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