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
18int memcmp(const void *s1, const void *s2, size_t len)
19{
20	u8 diff;
21	asm("repe; cmpsb; setnz %0"
22	    : "=qm" (diff), "+D" (s1), "+S" (s2), "+c" (len));
23	return diff;
24}
25
26int strcmp(const char *str1, const char *str2)
27{
28	const unsigned char *s1 = (const unsigned char *)str1;
29	const unsigned char *s2 = (const unsigned char *)str2;
30	int delta = 0;
31
32	while (*s1 || *s2) {
33		delta = *s1 - *s2;
34		if (delta)
35			return delta;
36		s1++;
37		s2++;
38	}
39	return 0;
40}
41
42int strncmp(const char *cs, const char *ct, size_t count)
43{
44	unsigned char c1, c2;
45
46	while (count) {
47		c1 = *cs++;
48		c2 = *ct++;
49		if (c1 != c2)
50			return c1 < c2 ? -1 : 1;
51		if (!c1)
52			break;
53		count--;
54	}
55	return 0;
56}
57
58size_t strnlen(const char *s, size_t maxlen)
59{
60	const char *es = s;
61	while (*es && maxlen) {
62		es++;
63		maxlen--;
64	}
65
66	return (es - s);
67}
68
69unsigned int atou(const char *s)
70{
71	unsigned int i = 0;
72	while (isdigit(*s))
73		i = i * 10 + (*s++ - '0');
74	return i;
75}
76
77/* Works only for digits and letters, but small and fast */
78#define TOLOWER(x) ((x) | 0x20)
79
80static unsigned int simple_guess_base(const char *cp)
81{
82	if (cp[0] == '0') {
83		if (TOLOWER(cp[1]) == 'x' && isxdigit(cp[2]))
84			return 16;
85		else
86			return 8;
87	} else {
88		return 10;
89	}
90}
91
92/**
93 * simple_strtoull - convert a string to an unsigned long long
94 * @cp: The start of the string
95 * @endp: A pointer to the end of the parsed string will be placed here
96 * @base: The number base to use
97 */
98
99unsigned long long simple_strtoull(const char *cp, char **endp, unsigned int base)
100{
101	unsigned long long result = 0;
102
103	if (!base)
104		base = simple_guess_base(cp);
105
106	if (base == 16 && cp[0] == '0' && TOLOWER(cp[1]) == 'x')
107		cp += 2;
108
109	while (isxdigit(*cp)) {
110		unsigned int value;
111
112		value = isdigit(*cp) ? *cp - '0' : TOLOWER(*cp) - 'a' + 10;
113		if (value >= base)
114			break;
115		result = result * base + value;
116		cp++;
117	}
118	if (endp)
119		*endp = (char *)cp;
120
121	return result;
122}
123
124/**
125 * strlen - Find the length of a string
126 * @s: The string to be sized
127 */
128size_t strlen(const char *s)
129{
130	const char *sc;
131
132	for (sc = s; *sc != '\0'; ++sc)
133		/* nothing */;
134	return sc - s;
135}
136
137/**
138 * strstr - Find the first substring in a %NUL terminated string
139 * @s1: The string to be searched
140 * @s2: The string to search for
141 */
142char *strstr(const char *s1, const char *s2)
143{
144	size_t l1, l2;
145
146	l2 = strlen(s2);
147	if (!l2)
148		return (char *)s1;
149	l1 = strlen(s1);
150	while (l1 >= l2) {
151		l1--;
152		if (!memcmp(s1, s2, l2))
153			return (char *)s1;
154		s1++;
155	}
156	return NULL;
157}
158