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 strncat
36 /*#define strncat TESTING*/
strncat(char * dest,const char * src,size_t count)37 char *strncat(char * dest, const char * src, size_t count)
38 {
39 int esi, edi, eax, ecx, edx;
40 __asm__ __volatile__(
41 " xorl %%eax, %%eax\n"
42 " incl %%edx\n"
43 " pushl %%edi\n" /* save dest */
44 " repne; scasb\n"
45 " decl %%edi\n" /* edi => NUL in dest */
46 /* count-- */
47 "1: decl %%edx\n"
48 /* if count reached 0, store NUL and bail out */
49 " movl %%edx, %%eax\n"
50 " jz 2f\n"
51 /* else copy a char */
52 " lodsb\n"
53 "2: stosb\n"
54 " testb %%al, %%al\n"
55 " jnz 1b\n"
56 /* end of loop */
57 " popl %%eax\n" /* restore dest into eax */
58 : "=&S" (esi), "=&D" (edi), "=&a" (eax), "=&c" (ecx), "=&d" (edx)
59 : "0" (src), "1" (dest), "3" (0xffffffff), "4" (count)
60 : "memory"
61 );
62 return (char *)eax;
63 }
64 #ifndef strncat
65 libc_hidden_def(strncat)
66 #else
67 /* Uncomment TESTING, gcc -m32 -Os strncat.c -o strncat
68 * and run ./strncat
69 */
70 int main()
71 {
72 char buf[99];
73
74 strcpy(buf, "abc"); buf[4] = '*'; strncat(buf, "def", 0);
75 printf(strcmp(buf, "abc") == 0 && buf[4] == '*' ? "ok\n" : "BAD!\n");
76
77 strcpy(buf, "abc"); buf[6] = 1; buf[7] = '*'; strncat(buf, "def", 50);
78 printf(strcmp(buf, "abcdef") == 0 && buf[7] == '*' ? "ok\n" : "BAD!\n");
79
80 strcpy(buf, "abc"); buf[6] = 1; buf[7] = '*'; strncat(buf, "def", -1);
81 printf(strcmp(buf, "abcdef") == 0 && buf[7] == '*' ? "ok\n" : "BAD!\n");
82
83 strcpy(buf, "abc"); buf[6] = 1; buf[7] = '*'; strncat(buf, "def123", 3);
84 printf(strcmp(buf, "abcdef") == 0 && buf[7] == '*' ? "ok\n" : "BAD!\n");
85 }
86 #endif
87