From e3c00669c1782b94df4773ae8622fecc233bfaee Mon Sep 17 00:00:00 2001
From: Irmen de Jong <irmen@razorvine.net>
Date: Sun, 31 Oct 2021 02:39:45 +0200
Subject: [PATCH] fixed improved asm generation for conditions that compare
 signed word to zero

---
 .../cpu6502/codegen/ExpressionsAsmGen.kt      | 37 +++++++---
 examples/test.p8                              | 68 +++----------------
 2 files changed, 36 insertions(+), 69 deletions(-)

diff --git a/codeGeneration/src/prog8/compiler/target/cpu6502/codegen/ExpressionsAsmGen.kt b/codeGeneration/src/prog8/compiler/target/cpu6502/codegen/ExpressionsAsmGen.kt
index 10f746edf..04309a8d8 100644
--- a/codeGeneration/src/prog8/compiler/target/cpu6502/codegen/ExpressionsAsmGen.kt
+++ b/codeGeneration/src/prog8/compiler/target/cpu6502/codegen/ExpressionsAsmGen.kt
@@ -93,15 +93,10 @@ internal class ExpressionsAsmGen(private val program: Program, private val asmge
                     else -> throw AssemblyError("invalid comparison operator $operator")
                 }
             }
-            DataType.BYTE, DataType.WORD -> {
-                if(dt==DataType.BYTE) {
-                    asmgen.assignExpressionToRegister(left, RegisterOrPair.A)
-                    if (left is FunctionCall && !left.isSimple)
-                        asmgen.out("  cmp  #0")
-                } else {
-                    asmgen.assignExpressionToRegister(left, RegisterOrPair.AY)
-                    asmgen.out("  sty  P8ZP_SCRATCH_B1 |  ora  P8ZP_SCRATCH_B1")        // TODO PROBABLY NOT OKAY FOR WORDS
-                }
+            DataType.BYTE -> {
+                asmgen.assignExpressionToRegister(left, RegisterOrPair.A)
+                if (left is FunctionCall && !left.isSimple)
+                    asmgen.out("  cmp  #0")
                 when (operator) {
                     "==" -> asmgen.out("  bne  $jumpIfFalseLabel")
                     "!=" -> asmgen.out("  beq  $jumpIfFalseLabel")
@@ -115,6 +110,30 @@ internal class ExpressionsAsmGen(private val program: Program, private val asmge
                     else -> throw AssemblyError("invalid comparison operator $operator")
                 }
             }
+            DataType.WORD -> {
+                asmgen.assignExpressionToRegister(left, RegisterOrPair.AY)
+                when (operator) {
+                    "==" -> asmgen.out("  bne  $jumpIfFalseLabel |  cpy  #0 |  bne  $jumpIfFalseLabel")
+                    "!=" -> asmgen.out("  sty  P8ZP_SCRATCH_B1 |  ora  P8ZP_SCRATCH_B1 |  beq  $jumpIfFalseLabel")
+                    ">" -> asmgen.out("""
+                            cpy  #0
+                            bmi  $jumpIfFalseLabel
+                            bne  +
+                            cmp  #0
+                            beq  $jumpIfFalseLabel
+                        +   """)
+                    "<" -> asmgen.out("  cpy  #0 |  bpl  $jumpIfFalseLabel")
+                    ">=" -> asmgen.out("  cpy  #0 |  bmi  $jumpIfFalseLabel")
+                    "<=" -> asmgen.out("""
+                            cpy  #0
+                            bmi  +
+                            bne  $jumpIfFalseLabel
+                            cmp  #0
+                            bne  $jumpIfFalseLabel
+                        +   """)
+                    else -> throw AssemblyError("invalid comparison operator $operator")
+                }
+            }
             DataType.FLOAT -> {
                 asmgen.assignExpressionToRegister(left, RegisterOrPair.FAC1)
                 asmgen.out("  jsr  floats.SIGN")   // SIGN(fac1) to A, $ff, $0, $1 for negative, zero, positive
diff --git a/examples/test.p8 b/examples/test.p8
index 3cc40bfb6..203e1b84f 100644
--- a/examples/test.p8
+++ b/examples/test.p8
@@ -4,76 +4,24 @@
 main {
 
     sub start() {
-        byte xx
+        word xx
 
-        xx=0
+        xx=-$7f00
 
-        if xx>=0 {
-            txt.print("xx>=0\n")
-        } else {
-            txt.print("error1\n")
-        }
-        if xx<=0 {
-            txt.print("xx<=0\n")
-        } else {
-            txt.print("error1qq\n")
-        }
-        if xx>0 {
-            txt.print("xx>0 error\n")
-        } else {
-            txt.print("ok1\n")
-        }
-        if xx<0 {
-            txt.print("xx<0 error\n")
-        } else {
-            txt.print("ok1\n")
-        }
+        txt.print_w(xx)
         txt.nl()
-
-        xx=22
         if xx>=0 {
-            txt.print("xx>=0\n")
+            txt.print(">=0\n")
         } else {
-            txt.print("error2\n")
+            txt.print("<0\n")
         }
         if xx<=0 {
-            txt.print("xx<=0 error\n")
+            txt.print("<=0\n")
         } else {
-            txt.print("ok2\n")
+            txt.print(">0\n")
         }
-        if xx>0 {
-            txt.print("xx>0\n")
-        } else {
-            txt.print("error2\n")
-        }
-        if xx<0 {
-            txt.print("xx<0 error\n")
-        } else {
-            txt.print("ok2\n")
-        }
-        txt.nl()
 
-        xx=-11
-        if xx>=0 {
-            txt.print("xx>=0 error\n")
-        } else {
-            txt.print("ok3\n")
-        }
-        if xx<=0 {
-            txt.print("xx<=0\n")
-        } else {
-            txt.print("error3\n")
-        }
-        if xx>0 {
-            txt.print("xx>0 error\n")
-        } else {
-            txt.print("ok3\n")
-        }
-        if xx<0 {
-            txt.print("xx<0\n")
-        } else {
-            txt.print("error3\n")
-        }
+        return