@@ -680,6 +681,20 @@ _done
        }
    }

+    sub position2(uword @zp x, uword y, ubyte also_port_1) {
+        position(x, y)
+        if also_port_1 {
+            when active_mode {
+                1, 5 -> cx16.vaddr(0, cx16.r0, 1, 1)
+                ; TODO modes 2, 3
+                4, 6 -> {
+                    ubyte bank = lsb(cx16.r1)
+                    cx16.vaddr(bank, cx16.r0, 1, 1)
+                }
+            }
+        }
+    }
+
    inline asmsub next_pixel(ubyte color @A) {
        ; -- sets the next pixel byte to the graphics chip.
        ;    for 8 bpp screens this will plot 1 pixel.
@@ -759,13 +774,14 @@ _done
    sub text(uword @zp x, uword y, ubyte color, uword sctextptr) {
        ; -- Write some text at the given pixel position. The text string must be in screencode encoding (not petscii!).
        ;    You must also have called text_charset() first to select and prepare the character set to use.
-        ;    NOTE: in monochrome (1bpp) screen modes, x position is currently constrained to mulitples of 8 !  TODO allow per-pixel horizontal positioning
+        ;    NOTE: in monochrome (1bpp) screen modes, x position is currently constrained to multiples of 8 !  TODO allow per-pixel horizontal positioning
+        ; TODO draw whole horizontal spans using vera auto increment if possible, instead of per-character columns
        uword chardataptr
        when active_mode {
            1, 5 -> {
                ; monochrome mode, either resolution
                cx16.r2 = 40
-                if active_mode>=5
+                if active_mode==5
                    cx16.r2 = 80
                while @(sctextptr) {
                    chardataptr = charset_addr + (@(sctextptr) as uword)*8
@@ -793,11 +809,8 @@ _done
                        sta  cx16.VERA_ADDR_L
                        bcc  +
                        inc  cx16.VERA_ADDR_M
-+                       lda  x
-                        clc
-                        adc  #1
-                        sta  x
-                        bcc  +
+                       inc  x
+                        bne  +
                        inc  x+1
 +                       dey
                        bne  -
@@ -811,7 +824,6 @@ _done
                    chardataptr = charset_addr + (@(sctextptr) as uword)*8
                    cx16.vaddr(charset_bank, chardataptr, 1, 1)
                    repeat 8 {
-                        ; TODO rewrite this inner loop fully in assembly
                        position(x,y)
                        y++
                        %asm {{
@@ -840,7 +852,9 @@ _done
                while @(sctextptr) {
                    chardataptr = charset_addr + (@(sctextptr) as uword)*8
                    repeat 8 {
-                        ; TODO rewrite this inner loop fully in assembly
+                        ; TODO rewrite this inner loop partly in assembly
+                        ;      requires expanding the charbits to 2-bits per pixel (based on color)
+                        ;      also it's way more efficient to draw whole horizontal spans instead of per-character
                        ubyte charbits = cx16.vpeek(charset_bank, chardataptr)
                        repeat 8 {
                            charbits <<= 1
@@ -1,4 +1,3 @@
-%target cx16
 %import syslib
 %import textio

@@ -1,5 +1,3 @@
-%target cx16
-
 ; Manipulate the Commander X16's display color palette.
 ; Should you want to restore the default palette, you have to reinitialize the Vera yourself.

@@ -9,7 +7,7 @@ palette {
    ubyte c

    sub set_color(ubyte index, uword color) {
-        vera_palette_ptr = $fa00+index*2
+        vera_palette_ptr = $fa00+(index as uword * 2)
        cx16.vpoke(1, vera_palette_ptr, lsb(color))
        vera_palette_ptr++
        cx16.vpoke(1, vera_palette_ptr, msb(color))
@@ -70,6 +68,14 @@ palette {
        }
    }

+    sub set_all_black() {
+        set_monochrome($000, $000)
+    }
+
+    sub set_all_white() {
+        set_monochrome($fff, $fff)
+    }
+
    sub set_grayscale() {
        vera_palette_ptr = $fa00
        repeat 16 {
@@ -5,9 +5,6 @@
 ;
 ; indent format: TABS, size=8

-%target cx16
-
-
 c64 {

 ; ---- kernal routines, these are the same as on the Commodore-64 (hence the same block name) ----
@@ -24,7 +21,7 @@ romsub $FF8D = VECTOR(uword userptr @ XY, ubyte dir @ Pc) clobbers(A,Y)     ; re
 romsub $FF90 = SETMSG(ubyte value @ A)                          ; set Kernal message control flag
 romsub $FF93 = SECOND(ubyte address @ A) clobbers(A)            ; (alias: LSTNSA) send secondary address after LISTEN
 romsub $FF96 = TKSA(ubyte address @ A) clobbers(A)              ; (alias: TALKSA) send secondary address after TALK
-romsub $FF99 = MEMTOP(uword address @ XY, ubyte dir @ Pc) -> uword @ XY     ; read/set top of memory  pointer.   NOTE: as a Cx16 extension, also returns the number of RAM memory banks in register A !  See MEMTOP2
+romsub $FF99 = MEMTOP(uword address @ XY, ubyte dir @ Pc) -> uword @ XY     ; read/set top of memory  pointer.   NOTE: as a Cx16 extension, also returns the number of RAM memory banks in register A !  See cx16.numbanks()
 romsub $FF9C = MEMBOT(uword address @ XY, ubyte dir @ Pc) -> uword @ XY     ; read/set bottom of memory  pointer
 romsub $FF9F = SCNKEY() clobbers(A,X,Y)                         ; scan the keyboard
 romsub $FFA2 = SETTMO(ubyte timeout @ A)                        ; set time-out flag for IEEE bus
@@ -47,7 +44,7 @@ romsub $FFD2 = CHROUT(ubyte char @ A)                           ; (via 806 ($326
 romsub $FFD5 = LOAD(ubyte verify @ A, uword address @ XY) -> ubyte @Pc, ubyte @ A, uword @ XY     ; (via 816 ($330)) load from device
 romsub $FFD8 = SAVE(ubyte zp_startaddr @ A, uword endaddr @ XY) -> ubyte @ Pc, ubyte @ A          ; (via 818 ($332)) save to a device
 romsub $FFDB = SETTIM(ubyte low @ A, ubyte middle @ X, ubyte high @ Y)      ; set the software clock
-romsub $FFDE = RDTIM() -> ubyte @ A, ubyte @ X, ubyte @ Y       ; read the software clock
+romsub $FFDE = RDTIM() -> ubyte @ A, ubyte @ X, ubyte @ Y       ; read the software clock (A=lo,X=mid,Y=high)
 romsub $FFE1 = STOP() clobbers(X) -> ubyte @ Pz, ubyte @ A      ; (via 808 ($328)) check the STOP key (and some others in A)
 romsub $FFE4 = GETIN() clobbers(X,Y) -> ubyte @Pc, ubyte @ A    ; (via 810 ($32A)) get a character
 romsub $FFE7 = CLALL() clobbers(A,X)                            ; (via 812 ($32C)) close all files
@@ -74,7 +71,7 @@ asmsub STOP2() -> ubyte @A  {
 }

 asmsub RDTIM16() -> uword @AY {
-    ; --  like RDTIM() but only returning the lower 16 bits for convenience
+    ; --  like RDTIM() but only returning the lower 16 bits in AY for convenience
    %asm {{
        phx
        jsr  c64.RDTIM
@@ -87,17 +84,6 @@ asmsub RDTIM16() -> uword @AY {
    }}
 }

-asmsub MEMTOP2() -> ubyte @A {
-    ; -- uses MEMTOP's cx16 extension to query the number of available RAM banks.
-    %asm {{
-        phx
-        sec
-        jsr  c64.MEMTOP
-        plx
-        rts
-    }}
-}
-
 }

 cx16 {
@@ -109,7 +95,7 @@ cx16 {
    &uword  IRQ_VEC         = $FFFE     ; 65c02 interrupt vector, determined by the kernal if banked in


-; the sixteen virtual 16-bit registers
+; the sixteen virtual 16-bit registers in both normal unsigned mode and signed mode (s)
    &uword r0  = $0002
    &uword r1  = $0004
    &uword r2  = $0006
@@ -127,6 +113,91 @@ cx16 {
    &uword r14 = $001e
    &uword r15 = $0020

+    &word r0s  = $0002
+    &word r1s  = $0004
+    &word r2s  = $0006
+    &word r3s  = $0008
+    &word r4s  = $000a
+    &word r5s  = $000c
+    &word r6s  = $000e
+    &word r7s  = $0010
+    &word r8s  = $0012
+    &word r9s  = $0014
+    &word r10s = $0016
+    &word r11s = $0018
+    &word r12s = $001a
+    &word r13s = $001c
+    &word r14s = $001e
+    &word r15s = $0020
+
+    &ubyte r0L  = $0002
+    &ubyte r1L  = $0004
+    &ubyte r2L  = $0006
+    &ubyte r3L  = $0008
+    &ubyte r4L  = $000a
+    &ubyte r5L  = $000c
+    &ubyte r6L  = $000e
+    &ubyte r7L  = $0010
+    &ubyte r8L  = $0012
+    &ubyte r9L  = $0014
+    &ubyte r10L = $0016
+    &ubyte r11L = $0018
+    &ubyte r12L = $001a
+    &ubyte r13L = $001c
+    &ubyte r14L = $001e
+    &ubyte r15L = $0020
+
+    &ubyte r0H  = $0003
+    &ubyte r1H  = $0005
+    &ubyte r2H  = $0007
+    &ubyte r3H  = $0009
+    &ubyte r4H  = $000b
+    &ubyte r5H  = $000d
+    &ubyte r6H  = $000f
+    &ubyte r7H  = $0011
+    &ubyte r8H  = $0013
+    &ubyte r9H  = $0015
+    &ubyte r10H = $0017
+    &ubyte r11H = $0019
+    &ubyte r12H = $001b
+    &ubyte r13H = $001d
+    &ubyte r14H = $001f
+    &ubyte r15H = $0021
+
+    &byte r0sL  = $0002
+    &byte r1sL  = $0004
+    &byte r2sL  = $0006
+    &byte r3sL  = $0008
+    &byte r4sL  = $000a
+    &byte r5sL  = $000c
+    &byte r6sL  = $000e
+    &byte r7sL  = $0010
+    &byte r8sL  = $0012
+    &byte r9sL  = $0014
+    &byte r10sL = $0016
+    &byte r11sL = $0018
+    &byte r12sL = $001a
+    &byte r13sL = $001c
+    &byte r14sL = $001e
+    &byte r15sL = $0020
+
+    &byte r0sH  = $0003
+    &byte r1sH  = $0005
+    &byte r2sH  = $0007
+    &byte r3sH  = $0009
+    &byte r4sH  = $000b
+    &byte r5sH  = $000d
+    &byte r6sH  = $000f
+    &byte r7sH  = $0011
+    &byte r8sH  = $0013
+    &byte r9sH  = $0015
+    &byte r10sH = $0017
+    &byte r11sH = $0019
+    &byte r12sH = $001b
+    &byte r13sH = $001d
+    &byte r14sH = $001f
+    &byte r15sH = $0021
+
 ; VERA registers

    const uword VERA_BASE       = $9F20
@@ -172,7 +243,7 @@ cx16 {

 ; I/O

-    const uword  via1   = $9f60                  ;VIA 6522 #1
+    const uword  via1   = $9f00                  ;VIA 6522 #1
    &ubyte  d1prb	= via1+0
    &ubyte  d1pra	= via1+1
    &ubyte  d1ddrb	= via1+2
@@ -190,7 +261,7 @@ cx16 {
    &ubyte  d1ier	= via1+14
    &ubyte  d1ora	= via1+15

-    const uword  via2   = $9f70                  ;VIA 6522 #2
+    const uword  via2   = $9f10                  ;VIA 6522 #2
    &ubyte  d2prb	= via2+0
    &ubyte  d2pra	= via2+1
    &ubyte  d2ddrb	= via2+2
@@ -208,6 +279,11 @@ cx16 {
    &ubyte  d2ier	= via2+14
    &ubyte  d2ora	= via2+15

+    &ubyte  ym2151adr	= $9f40
+    &ubyte  ym2151dat	= $9f41
+
+    const uword  extdev	= $9f60
+

