1 /*
2 * Copyright (c) 2013-2014, ARM Limited and Contributors. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions are met:
6 *
7 * Redistributions of source code must retain the above copyright notice, this
8 * list of conditions and the following disclaimer.
9 *
10 * Redistributions in binary form must reproduce the above copyright notice,
11 * this list of conditions and the following disclaimer in the documentation
12 * and/or other materials provided with the distribution.
13 *
14 * Neither the name of ARM nor the names of its contributors may be used
15 * to endorse or promote products derived from this software without specific
16 * prior written permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
19 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
22 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
23 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
24 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
25 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
26 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
27 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
28 * POSSIBILITY OF SUCH DAMAGE.
29 */
30
31 #include <stddef.h> /* size_t */
32
33 /*
34 * Fill @count bytes of memory pointed to by @dst with @val
35 */
memset(void * dst,int val,size_t count)36 void *memset(void *dst, int val, size_t count)
37 {
38 char *ptr = dst;
39
40 while (count--)
41 *ptr++ = val;
42
43 return dst;
44 }
45
46 /*
47 * Compare @len bytes of @s1 and @s2
48 */
memcmp(const void * s1,const void * s2,size_t len)49 int memcmp(const void *s1, const void *s2, size_t len)
50 {
51 const char *s = s1;
52 const char *d = s2;
53 char dc;
54 char sc;
55
56 while (len--) {
57 sc = *s++;
58 dc = *d++;
59 if (sc - dc)
60 return (sc - dc);
61 }
62
63 return 0;
64 }
65
66 /*
67 * Copy @len bytes from @src to @dst
68 */
memcpy(void * dst,const void * src,size_t len)69 void *memcpy(void *dst, const void *src, size_t len)
70 {
71 const char *s = src;
72 char *d = dst;
73
74 while (len--)
75 *d++ = *s++;
76
77 return dst;
78 }
79
80 /*
81 * Move @len bytes from @src to @dst
82 */
memmove(void * dst,const void * src,size_t len)83 void *memmove(void *dst, const void *src, size_t len)
84 {
85 /*
86 * The following test makes use of unsigned arithmetic overflow to
87 * more efficiently test the condition !(src <= dst && dst < str+len).
88 * It also avoids the situation where the more explicit test would give
89 * incorrect results were the calculation str+len to overflow (though
90 * that issue is probably moot as such usage is probably undefined
91 * behaviour and a bug anyway.
92 */
93 if ((size_t)dst - (size_t)src >= len) {
94 /* destination not in source data, so can safely use memcpy */
95 return memcpy(dst, src, len);
96 } else {
97 /* copy backwards... */
98 const char *end = dst;
99 const char *s = (const char *)src + len;
100 char *d = (char *)dst + len;
101 while (d != end)
102 *--d = *--s;
103 }
104 return dst;
105 }
106
107 /*
108 * Scan @len bytes of @src for value @c
109 */
memchr(const void * src,int c,size_t len)110 void *memchr(const void *src, int c, size_t len)
111 {
112 const char *s = src;
113
114 while (len--) {
115 if (*s == c)
116 return (void *) s;
117 s++;
118 }
119
120 return NULL;
121 }
122