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optimized repeat loop for word counts

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This commit is contained in:
Irmen de Jong 2021-02-28 17:34:18 +01:00
parent 07b5c44a54
commit 51e6bf0d45
2 changed files with 54 additions and 26 deletions
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34
compiler/src/prog8/compiler/target/cpu6502/codegen/AsmGen.kt
View File

@ -1008,28 +1008,30 @@ internal class AsmGen(private val program: Program,
}
private fun repeatWordCountInAY(constIterations: Int?, repeatLabel: String, endLabel: String, body: AnonymousScope) {
// note: A/Y must have been loaded with the number of iterations!
if(constIterations==0)
return
// note: A/Y must have been loaded with the number of iterations already!
if(constIterations==null) {
out( """
cmp #0
bne +
cpy #0
beq $endLabel ; skip if 0 iterations
+""")
}
val counterVar = makeLabel("repeatcounter")
out("""
cmp #0
bne +
cpy #0
beq $endLabel ; skip if 0 iterations
+ sta $counterVar
sta $counterVar
iny
sty $counterVar+1
$repeatLabel
lda $counterVar
bne +
lda $counterVar+1
beq $endLabel
+ lda $counterVar
bne +
dec $counterVar+1
+ dec $counterVar""")
$repeatLabel""")
translate(body)
jmp(repeatLabel)
out("""
dec $counterVar
bne $repeatLabel
dec $counterVar+1
bne $repeatLabel
beq $endLabel""")
if(constIterations!=null && constIterations>=16 && zeropage.available() > 1) {
// allocate count var on ZP

46
examples/test.p8
View File

@ -3,25 +3,51 @@
main {
sub iter(uword iterations) -> uword {
uword total = 0
repeat iterations {
repeat iterations {
total++
}
}
return total
}
sub start() {
uword xx1
uword xx2
uword xx3
uword iterations
xx1 = iter(0)
txt.print_uw(xx1) ; 0
txt.nl()
xx1 = iter(10)
txt.print_uw(xx1) ; 100
txt.nl()
xx1 = iter(16)
txt.print_uw(xx1) ; 256
txt.nl()
xx1 = iter(20)
txt.print_uw(xx1) ; 400
txt.nl()
xx1 = iter(200)
txt.print_uw(xx1) ; 4000
txt.nl()
xx1 = iter(600)
txt.print_uw(xx1) ; 32320
txt.nl()
c64.SETTIM(0,0,0)
iterations = 0
repeat iterations {
repeat iterations {
xx1++
xx2++
xx3++
}
}
xx1=0
xx2=0
xx3=0
iterations = 600
repeat iterations {
repeat 600 {
repeat iterations {
xx1++
xx2++