 ; ---- Commander X-16 additions on top of C64 kernal routines ----
 ; spelling of the names is taken from the Commander X-16 rom sources
@@ -236,7 +312,7 @@ romsub $ff56 = joystick_get(ubyte joynr @A) -> ubyte @A, ubyte @X, ubyte @Y
 romsub $ff4d = clock_set_date_time(uword yearmonth @R0, uword dayhours @R1, uword minsecs @R2, ubyte jiffies @R3)  clobbers(A, X, Y)
 romsub $ff50 = clock_get_date_time()  clobbers(A, X, Y)  -> uword @R0, uword @R1, uword @R2, ubyte @R3   ; result registers see clock_set_date_time()

-; TODO specify the correct clobbers for alle these functions below, we now assume all 3 regs are clobbered
+; TODO specify the correct clobbers for all functions below, we now assume all 3 regs are clobbered

 ; high level graphics & fonts
 romsub $ff20 = GRAPH_init(uword vectors @R0)  clobbers(A,X,Y)
@@ -291,19 +367,28 @@ romsub $fecc = monitor()  clobbers(A,X,Y)

 ; ---- utilities -----

-inline asmsub rombank(ubyte rombank @A) {
+inline asmsub rombank(ubyte bank @A) {
    ; -- set the rom banks
    %asm {{
-        sta  $01            ; rom bank register (new)
-        sta  cx16.d1prb     ; rom bank register (old)
+        sta  $01            ; rom bank register (v39+, used to be cx16.d1prb $9f60 in v38)
    }}
 }

-inline asmsub rambank(ubyte rambank @A) {
+inline asmsub rambank(ubyte bank @A) {
    ; -- set the ram bank
    %asm {{
-        sta  $00            ; ram bank register (new)
-        sta  cx16.d1pra     ; ram bank register (old)
+        sta  $00            ; ram bank register (v39+, used to be cx16.d1pra $9f61 in v38)
+    }}
+}
+
+asmsub numbanks() -> ubyte @A {
+    ; -- uses MEMTOP's cx16 extension to query the number of available RAM banks. (each is 8 Kb)
+    %asm {{
+        phx
+        sec
+        jsr  c64.MEMTOP
+        plx
+        rts
    }}
 }

@@ -458,6 +543,17 @@ asmsub vload(str name @R0, ubyte device @Y, ubyte bank @A, uword address @R1) ->
    }}
 }

+inline asmsub joystick_get2(ubyte joynr @A) clobbers(Y) -> uword @AX  {
+    ; convenience routine to get the joystick state without requiring inline assembly that deals with the multiple return values.
+    ; Also disables interrupts to avoid the IRQ race condition mentioned here: https://github.com/commanderx16/x16-rom/issues/203
+    ; TODO once that issue is resolved, this routine can be redefined as:  romsub $ff56 = joystick_get2(ubyte joynr @A) clobbers(Y) -> uword @AX
+    %asm {{
+        sei
+        jsr  cx16.joystick_get
+        cli
+    }}
+}
+

 sub FB_set_pixels_from_buf(uword buffer, uword count) {
    %asm {{
@@ -500,11 +596,9 @@ asmsub  init_system()  {
    %asm {{
        sei
        cld
-        ;stz  $00
-        ;stz  $01
-        ;stz  d1prb      ; select rom bank 0 (enable kernal)
        lda  #$80
        sta  VERA_CTRL
+        stz  $01        ; select rom bank 0 (enable kernal)
        jsr  c64.IOINIT
        jsr  c64.RESTOR
        jsr  c64.CINT
@@ -704,23 +798,37 @@ sys {


    asmsub reset_system() {
-        ; Soft-reset the system back to Basic prompt.
+        ; Soft-reset the system back to initial power-on Basic prompt.
        %asm {{
            sei
-            stz  $01            ; bank the kernal in (new rom bank register)
-            stz  cx16.d1prb     ; bank the kernal in (old rom bank register)
+            stz  $01            ; bank the kernal in
            jmp  (cx16.RESET_VEC)
        }}
    }

-    sub wait(uword jiffies) {
-        ; --- wait approximately the given number of jiffies (1/60th seconds)
-        repeat jiffies {
-            ubyte jiff = lsb(c64.RDTIM16())
-            while jiff==lsb(c64.RDTIM16()) {
-                ; wait until 1 jiffy has passed
-            }
-        }
+    asmsub wait(uword jiffies @AY) {
+        ; --- wait approximately the given number of jiffies (1/60th seconds) (N or N+1)
+        ;     note: regular system vsync irq handler must be running, and no nother irqs
+        %asm {{
+-           wai             ; wait for irq (assume it was vsync)
+            cmp  #0
+            bne  +
+            dey
+           dec  a
+            bne  -
+            cpy  #0
+            bne  -
+            rts
+        }}
+    }
+
+    inline asmsub waitvsync()  {
+        ; --- suspend execution until the next vsync has occurred, without depending on custom irq handling.
+        ;     note: system vsync irq handler has to be active for this routine to work (and no other irqs-- which is the default).
+        ;     note: a more accurate way to wait for vsync is to set up a vsync irq handler instead.
+        %asm {{
+            wai
+        }}
    }

    inline asmsub memcopy(uword source @R0, uword target @R1, uword count @AY) clobbers(A,X,Y) {
@@ -751,27 +859,6 @@ sys {
        }}
    }

-    inline asmsub rsave() {
-        ; save cpu status flag and all registers A, X, Y.
-        ; see http://6502.org/tutorials/register_preservation.html
-        %asm {{
-            php
-            pha
-            phy
-            phx
-        }}
-    }
-
-    inline asmsub rrestore() {
-        ; restore all registers and cpu status flag
-        %asm {{
-            plx
-            ply
-            pla
-            plp
-        }}
-    }
-
    inline asmsub read_flags() -> ubyte @A {
        %asm {{
            php
@@ -781,25 +868,25 @@ sys {

    inline asmsub clear_carry() {
        %asm {{
-            clc
+        clc
        }}
    }

    inline asmsub set_carry() {
        %asm {{
-            sec
+        sec
        }}
    }

    inline asmsub clear_irqd() {
        %asm {{
-            cli
+        cli
        }}
    }

    inline asmsub set_irqd() {
        %asm {{
-            sei
+        sei
        }}
    }

@@ -4,7 +4,6 @@
 ;
 ; indent format: TABS, size=8

-%target cx16
 %import syslib
 %import conv

@@ -566,9 +565,8 @@ asmsub  print_w  (word value @ AY) clobbers(A,Y)  {
 		tay
 		pla
 		eor  #255
-		clc
-		adc  #1
-		bcc  +
+		ina
+		bne +
 		iny
 +		bra  print_uw
 	}}
@@ -336,6 +336,45 @@ _end        rts
    }


+    ; ----- iterative file saver functions (uses io channel 14) -----
+
+    sub f_open_w(ubyte drivenumber, uword filenameptr) -> ubyte {
+        ; -- open a file for iterative writing with f_write
+        f_close_w()
+
+        c64.SETNAM(string.length(filenameptr), filenameptr)
+        c64.SETLFS(14, drivenumber, 1)
+        void c64.OPEN()          ; open 14,8,1,"filename"
+        if_cc {
+            void c64.CHKOUT(14)        ; use #14 as input channel
+            return not c64.READST()
+        }
+        f_close_w()
+        return false
+    }
+
+    sub f_write(uword bufferpointer, uword num_bytes) -> ubyte {
+        ; -- write the given umber of bytes to the currently open file
+        if num_bytes!=0 {
+            void c64.CHKOUT(14)        ; use #14 as input channel again
+            repeat num_bytes {
+                c64.CHROUT(@(bufferpointer))
+                bufferpointer++
+            }
+            return not c64.READST()
+        }
+        return true
+    }
+
+    sub f_close_w() {
+        ; -- end an iterative file writing session (close channels).
+        c64.CLRCHN()
+        c64.CLOSE(14)
+    }
+
+
+    ; ---- other functions ----
+
    sub status(ubyte drivenumber) -> uword {
        ; -- retrieve the disk drive's current status message
        uword messageptr = &filename
@@ -353,18 +392,22 @@ _end        rts
            messageptr++
        }

-io_error:
        @(messageptr) = 0
+done:
        c64.CLRCHN()        ; restore default i/o devices
        c64.CLOSE(15)
        return filename
-    }

+io_error:
+        filename = "?disk error"
+        goto done
+    }

    sub save(ubyte drivenumber, uword filenameptr, uword address, uword size) -> ubyte {
        c64.SETNAM(string.length(filenameptr), filenameptr)
        c64.SETLFS(1, drivenumber, 0)
        uword end_address = address + size
+        first_byte = 0      ; result var reuse

        %asm {{
            lda  address
@@ -381,7 +424,6 @@ io_error:
            plp
        }}

-        first_byte = 0      ; result var reuse
        if_cc
            first_byte = c64.READST()==0

@@ -244,25 +244,6 @@ randseed	.proc
 		.pend


-fast_randbyte	.proc
-	; -- fast but bad 8-bit pseudo random number generator into A
-		lda  _seed
-		beq  _eor
-		asl  a
-		beq  _done	; if the input was $80, skip the EOR
-		bcc  _done
-_eor		eor  #$1d	; xor with magic value see below for possible values
-_done		sta  _seed
-		rts
-
-_seed		.byte  $3a
-
-		; possible 'magic' eor bytes are:
-		; $1d, $2b, $2d, $4d, $5f, $63, $65, $69
-		; $71, $87, $8d, $a9, $c3, $cf, $e7, $f5
-
-		.pend
-
 randbyte        .proc
 	; -- 8 bit pseudo random number generator into A (by just reusing randword)
 		jmp  randword
@@ -271,45 +252,37 @@ randbyte        .proc
 randword	.proc
 	; -- 16 bit pseudo random number generator into AY

-magic_eor = $3f1d
-		; possible magic eor words are:
-		; $3f1d, $3f81, $3fa5, $3fc5, $4075, $409d, $40cd, $4109
- 		; $413f, $414b, $4153, $4159, $4193, $4199, $41af, $41bb
+		; rand64k       ;Factors of 65535: 3 5 17 257
+		lda sr1+1
+		asl a
+		asl a
+		eor sr1+1
+		asl a
+		eor sr1+1
+		asl a
+		asl a
+		eor sr1+1
+		asl a
+		rol sr1         ;shift this left, "random" bit comes from low
+		rol sr1+1
+		; rand32k       ;Factors of 32767: 7 31 151 are independent and can be combined
+		lda sr2+1
+		asl a
+		eor sr2+1
+		asl a
+		asl a
+		ror sr2         ;shift this right, random bit comes from high - nicer when eor with sr1
+		rol sr2+1
+		lda sr1+1         ;can be left out
+		eor sr2+1         ;if you dont use
+		tay               ;y as suggested
+		lda sr1           ;mix up lowbytes of SR1
+		eor sr2           ;and SR2 to combine both
+		rts

-		lda  _seed
-		beq  _lowZero	; $0000 and $8000 are special values to test for
+sr1     	.word $a55a
+sr2     	.word $7653

- 		; Do a normal shift
-		asl  _seed
-		lda  _seed+1
-		rol  a
-		bcc  _noEor
-
-_doEor		; high byte is in A
-		eor  #>magic_eor
-  		sta  _seed+1
-  		lda  _seed
-  		eor  #<magic_eor
-  		sta  _seed
-  		ldy  _seed+1
-  		rts
-
-_lowZero	lda  _seed+1
-		beq  _doEor	; High byte is also zero, so apply the EOR
-				; For speed, you could store 'magic' into 'seed' directly
-				; instead of running the EORs
-
- 		; wasn't zero, check for $8000
-		asl  a
-		beq  _noEor	; if $00 is left after the shift, then it was $80
-		bcs  _doEor	; else, do the EOR based on the carry bit as usual
-
-_noEor		sta  _seed+1
-		tay
-		lda  _seed
- 		rts
-
-_seed		.word	$2c9e
 		.pend


@@ -801,6 +774,13 @@ stack_mul_word_320	.proc
 		rts
 		.pend

+stack_mul_word_640	.proc
+		; stackW = (stackLo * 2 * 320)    (stackHi doesn't matter)
+		asl  P8ESTACK_LO+1,x
+		jmp  stack_mul_word_320
+		.pend
+
+
 ; ----------- optimized multiplications (in-place A (byte) and ?? (word)) : ---------
 mul_byte_3	.proc
 		; A = A + A*2
@@ -1291,6 +1271,13 @@ mul_word_320	.proc
 		rts
 		.pend

+mul_word_640	.proc
+		; AY = (A * 2 * 320) (msb in Y doesn't matter)
+		asl  a
+		jmp  mul_word_320
+		.pend
+
+
 ; ----------- end optimized multiplications -----------


