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 strncpy
36 /*#define strncpy TESTING*/
strncpy(char * dest,const char * src,size_t count)37 char *strncpy(char * dest, const char * src, size_t count)
38 {
39 int esi, edi, ecx, eax;
40 __asm__ __volatile__(
41 "1: subl $1, %%ecx\n" /* not dec! it doesnt set CF */
42 " jc 2f\n"
43 " lodsb\n"
44 " stosb\n"
45 " testb %%al, %%al\n"
46 " jnz 1b\n"
47 " rep; stosb\n"
48 "2:\n"
49 : "=&S" (esi), "=&D" (edi), "=&c" (ecx), "=&a" (eax)
50 : "0" (src), "1" (dest), "2" (count)
51 : "memory"
52 );
53 return dest;
54 }
55 #ifndef strncpy
56 libc_hidden_def(strncpy)
57 #else
58 /* Uncomment TESTING, gcc -D_GNU_SOURCE -m32 -Os strncpy.c -o strncpy
59 * and run ./strncpy
60 */
61 int main()
62 {
63 static char str[99];
64
65 str[3] = '*'; str[4] = 0; strncpy(str, "abc", 3);
66 printf(strcmp(str, "abc*") == 0 ? "ok\n" : "BAD!\n");
67
68 str[4] = '*'; str[5] = '+'; strncpy(str, "abc", 5);
69 printf(strcmp(str, "abc") == 0 && str[4] == 0 && str[5] == '+' ?
70 "ok\n" : "BAD!\n");
71 strncpy(str, "def", 0); /* should do nothing */
72 printf(strcmp(str, "abc") == 0 && str[4] == 0 && str[5] == '+' ?
73 "ok\n" : "BAD!\n");
74 }
75 #endif
76