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 <asm/asm.h> 17 #include "ctype.h" 18 #include "string.h" 19 20 /* 21 * Undef these macros so that the functions that we provide 22 * here will have the correct names regardless of how string.h 23 * may have chosen to #define them. 24 */ 25 #undef memcpy 26 #undef memset 27 #undef memcmp 28 29 int memcmp(const void *s1, const void *s2, size_t len) 30 { 31 bool diff; 32 asm("repe; cmpsb" CC_SET(nz) 33 : CC_OUT(nz) (diff), "+D" (s1), "+S" (s2), "+c" (len)); 34 return diff; 35 } 36 37 int strcmp(const char *str1, const char *str2) 38 { 39 const unsigned char *s1 = (const unsigned char *)str1; 40 const unsigned char *s2 = (const unsigned char *)str2; 41 int delta = 0; 42 43 while (*s1 || *s2) { 44 delta = *s1 - *s2; 45 if (delta) 46 return delta; 47 s1++; 48 s2++; 49 } 50 return 0; 51 } 52 53 int strncmp(const char *cs, const char *ct, size_t count) 54 { 55 unsigned char c1, c2; 56 57 while (count) { 58 c1 = *cs++; 59 c2 = *ct++; 60 if (c1 != c2) 61 return c1 < c2 ? -1 : 1; 62 if (!c1) 63 break; 64 count--; 65 } 66 return 0; 67 } 68 69 size_t strnlen(const char *s, size_t maxlen) 70 { 71 const char *es = s; 72 while (*es && maxlen) { 73 es++; 74 maxlen--; 75 } 76 77 return (es - s); 78 } 79 80 unsigned int atou(const char *s) 81 { 82 unsigned int i = 0; 83 while (isdigit(*s)) 84 i = i * 10 + (*s++ - '0'); 85 return i; 86 } 87 88 /* Works only for digits and letters, but small and fast */ 89 #define TOLOWER(x) ((x) | 0x20) 90 91 static unsigned int simple_guess_base(const char *cp) 92 { 93 if (cp[0] == '0') { 94 if (TOLOWER(cp[1]) == 'x' && isxdigit(cp[2])) 95 return 16; 96 else 97 return 8; 98 } else { 99 return 10; 100 } 101 } 102 103 /** 104 * simple_strtoull - convert a string to an unsigned long long 105 * @cp: The start of the string 106 * @endp: A pointer to the end of the parsed string will be placed here 107 * @base: The number base to use 108 */ 109 110 unsigned long long simple_strtoull(const char *cp, char **endp, unsigned int base) 111 { 112 unsigned long long result = 0; 113 114 if (!base) 115 base = simple_guess_base(cp); 116 117 if (base == 16 && cp[0] == '0' && TOLOWER(cp[1]) == 'x') 118 cp += 2; 119 120 while (isxdigit(*cp)) { 121 unsigned int value; 122 123 value = isdigit(*cp) ? *cp - '0' : TOLOWER(*cp) - 'a' + 10; 124 if (value >= base) 125 break; 126 result = result * base + value; 127 cp++; 128 } 129 if (endp) 130 *endp = (char *)cp; 131 132 return result; 133 } 134 135 long simple_strtol(const char *cp, char **endp, unsigned int base) 136 { 137 if (*cp == '-') 138 return -simple_strtoull(cp + 1, endp, base); 139 140 return simple_strtoull(cp, endp, base); 141 } 142 143 /** 144 * strlen - Find the length of a string 145 * @s: The string to be sized 146 */ 147 size_t strlen(const char *s) 148 { 149 const char *sc; 150 151 for (sc = s; *sc != '\0'; ++sc) 152 /* nothing */; 153 return sc - s; 154 } 155 156 /** 157 * strstr - Find the first substring in a %NUL terminated string 158 * @s1: The string to be searched 159 * @s2: The string to search for 160 */ 161 char *strstr(const char *s1, const char *s2) 162 { 163 size_t l1, l2; 164 165 l2 = strlen(s2); 166 if (!l2) 167 return (char *)s1; 168 l1 = strlen(s1); 169 while (l1 >= l2) { 170 l1--; 171 if (!memcmp(s1, s2, l2)) 172 return (char *)s1; 173 s1++; 174 } 175 return NULL; 176 } 177 178 /** 179 * strchr - Find the first occurrence of the character c in the string s. 180 * @s: the string to be searched 181 * @c: the character to search for 182 */ 183 char *strchr(const char *s, int c) 184 { 185 while (*s != (char)c) 186 if (*s++ == '\0') 187 return NULL; 188 return (char *)s; 189 } 190