mirror of
https://github.com/cc65/cc65.git
synced 2024-11-18 00:07:21 +00:00
58 lines
938 B
ArmAsm
58 lines
938 B
ArmAsm
|
;
|
||
|
|
; Ullrich von Bassewitz, 09.06.1998
|
||
|
|
;
|
||
|
|
; void* memchr (const void* p, int c, size_t n);
|
||
|
|
;
|
||
|
|
|
||
|
|
.export _memchr
|
||
|
|
.import popax, return0
|
||
|
|
.importzp ptr1, ptr2, tmp1
|
||
|
|
|
||
|
|
|
||
|
|
_memchr:
|
||
|
|
sta ptr2 ; Save n
|
||
|
|
stx ptr2+1
|
||
|
|
jsr popax ; get c
|
||
|
|
sta tmp1
|
||
|
|
jsr popax ; get p
|
||
|
|
sta ptr1
|
||
|
|
stx ptr1+1
|
||
|
|
|
||
|
|
ldy #0
|
||
|
|
lda tmp1 ; get c
|
||
|
|
ldx ptr2 ; use X as low counter byte
|
||
|
|
beq L3 ; check high byte
|
||
|
|
|
||
|
|
; Search for the char
|
||
|
|
|
||
|
|
L1: cmp (ptr1),y
|
||
|
|
beq L5 ; jump if found
|
||
|
|
iny
|
||
|
|
bne L2
|
||
|
|
inc ptr1+1
|
||
|
|
L2: cpx #0
|
||
|
|
beq L3
|
||
|
|
dex
|
||
|
|
jmp L1
|
||
|
|
L3: ldx ptr2+1 ; Check high byte
|
||
|
|
beq L4 ; Jump if counter off
|
||
|
|
dec ptr2+1
|
||
|
|
ldx #$FF
|
||
|
|
bne L1 ; branch always
|
||
|
|
|
||
|
|
; Character not found, return zero
|
||
|
|
|
||
|
|
L4: jmp return0
|
||
|
|
|
||
|
|
; Character found, calculate pointer
|
||
|
|
|
||
|
|
L5: ldx ptr1+1 ; get high byte of pointer
|
||
|
|
tya ; low byte offset
|
||
|
|
clc
|
||
|
|
adc ptr1
|
||
|
|
bcc L6
|
||
|
|
inx
|
||
|
|
L6: rts
|
||
|
|
|
||
|
|
|