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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 .export _memchr
.import popax, return0 .import popax, return0
.importzp ptr1, ptr2, tmp1 .importzp ptr1, ptr2
_memchr: .proc _memchr
sta ptr2 ; Save n
stx ptr2+1 eor #$FF
sta ptr2
txa
eor #$FF
sta ptr2+1 ; Save ones complement of n
jsr popax ; get c jsr popax ; get c
sta tmp1 pha
jsr popax ; get p jsr popax ; get p
sta ptr1 sta ptr1
stx ptr1+1 stx ptr1+1
ldy #0 ldy #$00
lda tmp1 ; get c pla ; Get c
ldx ptr2 ; use X as low counter byte ldx ptr2 ; Use X as low counter byte
beq L3 ; check high byte
; Search for the char L1: inx
L1: cmp (ptr1),y
beq L5 ; jump if found
iny
bne L2
inc ptr1+1
L2: cpx #0
beq L3 beq L3
dex L2: cmp (ptr1),y
jmp L1 beq found
L3: ldx ptr2+1 ; Check high byte iny
beq L4 ; Jump if counter off bne L1
dec ptr2+1 inc ptr1+1
ldx #$FF bne L1 ; Branch always
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 tya ; low byte offset
clc clc
adc ptr1 adc ptr1
bcc L6 bcc L9
inx inx
L6: rts L9: rts
.endproc