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/*
* ====================================================
* Copyright (C) 1998, 2002, 2008 by Red Hat Inc. 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 (strlen)
SOTYPE_FUNCTION(strlen)
SYM (strlen):
pushl ebp
movl esp,ebp
pushl edi
#ifdef __iamcu__
movl eax,edx
#else
movl 8(ebp),edx
#endif
#if defined __OPTIMIZE_SIZE__ || defined __iamcu__
cld
movl edx,edi
movl $4294967295,ecx
xor eax,eax
repnz
scasb
#else
/* Modern x86 hardware is much faster at double-word
manipulation than with bytewise repnz scasb. */
/* Do byte-wise checks until string is aligned. */
movl edx,edi
test $3,edi
je L5
movb (edi),cl
incl edi
testb cl,cl
je L15
test $3,edi
je L5
movb (edi),cl
incl edi
testb cl,cl
je L15
test $3,edi
je L5
movb (edi),cl
incl edi
testb cl,cl
je L15
L5:
subl $4,edi
/* loop performing 4 byte mask checking for desired 0 byte */
.p2align 4,,7
L10:
addl $4,edi
movl (edi),ecx
leal -16843009(ecx),eax
notl ecx
andl ecx,eax
testl $-2139062144,eax
je L10
/* Find which of four bytes is 0. */
notl ecx
incl edi
testb cl,cl
je L15
incl edi
shrl $8,ecx
testb cl,cl
je L15
incl edi
shrl $8,ecx
testb cl,cl
je L15
incl edi
#endif
L15:
subl edx,edi
leal -1(edi),eax
leal -4(ebp),esp
popl edi
leave
ret
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