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