mirror of
https://github.com/cc65/cc65.git
synced 2024-08-16 12:29:03 +00:00
96 lines
1.5 KiB
ArmAsm
96 lines
1.5 KiB
ArmAsm
|
;
|
||
|
; Ullrich von Bassewitz, 20.09.1998
|
||
|
;
|
||
|
; CC65 runtime: left shift support for longs
|
||
|
;
|
||
|
|
||
|
|
||
|
.export tosasleax, tosshleax
|
||
|
.import addysp1
|
||
|
.importzp sp, sreg, ptr1, ptr2
|
||
|
|
||
|
|
||
|
tosshleax:
|
||
|
tosasleax:
|
||
|
|
||
|
; Get the lhs from stack into ptr1/ptr2
|
||
|
|
||
|
pha
|
||
|
ldy #0
|
||
|
lda (sp),y
|
||
|
sta ptr1
|
||
|
iny
|
||
|
lda (sp),y
|
||
|
sta ptr1+1
|
||
|
iny
|
||
|
lda (sp),y
|
||
|
sta ptr2
|
||
|
iny
|
||
|
lda (sp),y
|
||
|
sta ptr2+1
|
||
|
pla
|
||
|
jsr addysp1
|
||
|
|
||
|
; Check for shift overflow or zero shift
|
||
|
|
||
|
tay ; Low byte of shift count into y
|
||
|
txa ; Get byte 2
|
||
|
ora sreg
|
||
|
ora sreg+1 ; Check high 24 bit
|
||
|
bne @L6 ; Shift count too large
|
||
|
cpy #32
|
||
|
bcs @L6
|
||
|
|
||
|
cpy #0 ; Shift count zero?
|
||
|
beq @L5
|
||
|
|
||
|
; We must shift. Shift by multiples of eight if possible
|
||
|
|
||
|
tya
|
||
|
@L1: cmp #8
|
||
|
bcc @L3
|
||
|
sbc #8
|
||
|
ldx ptr2
|
||
|
stx ptr2+1
|
||
|
ldx ptr1+1
|
||
|
stx ptr2
|
||
|
ldx ptr1
|
||
|
stx ptr1+1
|
||
|
ldx #0
|
||
|
stx ptr1
|
||
|
beq @L1
|
||
|
|
||
|
; Shift count is now less than eight. Do a real shift.
|
||
|
|
||
|
@L3: tay ; Shift count to Y
|
||
|
lda ptr1 ; Get one byte into A for speed
|
||
|
cpy #0
|
||
|
beq @L4a ; Jump if done
|
||
|
@L4: asl a
|
||
|
rol ptr1+1
|
||
|
rol ptr2
|
||
|
rol ptr2+1
|
||
|
dey
|
||
|
bne @L4
|
||
|
|
||
|
; Put the result in place
|
||
|
|
||
|
@L4a: ldx ptr2
|
||
|
stx sreg
|
||
|
ldx ptr2+1
|
||
|
stx sreg+1
|
||
|
ldx ptr1+1
|
||
|
@L5: rts
|
||
|
|
||
|
; Jump here if shift count overflow
|
||
|
|
||
|
@L6: lda #0
|
||
|
sta sreg+1
|
||
|
sta sreg
|
||
|
tax
|
||
|
rts
|
||
|
|
||
|
|
||
|
|
||
|
|