@@ -3,5 +3,5 @@
 ; Written by Irmen de Jong (irmen@razorvine.net) - license: GNU GPL 3.0

 math {
-	%asminclude "library:math.asm", ""
+	%asminclude "library:math.asm"
 }
@@ -91,6 +91,13 @@ func_sin8_into_A	.proc
 _sinecos8	.char  trunc(127.0 * sin(range(256+64) * rad(360.0/256.0)))
 		.pend

+func_sinr8_into_A	.proc
+		tay
+		lda  _sinecosR8,y
+		rts
+_sinecosR8	.char  trunc(127.0 * sin(range(180+45) * rad(360.0/180.0)))
+		.pend
+
 func_sin8u_into_A	.proc
 		tay
 		lda  _sinecos8u,y
@@ -98,6 +105,13 @@ func_sin8u_into_A	.proc
 _sinecos8u	.byte  trunc(128.0 + 127.5 * sin(range(256+64) * rad(360.0/256.0)))
 		.pend

+func_sinr8u_into_A	.proc
+		tay
+		lda  _sinecosR8u,y
+		rts
+_sinecosR8u	.byte  trunc(128.0 + 127.5 * sin(range(180+45) * rad(360.0/180.0)))
+		.pend
+
 func_sin8_stack	.proc
 		tay
 		lda  func_sin8_into_A._sinecos8,y
@@ -106,6 +120,14 @@ func_sin8_stack	.proc
 		rts
 		.pend

+func_sinr8_stack	.proc
+		tay
+		lda  func_sinr8_into_A._sinecosR8,y
+		sta  P8ESTACK_LO,x
+		dex
+		rts
+		.pend
+
 func_sin8u_stack	.proc
 		tay
 		lda  func_sin8u_into_A._sinecos8u,y
@@ -114,18 +136,38 @@ func_sin8u_stack	.proc
 		rts
 		.pend

+func_sinr8u_stack	.proc
+		tay
+		lda  func_sinr8u_into_A._sinecosR8u,y
+		sta  P8ESTACK_LO,x
+		dex
+		rts
+		.pend
+
 func_cos8_into_A	.proc
 		tay
 		lda  func_sin8_into_A._sinecos8+64,y
 		rts
 		.pend

+func_cosr8_into_A	.proc
+		tay
+		lda  func_sinr8_into_A._sinecosR8+45,y
+		rts
+		.pend
+
 func_cos8u_into_A	.proc
 		tay
 		lda  func_sin8u_into_A._sinecos8u+64,y
 		rts
 		.pend

+func_cosr8u_into_A	.proc
+		tay
+		lda  func_sinr8u_into_A._sinecosR8u+45,y
+		rts
+		.pend
+
 func_cos8_stack	.proc
 		tay
 		lda  func_sin8_into_A._sinecos8+64,y
@@ -134,6 +176,14 @@ func_cos8_stack	.proc
 		rts
 		.pend

+func_cosr8_stack	.proc
+		tay
+		lda  func_sinr8_into_A._sinecosR8+45,y
+		sta  P8ESTACK_LO,x
+		dex
+		rts
+		.pend
+
 func_cos8u_stack	.proc
 		tay
 		lda  func_sin8u_into_A._sinecos8u+64,y
@@ -142,6 +192,14 @@ func_cos8u_stack	.proc
 		rts
 		.pend

+func_cosr8u_stack	.proc
+		tay
+		lda  func_sinr8u_into_A._sinecosR8u+45,y
+		sta  P8ESTACK_LO,x
+		dex
+		rts
+		.pend
+
 func_sin16_into_AY	.proc
 		tay
 		lda  _sinecos8lo,y
@@ -155,6 +213,19 @@ _sinecos8lo     .byte  <_
 _sinecos8hi     .byte  >_
 		.pend

+func_sinr16_into_AY	.proc
+		tay
+		lda  _sinecosR8lo,y
+		pha
+		lda  _sinecosR8hi,y
+		tay
+		pla
+		rts
+_  :=  trunc(32767.0 * sin(range(180+45) * rad(360.0/180.0)))
+_sinecosR8lo     .byte  <_
+_sinecosR8hi     .byte  >_
+		.pend
+
 func_sin16u_into_AY	.proc
 		tay
 		lda  _sinecos8ulo,y
@@ -168,6 +239,18 @@ _sinecos8ulo     .byte  <_
 _sinecos8uhi     .byte  >_
 		.pend

+func_sinr16u_into_AY	.proc
+		tay
+		lda  _sinecosR8ulo,y
+		pha
+		lda  _sinecosR8uhi,y
+		tay
+		pla
+		rts
+_  :=  trunc(32768.0 + 32767.5 * sin(range(180+45) * rad(360.0/180.0)))
+_sinecosR8ulo     .byte  <_
+_sinecosR8uhi     .byte  >_
+		.pend

 func_sin16_stack	.proc
 		tay
@@ -179,6 +262,16 @@ func_sin16_stack	.proc
 		rts
 		.pend

+func_sinr16_stack	.proc
+		tay
+		lda  func_sinr16_into_AY._sinecosR8lo,y
+		sta  P8ESTACK_LO,x
+		lda  func_sinr16_into_AY._sinecosR8hi,y
+		sta  P8ESTACK_HI,x
+		dex
+		rts
+		.pend
+
 func_sin16u_stack	.proc
 		tay
 		lda  func_sin16u_into_AY._sinecos8ulo,y
@@ -189,6 +282,16 @@ func_sin16u_stack	.proc
 		rts
 		.pend

+func_sinr16u_stack	.proc
+		tay
+		lda  func_sinr16u_into_AY._sinecosR8ulo,y
+		sta  P8ESTACK_LO,x
+		lda  func_sinr16u_into_AY._sinecosR8uhi,y
+		sta  P8ESTACK_HI,x
+		dex
+		rts
+		.pend
+
 func_cos16_into_AY	.proc
 		tay
 		lda  func_sin16_into_AY._sinecos8lo+64,y
@@ -199,6 +302,16 @@ func_cos16_into_AY	.proc
 		rts
 		.pend

+func_cosr16_into_AY	.proc
+		tay
+		lda  func_sinr16_into_AY._sinecosR8lo+45,y
+		pha
+		lda  func_sinr16_into_AY._sinecosR8hi+45,y
+		tay
+		pla
+		rts
+		.pend
+
 func_cos16u_into_AY	.proc
 		tay
 		lda  func_sin16u_into_AY._sinecos8ulo+64,y
@@ -209,6 +322,16 @@ func_cos16u_into_AY	.proc
 		rts
 		.pend

+func_cosr16u_into_AY	.proc
+		tay
+		lda  func_sinr16u_into_AY._sinecosR8ulo+45,y
+		pha
+		lda  func_sinr16u_into_AY._sinecosR8uhi+45,y
+		tay
+		pla
+		rts
+		.pend
+
 func_cos16_stack	.proc
 		tay
 		lda  func_sin16_into_AY._sinecos8lo+64,y
@@ -219,6 +342,16 @@ func_cos16_stack	.proc
 		rts
 		.pend

+func_cosr16_stack	.proc
+		tay
+		lda  func_sinr16_into_AY._sinecosR8lo+45,y
+		sta  P8ESTACK_LO,x
+		lda  func_sinr16_into_AY._sinecosR8hi+45,y
+		sta  P8ESTACK_HI,x
+		dex
+		rts
+		.pend
+
 func_cos16u_stack	.proc
 		tay
 		lda  func_sin16u_into_AY._sinecos8ulo+64,y
@@ -229,6 +362,16 @@ func_cos16u_stack	.proc
 		rts
 		.pend

+func_cosr16u_stack	.proc
+		tay
+		lda  func_sinr16u_into_AY._sinecosR8ulo+45,y
+		sta  P8ESTACK_LO,x
+		lda  func_sinr16u_into_AY._sinecosR8uhi+45,y
+		sta  P8ESTACK_HI,x
+		dex
+		rts
+		.pend
+
 abs_b_stack	.proc
 	; -- push abs(A) on stack (as byte)
 		jsr  abs_b_into_A
@@ -387,14 +530,6 @@ func_sqrt16_into_A	.proc
 		rts
 		.pend

-func_fastrnd8_stack	.proc
-	; -- put a random ubyte on the estack (using fast but bad RNG)
-		jsr  math.fast_randbyte
-		sta  P8ESTACK_LO,x
-		dex
-		rts
-		.pend
-
 func_rnd_stack	.proc
 	; -- put a random ubyte on the estack
 		jsr  math.randbyte
@@ -3,13 +3,27 @@
 ; Written by Irmen de Jong (irmen@razorvine.net) - license: GNU GPL 3.0

 prog8_lib {
-	%asminclude "library:prog8_lib.asm", ""
-	%asminclude "library:prog8_funcs.asm", ""
+	%asminclude "library:prog8_lib.asm"
+	%asminclude "library:prog8_funcs.asm"
+
+	; to store intermediary expression results for return values:
+	; NOTE: these variables are used in the StatementReorderer and StatementOptimizer
+	uword @zp retval_interm_uw
+	word @zp retval_interm_w
+	ubyte @zp retval_interm_ub
+	byte @zp retval_interm_b
+	word retval_interm_w2
+	byte retval_interm_b2
+
+        ; prog8 "hooks" to be able to access the temporary scratch variables
+        ; YOU SHOULD NOT USE THESE IN USER CODE - THESE ARE MEANT FOR INTERNAL COMPILER USE
+        ; NOTE: the assembly code generator will match these names and not generate
+        ;       new variables/memdefs for them, rather, they'll point to the scratch variables directly.
+        &ubyte P8ZP_SCRATCH_REG = $ff
+        &byte P8ZP_SCRATCH_B1 = $ff
+        &uword P8ZP_SCRATCH_W1 = $ff
+        &word P8ZP_SCRATCH_W2 = $ff

-	uword @zp retval_interm_uw      ; to store intermediary expression results for return values (hopefully allocated on ZP to reduce code size)
-	word @zp retval_interm_w        ; to store intermediary expression results for return values (hopefully allocated on ZP to reduce code size)
-	ubyte @zp retval_interm_ub      ; to store intermediary expression results for return values (hopefully allocated on ZP to reduce code size)
-	byte @zp retval_interm_b        ; to store intermediary expression results for return values (hopefully allocated on ZP to reduce code size)

 	asmsub pattern_match(str string @AY, str pattern @R0) clobbers(Y) -> ubyte @A {
 		%asm {{
@@ -178,7 +178,7 @@ _found		sty  P8ZP_SCRATCH_B1

    asmsub compare(uword string1 @R0, uword string2 @AY) clobbers(Y) -> byte @A {
        ; Compares two strings for sorting.
-        ; Returns -1 (255), 0 or 1 depeding on wether string1 sorts before, equal or after string2.
+        ; Returns -1 (255), 0 or 1 depending on wether string1 sorts before, equal or after string2.
        ; Note that you can also directly compare strings and string values with eachother using
        ; comparison operators ==, < etcetera (it will use strcmp for you under water automatically).
        %asm {{
@@ -190,8 +190,8 @@ _found		sty  P8ZP_SCRATCH_B1
        }}
    }

-    asmsub lower(uword st @AY) {
-        ; Lowercases the petscii string in-place.
+    asmsub lower(uword st @AY) -> ubyte @Y {
+        ; Lowercases the petscii string in-place. Returns length of the string.
        ; (for efficiency, non-letter characters > 128 will also not be left intact,
        ;  but regular text doesn't usually contain those characters anyway.)
        %asm {{
@@ -213,8 +213,8 @@ _done       rts
        }}
    }

-    asmsub upper(uword st @AY) {
-        ; Uppercases the petscii string in-place.
+    asmsub upper(uword st @AY) -> ubyte @Y {
+        ; Uppercases the petscii string in-place. Returns length of the string.
        %asm {{
            sta  P8ZP_SCRATCH_W1
            sty  P8ZP_SCRATCH_W1+1
@@ -1 +1 @@
-6.4
+7.4
@@ -1,15 +1,13 @@
 package prog8

