xref: /openbsd-src/lib/libc/string/strcasecmp.c (revision 47911bd667ac77dc523b8a13ef40b012dbffa741)
1 /*	$OpenBSD: strcasecmp.c,v 1.3 1997/08/20 04:13:57 millert Exp $	*/
2 
3 /*
4  * Copyright (c) 1987, 1993
5  *	The Regents of the University of California.  All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  * 3. All advertising materials mentioning features or use of this software
16  *    must display the following acknowledgement:
17  *	This product includes software developed by the University of
18  *	California, Berkeley and its contributors.
19  * 4. Neither the name of the University nor the names of its contributors
20  *    may be used to endorse or promote products derived from this software
21  *    without specific prior written permission.
22  *
23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33  * SUCH DAMAGE.
34  */
35 
36 #include <string.h>
37 
38 #if defined(LIBC_SCCS) && !defined(lint)
39 #if 0
40 static char sccsid[] = "@(#)strcasecmp.c	8.1 (Berkeley) 6/4/93";
41 #else
42 static char *rcsid = "$OpenBSD: strcasecmp.c,v 1.3 1997/08/20 04:13:57 millert Exp $";
43 #endif
44 #endif /* LIBC_SCCS and not lint */
45 
46 typedef unsigned char u_char;
47 
48 /*
49  * This array is designed for mapping upper and lower case letter
50  * together for a case independent comparison.  The mappings are
51  * based upon ascii character sequences.
52  */
53 static const u_char charmap[] = {
54 	'\000', '\001', '\002', '\003', '\004', '\005', '\006', '\007',
55 	'\010', '\011', '\012', '\013', '\014', '\015', '\016', '\017',
56 	'\020', '\021', '\022', '\023', '\024', '\025', '\026', '\027',
57 	'\030', '\031', '\032', '\033', '\034', '\035', '\036', '\037',
58 	'\040', '\041', '\042', '\043', '\044', '\045', '\046', '\047',
59 	'\050', '\051', '\052', '\053', '\054', '\055', '\056', '\057',
60 	'\060', '\061', '\062', '\063', '\064', '\065', '\066', '\067',
61 	'\070', '\071', '\072', '\073', '\074', '\075', '\076', '\077',
62 	'\100', '\141', '\142', '\143', '\144', '\145', '\146', '\147',
63 	'\150', '\151', '\152', '\153', '\154', '\155', '\156', '\157',
64 	'\160', '\161', '\162', '\163', '\164', '\165', '\166', '\167',
65 	'\170', '\171', '\172', '\133', '\134', '\135', '\136', '\137',
66 	'\140', '\141', '\142', '\143', '\144', '\145', '\146', '\147',
67 	'\150', '\151', '\152', '\153', '\154', '\155', '\156', '\157',
68 	'\160', '\161', '\162', '\163', '\164', '\165', '\166', '\167',
69 	'\170', '\171', '\172', '\173', '\174', '\175', '\176', '\177',
70 	'\200', '\201', '\202', '\203', '\204', '\205', '\206', '\207',
71 	'\210', '\211', '\212', '\213', '\214', '\215', '\216', '\217',
72 	'\220', '\221', '\222', '\223', '\224', '\225', '\226', '\227',
73 	'\230', '\231', '\232', '\233', '\234', '\235', '\236', '\237',
74 	'\240', '\241', '\242', '\243', '\244', '\245', '\246', '\247',
75 	'\250', '\251', '\252', '\253', '\254', '\255', '\256', '\257',
76 	'\260', '\261', '\262', '\263', '\264', '\265', '\266', '\267',
77 	'\270', '\271', '\272', '\273', '\274', '\275', '\276', '\277',
78 	'\300', '\301', '\302', '\303', '\304', '\305', '\306', '\307',
79 	'\310', '\311', '\312', '\313', '\314', '\315', '\316', '\317',
80 	'\320', '\321', '\322', '\323', '\324', '\325', '\326', '\327',
81 	'\330', '\331', '\332', '\333', '\334', '\335', '\336', '\337',
82 	'\340', '\341', '\342', '\343', '\344', '\345', '\346', '\347',
83 	'\350', '\351', '\352', '\353', '\354', '\355', '\356', '\357',
84 	'\360', '\361', '\362', '\363', '\364', '\365', '\366', '\367',
85 	'\370', '\371', '\372', '\373', '\374', '\375', '\376', '\377',
86 };
87 
88 int
89 strcasecmp(s1, s2)
90 	const char *s1, *s2;
91 {
92 	register const u_char *cm = charmap,
93 			*us1 = (const u_char *)s1,
94 			*us2 = (const u_char *)s2;
95 
96 	while (cm[*us1] == cm[*us2++])
97 		if (*us1++ == '\0')
98 			return (0);
99 	return (cm[*us1] - cm[*--us2]);
100 }
101 
102 int
103 strncasecmp(s1, s2, n)
104 	const char *s1, *s2;
105 	register size_t n;
106 {
107 	if (n != 0) {
108 		register const u_char *cm = charmap,
109 				*us1 = (const u_char *)s1,
110 				*us2 = (const u_char *)s2;
111 
112 		do {
113 			if (cm[*us1] != cm[*us2++])
114 				return (cm[*us1] - cm[*--us2]);
115 			if (*us1++ == '\0')
116 				break;
117 		} while (--n != 0);
118 	}
119 	return (0);
120 }
121