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Minor optimization

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git-svn-id: svn://svn.cc65.org/cc65/trunk@46 b7a2c559-68d2-44c3-8de9-860c34a00d81
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cuz 2000-06-10 16:05:59 +00:00
parent 66e7d9cd1b
commit 6481395a94
1 changed files with 12 additions and 11 deletions
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23
libsrc/runtime/lbneg.s
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@ -6,17 +6,18 @@
.export bnegeax .export bnegeax
.import return0, return1 .import return0, return1
.importzp sreg .importzp sreg, tmp1
bnegeax: bnegeax:
cmp #0 stx tmp1
bne L1 ldx #0 ; High byte of result
cpx #0 ora tmp1
bne L1 ora sreg
lda sreg ora sreg+1
bne L1 bne @L0
lda sreg+1 lda #1
bne L1 rts
jmp return1
L1: jmp return0 @L0: txa ; X is zero
rts