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cc65/libsrc/runtime/push.s
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1.5 KiB
ArmAsm

;
; Ullrich von Bassewitz, 05.08.1998
;
; CC65 runtime: Push ints onto the stack
;
;
; push/pop things on stack
;
.export push0, push1, push2, push3, push4, push5
.export push6, push7, pusha0, pushaFF, pushax
.export pusha, pushaysp, pushc0, pushc1, pushc2
.importzp sp
pushaFF:
ldx #$FF
bne pushax
push7: lda #7
bne pusha0
push6: lda #6
bne pusha0
push5: lda #5
bne pusha0
push4: lda #4
bne pusha0
push3: lda #3
bne pusha0
push2: lda #2
bne pusha0
push1: lda #1
bne pusha0
push0: lda #0
; beq pusha0
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!
pushax: ldy sp
beq @L1
dey
beq @L2
dey
@L0: sty sp
ldy #0 ; get index
sta (sp),y ; store lo byte
pha ; save it
txa ; get hi byte
iny ; bump idx
sta (sp),y ; store hi byte
pla ; get A back
rts ; done
@L1: dey
@L2: dey
dec sp+1
bne @L0 ; Branch always
; Push for chars, same warning as above: The optimizer expects the value
; 0 in the Y register after this function.
pushc2: lda #2
bne pusha
pushc1: lda #1
bne pusha
pushc0: lda #0
beq pusha
pushaysp:
lda (sp),y
pusha: ldy sp
beq @L1
dec sp
ldy #0
sta (sp),y
rts
@L1: dec sp+1
dec sp
sta (sp),y
rts