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cc65/libsrc/runtime/negabs.s

27 lines
421 B
ArmAsm

;
; Ullrich von Bassewitz, 05.08.1998
;
; int abs (int x);
; and
; CC65 runtime: negation on ints
;
.export negax
.export _abs
_abs: cpx #$00 ; Test hi byte
bpl L1 ; Don't touch if positive
negax: clc
eor #$FF
adc #1
pha
txa
eor #$FF
adc #0
tax
pla
L1: rts