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cc65/libsrc/runtime/ldec.s
2018-03-07 20:45:50 +01:00

25 lines
417 B
ArmAsm

;
; Piotr Fusik, 07.03.2018
; originally by Ullrich von Bassewitz
;
; CC65 runtime: Decrement eax by value in Y
;
.export deceaxy
.importzp sreg, tmp1
deceaxy:
sty tmp1
sec
sbc tmp1
bcs @L9
dex
cpx #$ff
bne @L9
dec sreg
cpx sreg
bne @L9
dec sreg+1
@L9: rts