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cc65/libsrc/runtime/pushax.s
cuz d1530bc0a2 Squeeze one cycle and several bytes out of the pushax routine.
git-svn-id: svn://svn.cc65.org/cc65/trunk@666 b7a2c559-68d2-44c3-8de9-860c34a00d81
2001-03-24 16:25:08 +00:00

36 lines
568 B
ArmAsm

;
; Ullrich von Bassewitz, 26.10.2000
;
; CC65 runtime: Push value in a/x onto the stack
;
.export push0, pusha0, pushax
.importzp sp
push0: lda #0
pusha0: ldx #0
; This function is used *a lot*, so don't call any subroutines here.
; Beware: The value in ax must not be changed by this function!
; Beware^2: The optimizer knows about the value of Y after the function
; returns!
.proc pushax
pha
lda sp
sec
sbc #2
sta sp ; (13)
bcs @L1
dec sp+1
@L1: ldy #1
txa ; (20)
sta (sp),y
pla
dey
sta (sp),y ; (38)
rts
.endproc