1 /* 2 * Copyright (c) 2013-2014, ARM Limited and Contributors. All rights reserved. 3 * 4 * SPDX-License-Identifier: BSD-3-Clause 5 */ 6 7 #include <stddef.h> /* size_t */ 8 9 /* 10 * Fill @count bytes of memory pointed to by @dst with @val 11 */ 12 void *memset(void *dst, int val, size_t count) 13 { 14 char *ptr = dst; 15 16 while (count--) 17 *ptr++ = val; 18 19 return dst; 20 } 21 22 /* 23 * Compare @len bytes of @s1 and @s2 24 */ 25 int memcmp(const void *s1, const void *s2, size_t len) 26 { 27 const unsigned char *s = s1; 28 const unsigned char *d = s2; 29 unsigned char sc; 30 unsigned char dc; 31 32 while (len--) { 33 sc = *s++; 34 dc = *d++; 35 if (sc - dc) 36 return (sc - dc); 37 } 38 39 return 0; 40 } 41 42 /* 43 * Copy @len bytes from @src to @dst 44 */ 45 void *memcpy(void *dst, const void *src, size_t len) 46 { 47 const char *s = src; 48 char *d = dst; 49 50 while (len--) 51 *d++ = *s++; 52 53 return dst; 54 } 55 56 /* 57 * Move @len bytes from @src to @dst 58 */ 59 void *memmove(void *dst, const void *src, size_t len) 60 { 61 /* 62 * The following test makes use of unsigned arithmetic overflow to 63 * more efficiently test the condition !(src <= dst && dst < str+len). 64 * It also avoids the situation where the more explicit test would give 65 * incorrect results were the calculation str+len to overflow (though 66 * that issue is probably moot as such usage is probably undefined 67 * behaviour and a bug anyway. 68 */ 69 if ((size_t)dst - (size_t)src >= len) { 70 /* destination not in source data, so can safely use memcpy */ 71 return memcpy(dst, src, len); 72 } else { 73 /* copy backwards... */ 74 const char *end = dst; 75 const char *s = (const char *)src + len; 76 char *d = (char *)dst + len; 77 while (d != end) 78 *--d = *--s; 79 } 80 return dst; 81 } 82 83 /* 84 * Scan @len bytes of @src for value @c 85 */ 86 void *memchr(const void *src, int c, size_t len) 87 { 88 const char *s = src; 89 90 while (len--) { 91 if (*s == c) 92 return (void *) s; 93 s++; 94 } 95 96 return NULL; 97 } 98
