From 78af2cd4dcf38d110bb071f549556148305fa255 Mon Sep 17 00:00:00 2001
From: Irmen de Jong <irmen@razorvine.net>
Date: Sat, 13 Feb 2021 23:50:03 +0100
Subject: [PATCH] optimize peekw()

---
 .../c64/codegen/BuiltinFunctionsAsmGen.kt     | 56 ++++++++++++++++++-
 examples/test.p8                              | 15 ++---
 2 files changed, 62 insertions(+), 9 deletions(-)

diff --git a/compiler/src/prog8/compiler/target/c64/codegen/BuiltinFunctionsAsmGen.kt b/compiler/src/prog8/compiler/target/c64/codegen/BuiltinFunctionsAsmGen.kt
index 58139e92b..516aec86e 100644
--- a/compiler/src/prog8/compiler/target/c64/codegen/BuiltinFunctionsAsmGen.kt
+++ b/compiler/src/prog8/compiler/target/c64/codegen/BuiltinFunctionsAsmGen.kt
@@ -9,6 +9,7 @@ import prog8.ast.statements.*
 import prog8.ast.toHex
 import prog8.compiler.AssemblyError
 import prog8.compiler.functions.FSignature
+import prog8.compiler.target.CpuType
 import prog8.compiler.target.c64.codegen.assignment.*
 import prog8.compiler.target.subroutineFloatEvalResultVar2
 
@@ -969,8 +970,59 @@ internal class BuiltinFunctionsAsmGen(private val program: Program, private val
     }
 
     private fun funcPeekW(fcall: IFunctionCall, resultToStack: Boolean, resultRegister: RegisterOrPair?) {
-        asmgen.assignExpressionToRegister(fcall.args[0], RegisterOrPair.AY)
-        asmgen.out("  jsr  prog8_lib.func_peekw")
+        when(val addrExpr = fcall.args[0]) {
+            is NumericLiteralValue -> {
+                val addr = addrExpr.number.toHex()
+                asmgen.out("  lda  $addr |  ldy  ${addr}+1")
+            }
+            is IdentifierReference -> {
+                val varname = asmgen.asmVariableName(addrExpr)
+                if(asmgen.isZpVar(addrExpr)) {
+                    // pointervar is already in the zero page, no need to copy
+                    if (asmgen.compTarget.machine.cpu == CpuType.CPU65c02) {
+                        asmgen.out("""
+                            ldy  #1
+                            lda  ($varname),y
+                            tay
+                            lda  ($varname)""")
+                    } else {
+                        asmgen.out("""
+                            ldy  #0
+                            lda  ($varname),y
+                            pha
+                            iny
+                            lda  ($varname),y
+                            tay
+                            pla""")
+                    }
+                } else {
+                    asmgen.assignExpressionToRegister(fcall.args[0], RegisterOrPair.AY)
+                    asmgen.out("  jsr  prog8_lib.func_peekw")
+                }
+            }
+            is BinaryExpression -> {
+                if(addrExpr.operator=="+" && addrExpr.left is IdentifierReference && addrExpr.right is NumericLiteralValue) {
+                    val varname = asmgen.asmVariableName(addrExpr.left as IdentifierReference)
+                    val index = (addrExpr.right as NumericLiteralValue).number.toHex()
+                    asmgen.out("""
+                        ldy  #$index
+                        lda  ($varname),y
+                        pha
+                        iny
+                        lda  ($varname),y
+                        tay
+                        pla""")
+                } else {
+                    asmgen.assignExpressionToRegister(fcall.args[0], RegisterOrPair.AY)
+                    asmgen.out("  jsr  prog8_lib.func_peekw")
+                }
+            }
+            else -> {
+                asmgen.assignExpressionToRegister(fcall.args[0], RegisterOrPair.AY)
+                asmgen.out("  jsr  prog8_lib.func_peekw")
+            }
+        }
+
         if(resultToStack){
             asmgen.out("  sta  P8ESTACK_LO,x |  tya |  sta  P8ESTACK_HI,x |  dex")
         } else {
diff --git a/examples/test.p8 b/examples/test.p8
index 69942577e..522f05b82 100644
--- a/examples/test.p8
+++ b/examples/test.p8
@@ -6,14 +6,10 @@ main {
     sub start() {
 
         uword ptr = $4000
+        uword ww
 
-        poke(ptr, $34)
-        poke(ptr+1, $ea)
-        txt.print_ubhex(peek(ptr), 1)
-        txt.print_ubhex(peek(ptr+1), 1)
-        txt.nl()
-
-        uword ww = peekw(ptr)
+        pokew($4000, $98cf)
+        ww = peekw($4000)
         txt.print_uwhex(ww,1)
         txt.nl()
 
@@ -21,5 +17,10 @@ main {
         ww = peekw(ptr)
         txt.print_uwhex(ww,1)
         txt.nl()
+
+        pokew(ptr+2, $1234)
+        ww = peekw(ptr+2)
+        txt.print_uwhex(ww,1)
+        txt.nl()
     }
 }