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cc65/libsrc/runtime/shelp.s

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;
; Ullrich von Bassewitz, 07.08.1998
;
; CC65 runtime: helper stuff for mod/div/mul with signed ints
;
; When negating values, we will ignore the possibility here, that one of the
; values if $8000, in which case the negate will fail.
.export popsargs
.import negax, popax
.importzp sreg, tmp1, tmp2, ptr4
popsargs:
stx tmp2 ; Remember sign
cpx #0
bpl L1
jsr negax ; Negate accumulator
L1: sta ptr4
stx ptr4+1 ; Save right operand
jsr popax
stx tmp1 ; Remember sign
cpx #0
bpl L2
jsr negax
L2: sta sreg
stx sreg+1
rts