1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
|
/*
* 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
*/
#include <string.h>
#ifdef __USE_GNU
#undef strnlen
/*#define strnlen TESTING*/
size_t strnlen(const char *s, size_t count)
{
int edx;
int eax;
__asm__ __volatile__(
" leal -1(%%ecx), %%eax\n"
"1: incl %%eax\n"
" decl %%edx\n"
" jz 3f\n"
" cmpb $0, (%%eax)\n"
" jnz 1b\n"
"3: subl %%ecx, %%eax"
: "=a" (eax), "=&d" (edx)
: "c" (s), "1" (count + 1)
);
return eax;
}
#ifndef strnlen
libc_hidden_def(strnlen)
#else
/* Uncomment TESTING, gcc -D_GNU_SOURCE -m32 -Os strnlen.c -o strnlen
* and run ./strnlen
*/
int main()
{
printf(strnlen("abc\0def", -2) == 3 ? "ok\n" : "BAD!\n");
printf(strnlen("abc\0def", -1) == 3 ? "ok\n" : "BAD!\n");
printf(strnlen("abc\0def", 0) == 0 ? "ok\n" : "BAD!\n");
printf(strnlen("abc\0def", 1) == 1 ? "ok\n" : "BAD!\n");
printf(strnlen("abc\0def", 2) == 2 ? "ok\n" : "BAD!\n");
printf(strnlen("abc\0def", 3) == 3 ? "ok\n" : "BAD!\n");
printf(strnlen("abc\0def", 4) == 3 ? "ok\n" : "BAD!\n");
printf(strnlen("abc\0def", 5) == 3 ? "ok\n" : "BAD!\n");
}
#endif
#endif
|
