1 /* -*- linux-c -*- ------------------------------------------------------- * 2 * 3 * Copyright (C) 1991, 1992 Linus Torvalds 4 * Copyright 2007 rPath, Inc. - All Rights Reserved 5 * 6 * This file is part of the Linux kernel, and is made available under 7 * the terms of the GNU General Public License version 2. 8 * 9 * ----------------------------------------------------------------------- */ 10 11 /* 12 * Very basic string functions 13 */ 14 15 #include <linux/types.h> 16 #include "ctype.h" 17 #include "string.h" 18 19 /* 20 * Undef these macros so that the functions that we provide 21 * here will have the correct names regardless of how string.h 22 * may have chosen to #define them. 23 */ 24 #undef memcpy 25 #undef memset 26 #undef memcmp 27 28 int memcmp(const void *s1, const void *s2, size_t len) 29 { 30 bool diff; 31 asm("repe; cmpsb; setnz %0" 32 : "=qm" (diff), "+D" (s1), "+S" (s2), "+c" (len)); 33 return diff; 34 } 35 36 int strcmp(const char *str1, const char *str2) 37 { 38 const unsigned char *s1 = (const unsigned char *)str1; 39 const unsigned char *s2 = (const unsigned char *)str2; 40 int delta = 0; 41 42 while (*s1 || *s2) { 43 delta = *s1 - *s2; 44 if (delta) 45 return delta; 46 s1++; 47 s2++; 48 } 49 return 0; 50 } 51 52 int strncmp(const char *cs, const char *ct, size_t count) 53 { 54 unsigned char c1, c2; 55 56 while (count) { 57 c1 = *cs++; 58 c2 = *ct++; 59 if (c1 != c2) 60 return c1 < c2 ? -1 : 1; 61 if (!c1) 62 break; 63 count--; 64 } 65 return 0; 66 } 67 68 size_t strnlen(const char *s, size_t maxlen) 69 { 70 const char *es = s; 71 while (*es && maxlen) { 72 es++; 73 maxlen--; 74 } 75 76 return (es - s); 77 } 78 79 unsigned int atou(const char *s) 80 { 81 unsigned int i = 0; 82 while (isdigit(*s)) 83 i = i * 10 + (*s++ - '0'); 84 return i; 85 } 86 87 /* Works only for digits and letters, but small and fast */ 88 #define TOLOWER(x) ((x) | 0x20) 89 90 static unsigned int simple_guess_base(const char *cp) 91 { 92 if (cp[0] == '0') { 93 if (TOLOWER(cp[1]) == 'x' && isxdigit(cp[2])) 94 return 16; 95 else 96 return 8; 97 } else { 98 return 10; 99 } 100 } 101 102 /** 103 * simple_strtoull - convert a string to an unsigned long long 104 * @cp: The start of the string 105 * @endp: A pointer to the end of the parsed string will be placed here 106 * @base: The number base to use 107 */ 108 109 unsigned long long simple_strtoull(const char *cp, char **endp, unsigned int base) 110 { 111 unsigned long long result = 0; 112 113 if (!base) 114 base = simple_guess_base(cp); 115 116 if (base == 16 && cp[0] == '0' && TOLOWER(cp[1]) == 'x') 117 cp += 2; 118 119 while (isxdigit(*cp)) { 120 unsigned int value; 121 122 value = isdigit(*cp) ? *cp - '0' : TOLOWER(*cp) - 'a' + 10; 123 if (value >= base) 124 break; 125 result = result * base + value; 126 cp++; 127 } 128 if (endp) 129 *endp = (char *)cp; 130 131 return result; 132 } 133 134 long simple_strtol(const char *cp, char **endp, unsigned int base) 135 { 136 if (*cp == '-') 137 return -simple_strtoull(cp + 1, endp, base); 138 139 return simple_strtoull(cp, endp, base); 140 } 141 142 /** 143 * strlen - Find the length of a string 144 * @s: The string to be sized 145 */ 146 size_t strlen(const char *s) 147 { 148 const char *sc; 149 150 for (sc = s; *sc != '\0'; ++sc) 151 /* nothing */; 152 return sc - s; 153 } 154 155 /** 156 * strstr - Find the first substring in a %NUL terminated string 157 * @s1: The string to be searched 158 * @s2: The string to search for 159 */ 160 char *strstr(const char *s1, const char *s2) 161 { 162 size_t l1, l2; 163 164 l2 = strlen(s2); 165 if (!l2) 166 return (char *)s1; 167 l1 = strlen(s1); 168 while (l1 >= l2) { 169 l1--; 170 if (!memcmp(s1, s2, l2)) 171 return (char *)s1; 172 s1++; 173 } 174 return NULL; 175 } 176 177 /** 178 * strchr - Find the first occurrence of the character c in the string s. 179 * @s: the string to be searched 180 * @c: the character to search for 181 */ 182 char *strchr(const char *s, int c) 183 { 184 while (*s != (char)c) 185 if (*s++ == '\0') 186 return NULL; 187 return (char *)s; 188 } 189