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 <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 }