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 <asm/asm.h>
17 #include "ctype.h"
18 #include "string.h"
19
20 /*
21 * Undef these macros so that the functions that we provide
22 * here will have the correct names regardless of how string.h
23 * may have chosen to #define them.
24 */
25 #undef memcpy
26 #undef memset
27 #undef memcmp
28
memcmp(const void * s1,const void * s2,size_t len)29 int memcmp(const void *s1, const void *s2, size_t len)
30 {
31 bool diff;
32 asm("repe; cmpsb" CC_SET(nz)
33 : CC_OUT(nz) (diff), "+D" (s1), "+S" (s2), "+c" (len));
34 return diff;
35 }
36
strcmp(const char * str1,const char * str2)37 int strcmp(const char *str1, const char *str2)
38 {
39 const unsigned char *s1 = (const unsigned char *)str1;
40 const unsigned char *s2 = (const unsigned char *)str2;
41 int delta = 0;
42
43 while (*s1 || *s2) {
44 delta = *s1 - *s2;
45 if (delta)
46 return delta;
47 s1++;
48 s2++;
49 }
50 return 0;
51 }
52
strncmp(const char * cs,const char * ct,size_t count)53 int strncmp(const char *cs, const char *ct, size_t count)
54 {
55 unsigned char c1, c2;
56
57 while (count) {
58 c1 = *cs++;
59 c2 = *ct++;
60 if (c1 != c2)
61 return c1 < c2 ? -1 : 1;
62 if (!c1)
63 break;
64 count--;
65 }
66 return 0;
67 }
68
strnlen(const char * s,size_t maxlen)69 size_t strnlen(const char *s, size_t maxlen)
70 {
71 const char *es = s;
72 while (*es && maxlen) {
73 es++;
74 maxlen--;
75 }
76
77 return (es - s);
78 }
79
atou(const char * s)80 unsigned int atou(const char *s)
81 {
82 unsigned int i = 0;
83 while (isdigit(*s))
84 i = i * 10 + (*s++ - '0');
85 return i;
86 }
87
88 /* Works only for digits and letters, but small and fast */
89 #define TOLOWER(x) ((x) | 0x20)
90
simple_guess_base(const char * cp)91 static unsigned int simple_guess_base(const char *cp)
92 {
93 if (cp[0] == '0') {
94 if (TOLOWER(cp[1]) == 'x' && isxdigit(cp[2]))
95 return 16;
96 else
97 return 8;
98 } else {
99 return 10;
100 }
101 }
102
103 /**
104 * simple_strtoull - convert a string to an unsigned long long
105 * @cp: The start of the string
106 * @endp: A pointer to the end of the parsed string will be placed here
107 * @base: The number base to use
108 */
109
simple_strtoull(const char * cp,char ** endp,unsigned int base)110 unsigned long long simple_strtoull(const char *cp, char **endp, unsigned int base)
111 {
112 unsigned long long result = 0;
113
114 if (!base)
115 base = simple_guess_base(cp);
116
117 if (base == 16 && cp[0] == '0' && TOLOWER(cp[1]) == 'x')
118 cp += 2;
119
120 while (isxdigit(*cp)) {
121 unsigned int value;
122
123 value = isdigit(*cp) ? *cp - '0' : TOLOWER(*cp) - 'a' + 10;
124 if (value >= base)
125 break;
126 result = result * base + value;
127 cp++;
128 }
129 if (endp)
130 *endp = (char *)cp;
131
132 return result;
133 }
134
simple_strtol(const char * cp,char ** endp,unsigned int base)135 long simple_strtol(const char *cp, char **endp, unsigned int base)
136 {
137 if (*cp == '-')
138 return -simple_strtoull(cp + 1, endp, base);
139
140 return simple_strtoull(cp, endp, base);
141 }
142
143 /**
144 * strlen - Find the length of a string
145 * @s: The string to be sized
146 */
strlen(const char * s)147 size_t strlen(const char *s)
148 {
149 const char *sc;
150
151 for (sc = s; *sc != '\0'; ++sc)
152 /* nothing */;
153 return sc - s;
154 }
155
156 /**
157 * strstr - Find the first substring in a %NUL terminated string
158 * @s1: The string to be searched
159 * @s2: The string to search for
160 */
strstr(const char * s1,const char * s2)161 char *strstr(const char *s1, const char *s2)
162 {
163 size_t l1, l2;
164
165 l2 = strlen(s2);
166 if (!l2)
167 return (char *)s1;
168 l1 = strlen(s1);
169 while (l1 >= l2) {
170 l1--;
171 if (!memcmp(s1, s2, l2))
172 return (char *)s1;
173 s1++;
174 }
175 return NULL;
176 }
177
178 /**
179 * strchr - Find the first occurrence of the character c in the string s.
180 * @s: the string to be searched
181 * @c: the character to search for
182 */
strchr(const char * s,int c)183 char *strchr(const char *s, int c)
184 {
185 while (*s != (char)c)
186 if (*s++ == '\0')
187 return NULL;
188 return (char *)s;
189 }
190
