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git-svn-id: svn://svn.cc65.org/cc65/trunk@2151 b7a2c559-68d2-44c3-8de9-860c34a00d81
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cuz 2003-05-05 17:19:48 +00:00
parent ebb44b8a4f
commit 32389dc678
1 changed files with 35 additions and 35 deletions
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64
libsrc/common/memchr.s
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@ -1,57 +1,57 @@
;
; Ullrich von Bassewitz, 09.06.1998
; Ullrich von Bassewitz, 2003-05-05
;
; void* memchr (const void* p, int c, size_t n);
; void* __fastcall__ memchr (const void* p, int c, size_t n);
;
.export _memchr
.import popax, return0
.importzp ptr1, ptr2, tmp1
.importzp ptr1, ptr2
_memchr:
sta ptr2 ; Save n
stx ptr2+1
.proc _memchr
eor #$FF
sta ptr2
txa
eor #$FF
sta ptr2+1 ; Save ones complement of n
jsr popax ; get c
sta tmp1
pha
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
ldy #$00
pla ; Get c
ldx ptr2 ; Use X as low counter byte
; Search for the char
L1: cmp (ptr1),y
beq L5 ; jump if found
iny
bne L2
inc ptr1+1
L2: cpx #0
L1: inx
beq L3
dex
jmp L1
L3: ldx ptr2+1 ; Check high byte
beq L4 ; Jump if counter off
dec ptr2+1
ldx #$FF
bne L1 ; branch always
L2: cmp (ptr1),y
beq found
iny
bne L1
inc ptr1+1
bne L1 ; Branch always
; Character not found, return zero
L3: inc ptr2+1 ; Bump counter high byte
bne L2
L4: jmp return0
; Not found, return NULL
; Character found, calculate pointer
notfound:
jmp return0
L5: ldx ptr1+1 ; get high byte of pointer
; Found, return pointer to char
found: ldx ptr1+1 ; get high byte of pointer
tya ; low byte offset
clc
adc ptr1
bcc L6
bcc L9
inx
L6: rts
L9: rts
.endproc