-import kotlinx.cli.ArgParser
-import kotlinx.cli.ArgType
-import kotlinx.cli.default
-import kotlinx.cli.multiple
+import kotlinx.cli.*
 import prog8.ast.base.AstException
 import prog8.compiler.CompilationResult
+import prog8.compiler.CompilerArguments
 import prog8.compiler.compileProgram
 import prog8.compiler.target.C64Target
 import prog8.compiler.target.Cx16Target
-import prog8.parser.ParsingFailedError
+import java.io.File
 import java.nio.file.FileSystems
 import java.nio.file.Path
 import java.nio.file.StandardWatchEventKinds
@@ -18,43 +16,60 @@ import kotlin.system.exitProcess


 fun main(args: Array<String>) {
-    printSoftwareHeader("compiler")
-
-    compileMain(args)
-}
-
-internal fun printSoftwareHeader(what: String) {
    val buildVersion = object {}.javaClass.getResource("/version.txt").readText().trim()
-    println("\nProg8 $what v$buildVersion by Irmen de Jong (irmen@razorvine.net)")
+    println("\nProg8 compiler v$buildVersion by Irmen de Jong (irmen@razorvine.net)")
    println("This software is licensed under the GNU GPL 3.0, see https://www.gnu.org/licenses/gpl.html\n")
+
+    val succes = compileMain(args)
+    if(!succes)
+        exitProcess(1)
 }


 fun pathFrom(stringPath: String, vararg rest: String): Path  = FileSystems.getDefault().getPath(stringPath, *rest)


-private fun compileMain(args: Array<String>) {
+private fun compileMain(args: Array<String>): Boolean {
    val cli = ArgParser("prog8compiler", prefixStyle = ArgParser.OptionPrefixStyle.JVM)
-    val startEmulator by cli.option(ArgType.Boolean, fullName = "emu", description = "auto-start emulator after successful compilation")
+    val startEmulator1 by cli.option(ArgType.Boolean, fullName = "emu", description = "auto-start emulator after successful compilation")
+    val startEmulator2 by cli.option(ArgType.Boolean, fullName = "emu2", description = "auto-start alternative emulator after successful compilation")
    val outputDir by cli.option(ArgType.String, fullName = "out", description = "directory for output files instead of current directory").default(".")
    val dontWriteAssembly by cli.option(ArgType.Boolean, fullName = "noasm", description="don't create assembly code")
    val dontOptimize by cli.option(ArgType.Boolean, fullName = "noopt", description = "don't perform any optimizations")
+    val optimizeFloatExpressions by cli.option(ArgType.Boolean, fullName = "optfloatx", description = "optimize float expressions (warning: can increase program size)")
    val watchMode by cli.option(ArgType.Boolean, fullName = "watch", description = "continuous compilation mode (watches for file changes), greatly increases compilation speed")
    val slowCodegenWarnings by cli.option(ArgType.Boolean, fullName = "slowwarn", description="show debug warnings about slow/problematic assembly code generation")
+    val quietAssembler by cli.option(ArgType.Boolean, fullName = "quietasm", description = "don't print assembler output results")
    val compilationTarget by cli.option(ArgType.String, fullName = "target", description = "target output of the compiler, currently '${C64Target.name}' and '${Cx16Target.name}' available").default(C64Target.name)
+    val sourceDirs by cli.option(ArgType.String, fullName="srcdirs", description = "list of extra paths, separated with ${File.pathSeparator}, to search in for imported modules").multiple().delimiter(File.pathSeparator)
    val moduleFiles by cli.argument(ArgType.String, fullName = "modules", description = "main module file(s) to compile").multiple(999)

    try {
        cli.parse(args)
    } catch (e: IllegalStateException) {
        System.err.println(e.message)
-        exitProcess(1)
+        return false
    }

    val outputPath = pathFrom(outputDir)
    if(!outputPath.toFile().isDirectory) {
        System.err.println("Output path doesn't exist")
-        exitProcess(1)
+        return false
+    }
+
+    val faultyOption = moduleFiles.firstOrNull { it.startsWith('-') }
+    if(faultyOption!=null) {
+        System.err.println("Unknown command line option given: $faultyOption")
+        return false
+    }
+
+    val srcdirs = sourceDirs.toMutableList()
+    if(srcdirs.firstOrNull()!=".")
+        srcdirs.add(0, ".")
+
+    if (compilationTarget != C64Target.name && compilationTarget != Cx16Target.name) {
+        System.err.println("Invalid compilation target: $compilationTarget")
+        return false
    }

    if(watchMode==true) {
@@ -66,7 +81,18 @@ private fun compileMain(args: Array<String>) {
            val results = mutableListOf<CompilationResult>()
            for(filepathRaw in moduleFiles) {
                val filepath = pathFrom(filepathRaw).normalize()
-                val compilationResult = compileProgram(filepath, dontOptimize!=true, dontWriteAssembly!=true, slowCodegenWarnings==true, compilationTarget, outputPath)
+                val args = CompilerArguments(
+                    filepath,
+                    dontOptimize != true,
+                    optimizeFloatExpressions == true,
+                    dontWriteAssembly != true,
+                    slowCodegenWarnings == true,
+                    quietAssembler == true,
+                    compilationTarget,
+                    srcdirs,
+                    outputPath
+                )
+                val compilationResult = compileProgram(args)
                results.add(compilationResult)
            }

@@ -77,7 +103,7 @@ private fun compileMain(args: Array<String>) {
            for (importedFile in allImportedFiles) {
                print("  ")
                println(importedFile)
-                val watchDir = importedFile.parent ?: Path.of(".")
+                val watchDir = importedFile.parent ?: Path.of("")
                watchDir.register(watchservice, StandardWatchEventKinds.ENTRY_MODIFY)
            }
            println("[${LocalDateTime.now().withNano(0)}]  Waiting for file changes.")
@@ -103,22 +129,39 @@ private fun compileMain(args: Array<String>) {
            val filepath = pathFrom(filepathRaw).normalize()
            val compilationResult: CompilationResult
            try {
-                compilationResult = compileProgram(filepath, dontOptimize!=true, dontWriteAssembly!=true, slowCodegenWarnings==true, compilationTarget, outputPath)
-                if(!compilationResult.success)
-                    exitProcess(1)
-            } catch (x: ParsingFailedError) {
-                exitProcess(1)
+                val args = CompilerArguments(
+                    filepath,
+                    dontOptimize != true,
+                    optimizeFloatExpressions == true,
+                    dontWriteAssembly != true,
+                    slowCodegenWarnings == true,
+                    quietAssembler == true,
+                    compilationTarget,
+                    srcdirs,
+                    outputPath
+                )
+                compilationResult = compileProgram(args)
+                if (!compilationResult.success)
+                    return false
            } catch (x: AstException) {
-                exitProcess(1)
+                return false
            }

-            if (startEmulator==true) {
-                if (compilationResult.programName.isEmpty())
+            if(startEmulator1==true || startEmulator2==true) {
+                if (compilationResult.programName.isEmpty()) {
                    println("\nCan't start emulator because no program was assembled.")
-                else {
-                    compilationResult.compTarget.machine.launchEmulator(compilationResult.programName)
+                    return true
                }
            }
+
+            val programNameInPath = outputPath.resolve(compilationResult.programName)
+
+            if (startEmulator1==true)
+                compilationResult.compTarget.machine.launchEmulator(1, programNameInPath)
+            else if (startEmulator2==true)
+                compilationResult.compTarget.machine.launchEmulator(2, programNameInPath)
        }
    }
+
+    return true
 }
@@ -1,3 +0,0 @@
-package prog8.compiler
-
-internal class AssemblyError(msg: String) : RuntimeException(msg)
@@ -1,6 +1,7 @@
 package prog8.compiler

 import prog8.ast.IFunctionCall
+import prog8.ast.IStatementContainer
 import prog8.ast.Node
 import prog8.ast.Program
 import prog8.ast.base.*
@@ -9,27 +10,31 @@ import prog8.ast.statements.*
 import prog8.ast.walk.AstWalker
 import prog8.ast.walk.IAstModification
 import prog8.ast.walk.IAstVisitor
-import prog8.compiler.target.ICompilationTarget
+import prog8.compiler.astprocessing.isSubroutineParameter
+import prog8.compiler.target.AssemblyError
+import prog8.compilerinterface.*
+import prog8.optimizer.getTempVarName


-internal class BeforeAsmGenerationAstChanger(val program: Program, val errors: IErrorReporter, private val compTarget: ICompilationTarget) : AstWalker() {
+internal class BeforeAsmGenerationAstChanger(val program: Program, private val options: CompilationOptions,
+                                             private val errors: IErrorReporter) : AstWalker() {

-    private val noModifications = emptyList<IAstModification>()
+    private val subroutineVariables = mutableMapOf<Subroutine, MutableList<Pair<String, VarDecl>>>()
+
+    private fun rememberSubroutineVar(decl: VarDecl) {
+        val sub = decl.definingSubroutine ?: return
+        var varsList = subroutineVariables[sub]
+        if(varsList==null) {
+            varsList = mutableListOf()
+            subroutineVariables[sub] = varsList
+        }
+        varsList.add(decl.name to decl)
+    }

    override fun after(decl: VarDecl, parent: Node): Iterable<IAstModification> {
-        subroutineVariables.add(decl.name to decl)
-        if (decl.value == null && !decl.autogeneratedDontRemove && decl.type == VarDeclType.VAR && decl.datatype in NumericDatatypes) {
-            // a numeric vardecl without an initial value is initialized with zero,
-            // unless there's already an assignment below, that initializes the value
-            if(decl.allowInitializeWithZero)
-            {
-                val nextAssign = decl.definingScope().nextSibling(decl) as? Assignment
-                if (nextAssign != null && nextAssign.target.isSameAs(IdentifierReference(listOf(decl.name), Position.DUMMY)))
-                    decl.value = null
-                else
-                    decl.value = decl.zeroElementValue()
-            }
-        }
+        if(decl.type==VarDeclType.VAR && decl.value != null && decl.datatype in NumericDatatypes)
+            throw FatalAstException("vardecls for variables, with initial numerical value, should have been rewritten as plain vardecl + assignment $decl")
+        rememberSubroutineVar(decl)
        return noModifications
    }

@@ -39,26 +44,34 @@ internal class BeforeAsmGenerationAstChanger(val program: Program, val errors: I
        // But it can only be done if the target variable IS NOT OCCURRING AS AN OPERAND ITSELF.
        if(!assignment.isAugmentable
                && assignment.target.identifier != null
-                && compTarget.isInRegularRAM(assignment.target, program)) {
+                && !assignment.target.isIOAddress(options.compTarget.machine)) {
            val binExpr = assignment.value as? BinaryExpression
+
+            if(binExpr!=null && binExpr.inferType(program).istype(DataType.FLOAT) && !options.optimizeFloatExpressions)
+                return noModifications
+
            if (binExpr != null && binExpr.operator !in comparisonOperators) {
                if (binExpr.left !is BinaryExpression) {
-                    if (binExpr.right.referencesIdentifier(*assignment.target.identifier!!.nameInSource.toTypedArray())) {
+                    if (binExpr.right.referencesIdentifier(assignment.target.identifier!!.nameInSource)) {
                        // the right part of the expression contains the target variable itself.
                        // we can't 'split' it trivially because the variable will be changed halfway through.
                        if(binExpr.operator in associativeOperators) {
                            // A = <something-without-A>  <associativeoperator>  <otherthing-with-A>
                            // use the other part of the expression to split.
-                            val assignRight = Assignment(assignment.target, binExpr.right, assignment.position)
+                            val sourceDt = binExpr.right.inferType(program).getOrElse { throw AssemblyError("invalid dt") }
+                            val (_, right) = binExpr.right.typecastTo(assignment.target.inferType(program).getOr(DataType.UNDEFINED), sourceDt, implicit=true)
+                            val assignRight = Assignment(assignment.target, right, assignment.position)
                            return listOf(
-                                    IAstModification.InsertBefore(assignment, assignRight, assignment.definingScope()),
+                                    IAstModification.InsertBefore(assignment, assignRight, parent as IStatementContainer),
                                    IAstModification.ReplaceNode(binExpr.right, binExpr.left, binExpr),
                                    IAstModification.ReplaceNode(binExpr.left, assignment.target.toExpression(), binExpr))
                        }
                    } else {
-                        val assignLeft = Assignment(assignment.target, binExpr.left, assignment.position)
+                        val sourceDt = binExpr.left.inferType(program).getOrElse { throw AssemblyError("invalid dt") }
+                        val (_, left) = binExpr.left.typecastTo(assignment.target.inferType(program).getOr(DataType.UNDEFINED), sourceDt, implicit=true)
+                        val assignLeft = Assignment(assignment.target, left, assignment.position)
                        return listOf(
-                                IAstModification.InsertBefore(assignment, assignLeft, assignment.definingScope()),
+                                IAstModification.InsertBefore(assignment, assignLeft, parent as IStatementContainer),
                                IAstModification.ReplaceNode(binExpr.left, assignment.target.toExpression(), binExpr))
                    }
                }
@@ -67,38 +80,16 @@ internal class BeforeAsmGenerationAstChanger(val program: Program, val errors: I
        return noModifications
    }

