From 39b07a8bae4df9cd7686ff410329f838f6f1bc7d Mon Sep 17 00:00:00 2001
From: Karol Stasiak <karol.m.stasiak@gmail.com>
Date: Fri, 28 Jun 2019 16:44:41 +0200
Subject: [PATCH] Fix init_rw_memory on Atari 2600

---
 docs/lang/preprocessor.md                              |  2 +-
 examples/vcs/colors.mfk                                |  1 +
 src/main/scala/millfork/Platform.scala                 | 10 +++-------
 src/main/scala/millfork/output/VariableAllocator.scala |  4 ++--
 src/test/scala/millfork/test/emu/EmuPlatform.scala     |  2 +-
 5 files changed, 8 insertions(+), 11 deletions(-)

diff --git a/docs/lang/preprocessor.md b/docs/lang/preprocessor.md
index dffb4fc4..8e334640 100644
--- a/docs/lang/preprocessor.md
+++ b/docs/lang/preprocessor.md
@@ -66,7 +66,7 @@ See [the ROM vs RAM guide](../api/rom-vs-ram.md) for more information.
 
 * `ZPREG_SIZE` – size of the pseudoregister in bytes, or 0 on platforms that don't use it
 
-* `TINY_MAIN_RAM` – 1 if the main ram is 256 bytes or less, 0 otherwise
+* `TINY_RW_MEMORY` – 1 if the main ram is 256 bytes or less, 0 otherwise
 
 * `USES_IX_STACK`, `USES_IY_STACK` – 1 if given index register is used as a base pointer for stack-allocated variables, 0 otherwise 
 
diff --git a/examples/vcs/colors.mfk b/examples/vcs/colors.mfk
index 5c29987a..2944627a 100644
--- a/examples/vcs/colors.mfk
+++ b/examples/vcs/colors.mfk
@@ -1,4 +1,5 @@
 void main() {
+    init_rw_memory()
     byte y
     while true {
         start_frame()
diff --git a/src/main/scala/millfork/Platform.scala b/src/main/scala/millfork/Platform.scala
index 98f60711..c2aeb2c9 100644
--- a/src/main/scala/millfork/Platform.scala
+++ b/src/main/scala/millfork/Platform.scala
@@ -157,16 +157,12 @@ object Platform {
       case "default" =>
         log.error("Cannot use default as ram_init_segment")
         None
-      case x if banks.contains(x) =>
-        if (CpuFamily.forType(cpu) == CpuFamily.M6502 && zpRegisterSize < 4) {
-          log.error("Using ram_init_segment requires zeropage register of size at least 4")
-        }
-        Some(x)
+      case x if banks.contains(x) => Some(x)
       case x =>
         log.error("Invalid ram_init_segment: " + x)
         None
     }
-    // used by 65816:
+    // used by 65816 and in NES debugging:
     val bankNumbers = banks.map(b => b -> (as.get(classOf[String], s"segment_${b}_bank", "00") match {
       case "" => 0
       case x => parseNumber(x)
@@ -204,7 +200,7 @@ object Platform {
     val codeAllocators = banks.map(b => b -> new UpwardByteAllocator(bankStarts(b), bankCodeEnds(b)))
     val variableAllocators = banks.map(b => b -> new VariableAllocator(
       if (b == "default" && CpuFamily.forType(cpu) == CpuFamily.M6502) freeZpBytes else Nil, bankDataStarts(b) match {
-        case None => new AfterCodeByteAllocator(bankEnds(b))
+        case None => new AfterCodeByteAllocator(bankStarts(b), bankEnds(b))
         case Some(start) => new UpwardByteAllocator(start, bankEnds(b))
       }))
 
diff --git a/src/main/scala/millfork/output/VariableAllocator.scala b/src/main/scala/millfork/output/VariableAllocator.scala
index 783e686a..cc341f0b 100644
--- a/src/main/scala/millfork/output/VariableAllocator.scala
+++ b/src/main/scala/millfork/output/VariableAllocator.scala
@@ -84,8 +84,8 @@ class ZeropageAllocator(val freeZpBytes: List[Int]) extends ByteAllocator {
   override def heapStart: Int = 0
 }
 
-class AfterCodeByteAllocator(val endBefore: Int) extends ByteAllocator {
-  var startAt = 0x200
+class AfterCodeByteAllocator(startIfNoCode: Int, val endBefore: Int) extends ByteAllocator {
+  var startAt = startIfNoCode
   def notifyAboutEndOfCode(org: Int): Unit = startAt = org
 
   override def preferredOrder: Option[List[Int]] = None
diff --git a/src/test/scala/millfork/test/emu/EmuPlatform.scala b/src/test/scala/millfork/test/emu/EmuPlatform.scala
index a64b5c2a..5d4acb98 100644
--- a/src/test/scala/millfork/test/emu/EmuPlatform.scala
+++ b/src/test/scala/millfork/test/emu/EmuPlatform.scala
@@ -21,7 +21,7 @@ object EmuPlatform {
     Map("default" -> (if (cpu == Cpu.Intel8086) new UpwardByteAllocator(0x100, 0xb000) else new UpwardByteAllocator(0x200, 0xb000))),
     Map("default" -> new VariableAllocator(
       if (CpuFamily.forType(cpu) == CpuFamily.M6502) pointers else Nil,
-      new AfterCodeByteAllocator(0xff00))),
+      new AfterCodeByteAllocator(0x200, 0xff00))),
     if (CpuFamily.forType(cpu) == CpuFamily.M6502) 4 else 0,
     pointers,
     ".bin",