1 /*
2 * This string-include defines all string functions as inline
3 * functions. Use gcc. It also assumes ds=es=data space, this should be
4 * normal. Most of the string-functions are rather heavily hand-optimized,
5 * see especially strtok,strstr,str[c]spn. They should work, but are not
6 * very easy to understand. Everything is done entirely within the register
7 * set, making the functions fast and clean. String instructions have been
8 * used through-out, making for "slightly" unclear code :-)
9 *
10 * NO Copyright (C) 1991, 1992 Linus Torvalds,
11 * consider these trivial functions to be PD.
12 */
13
14 /*
15 * Copyright (C) 2000-2005 Erik Andersen <andersen@uclibc.org>
16 *
17 * Licensed under the LGPL v2.1, see the file COPYING.LIB in this tarball.
18 */
19
20 /*
21 * Modified for uClibc by Erik Andersen <andersen@codepoet.org>
22 * These make no attempt to use nifty things like mmx/3dnow/etc.
23 * These are not inline, and will therefore not be as fast as
24 * modifying the headers to use inlines (and cannot therefore
25 * do tricky things when dealing with const memory). But they
26 * should (I hope!) be faster than their generic equivalents....
27 *
28 * More importantly, these should provide a good example for
29 * others to follow when adding arch specific optimizations.
30 * -Erik
31 */
32
33 #include <string.h>
34
35 #undef memmove
36 /*#define memmove TESTING*/
memmove(void * dest,const void * src,size_t n)37 void *memmove(void *dest, const void *src, size_t n)
38 {
39 int eax, ecx, esi, edi;
40 __asm__ __volatile__(
41 " movl %%eax, %%edi\n"
42 " cmpl %%esi, %%eax\n"
43 " je 2f\n" /* (optional) src == dest -> NOP */
44 " jb 1f\n" /* src > dest -> simple copy */
45 " leal -1(%%esi,%%ecx), %%esi\n"
46 " leal -1(%%eax,%%ecx), %%edi\n"
47 " std\n"
48 "1: rep; movsb\n"
49 " cld\n"
50 "2:\n"
51 : "=&c" (ecx), "=&S" (esi), "=&a" (eax), "=&D" (edi)
52 : "0" (n), "1" (src), "2" (dest)
53 : "memory"
54 );
55 return (void*)eax;
56 }
57 #ifndef memmove
58 libc_hidden_def(memmove)
59 #else
60 /* Uncomment TESTING, gcc -D_GNU_SOURCE -m32 -Os memmove.c -o memmove
61 * and run ./memmove
62 */
63 int main()
64 {
65 static char str[] = "abcdef.123";
66 memmove(str + 1, str, 5);
67 printf(strcmp(str, "aabcde.123") == 0 ? "ok\n" : "BAD!\n");
68 memmove(str, str + 1, 5);
69 printf(strcmp(str, "abcdee.123") == 0 ? "ok\n" : "BAD!\n");
70 }
71 #endif
72