-    private val subroutineVariables = mutableListOf<Pair<String, VarDecl>>()
-
-    override fun before(subroutine: Subroutine, parent: Node): Iterable<IAstModification> {
-        subroutineVariables.clear()
-        return noModifications
-    }
-
    override fun after(scope: AnonymousScope, parent: Node): Iterable<IAstModification> {
-        val decls = scope.statements.filterIsInstance<VarDecl>()
-        subroutineVariables.addAll(decls.map { it.name to it })
-
-        val sub = scope.definingSubroutine()
-        if (sub != null) {
-            // move vardecls of the scope into the upper scope. Make sure the position remains the same!
-            val numericVarsWithValue = decls.filter { it.value != null && it.datatype in NumericDatatypes }
-            val replaceVardecls =numericVarsWithValue.map {
-                val initValue = it.value!!  // assume here that value has always been set by now
-                it.value = null     // make sure no value init assignment for this vardecl will be created later (would be superfluous)
-                val target = AssignTarget(IdentifierReference(listOf(it.name), it.position), null, null, it.position)
-                val assign = Assignment(target, initValue, it.position)
-                initValue.parent = assign
-                IAstModification.ReplaceNode(it, assign, scope)
-            }
-            val moveVardeclsUp = decls.map { IAstModification.InsertFirst(it, sub) }
-            return replaceVardecls + moveVardeclsUp
-        }
+        if(scope.statements.any { it is VarDecl || it is IStatementContainer })
+            throw FatalAstException("anonymousscope may no longer contain any vardecls or subscopes")
        return noModifications
    }

    override fun after(subroutine: Subroutine, parent: Node): Iterable<IAstModification> {
        val firstDeclarations = mutableMapOf<String, VarDecl>()
-        for(decl in subroutineVariables) {
+        val rememberedSubroutineVars = subroutineVariables.getOrDefault(subroutine, mutableListOf())
+        for(decl in rememberedSubroutineVars) {
            val existing = firstDeclarations[decl.first]
            if(existing!=null && existing !== decl.second) {
                errors.err("variable ${decl.first} already defined in subroutine ${subroutine.name} at ${existing.position}", decl.second.position)
@@ -106,23 +97,23 @@ internal class BeforeAsmGenerationAstChanger(val program: Program, val errors: I
                firstDeclarations[decl.first] = decl.second
            }
        }
-
+        rememberedSubroutineVars.clear()

        // add the implicit return statement at the end (if it's not there yet), but only if it's not a kernal routine.
        // and if an assembly block doesn't contain a rts/rti, and some other situations.
        val mods = mutableListOf<IAstModification>()
        val returnStmt = Return(null, subroutine.position)
-        if (subroutine.asmAddress == null
-                && !subroutine.inline
-                && subroutine.statements.isNotEmpty()
-                && subroutine.amountOfRtsInAsm() == 0
+        if (subroutine.asmAddress == null && !subroutine.inline) {
+            if(subroutine.statements.isEmpty() ||
+                (subroutine.amountOfRtsInAsm() == 0
                && subroutine.statements.lastOrNull { it !is VarDecl } !is Return
-                && subroutine.statements.last() !is Subroutine) {
-            mods += IAstModification.InsertLast(returnStmt, subroutine)
+                && subroutine.statements.last() !is Subroutine)) {
+                    mods += IAstModification.InsertLast(returnStmt, subroutine)
+            }
        }

        // precede a subroutine with a return to avoid falling through into the subroutine from code above it
-        val outerScope = subroutine.definingScope()
+        val outerScope = subroutine.definingScope
        val outerStatements = outerScope.statements
        val subroutineStmtIdx = outerStatements.indexOf(subroutine)
        if (subroutineStmtIdx > 0
@@ -136,10 +127,11 @@ internal class BeforeAsmGenerationAstChanger(val program: Program, val errors: I
    }

    override fun after(typecast: TypecastExpression, parent: Node): Iterable<IAstModification> {
-        // see if we can remove superfluous typecasts (outside of expressions)
+        // see if we can remove redundant typecasts (outside of expressions)
        // such as casting byte<->ubyte,  word<->uword
-        // Also the special typecast of a reference type (str, array) to an UWORD will be changed into address-of.
-        val sourceDt = typecast.expression.inferType(program).typeOrElse(DataType.STRUCT)
+        // Also the special typecast of a reference type (str, array) to an UWORD will be changed into address-of,
+        //   UNLESS it's a str parameter in the containing subroutine - then we remove the typecast altogether
+        val sourceDt = typecast.expression.inferType(program).getOr(DataType.UNDEFINED)
        if (typecast.type in ByteDatatypes && sourceDt in ByteDatatypes
                || typecast.type in WordDatatypes && sourceDt in WordDatatypes) {
            if(typecast.parent !is Expression) {
@@ -147,22 +139,23 @@ internal class BeforeAsmGenerationAstChanger(val program: Program, val errors: I
            }
        }

-
-        // Note: for various reasons (most importantly, code simplicity), the code generator assumes/requires
-        // that the types of assignment values and their target are the same,
-        // and that the types of both operands of a binaryexpression node are the same.
-        // So, it is not easily possible to remove the typecasts that are there to make these conditions true.
-        // The only place for now where we can do this is for:
-        //    asmsub register pair parameter.
-
        if(sourceDt in PassByReferenceDatatypes) {
            if(typecast.type==DataType.UWORD) {
-                if(typecast.expression is IdentifierReference) {
-                    return listOf(IAstModification.ReplaceNode(
+                val identifier = typecast.expression as? IdentifierReference
+                if(identifier!=null) {
+                    return if(identifier.isSubroutineParameter(program)) {
+                        listOf(IAstModification.ReplaceNode(
                            typecast,
-                            AddressOf(typecast.expression as IdentifierReference, typecast.position),
+                            typecast.expression,
                            parent
-                    ))
+                        ))
+                    } else {
+                        listOf(IAstModification.ReplaceNode(
+                            typecast,
+                            AddressOf(identifier, typecast.position),
+                            parent
+                        ))
+                    }
                } else if(typecast.expression is IFunctionCall) {
                    return listOf(IAstModification.ReplaceNode(
                            typecast,
@@ -178,33 +171,158 @@ internal class BeforeAsmGenerationAstChanger(val program: Program, val errors: I
        return noModifications
    }

+    @Suppress("DuplicatedCode")
    override fun after(ifStatement: IfStatement, parent: Node): Iterable<IAstModification> {
+        val prefixExpr = ifStatement.condition as? PrefixExpression
+        if(prefixExpr!=null && prefixExpr.operator=="not") {
+            // if not x -> if x==0
+            val booleanExpr = BinaryExpression(prefixExpr.expression, "==", NumericLiteralValue.optimalInteger(0, ifStatement.condition.position), ifStatement.condition.position)
+            return listOf(IAstModification.ReplaceNode(ifStatement.condition, booleanExpr, ifStatement))
+        }
+
        val binExpr = ifStatement.condition as? BinaryExpression
        if(binExpr==null || binExpr.operator !in comparisonOperators) {
            // if x  ->  if x!=0,    if x+5  ->  if x+5 != 0
            val booleanExpr = BinaryExpression(ifStatement.condition, "!=", NumericLiteralValue.optimalInteger(0, ifStatement.condition.position), ifStatement.condition.position)
            return listOf(IAstModification.ReplaceNode(ifStatement.condition, booleanExpr, ifStatement))
        }
-        return noModifications
+
+        if((binExpr.left as? NumericLiteralValue)?.number==0.0 &&
+            (binExpr.right as? NumericLiteralValue)?.number!=0.0)
+            throw FatalAstException("0==X should have been swapped to if X==0")
+
+        // simplify the conditional expression, introduce simple assignments if required.
+        // NOTE: sometimes this increases code size because additional stores/loads are generated for the
+        //       intermediate variables. We assume these are optimized away from the resulting assembly code later.
+        val simplify = simplifyConditionalExpression(binExpr)
+        val modifications = mutableListOf<IAstModification>()
+        if(simplify.rightVarAssignment!=null) {
+            modifications += IAstModification.ReplaceNode(binExpr.right, simplify.rightOperandReplacement!!, binExpr)
+            modifications += IAstModification.InsertBefore(ifStatement, simplify.rightVarAssignment, parent as IStatementContainer)
+        }
+        if(simplify.leftVarAssignment!=null) {
+            modifications += IAstModification.ReplaceNode(binExpr.left, simplify.leftOperandReplacement!!, binExpr)
+            modifications += IAstModification.InsertBefore(ifStatement, simplify.leftVarAssignment, parent as IStatementContainer)
+        }
+
+        return modifications
    }

+    private class CondExprSimplificationResult(
+        val leftVarAssignment: Assignment?,
+        val leftOperandReplacement: Expression?,
+        val rightVarAssignment: Assignment?,
+        val rightOperandReplacement: Expression?
+    )
+
+    private fun simplifyConditionalExpression(expr: BinaryExpression): CondExprSimplificationResult {
+
+        // TODO: somehow figure out if the expr will result in stack-evaluation STILL after being split off,
+        //       in that case: do *not* split it off but just keep it as it is (otherwise code size increases)
+
+        var leftAssignment: Assignment? = null
+        var leftOperandReplacement: Expression? = null
+        var rightAssignment: Assignment? = null
+        var rightOperandReplacement: Expression? = null
+
+        val separateLeftExpr = !expr.left.isSimple && expr.left !is IFunctionCall
+        val separateRightExpr = !expr.right.isSimple && expr.right !is IFunctionCall
+
+        if(separateLeftExpr) {
+            val name = getTempVarName(expr.left.inferType(program))
+            leftOperandReplacement = IdentifierReference(name, expr.position)
+            leftAssignment = Assignment(
+                AssignTarget(IdentifierReference(name, expr.position), null, null, expr.position),
+                expr.left,
+                expr.position
+            )
+        }
+        if(separateRightExpr) {
+            val dt = expr.right.inferType(program)
+            val name = when {
+                dt.istype(DataType.UBYTE) -> listOf("prog8_lib","retval_interm_ub")
+                dt.istype(DataType.UWORD) -> listOf("prog8_lib","retval_interm_uw")
+                dt.istype(DataType.BYTE) -> listOf("prog8_lib","retval_interm_b2")
+                dt.istype(DataType.WORD) -> listOf("prog8_lib","retval_interm_w2")
+                else -> throw AssemblyError("invalid dt")
+            }
+            rightOperandReplacement = IdentifierReference(name, expr.position)
+            rightAssignment = Assignment(
+                AssignTarget(IdentifierReference(name, expr.position), null, null, expr.position),
+                expr.right,
+                expr.position
+            )
+        }
+        return CondExprSimplificationResult(
+            leftAssignment, leftOperandReplacement,
+            rightAssignment, rightOperandReplacement
+        )
+    }
+
+    @Suppress("DuplicatedCode")
    override fun after(untilLoop: UntilLoop, parent: Node): Iterable<IAstModification> {
+        val prefixExpr = untilLoop.condition as? PrefixExpression
+        if(prefixExpr!=null && prefixExpr.operator=="not") {
+            // until not x -> until x==0
+            val booleanExpr = BinaryExpression(prefixExpr.expression, "==", NumericLiteralValue.optimalInteger(0, untilLoop.condition.position), untilLoop.condition.position)
+            return listOf(IAstModification.ReplaceNode(untilLoop.condition, booleanExpr, untilLoop))
+        }
+
        val binExpr = untilLoop.condition as? BinaryExpression
        if(binExpr==null || binExpr.operator !in comparisonOperators) {
            // until x  ->  until x!=0,    until x+5  ->  until x+5 != 0
            val booleanExpr = BinaryExpression(untilLoop.condition, "!=", NumericLiteralValue.optimalInteger(0, untilLoop.condition.position), untilLoop.condition.position)
            return listOf(IAstModification.ReplaceNode(untilLoop.condition, booleanExpr, untilLoop))
        }
-        return noModifications
+
+        if((binExpr.left as? NumericLiteralValue)?.number==0.0 &&
+            (binExpr.right as? NumericLiteralValue)?.number!=0.0)
+            throw FatalAstException("0==X should have been swapped to if X==0")
+
+        // simplify the conditional expression, introduce simple assignments if required.
+        // NOTE: sometimes this increases code size because additional stores/loads are generated for the
+        //       intermediate variables. We assume these are optimized away from the resulting assembly code later.
+        val simplify = simplifyConditionalExpression(binExpr)
+        val modifications = mutableListOf<IAstModification>()
+        if(simplify.rightVarAssignment!=null) {
+            modifications += IAstModification.ReplaceNode(binExpr.right, simplify.rightOperandReplacement!!, binExpr)
+            modifications += IAstModification.InsertLast(simplify.rightVarAssignment, untilLoop.body)
+        }
+        if(simplify.leftVarAssignment!=null) {
+            modifications += IAstModification.ReplaceNode(binExpr.left, simplify.leftOperandReplacement!!, binExpr)
+            modifications += IAstModification.InsertLast(simplify.leftVarAssignment, untilLoop.body)
+        }
+
+        return modifications
    }

