newlib-cygwin/newlib/libc/machine/i386/strchr.S

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2000-02-18 03:39:52 +08:00
/*
* ====================================================
* Copyright (C) 1998 by Cygnus Solutions. All rights reserved.
*
* Permission to use, copy, modify, and distribute this
* software is freely granted, provided that this notice
* is preserved.
* ====================================================
*/
#include "i386mach.h"
.global SYM (strchr)
SOTYPE_FUNCTION(strchr)
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SYM (strchr):
pushl ebp
movl esp,ebp
pushl edi
pushl ebx
xorl ebx,ebx
movl 8(ebp),edi
movb 12(ebp),bl
#ifndef __OPTIMIZE_SIZE__
/* check if string is aligned, if not do check one byte at a time */
test $3,edi
jne L9
/* create 4 byte mask which is just the desired byte repeated 4 times */
movl ebx,ecx
sall $8,ebx
subl $4,edi
orl ecx,ebx
movl ebx,edx
sall $16,ebx
orl edx,ebx
/* loop performing 4 byte mask checking for 0 byte or desired byte */
.p2align 4,,7
L10:
addl $4,edi
movl (edi),ecx
leal -16843009(ecx),edx
movl ecx,eax
notl eax
andl eax,edx
testl $-2139062144,edx
jne L9
movl ebx,eax
xorl ecx,eax
leal -16843009(eax),edx
notl eax
andl eax,edx
testl $-2139062144,edx
je L10
#endif /* not __OPTIMIZE_SIZE__ */
/* loop while (*s && *s++ != c) */
L9:
leal -1(edi),eax
.p2align 4,,7
L15:
incl eax
movb (eax),dl
testb dl,dl
je L14
cmpb bl,dl
jne L15
L14:
/* if (*s == c) return address otherwise return NULL */
cmpb bl,(eax)
je L19
xorl eax,eax
L19:
leal -8(ebp),esp
popl ebx
popl edi
leave
ret