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