+    @Suppress("DuplicatedCode")
    override fun after(whileLoop: WhileLoop, parent: Node): Iterable<IAstModification> {
+        val prefixExpr = whileLoop.condition as? PrefixExpression
+        if(prefixExpr!=null && prefixExpr.operator=="not") {
+            // while not x -> while x==0
+            val booleanExpr = BinaryExpression(prefixExpr.expression, "==", NumericLiteralValue.optimalInteger(0, whileLoop.condition.position), whileLoop.condition.position)
+            return listOf(IAstModification.ReplaceNode(whileLoop.condition, booleanExpr, whileLoop))
+        }
+
        val binExpr = whileLoop.condition as? BinaryExpression
        if(binExpr==null || binExpr.operator !in comparisonOperators) {
            // while x  ->  while x!=0,    while x+5  ->  while x+5 != 0
            val booleanExpr = BinaryExpression(whileLoop.condition, "!=", NumericLiteralValue.optimalInteger(0, whileLoop.condition.position), whileLoop.condition.position)
            return listOf(IAstModification.ReplaceNode(whileLoop.condition, booleanExpr, whileLoop))
        }
+
+        if((binExpr.left as? NumericLiteralValue)?.number==0.0 &&
+            (binExpr.right as? NumericLiteralValue)?.number!=0.0)
+            throw FatalAstException("0==X should have been swapped to if X==0")
+
+        // TODO simplify the conditional expression, introduce simple assignments if required.
+        // NOTE: sometimes this increases code size because additional stores/loads are generated for the
+        //       intermediate variables. We assume these are optimized away from the resulting assembly code later.
+        // NOTE: this is nasty for a while-statement as the condition occurs at the top of the loop
+        //       so the expression needs to be evaluated also before the loop is entered...
+        //       but I don't want to duplicate the expression.
+        // val simplify = simplifyConditionalExpression(binExpr)
        return noModifications
    }

@@ -213,18 +331,20 @@ internal class BeforeAsmGenerationAstChanger(val program: Program, val errors: I
            // if the datatype of the arguments of cmp() are different, cast the byte one to word.
            val arg1 = functionCallStatement.args[0]
            val arg2 = functionCallStatement.args[1]
-            val dt1 = arg1.inferType(program).typeOrElse(DataType.STRUCT)
-            val dt2 = arg2.inferType(program).typeOrElse(DataType.STRUCT)
+            val dt1 = arg1.inferType(program).getOr(DataType.UNDEFINED)
+            val dt2 = arg2.inferType(program).getOr(DataType.UNDEFINED)
            if(dt1 in ByteDatatypes) {
                if(dt2 in ByteDatatypes)
                    return noModifications
-                val cast1 = TypecastExpression(arg1, if(dt1==DataType.UBYTE) DataType.UWORD else DataType.WORD, true, functionCallStatement.position)
-                return listOf(IAstModification.ReplaceNode(arg1, cast1, functionCallStatement))
+                val (replaced, cast) = arg1.typecastTo(if(dt1==DataType.UBYTE) DataType.UWORD else DataType.WORD, dt1, true)
+                if(replaced)
+                    return listOf(IAstModification.ReplaceNode(arg1, cast, functionCallStatement))
            } else {
                if(dt2 in WordDatatypes)
                    return noModifications
-                val cast2 = TypecastExpression(arg2, if(dt2==DataType.UBYTE) DataType.UWORD else DataType.WORD, true, functionCallStatement.position)
-                return listOf(IAstModification.ReplaceNode(arg2, cast2, functionCallStatement))
+                val (replaced, cast) = arg2.typecastTo(if(dt2==DataType.UBYTE) DataType.UWORD else DataType.WORD, dt2, true)
+                if(replaced)
+                    return listOf(IAstModification.ReplaceNode(arg2, cast, functionCallStatement))
            }
        }
        return noModifications
@@ -286,12 +406,14 @@ internal class BeforeAsmGenerationAstChanger(val program: Program, val errors: I

    private fun getAutoIndexerVarFor(expr: ArrayIndexedExpression): MutableList<IAstModification> {
        val modifications = mutableListOf<IAstModification>()
-        val statement = expr.containingStatement()
+        val statement = expr.containingStatement
+        val dt = expr.indexer.indexExpr.inferType(program)
+        val register = if(dt istype DataType.UBYTE  || dt istype DataType.BYTE ) "retval_interm_ub" else "retval_interm_b"
        // replace the indexer with just the variable (simply use a cx16 virtual register r9, that we HOPE is not used for other things in the expression...)
        // assign the indexing expression to the helper variable, but only if that hasn't been done already
-        val target = AssignTarget(IdentifierReference(listOf("cx16", "r9"), expr.indexer.position), null, null, expr.indexer.position)
+        val target = AssignTarget(IdentifierReference(listOf("prog8_lib", register), expr.indexer.position), null, null, expr.indexer.position)
        val assign = Assignment(target, expr.indexer.indexExpr, expr.indexer.position)
-        modifications.add(IAstModification.InsertBefore(statement, assign, statement.definingScope()))
+        modifications.add(IAstModification.InsertBefore(statement, assign, statement.parent as IStatementContainer))
        modifications.add(IAstModification.ReplaceNode(expr.indexer.indexExpr, target.identifier!!.copy(), expr.indexer))
        return modifications
    }
@@ -1,8 +1,8 @@
 package prog8.compiler

-import prog8.ast.AstToSourceCode
+import com.github.michaelbull.result.*
+import prog8.ast.AstToSourceTextConverter
 import prog8.ast.IBuiltinFunctions
-import prog8.ast.IMemSizer
 import prog8.ast.Program
 import prog8.ast.base.AstException
 import prog8.ast.base.Position
@@ -10,108 +10,103 @@ import prog8.ast.expressions.Expression
 import prog8.ast.expressions.NumericLiteralValue
 import prog8.ast.statements.Directive
 import prog8.compiler.astprocessing.*
-import prog8.compiler.functions.*
 import prog8.compiler.target.C64Target
 import prog8.compiler.target.Cx16Target
-import prog8.compiler.target.ICompilationTarget
-import prog8.compiler.target.asmGeneratorFor
+import prog8.compiler.target.cpu6502.codegen.AsmGen
+import prog8.compilerinterface.*
 import prog8.optimizer.*
-import prog8.parser.ModuleImporter
-import prog8.parser.ParsingFailedError
-import prog8.parser.moduleName
-import java.io.File
-import java.io.InputStream
+import prog8.parser.ParseError
 import java.nio.file.Path
-import kotlin.system.exitProcess
+import kotlin.io.path.Path
+import kotlin.io.path.nameWithoutExtension
 import kotlin.system.measureTimeMillis


-enum class OutputType {
-    RAW,
-    PRG
-}
-
-enum class LauncherType {
-    BASIC,
-    NONE
-}
-
-enum class ZeropageType {
-    BASICSAFE,
-    FLOATSAFE,
-    KERNALSAFE,
-    FULL,
-    DONTUSE
-}
-
-data class CompilationOptions(val output: OutputType,
-                              val launcher: LauncherType,
-                              val zeropage: ZeropageType,
-                              val zpReserved: List<IntRange>,
-                              val floats: Boolean,
-                              val noSysInit: Boolean,
-                              val compTarget: ICompilationTarget) {
-    var slowCodegenWarnings = false
-    var optimize = false
-}
-
-
-class CompilerException(message: String?) : Exception(message)
-
 class CompilationResult(val success: Boolean,
-                        val programAst: Program,
+                        val program: Program,
                        val programName: String,
                        val compTarget: ICompilationTarget,
                        val importedFiles: List<Path>)

+class CompilerArguments(val filepath: Path,
+                        val optimize: Boolean,
+                        val optimizeFloatExpressions: Boolean,
+                        val writeAssembly: Boolean,
+                        val slowCodegenWarnings: Boolean,
+                        val quietAssembler: Boolean,
+                        val compilationTarget: String,
+                        val sourceDirs: List<String> = emptyList(),
+                        val outputDir: Path = Path(""),
+                        val errors: IErrorReporter = ErrorReporter())

-fun compileProgram(filepath: Path,
-                   optimize: Boolean,
-                   writeAssembly: Boolean,
-                   slowCodegenWarnings: Boolean,
-                   compilationTarget: String,
-                   outputDir: Path): CompilationResult {
+
+fun compileProgram(args: CompilerArguments): CompilationResult {
    var programName = ""
-    lateinit var programAst: Program
+    lateinit var program: Program
    lateinit var importedFiles: List<Path>
-    val errors = ErrorReporter()
+
+    val optimizeFloatExpr = if(args.optimize) args.optimizeFloatExpressions else false

    val compTarget =
-        when(compilationTarget) {
+        when(args.compilationTarget) {
            C64Target.name -> C64Target
            Cx16Target.name -> Cx16Target
-            else -> {
-                System.err.println("invalid compilation target")
-                exitProcess(1)
-            }
+            else -> throw IllegalArgumentException("invalid compilation target")
        }

    try {
        val totalTime = measureTimeMillis {
            // import main module and everything it needs
-            val (ast, compilationOptions, imported) = parseImports(filepath, errors, compTarget)
-            compilationOptions.slowCodegenWarnings = slowCodegenWarnings
-            compilationOptions.optimize = optimize
-            programAst = ast
+            val (programresult, compilationOptions, imported) = parseImports(args.filepath, args.errors, compTarget, args.sourceDirs)
+            with(compilationOptions) {
+                this.slowCodegenWarnings = args.slowCodegenWarnings
+                this.optimize = args.optimize
+                this.optimizeFloatExpressions = optimizeFloatExpr
+            }
+            program = programresult
            importedFiles = imported
-            processAst(programAst, errors, compilationOptions)
+            processAst(program, args.errors, compilationOptions)
            if (compilationOptions.optimize)
-                optimizeAst(programAst, errors, BuiltinFunctionsFacade(BuiltinFunctions), compTarget)
-            postprocessAst(programAst, errors, compilationOptions)
+                optimizeAst(
+                    program,
+                    compilationOptions,
+                    args.errors,
+                    BuiltinFunctionsFacade(BuiltinFunctions),
+                    compTarget
+                )
+            postprocessAst(program, args.errors, compilationOptions)

-            // printAst(programAst)
+//            println("*********** AST BEFORE ASSEMBLYGEN *************")
+//            printProgram(program)

-            if(writeAssembly)
-                programName = writeAssembly(programAst, errors, outputDir, compilationOptions)
+            if (args.writeAssembly) {
+                val result = writeAssembly(program, args.errors, args.outputDir, args.quietAssembler, compilationOptions)
+                when (result) {
+                    is WriteAssemblyResult.Ok -> programName = result.filename
+                    is WriteAssemblyResult.Fail -> {
+                        System.err.println(result.error)
+                        return CompilationResult(false, program, programName, compTarget, importedFiles)
+                    }
+                }
+            }
        }
        System.out.flush()
        System.err.flush()
        println("\nTotal compilation+assemble time: ${totalTime / 1000.0} sec.")
-        return CompilationResult(true, programAst, programName, compTarget, importedFiles)
-
-    } catch (px: ParsingFailedError) {
+        return CompilationResult(true, program, programName, compTarget, importedFiles)
+    } catch (px: ParseError) {
        System.err.print("\u001b[91m")  // bright red
-        System.err.println(px.message)
+        System.err.println("${px.position.toClickableStr()} parse error: ${px.message}".trim())
+        System.err.print("\u001b[0m")  // reset
+    } catch (ac: AbortCompilation) {
+        if(!ac.message.isNullOrEmpty()) {
+            System.err.print("\u001b[91m")  // bright red
+            System.err.println(ac.message)
+            System.err.print("\u001b[0m")  // reset
+        }
+    } catch (nsf: NoSuchFileException) {
+        System.err.print("\u001b[91m")  // bright red
+        System.err.println("File not found: ${nsf.message}")
        System.err.print("\u001b[0m")  // reset
    } catch (ax: AstException) {
        System.err.print("\u001b[91m")  // bright red
@@ -131,7 +126,7 @@ fun compileProgram(filepath: Path,
        throw x
    }

