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fix C64 floating point sign issue

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This commit is contained in:
Irmen de Jong
2024-09-30 21:56:34 +02:00
parent 413b86cc4a
commit 3cf39e072e
2 changed files with 20 additions and 20 deletions
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19
codeGenCpu6502/src/prog8/codegen/cpu6502/assignment/AnyExprAsmGen.kt
View File

@@ -175,17 +175,14 @@ internal class AnyExprAsmGen(
private fun assignFloatOperandsToFACandARG(left: PtExpression, right: PtExpression) {
when(asmgen.options.compTarget.name) {
C64Target.NAME -> {
// c64 has a quirk: always make sure FAC2 is loaded last (done using CONUPK) otherwise the result will be corrupt on C64
// this requires some more forced copying around of float values in certain cases
if (right.isSimple()) {
asmgen.assignExpressionToRegister(left, RegisterOrPair.FAC1, true)
asmgen.assignExpressionToRegister(right, RegisterOrPair.FAC2, true)
} else {
asmgen.assignExpressionToRegister(right, RegisterOrPair.FAC1, true)
asmgen.pushFAC1()
asmgen.assignExpressionToRegister(left, RegisterOrPair.FAC1, true)
asmgen.popFAC2()
}
// C64 math library has a quirk: you have always make sure FAC2/ARG is loaded last (done using CONUPK)
// otherwise the result of certain floating point operations such as FDIVT will be wrong.
// see https://www.c64-wiki.com/wiki/CONUPK
// Unfortunately this means we have to push and pop an intermediary floating point value to and from memory.
asmgen.assignExpressionToRegister(right, RegisterOrPair.FAC1, true)
asmgen.pushFAC1()
asmgen.assignExpressionToRegister(left, RegisterOrPair.FAC1, true)
asmgen.popFAC2()
}
Cx16Target.NAME -> {
asmgen.assignExpressionToRegister(left, RegisterOrPair.FAC1, true)

21
examples/test.p8
View File

@@ -1,19 +1,22 @@
%import textio
%import floats
%zeropage basicsafe
%option no_sysinit
main {
sub start() {
cx16.r0L = returns3()
cx16.r0L, cx16.r1L, cx16.r2L, cx16.r3L = returns3()
txt.print_uwhex()
txt.print_uwhex(1, true, 2, 3)
}
word x1 = -118
floats.print(x1 as float)
txt.nl()
floats.print(x1 as float/1.9)
txt.nl()
xf1 = x1/1.9
floats.print(xf1)
txt.nl()
asmsub returns3() -> ubyte @A, ubyte @X, bool @Pc {
%asm {{
rts
}}
float @shared xf1 = -118
floats.print(xf1/1.9)
txt.nl()
}
}