1 /* Copyright (c) 2017 SiFive Inc. All rights reserved.
2
3 This copyrighted material is made available to anyone wishing to use,
4 modify, copy, or redistribute it subject to the terms and conditions
5 of the FreeBSD License. This program is distributed in the hope that
6 it will be useful, but WITHOUT ANY WARRANTY expressed or implied,
7 including the implied warranties of MERCHANTABILITY or FITNESS FOR
8 A PARTICULAR PURPOSE. A copy of this license is available at
9 http://www.opensource.org/licenses.
10 */
11
12 #include <picolibc.h>
13
14 #include <string.h>
15 #include <stdint.h>
16 #include "local.h"
17
strlen(const char * str)18 size_t strlen(const char *str)
19 {
20 const char *start = str;
21
22 #if defined(PREFER_SIZE_OVER_SPEED) || defined(__OPTIMIZE_SIZE__)
23 while (*str++)
24 ;
25 return str - start - 1;
26 #else
27 if (__builtin_expect ((uintptr_t)str & (sizeof (long) - 1), 0)) do
28 {
29 char ch = *str;
30 str++;
31 if (!ch)
32 return str - start - 1;
33 } while ((uintptr_t)str & (sizeof (long) - 1));
34
35 unsigned long *ls = (unsigned long *)str;
36 while (!__libc_detect_null (*ls++))
37 ;
38 __asm__ volatile ("" : "+r"(ls)); /* prevent "optimization" */
39
40 str = (const char *)ls;
41 size_t ret = str - start, sl = sizeof (long);
42
43 char c0 = str[0 - sl], c1 = str[1 - sl], c2 = str[2 - sl], c3 = str[3 - sl];
44 if (c0 == 0) return ret + 0 - sl;
45 if (c1 == 0) return ret + 1 - sl;
46 if (c2 == 0) return ret + 2 - sl;
47 if (sl == 4 || c3 == 0) return ret + 3 - sl;
48
49 c0 = str[4 - sl], c1 = str[5 - sl], c2 = str[6 - sl], c3 = str[7 - sl];
50 if (c0 == 0) return ret + 4 - sl;
51 if (c1 == 0) return ret + 5 - sl;
52 if (c2 == 0) return ret + 6 - sl;
53
54 return ret + 7 - sl;
55 #endif /* not PREFER_SIZE_OVER_SPEED */
56 }
57