-    val failedProgram = Program("failed", mutableListOf(), BuiltinFunctionsFacade(BuiltinFunctions), compTarget)
+    val failedProgram = Program("failed", BuiltinFunctionsFacade(BuiltinFunctions), compTarget, compTarget)
    return CompilationResult(false, failedProgram, programName, compTarget, emptyList())
 }

@@ -141,13 +136,13 @@ private class BuiltinFunctionsFacade(functions: Map<String, FSignature>): IBuilt
    override val names = functions.keys
    override val purefunctionNames = functions.filter { it.value.pure }.map { it.key }.toSet()

-    override fun constValue(name: String, args: List<Expression>, position: Position, memsizer: IMemSizer): NumericLiteralValue? {
+    override fun constValue(name: String, args: List<Expression>, position: Position): NumericLiteralValue? {
        val func = BuiltinFunctions[name]
        if(func!=null) {
            val exprfunc = func.constExpressionFunc
            if(exprfunc!=null) {
                return try {
-                    exprfunc(args, position, program, memsizer)
+                    exprfunc(args, position, program)
                } catch(x: NotConstArgumentException) {
                    // const-evaluating the builtin function call failed.
                    null
@@ -165,178 +160,214 @@ private class BuiltinFunctionsFacade(functions: Map<String, FSignature>): IBuilt
        builtinFunctionReturnType(name, args, program)
 }

-private fun parseImports(filepath: Path, errors: IErrorReporter, compTarget: ICompilationTarget): Triple<Program, CompilationOptions, List<Path>> {
-    val compilationTargetName = compTarget.name
-    println("Compiler target: $compilationTargetName. Parsing...")
-    val importer = ModuleImporter()
+fun parseImports(filepath: Path,
+                 errors: IErrorReporter,
+                 compTarget: ICompilationTarget,
+                 sourceDirs: List<String>): Triple<Program, CompilationOptions, List<Path>> {
+    println("Compiler target: ${compTarget.name}. Parsing...")
    val bf = BuiltinFunctionsFacade(BuiltinFunctions)
-    val programAst = Program(moduleName(filepath.fileName), mutableListOf(), bf, compTarget)
-    bf.program = programAst
-    importer.importModule(programAst, filepath, compTarget, compilationTargetName)
+    val program = Program(filepath.nameWithoutExtension, bf, compTarget, compTarget)
+    bf.program = program
+
+    val importer = ModuleImporter(program, compTarget.name, errors, sourceDirs)
+    val importedModuleResult = importer.importModule(filepath)
+    importedModuleResult.onFailure { throw it }
    errors.report()

-    val importedFiles = programAst.modules.filter { !it.source.startsWith("@embedded@") }.map { it.source }
-    val compilerOptions = determineCompilationOptions(programAst, compTarget)
-    if (compilerOptions.launcher == LauncherType.BASIC && compilerOptions.output != OutputType.PRG)
-        throw ParsingFailedError("${programAst.modules.first().position} BASIC launcher requires output type PRG.")
-
+    val importedFiles = program.modules.map { it.source }
+        .filter { it.isFromFilesystem }
+        .map { Path(it.origin) }
+    val compilerOptions = determineCompilationOptions(program, compTarget)
    // depending on the machine and compiler options we may have to include some libraries
-    for(lib in compTarget.machine.importLibs(compilerOptions, compilationTargetName))
-        importer.importLibraryModule(programAst, lib, compTarget, compilationTargetName)
+    for(lib in compTarget.machine.importLibs(compilerOptions, compTarget.name))
+        importer.importLibraryModule(lib)

    // always import prog8_lib and math
-    importer.importLibraryModule(programAst, "math", compTarget, compilationTargetName)
-    importer.importLibraryModule(programAst, "prog8_lib", compTarget, compilationTargetName)
+    importer.importLibraryModule("math")
+    importer.importLibraryModule("prog8_lib")
+
+    if (compilerOptions.launcher == LauncherType.BASIC && compilerOptions.output != OutputType.PRG)
+        errors.err("BASIC launcher requires output type PRG", program.toplevelModule.position)
    errors.report()
-    return Triple(programAst, compilerOptions, importedFiles)
+
+    return Triple(program, compilerOptions, importedFiles)
 }

-private fun determineCompilationOptions(program: Program, compTarget: ICompilationTarget): CompilationOptions {
-    val mainModule = program.mainModule
-    val outputType = (mainModule.statements.singleOrNull { it is Directive && it.directive == "%output" }
-            as? Directive)?.args?.single()?.name?.toUpperCase()
-    val launcherType = (mainModule.statements.singleOrNull { it is Directive && it.directive == "%launcher" }
-            as? Directive)?.args?.single()?.name?.toUpperCase()
-    val zpoption: String? = (mainModule.statements.singleOrNull { it is Directive && it.directive == "%zeropage" }
-            as? Directive)?.args?.single()?.name?.toUpperCase()
-    val allOptions = program.modules.flatMap { it.statements }.filter { it is Directive && it.directive == "%option" }.flatMap { (it as Directive).args }.toSet()
+fun determineCompilationOptions(program: Program, compTarget: ICompilationTarget): CompilationOptions {
+    val toplevelModule = program.toplevelModule
+    val outputDirective = (toplevelModule.statements.singleOrNull { it is Directive && it.directive == "%output" } as? Directive)
+    val launcherDirective = (toplevelModule.statements.singleOrNull { it is Directive && it.directive == "%launcher" } as? Directive)
+    val outputTypeStr = outputDirective?.args?.single()?.name?.uppercase()
+    val launcherTypeStr = launcherDirective?.args?.single()?.name?.uppercase()
+    val zpoption: String? = (toplevelModule.statements.singleOrNull { it is Directive && it.directive == "%zeropage" }
+            as? Directive)?.args?.single()?.name?.uppercase()
+    val allOptions = program.modules.flatMap { it.statements }.filter { it is Directive && it.directive == "%option" }
+        .flatMap { (it as Directive).args }.toSet()
    val floatsEnabled = allOptions.any { it.name == "enable_floats" }
    val noSysInit = allOptions.any { it.name == "no_sysinit" }
    var zpType: ZeropageType =
-            if (zpoption == null)
-                if(floatsEnabled) ZeropageType.FLOATSAFE else ZeropageType.KERNALSAFE
-            else
-                try {
-                    ZeropageType.valueOf(zpoption)
-                } catch (x: IllegalArgumentException) {
-                    ZeropageType.KERNALSAFE
-                    // error will be printed by the astchecker
-                }
+        if (zpoption == null)
+            if (floatsEnabled) ZeropageType.FLOATSAFE else ZeropageType.KERNALSAFE
+        else
+            try {
+                ZeropageType.valueOf(zpoption)
+            } catch (x: IllegalArgumentException) {
+                ZeropageType.KERNALSAFE
+                // error will be printed by the astchecker
+            }

-    if (zpType==ZeropageType.FLOATSAFE && compTarget.name == Cx16Target.name) {
-        System.err.println("Warning: Cx16 target must use zp option basicsafe instead of floatsafe")
+    if (zpType == ZeropageType.FLOATSAFE && compTarget.name == Cx16Target.name) {
+        System.err.println("Warning: zp option floatsafe changed to basicsafe for cx16 target")
        zpType = ZeropageType.BASICSAFE
    }

-    val zpReserved = mainModule.statements
-            .asSequence()
-            .filter { it is Directive && it.directive == "%zpreserved" }
-            .map { (it as Directive).args }
-            .map { it[0].int!!..it[1].int!! }
-            .toList()
+    val zpReserved = toplevelModule.statements
+        .asSequence()
+        .filter { it is Directive && it.directive == "%zpreserved" }
+        .map { (it as Directive).args }
+        .map { it[0].int!!..it[1].int!! }
+        .toList()

-    if(outputType!=null && !OutputType.values().any {it.name==outputType}) {
-        System.err.println("invalid output type $outputType")
-        exitProcess(1)
+    val outputType = if (outputTypeStr == null) OutputType.PRG else {
+        try {
+            OutputType.valueOf(outputTypeStr)
+        } catch (x: IllegalArgumentException) {
+            // set default value; actual check and error handling of invalid option is handled in the AstChecker later
+            OutputType.PRG
+        }
    }
-    if(launcherType!=null && !LauncherType.values().any {it.name==launcherType}) {
-        System.err.println("invalid launcher type $launcherType")
-        exitProcess(1)
+    val launcherType = if (launcherTypeStr == null) LauncherType.BASIC else {
+        try {
+            LauncherType.valueOf(launcherTypeStr)
+        } catch (x: IllegalArgumentException) {
+            // set default value; actual check and error handling of invalid option is handled in the AstChecker later
+            LauncherType.BASIC
+        }
    }

    return CompilationOptions(
-            if (outputType == null) OutputType.PRG else OutputType.valueOf(outputType),
-            if (launcherType == null) LauncherType.BASIC else LauncherType.valueOf(launcherType),
-            zpType, zpReserved, floatsEnabled, noSysInit,
-            compTarget
+        outputType,
+        launcherType,
+        zpType, zpReserved, floatsEnabled, noSysInit,
+        compTarget
    )
 }

-private fun processAst(programAst: Program, errors: IErrorReporter, compilerOptions: CompilationOptions) {
+private fun processAst(program: Program, errors: IErrorReporter, compilerOptions: CompilationOptions) {
    // perform initial syntax checks and processings
    println("Processing for target ${compilerOptions.compTarget.name}...")
-    programAst.checkIdentifiers(errors, compilerOptions.compTarget)
+    program.preprocessAst(program)
+    program.checkIdentifiers(errors, compilerOptions)
    errors.report()
-    programAst.constantFold(errors, compilerOptions.compTarget)
+    // TODO: turning char literals into UBYTEs via an encoding should really happen in code gen - but for that we'd need DataType.CHAR
+    //       ...but what do we gain from this? We can leave it as it is now: where a char literal is no more than syntactic sugar for an UBYTE value.
+    //       By introduction a CHAR dt, we will also lose the opportunity to do constant-folding on any expression containing a char literal.
+    //       Yes this is different from strings that are only encoded in the code gen phase.
+    program.charLiteralsToUByteLiterals(compilerOptions.compTarget)
+    program.constantFold(errors, compilerOptions.compTarget)
    errors.report()
-    programAst.reorderStatements(errors)
+    program.reorderStatements(errors, compilerOptions)
    errors.report()
-    programAst.addTypecasts(errors)
+    program.addTypecasts(errors)
    errors.report()
-    programAst.variousCleanups()
-    programAst.checkValid(compilerOptions, errors, compilerOptions.compTarget)
+    program.variousCleanups(program, errors)
    errors.report()
-    programAst.checkIdentifiers(errors, compilerOptions.compTarget)
+    program.checkValid(errors, compilerOptions)
+    errors.report()
+    program.checkIdentifiers(errors, compilerOptions)
    errors.report()
 }

-private fun optimizeAst(programAst: Program, errors: IErrorReporter, functions: IBuiltinFunctions, compTarget: ICompilationTarget) {
+private fun optimizeAst(program: Program, compilerOptions: CompilationOptions, errors: IErrorReporter, functions: IBuiltinFunctions, compTarget: ICompilationTarget) {
    // optimize the parse tree
    println("Optimizing...")
+
+    val remover = UnusedCodeRemover(program, errors, compTarget)
+    remover.visit(program)
+    remover.applyModifications()
+
    while (true) {
        // keep optimizing expressions and statements until no more steps remain
-        val optsDone1 = programAst.simplifyExpressions()
-        val optsDone2 = programAst.splitBinaryExpressions(compTarget)
-        val optsDone3 = programAst.optimizeStatements(errors, functions, compTarget, ::loadAsmIncludeFile)
-        programAst.constantFold(errors, compTarget) // because simplified statements and expressions can result in more constants that can be folded away
+        val optsDone1 = program.simplifyExpressions()
+        val optsDone2 = program.splitBinaryExpressions(compilerOptions, compTarget)
+        val optsDone3 = program.optimizeStatements(errors, functions, compTarget)
+        program.constantFold(errors, compTarget) // because simplified statements and expressions can result in more constants that can be folded away
        errors.report()
        if (optsDone1 + optsDone2 + optsDone3 == 0)
            break
    }

