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optimize comparison against zero
This commit is contained in:
Irmen de Jong
parent
cfea8b3745
commit
09a7a4bbe5
@ -416,7 +416,6 @@ internal class AssignmentAsmGen(private val program: PtProgram,
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val translatedOk = when (expr.operator) {
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in ComparisonOperators -> optimizedComparison(expr, assign)
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in setOf("&", "|", "^", "and", "or", "xor") -> optimizedLogicalOrBitwiseExpr(expr, assign.target)
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"==", "!=" -> optimizedEqualityExpr(expr, assign.target)
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"+", "-" -> optimizedPlusMinExpr(expr, assign.target)
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"<<", ">>" -> optimizedBitshiftExpr(expr, assign.target)
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"*" -> optimizedMultiplyExpr(expr, assign.target)
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@ -888,63 +887,6 @@ internal class AssignmentAsmGen(private val program: PtProgram,
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return false
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}
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private fun optimizedEqualityExpr(expr: PtBinaryExpression, target: AsmAssignTarget): Boolean {
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// expression datatype is BOOL (ubyte) but operands can be anything
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if(expr.left.type in ByteDatatypes && expr.right.type in ByteDatatypes &&
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expr.left.isSimple() && expr.right.isSimple()) {
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assignExpressionToRegister(expr.left, RegisterOrPair.A, false)
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asmgen.saveRegisterStack(CpuRegister.A, false)
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assignExpressionToVariable(expr.right, "P8ZP_SCRATCH_B1", DataType.UBYTE)
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asmgen.restoreRegisterStack(CpuRegister.A, false)
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if(expr.operator=="==") {
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asmgen.out("""
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cmp P8ZP_SCRATCH_B1
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bne +
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lda #1
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bne ++
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+ lda #0
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+""")
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} else {
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asmgen.out("""
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cmp P8ZP_SCRATCH_B1
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beq +
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lda #1
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bne ++
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+ lda #0
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+""")
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}
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assignRegisterByte(target, CpuRegister.A, false)
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return true
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} else if(expr.left.type in WordDatatypes && expr.right.type in WordDatatypes &&
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expr.left.isSimple() && expr.right.isSimple()) {
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asmgen.assignWordOperandsToAYAndVar(expr.left, expr.right, "P8ZP_SCRATCH_W1")
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if(expr.operator=="==") {
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asmgen.out("""
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cmp P8ZP_SCRATCH_W1
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bne +
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cpy P8ZP_SCRATCH_W1+1
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bne +
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lda #1
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bne ++
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+ lda #0
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+""")
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} else {
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asmgen.out("""
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cmp P8ZP_SCRATCH_W1
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bne +
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cpy P8ZP_SCRATCH_W1+1
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bne +
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lda #0
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beq ++
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+ lda #1
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+""")
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}
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assignRegisterByte(target, CpuRegister.A, false)
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return true
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}
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return false
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}
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private fun optimizedLogicalOrBitwiseExpr(expr: PtBinaryExpression, target: AsmAssignTarget): Boolean {
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if (expr.left.type in ByteDatatypes && expr.right.type in ByteDatatypes) {
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if (expr.right.isSimple()) {
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@ -1085,7 +1027,6 @@ internal class AssignmentAsmGen(private val program: PtProgram,
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}
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}
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// checked OK:
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private fun byteLess(expr: PtBinaryExpression, signed: Boolean) {
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// note: this is the inverse of byteGreaterEqual
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when(expr.right) {
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@ -1232,78 +1173,6 @@ internal class AssignmentAsmGen(private val program: PtProgram,
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}
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}
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private fun byteLessEqualsWRONG(expr: PtBinaryExpression, signed: Boolean) {
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// note: this is the inverse of byteGreater
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when(expr.right) {
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is PtNumber -> {
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// TODO verify if this is correct code on all corner cases
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val number = (expr.right as PtNumber).number.toInt()
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asmgen.assignExpressionToRegister(expr.left, RegisterOrPair.A, signed)
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if(signed)
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asmgen.out("""
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sec
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sbc #$number
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bvc +
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eor #$80
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+ bmi +
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lda #0
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beq ++
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+ lda #1
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+""")
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else
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asmgen.out("""
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cmp #$number
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lda #0
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rol a
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eor #1""")
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}
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is PtIdentifier -> {
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// TODO verify if this is correct code on all corner cases
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val varname = (expr.right as PtIdentifier).name
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asmgen.assignExpressionToRegister(expr.left, RegisterOrPair.A, signed)
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if(signed)
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asmgen.out("""
