/* * 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 */