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 "boot.h" 16 17 /* 18 * This file gets included in compressed/string.c which might pull in 19 * string_32.h and which in turn maps memcmp to __builtin_memcmp(). Undo 20 * that first. 21 */ 22 #undef memcmp 23 int memcmp(const void *s1, const void *s2, size_t len) 24 { 25 u8 diff; 26 asm("repe; cmpsb; setnz %0" 27 : "=qm" (diff), "+D" (s1), "+S" (s2), "+c" (len)); 28 return diff; 29 } 30 31 int strcmp(const char *str1, const char *str2) 32 { 33 const unsigned char *s1 = (const unsigned char *)str1; 34 const unsigned char *s2 = (const unsigned char *)str2; 35 int delta = 0; 36 37 while (*s1 || *s2) { 38 delta = *s2 - *s1; 39 if (delta) 40 return delta; 41 s1++; 42 s2++; 43 } 44 return 0; 45 } 46 47 int strncmp(const char *cs, const char *ct, size_t count) 48 { 49 unsigned char c1, c2; 50 51 while (count) { 52 c1 = *cs++; 53 c2 = *ct++; 54 if (c1 != c2) 55 return c1 < c2 ? -1 : 1; 56 if (!c1) 57 break; 58 count--; 59 } 60 return 0; 61 } 62 63 size_t strnlen(const char *s, size_t maxlen) 64 { 65 const char *es = s; 66 while (*es && maxlen) { 67 es++; 68 maxlen--; 69 } 70 71 return (es - s); 72 } 73 74 unsigned int atou(const char *s) 75 { 76 unsigned int i = 0; 77 while (isdigit(*s)) 78 i = i * 10 + (*s++ - '0'); 79 return i; 80 } 81 82 /* Works only for digits and letters, but small and fast */ 83 #define TOLOWER(x) ((x) | 0x20) 84 85 static unsigned int simple_guess_base(const char *cp) 86 { 87 if (cp[0] == '0') { 88 if (TOLOWER(cp[1]) == 'x' && isxdigit(cp[2])) 89 return 16; 90 else 91 return 8; 92 } else { 93 return 10; 94 } 95 } 96 97 /** 98 * simple_strtoull - convert a string to an unsigned long long 99 * @cp: The start of the string 100 * @endp: A pointer to the end of the parsed string will be placed here 101 * @base: The number base to use 102 */ 103 104 unsigned long long simple_strtoull(const char *cp, char **endp, unsigned int base) 105 { 106 unsigned long long result = 0; 107 108 if (!base) 109 base = simple_guess_base(cp); 110 111 if (base == 16 && cp[0] == '0' && TOLOWER(cp[1]) == 'x') 112 cp += 2; 113 114 while (isxdigit(*cp)) { 115 unsigned int value; 116 117 value = isdigit(*cp) ? *cp - '0' : TOLOWER(*cp) - 'a' + 10; 118 if (value >= base) 119 break; 120 result = result * base + value; 121 cp++; 122 } 123 if (endp) 124 *endp = (char *)cp; 125 126 return result; 127 } 128 129 /** 130 * strlen - Find the length of a string 131 * @s: The string to be sized 132 */ 133 size_t strlen(const char *s) 134 { 135 const char *sc; 136 137 for (sc = s; *sc != '\0'; ++sc) 138 /* nothing */; 139 return sc - s; 140 } 141 142 /** 143 * strstr - Find the first substring in a %NUL terminated string 144 * @s1: The string to be searched 145 * @s2: The string to search for 146 */ 147 char *strstr(const char *s1, const char *s2) 148 { 149 size_t l1, l2; 150 151 l2 = strlen(s2); 152 if (!l2) 153 return (char *)s1; 154 l1 = strlen(s1); 155 while (l1 >= l2) { 156 l1--; 157 if (!memcmp(s1, s2, l2)) 158 return (char *)s1; 159 s1++; 160 } 161 return NULL; 162 } 163