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