From 6c233c6a0a28a89da2f68230ba3a6fb5dd1eaae9 Mon Sep 17 00:00:00 2001
From: Irmen de Jong <irmen@razorvine.net>
Date: Mon, 8 May 2023 02:41:34 +0200
Subject: [PATCH] optimize add/sub expr

---
 .../cpu6502/assignment/AssignmentAsmGen.kt    | 38 ++++++++++++++++++-
 examples/test.p8                              | 28 +++-----------
 2 files changed, 41 insertions(+), 25 deletions(-)

diff --git a/codeGenCpu6502/src/prog8/codegen/cpu6502/assignment/AssignmentAsmGen.kt b/codeGenCpu6502/src/prog8/codegen/cpu6502/assignment/AssignmentAsmGen.kt
index 9ce248775..859d671b2 100644
--- a/codeGenCpu6502/src/prog8/codegen/cpu6502/assignment/AssignmentAsmGen.kt
+++ b/codeGenCpu6502/src/prog8/codegen/cpu6502/assignment/AssignmentAsmGen.kt
@@ -529,7 +529,18 @@ internal class AssignmentAsmGen(private val program: PtProgram,
                         assignRegisterByte(assign.target, CpuRegister.A, dt in SignedDatatypes)
                         return true
                     }
-                    else -> return false
+                    else -> {
+                        assignExpressionToRegister(left, RegisterOrPair.A, left.type==DataType.BYTE)
+                        asmgen.out("  pha")
+                        assignExpressionToVariable(right, "P8ZP_SCRATCH_B1", right.type)
+                        asmgen.out("  pla")
+                        if(expr.operator=="+")
+                            asmgen.out("  clc |  adc  P8ZP_SCRATCH_B1")
+                        else
+                            asmgen.out("  sec |  sbc  P8ZP_SCRATCH_B1")
+                        assignRegisterByte(assign.target, CpuRegister.A, dt in SignedDatatypes)
+                        return true
+                    }
                 }
             } else if(dt in WordDatatypes) {
                 when (right) {
@@ -630,7 +641,30 @@ internal class AssignmentAsmGen(private val program: PtProgram,
                             }
                         }
                     }
-                    else -> return false
+                    else -> {
+                        assignExpressionToVariable(right, "P8ZP_SCRATCH_W2", right.type)
+                        assignExpressionToRegister(left, RegisterOrPair.AY, left.type==DataType.WORD)
+                        if(expr.operator=="+")
+                            asmgen.out("""
+                                clc
+                                adc  P8ZP_SCRATCH_W2
+                                pha
+                                tya
+                                adc  P8ZP_SCRATCH_W2+1
+                                tay
+                                pla""")
+                        else
+                            asmgen.out("""
+                                sec
+                                sbc  P8ZP_SCRATCH_W2
+                                pha
+                                tya
+                                sbc  P8ZP_SCRATCH_W2+1
+                                tay
+                                pla""")
+                        assignRegisterpairWord(assign.target, RegisterOrPair.AY)
+                        return true
+                    }
                 }
             }
         }
diff --git a/examples/test.p8 b/examples/test.p8
index 9b89dc426..53b2be513 100644
--- a/examples/test.p8
+++ b/examples/test.p8
@@ -3,31 +3,13 @@
 
 main {
 
-    uword vv = 60
-
-        sub print_time(uword seconds) {
-            ubyte remainder = seconds % $0003 ==0
-            txt.print_uw(remainder)
-            txt.nl()
-        }
-
-        sub print_time2(ubyte seconds) {
-            ubyte remainder = seconds % 3 ==0
-            txt.print_uw(remainder)
-            txt.nl()
-        }
-
+    word[5] dx = [111,222,333,444,555]
 
     sub start() {
-        print_time(9870)
-        print_time(9871)
-        print_time(9872)
-        print_time(9873)
-        txt.nl()
-        print_time2(50)
-        print_time2(51)
-        print_time2(52)
-        print_time2(53)
+        uword hit_x = 999
+        cx16.r0=2
+        uword new_head_x = hit_x + dx[cx16.r0L] as uword
+        txt.print_uw(new_head_x)
     }
 }