From 8d177beb78fb32d001249678f69746da7f2ee0c3 Mon Sep 17 00:00:00 2001
From: Irmen de Jong <irmen@razorvine.net>
Date: Sun, 24 Sep 2023 14:03:31 +0200
Subject: [PATCH] fix possible register corruption when calling asmsubs that
 require Carry flag as a parameter

---
 .../src/prog8/codegen/cpu6502/FunctionCallAsmGen.kt          | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/codeGenCpu6502/src/prog8/codegen/cpu6502/FunctionCallAsmGen.kt b/codeGenCpu6502/src/prog8/codegen/cpu6502/FunctionCallAsmGen.kt
index 25eaba7cd..e1d88b83f 100644
--- a/codeGenCpu6502/src/prog8/codegen/cpu6502/FunctionCallAsmGen.kt
+++ b/codeGenCpu6502/src/prog8/codegen/cpu6502/FunctionCallAsmGen.kt
@@ -141,13 +141,14 @@ internal class FunctionCallAsmGen(private val program: PtProgram, private val as
                     }
                     is PtIdentifier -> {
                         val sourceName = asmgen.asmVariableName(value)
+                        // note: cannot use X register here to store A because it might be used for other arguments
                         asmgen.out("""
-                            tax
+                            pha
                             clc
                             lda  $sourceName
                             beq  +
                             sec  
-+                           txa""")
++                           pla""")
                     }
                     else -> {
                         asmgen.assignExpressionToRegister(value, RegisterOrPair.A)