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/*
* This string-include defines all string functions as inline
* functions. Use gcc. It also assumes ds=es=data space, this should be
* normal. Most of the string-functions are rather heavily hand-optimized,
* see especially strtok,strstr,str[c]spn. They should work, but are not
* very easy to understand. Everything is done entirely within the register
* set, making the functions fast and clean. String instructions have been
* used through-out, making for "slightly" unclear code :-)
*
* NO Copyright (C) 1991, 1992 Linus Torvalds,
* consider these trivial functions to be PD.
*/
/*
* Copyright (C) 2000-2005 Erik Andersen <andersen@uclibc.org>
*
* Licensed under the LGPL v2.1, see the file COPYING.LIB in this tarball.
*/
/*
* Modified for uClibc by Erik Andersen <andersen@codepoet.org>
* These make no attempt to use nifty things like mmx/3dnow/etc.
* These are not inline, and will therefore not be as fast as
* modifying the headers to use inlines (and cannot therefore
* do tricky things when dealing with const memory). But they
* should (I hope!) be faster than their generic equivalents....
*
* More importantly, these should provide a good example for
* others to follow when adding arch specific optimizations.
* -Erik
*
* 2009-04: modified by Denys Vlasenko <vda.linux@googlemail.com>
* Fill byte-by-byte is a bit too slow. I prefer 46 byte function
* which fills x4 faster than 21 bytes one.
*/
#include <string.h>
#undef memset
void *memset(void *s, int c, size_t count)
{
int reg, edi;
__asm__ __volatile__(
/* Most of the time, count is divisible by 4 and nonzero */
/* It's better to make this case faster */
/* " jecxz 9f\n" - (optional) count == 0: goto ret */
" mov %%ecx, %1\n"
" shr $2, %%ecx\n"
" jz 1f\n" /* zero words: goto fill_bytes */
/* extend 8-bit fill to 32 bits */
" movzx %%al, %%eax\n" /* 3 bytes */
/* or: " and $0xff, %%eax\n" - 5 bytes */
" imul $0x01010101, %%eax\n" /* 6 bytes */
/* fill full words */
" rep; stosl\n"
/* fill 0-3 bytes */
"1: and $3, %1\n"
" jz 9f\n" /* (count & 3) == 0: goto end */
"2: stosb\n"
" dec %1\n"
" jnz 2b\n"
/* end */
"9:\n"
: "=&D" (edi), "=&r" (reg)
: "0" (s), "a" (c), "c" (count)
: "memory"
);
return s;
}
libc_hidden_def(memset)
/*
gcc 4.3.1
=========
57 push %edi
8b 7c 24 08 mov 0x8(%esp),%edi
8b 4c 24 10 mov 0x10(%esp),%ecx
8b 44 24 0c mov 0xc(%esp),%eax
89 ca mov %ecx,%edx
c1 e9 02 shr $0x2,%ecx
74 0b je 1f <__GI_memset+0x1f>
0f b6 c0 movzbl %al,%eax
69 c0 01 01 01 01 imul $0x1010101,%eax,%eax
f3 ab rep stos %eax,%es:(%edi)
83 e2 03 and $0x3,%edx
74 04 je 28 <__GI_memset+0x28>
aa stos %al,%es:(%edi)
4a dec %edx
75 fc jne 24 <__GI_memset+0x24>
8b 44 24 08 mov 0x8(%esp),%eax
5f pop %edi
c3 ret
*/
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