arch/x86/boot/string.c

   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 long simple_strtol(const char *cp, char **endp, unsigned int base)
 126 {
 127         if (*cp == '-')
 128                 return -simple_strtoull(cp + 1, endp, base);
 129
 130         return simple_strtoull(cp, endp, base);
 131 }
 132
 133 /**
 134  * strlen - Find the length of a string
 135  * @s: The string to be sized
 136  */
 137 size_t strlen(const char *s)
 138 {
 139         const char *sc;
 140
 141         for (sc = s; *sc != '\0'; ++sc)
 142                 /* nothing */;
 143         return sc - s;
 144 }
 145
 146 /**
 147  * strstr - Find the first substring in a %NUL terminated string
 148  * @s1: The string to be searched
 149  * @s2: The string to search for
 150  */
 151 char *strstr(const char *s1, const char *s2)
 152 {
 153         size_t l1, l2;
 154
 155         l2 = strlen(s2);
 156         if (!l2)
 157                 return (char *)s1;
 158         l1 = strlen(s1);
 159         while (l1 >= l2) {
 160                 l1--;
 161                 if (!memcmp(s1, s2, l2))
 162                         return (char *)s1;
 163                 s1++;
 164         }
 165         return NULL;
 166 }
 167
 168 /**
 169  * strchr - Find the first occurrence of the character c in the string s.
 170  * @s: the string to be searched
 171  * @c: the character to search for
 172  */
 173 char *strchr(const char *s, int c)
 174 {
 175         while (*s != (char)c)
 176                 if (*s++ == '\0')
 177                         return NULL;
 178         return (char *)s;
 179 }