LXR linux/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
  28int 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
  36int 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
  52int 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
  68size_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
  79unsigned 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
  90static 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
 109unsigned 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
 134long simple_strtol(const char *cp, char **endp, unsigned int base)
 135{
 136        if (*cp == '-')
 137                return -simple_strtoull(cp + 1, endp, base);
 138
 139        return simple_strtoull(cp, endp, base);
 140}
 141
 142/**
 143 * strlen - Find the length of a string
 144 * @s: The string to be sized
 145 */
 146size_t strlen(const char *s)
 147{
 148        const char *sc;
 149
 150        for (sc = s; *sc != '\0'; ++sc)
 151                /* nothing */;
 152        return sc - s;
 153}
 154
 155/**
 156 * strstr - Find the first substring in a %NUL terminated string
 157 * @s1: The string to be searched
 158 * @s2: The string to search for
 159 */
 160char *strstr(const char *s1, const char *s2)
 161{
 162        size_t l1, l2;
 163
 164        l2 = strlen(s2);
 165        if (!l2)
 166                return (char *)s1;
 167        l1 = strlen(s1);
 168        while (l1 >= l2) {
 169                l1--;
 170                if (!memcmp(s1, s2, l2))
 171                        return (char *)s1;
 172                s1++;
 173        }
 174        return NULL;
 175}
 176
 177/**
 178 * strchr - Find the first occurrence of the character c in the string s.
 179 * @s: the string to be searched
 180 * @c: the character to search for
 181 */
 182char *strchr(const char *s, int c)
 183{
 184        while (*s != (char)c)
 185                if (*s++ == '\0')
 186                        return NULL;
 187        return (char *)s;
 188}
 189