mirror of
https://github.com/cc65/cc65.git
synced 2024-12-30 20:29:25 +00:00
89 lines
1.4 KiB
ArmAsm
89 lines
1.4 KiB
ArmAsm
|
;
|
||
|
|
; Ullrich von Bassewitz, 17.08.1998
|
||
|
|
;
|
||
|
|
; CC65 runtime: switch statement with int selector
|
||
|
|
;
|
||
|
|
|
||
|
|
; Subroutine to handle a switch statement with an int selector. The table
|
||
|
|
; is located at the return address from the function. It contains the negative
|
||
|
|
; of the case label count as first word, followed by two words for each case
|
||
|
|
; label, the first one being the value, and the second one the label to jump
|
||
|
|
; to in case of a match. The default case is located at the end of the table.
|
||
|
|
|
||
|
|
.export switch
|
||
|
|
.importzp ptr1, ptr2, ptr3
|
||
|
|
|
||
|
|
switch: sta ptr1
|
||
|
|
stx ptr1+1 ; Save AX
|
||
|
|
clc
|
||
|
|
pla
|
||
|
|
adc #1
|
||
|
|
sta ptr2
|
||
|
|
pla
|
||
|
|
adc #0
|
||
|
|
sta ptr2+1 ; Get pointer to table
|
||
|
|
|
||
|
|
ldy #0
|
||
|
|
lda (ptr2),y
|
||
|
|
sta ptr3
|
||
|
|
iny
|
||
|
|
lda (ptr2),y
|
||
|
|
sta ptr3+1 ; Remember the count of labels
|
||
|
|
|
||
|
|
ldy #0
|
||
|
|
clc ; Skip the label count
|
||
|
|
lda ptr2
|
||
|
|
adc #2
|
||
|
|
sta ptr2
|
||
|
|
bcc L2
|
||
|
|
inc ptr2+1
|
||
|
|
bne L2 ; Branch always
|
||
|
|
|
||
|
|
; Search for the label
|
||
|
|
|
||
|
|
L0: lda (ptr2),y
|
||
|
|
iny
|
||
|
|
cmp ptr1
|
||
|
|
beq L4
|
||
|
|
L1: iny
|
||
|
|
iny
|
||
|
|
iny ; Overflow only here
|
||
|
|
bne L2
|
||
|
|
inc ptr2+1 ; Bump high byte
|
||
|
|
|
||
|
|
; Check if there are any labels left
|
||
|
|
|
||
|
|
L2: inc ptr3
|
||
|
|
bne L0
|
||
|
|
inc ptr3+1
|
||
|
|
bne L0
|
||
|
|
|
||
|
|
; Out of labels
|
||
|
|
|
||
|
|
tya
|
||
|
|
clc
|
||
|
|
adc ptr2
|
||
|
|
sta ptr2
|
||
|
|
bcc L3
|
||
|
|
inc ptr2+1
|
||
|
|
L3: jmp (ptr2)
|
||
|
|
|
||
|
|
|
||
|
|
; Check high byte
|
||
|
|
|
||
|
|
L4: lda (ptr2),y
|
||
|
|
cmp ptr1+1
|
||
|
|
bne L1
|
||
|
|
|
||
|
|
; Label found
|
||
|
|
|
||
|
|
iny
|
||
|
|
lda (ptr2),y
|
||
|
|
sta ptr3
|
||
|
|
iny
|
||
|
|
lda (ptr2),y
|
||
|
|
sta ptr3+1
|
||
|
|
jmp (ptr3)
|
||
|
|
|
||
|
|
|