-    val remover = UnusedCodeRemover(programAst, errors, compTarget, ::loadAsmIncludeFile)
-    remover.visit(programAst)
-    remover.applyModifications()
    errors.report()
 }

-private fun postprocessAst(programAst: Program, errors: IErrorReporter, compilerOptions: CompilationOptions) {
-    programAst.addTypecasts(errors)
+private fun postprocessAst(program: Program, errors: IErrorReporter, compilerOptions: CompilationOptions) {
+    program.addTypecasts(errors)
    errors.report()
-    programAst.variousCleanups()
-    programAst.checkValid(compilerOptions, errors, compilerOptions.compTarget)          // check if final tree is still valid
+    program.variousCleanups(program, errors)
+    program.checkValid(errors, compilerOptions)          // check if final tree is still valid
    errors.report()
-    val callGraph = CallGraph(programAst, ::loadAsmIncludeFile)
+    val callGraph = CallGraph(program)
    callGraph.checkRecursiveCalls(errors)
    errors.report()
-    programAst.verifyFunctionArgTypes()
-    programAst.moveMainAndStartToFirst()
+    program.verifyFunctionArgTypes()
+    program.moveMainAndStartToFirst()
 }

-private fun writeAssembly(programAst: Program,
+private sealed class WriteAssemblyResult {
+    class Ok(val filename: String): WriteAssemblyResult()
+    class Fail(val error: String): WriteAssemblyResult()
+}
+
+private fun writeAssembly(program: Program,
                          errors: IErrorReporter,
                          outputDir: Path,
-                          compilerOptions: CompilationOptions): String {
+                          quietAssembler: Boolean,
+                          compilerOptions: CompilationOptions
+): WriteAssemblyResult {
    // asm generation directly from the Ast
-    programAst.processAstBeforeAsmGeneration(errors, compilerOptions.compTarget)
+    program.processAstBeforeAsmGeneration(compilerOptions, errors)
    errors.report()

-    // printAst(programAst)
+//    println("*********** AST RIGHT BEFORE ASM GENERATION *************")
+//    printProgram(program)

    compilerOptions.compTarget.machine.initializeZeropage(compilerOptions)
    val assembly = asmGeneratorFor(compilerOptions.compTarget,
-            programAst,
+            program,
            errors,
            compilerOptions.compTarget.machine.zeropage,
            compilerOptions,
            outputDir).compileToAssembly()
-    assembly.assemble(compilerOptions)
    errors.report()
-    return assembly.name
-}

-fun printAst(programAst: Program) {
-    println()
-    val printer = AstToSourceCode(::print, programAst)
-    printer.visit(programAst)
-    println()
-}
-
-fun loadAsmIncludeFile(filename: String, source: Path): String {
-    return if (filename.startsWith("library:")) {
-        val resource = tryGetEmbeddedResource(filename.substring(8))
-            ?: throw IllegalArgumentException("library file '$filename' not found")
-        resource.bufferedReader().use { it.readText() }
+    return if(assembly.valid && errors.noErrors()) {
+        val assemblerReturnStatus = assembly.assemble(quietAssembler, compilerOptions)
+        if(assemblerReturnStatus!=0)
+            WriteAssemblyResult.Fail("assembler step failed with return code $assemblerReturnStatus")
+        else {
+            WriteAssemblyResult.Ok(assembly.name)
+        }
    } else {
-        // first try in the isSameAs folder as where the containing file was imported from
-        val sib = source.resolveSibling(filename)
-        if (sib.toFile().isFile)
-            sib.toFile().readText()
-        else
-            File(filename).readText()
+        WriteAssemblyResult.Fail("compiler failed with errors")
    }
 }

-internal fun tryGetEmbeddedResource(name: String): InputStream? {
-    return object{}.javaClass.getResourceAsStream("/prog8lib/$name")
+fun printProgram(program: Program) {
+    println()
+    val printer = AstToSourceTextConverter(::print, program)
+    printer.visit(program)
+    println()
+}
+
+internal fun asmGeneratorFor(
+    compTarget: ICompilationTarget,
+    program: Program,
+    errors: IErrorReporter,
+    zp: Zeropage,
+    options: CompilationOptions,
+    outputDir: Path
+): IAssemblyGenerator
+{
+    // at the moment we only have one code generation backend (for 6502 and 65c02)
+    return AsmGen(program, errors, zp, options, compTarget, outputDir)
 }
@@ -1,16 +1,7 @@
 package prog8.compiler

 import prog8.ast.base.Position
-import prog8.parser.ParsingFailedError
-
-
-interface IErrorReporter {
-    fun err(msg: String, position: Position)
-    fun warn(msg: String, position: Position)
-    fun isEmpty(): Boolean
-    fun report()
-}
-
+import prog8.compilerinterface.IErrorReporter

 internal class ErrorReporter: IErrorReporter {
    private enum class MessageSeverity {
@@ -33,25 +24,30 @@ internal class ErrorReporter: IErrorReporter {
        var numErrors = 0
        var numWarnings = 0
        messages.forEach {
+            val printer = when(it.severity) {
+                MessageSeverity.WARNING -> System.out
+                MessageSeverity.ERROR -> System.err
+            }
            when(it.severity) {
-                MessageSeverity.ERROR -> System.err.print("\u001b[91m")  // bright red
-                MessageSeverity.WARNING -> System.err.print("\u001b[93m")  // bright yellow
+                MessageSeverity.ERROR -> printer.print("\u001b[91m")  // bright red
+                MessageSeverity.WARNING -> printer.print("\u001b[93m")  // bright yellow
            }
            val msg = "${it.position.toClickableStr()} ${it.severity} ${it.message}".trim()
            if(msg !in alreadyReportedMessages) {
-                System.err.println(msg)
+                printer.println(msg)
                alreadyReportedMessages.add(msg)
                when(it.severity) {
                    MessageSeverity.WARNING -> numWarnings++
                    MessageSeverity.ERROR -> numErrors++
                }
            }
-            System.err.print("\u001b[0m")  // reset color
+            printer.print("\u001b[0m")      // reset color
        }
+        System.out.flush()
+        System.err.flush()
        messages.clear()
-        if(numErrors>0)
-            throw ParsingFailedError("There are $numErrors errors and $numWarnings warnings.")
+        finalizeNumErrors(numErrors, numWarnings)
    }

-    override fun isEmpty() = messages.isEmpty()
+    override fun noErrors() = messages.none { it.severity==MessageSeverity.ERROR }
 }
@@ -0,0 +1,159 @@
+package prog8.compiler
+
+import com.github.michaelbull.result.*
+import prog8.ast.Module
+import prog8.ast.Program
+import prog8.ast.base.Position
+import prog8.ast.base.SyntaxError
+import prog8.ast.statements.Directive
+import prog8.ast.statements.DirectiveArg
+import prog8.compilerinterface.IErrorReporter
+import prog8.parser.Prog8Parser
+import prog8.parser.SourceCode
+import java.io.File
+import java.nio.file.Path
+import kotlin.io.path.*
+
+
+class ModuleImporter(private val program: Program,
+                     private val compilationTargetName: String,
+                     val errors: IErrorReporter,
+                     sourceDirs: List<String>) {
+
+    private val sourcePaths: List<Path> = sourceDirs.map { Path(it) }
+
+    fun importModule(filePath: Path): Result<Module, NoSuchFileException> {
+        val currentDir = Path("").absolute()
+        val searchIn = listOf(currentDir) + sourcePaths
+        val candidates = searchIn
+            .map { it.absolute().div(filePath).normalize().absolute() }
+            .filter { it.exists() }
+            .map { currentDir.relativize(it) }
+            .map { if (it.isAbsolute) it else Path(".", "$it") }
+
+        val srcPath = when (candidates.size) {
+            0 -> return Err(NoSuchFileException(
+                    file = filePath.normalize().toFile(),
+                    reason = "Searched in $searchIn"))
+            1 -> candidates.first()
+            else -> candidates.first()  // when more candiates, pick the one from the first location
+        }
+
+        val logMsg = "importing '${filePath.nameWithoutExtension}' (from file $srcPath)"
+        println(logMsg)
+
+        val module = importModule(SourceCode.File(srcPath))
+        return if(module==null)
+            Err(NoSuchFileException(srcPath.toFile()))
+        else
+            Ok(module)
+    }
+
+    fun importLibraryModule(name: String): Module? {
+        val import = Directive("%import", listOf(
+                DirectiveArg("", name, 42u, position = Position("<<<implicit-import>>>", 0, 0, 0))
+        ), Position("<<<implicit-import>>>", 0, 0, 0))
+        return executeImportDirective(import, null)
+    }
+
+    private fun importModule(src: SourceCode) : Module? {
+        val moduleAst = Prog8Parser.parseModule(src)
+        program.addModule(moduleAst)
+
+        // accept additional imports
+        try {
+            val lines = moduleAst.statements.toMutableList()
+            lines.asSequence()
+                .mapIndexed { i, it -> i to it }
+                .filter { (it.second as? Directive)?.directive == "%import" }
+                .forEach { executeImportDirective(it.second as Directive, moduleAst) }
+            moduleAst.statements = lines
+            return moduleAst
+        } catch (x: Exception) {
+            // in case of error, make sure the module we're importing is no longer in the Ast
+            program.removeModule(moduleAst)
+            throw x
+        }
+    }
+
+    private fun executeImportDirective(import: Directive, importingModule: Module?): Module? {
+        if(import.directive!="%import" || import.args.size!=1)
+            throw SyntaxError("invalid import directive", import.position)
+        if(!import.args[0].str.isNullOrEmpty() || import.args[0].name==null)
+            throw SyntaxError("%import requires unquoted module name", import.position)
+        val moduleName = import.args[0].name!!
+        if("$moduleName.p8" == import.position.file)
+            throw SyntaxError("cannot import self", import.position)
+
+        val existing = program.modules.singleOrNull { it.name == moduleName }
+        if (existing!=null)
+            return existing
+
+        // try internal library first
+        val moduleResourceSrc = getModuleFromResource("$moduleName.p8", compilationTargetName)
+        val importedModule =
+            moduleResourceSrc.fold(
+                success = {
+                    println("importing '$moduleName' (from internal ${it.origin})")
+                    importModule(it)
+                },
+                failure = {
+                    // try filesystem next
+                    val moduleSrc = getModuleFromFile(moduleName, importingModule)
+                    moduleSrc.fold(
+                        success = {
+                            println("importing '$moduleName' (from file ${it.origin})")
+                            importModule(it)
+                        },
+                        failure = {
+                            errors.err("no module found with name $moduleName. Searched in: $sourcePaths (and internal libraries)", import.position)
+                            return null
+                        }
+                    )
+                }
+            )
+
+        if(importedModule!=null)
+            removeDirectivesFromImportedModule(importedModule)
+        return importedModule
+    }
+
+    private fun removeDirectivesFromImportedModule(importedModule: Module) {
+        // Most global directives don't apply for imported modules, so remove them
+        val moduleLevelDirectives = listOf("%output", "%launcher", "%zeropage", "%zpreserved", "%address")
+        var directives = importedModule.statements.filterIsInstance<Directive>()
+        importedModule.statements.removeAll(directives)
+        directives = directives.filter{ it.directive !in moduleLevelDirectives }
+        importedModule.statements.addAll(0, directives)
+    }
+
+    private fun getModuleFromResource(name: String, compilationTargetName: String): Result<SourceCode, NoSuchFileException> {
+        val result =
+            runCatching { SourceCode.Resource("/prog8lib/$compilationTargetName/$name") }
+            .orElse { runCatching { SourceCode.Resource("/prog8lib/$name") }  }
+
+        return result.mapError { NoSuchFileException(File(name)) }
+    }
+
+    private fun getModuleFromFile(name: String, importingModule: Module?): Result<SourceCode, NoSuchFileException> {
+        val fileName = "$name.p8"
+        val locations =
+            if (importingModule == null) { // <=> imported from library module
+                sourcePaths
+            } else {
+                val dropCurDir = if(sourcePaths.isNotEmpty() && sourcePaths[0].name == ".") 1 else 0
+                sourcePaths.drop(dropCurDir) +
+                listOf(Path(importingModule.position.file).parent ?: Path("")) +
+                listOf(Path(".", "prog8lib"))
+            }
+
+        locations.forEach {
+            try {
+                return Ok(SourceCode.File(it.resolve(fileName)))
+            } catch (e: NoSuchFileException) {
+            }
+        }
+
+        return Err(NoSuchFileException(File("name")))
+    }
+}
@@ -1 +1 @@
 .4
 .4