36 lines
518 B
ArmAsm
36 lines
518 B
ArmAsm
|
.define Sli4
|
||
|
|
|
||
|
|
! This subroutine shift a signed or unsigned fourbyte integer
|
||
|
|
! n times left. N is in register X.
|
||
|
|
|
||
|
|
|
||
|
|
Sli4:
|
||
|
|
cpx #0
|
||
|
|
beq 9f ! zero shift, return input
|
||
|
|
lda SP+2 ! the shifting is done on the stack
|
||
|
|
sta ADDR ! address of integer (lowbyte)
|
||
|
|
lda SP+1
|
||
|
|
sta ADDR+1 ! address of integer (highbyte)
|
||
|
|
2: ldy #0
|
||
|
|
clc
|
||
|
|
lda (ADDR),y
|
||
|
|
rol a
|
||
|
|
sta (ADDR),y
|
||
|
|
iny
|
||
|
|
lda (ADDR),y
|
||
|
|
rol a
|
||
|
|
sta (ADDR),y
|
||
|
|
iny
|
||
|
|
lda (ADDR),y
|
||
|
|
rol a
|
||
|
|
sta (ADDR),y
|
||
|
|
iny
|
||
|
|
lda (ADDR),y
|
||
|
|
rol a
|
||
|
|
sta (ADDR),y ! shift left
|
||
|
|
dex
|
||
|
|
bne 2b
|
||
|
|
9: rts
|
||
|
|
|
||
|
|
|