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sec
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sbc $varname
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bvc +
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eor #$80
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+ bmi +
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lda #0
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beq ++
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+ lda #1
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+""")
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else
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asmgen.out("""
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cmp $varname
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lda #0
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rol a
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eor #1""")
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}
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else -> {
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// TODO verify if this is correct code on all corner cases
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// note: left and right operands get reversed here to reduce code size
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asmgen.assignByteOperandsToAAndVar(expr.right, expr.left, "P8ZP_SCRATCH_B1")
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if(signed)
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asmgen.out("""
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sec
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sbc P8ZP_SCRATCH_B1
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bvc +
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eor #$80
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+ bmi +
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lda #1
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bne ++
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+ lda #0
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+""")
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else
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asmgen.out("""
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cmp P8ZP_SCRATCH_B1
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lda #0
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rol a""")
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}
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}
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}
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// checked OK:
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private fun byteGreater(expr: PtBinaryExpression, signed: Boolean) {
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// note: this is the inverse of byteLessEqual
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when(expr.right) {
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@ -1381,7 +1250,6 @@ internal class AssignmentAsmGen(private val program: PtProgram,
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}
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}
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// checked OK:
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private fun byteGreaterEquals(expr: PtBinaryExpression, signed: Boolean) {
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// note: this is the inverse of byteLess
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when(expr.right) {
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@ -1649,10 +1517,8 @@ internal class AssignmentAsmGen(private val program: PtProgram,
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assignExpressionToRegister(expr.left, RegisterOrPair.A, dt==DataType.BYTE)
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asmgen.out("""
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beq +
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lda #0
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beq ++
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+ lda #1
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+""")
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lda #1
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+ eor #1""")
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assignRegisterByte(assign.target, CpuRegister.A, false)
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return true
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}
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@ -1662,10 +1528,8 @@ internal class AssignmentAsmGen(private val program: PtProgram,
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sty P8ZP_SCRATCH_B1
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ora P8ZP_SCRATCH_B1
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beq +
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lda #0
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beq ++
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+ lda #1
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+""")
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lda #1
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+ eor #1""")
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assignRegisterByte(assign.target, CpuRegister.A, false)
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return true
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}
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@ -1,6 +1,6 @@
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TODO
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====
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- optimize assembly output for if word1 & word2 ... (no need for stack pushes)
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- optimize assembly output for ( word1 & word2 ==0) ... (no need for stack pushes)
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- prefix prog8 subroutines with p8s_ instead of p8_ to not let them clash with variables in the asm?
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@ -1,13 +1,45 @@
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%import textio
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%import math
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%zeropage basicsafe
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main {
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sub start() {
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thing()
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}
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sub thing() {
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ubyte start=22
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txt.print_ub(start)
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txt.print_uw(&main.start)
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uword w1
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uword w2
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ubyte b1
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ubyte b2
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b1 = 255
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b2 = 1
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txt.print_ub(b1&b2!=0) ; true
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txt.spc()
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txt.print_ub(b1&b2==0) ; false
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txt.nl()
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b1 = 255
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b2 = 0
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txt.print_ub(b1&b2!=0) ; false
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txt.spc()
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txt.print_ub(b1&b2==0) ; true
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txt.nl()
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w1 = $ff0f
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w2 = $0101
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txt.print_ub(w1&w2!=0) ; true
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txt.spc()
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txt.print_ub(w1&w2==0) ; false
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txt.nl()
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w1 = $ff0f
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w2 = $00f0
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txt.print_ub(w1&w2!=0) ; false
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txt.spc()
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txt.print_ub(w1&w2==0) ; true
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txt.nl()
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; if w1 & w2
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; cx16.r0++
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}
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}
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