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
 17int 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
 33int 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
 49size_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
 60unsigned 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
 71static 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
 90unsigned 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 */
119size_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 */
133char *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}