From a40b3134f4c04c52751b5743d864a43725fdd055 Mon Sep 17 00:00:00 2001
From: Irmen de Jong <irmen@razorvine.net>
Date: Tue, 22 Dec 2020 04:52:46 +0100
Subject: [PATCH] fix clobbering of A when restoring X or Y from stack

---
 .../src/prog8/compiler/target/c64/codegen/AsmGen.kt    |  6 +++---
 .../compiler/target/c64/codegen/FunctionCallAsmGen.kt  |  5 +++--
 examples/cx16/imageviewer/imageviewer.p8               |  2 ++
 examples/tehtriz.p8                                    |  2 --
 examples/test.p8                                       | 10 +++++++---
 examples/textelite.p8                                  |  3 ---
 examples/turtle-gfx.p8                                 |  2 ++
 7 files changed, 17 insertions(+), 13 deletions(-)

diff --git a/compiler/src/prog8/compiler/target/c64/codegen/AsmGen.kt b/compiler/src/prog8/compiler/target/c64/codegen/AsmGen.kt
index 2b61ef9ad..2f7695a0d 100644
--- a/compiler/src/prog8/compiler/target/c64/codegen/AsmGen.kt
+++ b/compiler/src/prog8/compiler/target/c64/codegen/AsmGen.kt
@@ -584,16 +584,16 @@ internal class AsmGen(private val program: Program,
                 CpuRegister.A -> out("  pla")
                 CpuRegister.X -> {
                     if (CompilationTarget.instance.machine.cpu == CpuType.CPU65c02) out("  plx")
-                    else out("  pla |  tax")
+                    else out("  sta  P8ZP_SCRATCH_REG |  pla |  tax |  lda  P8ZP_SCRATCH_REG")
                 }
                 CpuRegister.Y -> {
                     if (CompilationTarget.instance.machine.cpu == CpuType.CPU65c02) out("  ply")
-                    else out("  pla |  tay")
+                    else out("  sta  P8ZP_SCRATCH_REG |  pla |  tay |  lda  P8ZP_SCRATCH_REG")
                 }
             }
         } else {
             when (register) {
-                CpuRegister.A -> out("  sta  _prog8_regsaveA")
+                CpuRegister.A -> out("  lda  _prog8_regsaveA")
                 CpuRegister.X -> out("  ldx  _prog8_regsaveX")
                 CpuRegister.Y -> out("  ldy  _prog8_regsaveY")
             }
diff --git a/compiler/src/prog8/compiler/target/c64/codegen/FunctionCallAsmGen.kt b/compiler/src/prog8/compiler/target/c64/codegen/FunctionCallAsmGen.kt
index a67c50c5f..77bfaab9f 100644
--- a/compiler/src/prog8/compiler/target/c64/codegen/FunctionCallAsmGen.kt
+++ b/compiler/src/prog8/compiler/target/c64/codegen/FunctionCallAsmGen.kt
@@ -25,8 +25,9 @@ internal class FunctionCallAsmGen(private val program: Program, private val asmg
         // does NOT output the code to deal with the result values!
         val sub = stmt.target.targetSubroutine(program.namespace) ?: throw AssemblyError("undefined subroutine ${stmt.target}")
         val saveX = 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
         if(saveX)
-            asmgen.saveRegister(CpuRegister.X, (stmt as Node).definingSubroutine()!!, true)
+            asmgen.saveRegister(CpuRegister.X, (stmt as Node).definingSubroutine()!!, regSaveOnStack)
 
         val subName = asmgen.asmSymbolName(stmt.target)
         if(stmt.args.isNotEmpty()) {
@@ -64,7 +65,7 @@ internal class FunctionCallAsmGen(private val program: Program, private val asmg
         }
         asmgen.out("  jsr  $subName")
         if(saveX)
-            asmgen.restoreRegister(CpuRegister.X, true)
+            asmgen.restoreRegister(CpuRegister.X, regSaveOnStack)
     }
 
     private fun registerArgsViaStackEvaluation(stmt: IFunctionCall, sub: Subroutine) {
diff --git a/examples/cx16/imageviewer/imageviewer.p8 b/examples/cx16/imageviewer/imageviewer.p8
index 027bd5472..51902b0c2 100644
--- a/examples/cx16/imageviewer/imageviewer.p8
+++ b/examples/cx16/imageviewer/imageviewer.p8
@@ -8,6 +8,8 @@
 %import bmp_module
 ;; %import ci_module
 
+; TODO WHY is this 400 bytes larger than a few hours ago?
+
 main {
     sub start() {
         ; trick to check if we're running on sdcard or host system shared folder
diff --git a/examples/tehtriz.p8 b/examples/tehtriz.p8
index 824eca03d..94481e21f 100644
--- a/examples/tehtriz.p8
+++ b/examples/tehtriz.p8
@@ -7,8 +7,6 @@
 ;   staged speed increase
 ;   some simple sound effects
 
-; TODO BROKEN: DOESN'T REGISTER KEYSTROKES ANYMORE (CAN'T START GAME)
-
 
 %target c64
 %import syslib
diff --git a/examples/test.p8 b/examples/test.p8
index 081a53e53..f715c78a1 100644
--- a/examples/test.p8
+++ b/examples/test.p8
@@ -71,9 +71,13 @@ _y  .byte 0
 
     sub start () {
 
-                while c64.CHRIN() {
-                    ; read the rest of the entry until the end
-                }
+        txt.print("status 8: ")
+        uword ss = diskio.status(8)
+        txt.print(ss)
+        txt.print("\nstatus 9: ")
+        ss = diskio.status(9)
+        txt.print(ss)
+        txt.chrout('\n')
 
 ;        cx16.r0 = 65535
 ;        set_8_pixels_opaque_OLD(111,222,33)
diff --git a/examples/textelite.p8 b/examples/textelite.p8
index 35f6acfe1..3c660e829 100644
--- a/examples/textelite.p8
+++ b/examples/textelite.p8
@@ -10,9 +10,6 @@
 
 ; Note: this program is compatible with C64 and CX16.
 
-; TODO BROKEN IN VICE WHEN LOADING WITHOUT DISK: PRINTS WEIRD CHARACTERS FOR IO-ERROR
-
-
 main {
 
     const ubyte numforLave = 7      ;  Lave is 7th generated planet in galaxy one
diff --git a/examples/turtle-gfx.p8 b/examples/turtle-gfx.p8
index 08a038069..b9a2ba60e 100644
--- a/examples/turtle-gfx.p8
+++ b/examples/turtle-gfx.p8
@@ -4,6 +4,8 @@
 %import test_stack
 %zeropage floatsafe
 
+; TODO WHY is this a couple of 100 bytes larger than a few hours ago?
+
 main {
 
     sub start() {