xref: /original-bsd/lib/libc/string/strcasecmp.c (revision 6cca134b)
1 /*
2  * Copyright (c) 1987 Regents of the University of California.
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms are permitted
6  * provided that the above copyright notice and this paragraph are
7  * duplicated in all such forms and that any documentation,
8  * advertising materials, and other materials related to such
9  * distribution and use acknowledge that the software was developed
10  * by the University of California, Berkeley.  The name of the
11  * University may not be used to endorse or promote products derived
12  * from this software without specific prior written permission.
13  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
14  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
15  * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
16  */
17 
18 #if defined(LIBC_SCCS) && !defined(lint)
19 static char sccsid[] = "@(#)strcasecmp.c	5.6 (Berkeley) 06/27/88";
20 #endif /* LIBC_SCCS and not lint */
21 
22 #include <sys/types.h>
23 
24 /*
25  * This array is designed for mapping upper and lower case letter
26  * together for a case independent comparison.  The mappings are
27  * based upon ascii character sequences.
28  */
29 static u_char charmap[] = {
30 	'\000', '\001', '\002', '\003', '\004', '\005', '\006', '\007',
31 	'\010', '\011', '\012', '\013', '\014', '\015', '\016', '\017',
32 	'\020', '\021', '\022', '\023', '\024', '\025', '\026', '\027',
33 	'\030', '\031', '\032', '\033', '\034', '\035', '\036', '\037',
34 	'\040', '\041', '\042', '\043', '\044', '\045', '\046', '\047',
35 	'\050', '\051', '\052', '\053', '\054', '\055', '\056', '\057',
36 	'\060', '\061', '\062', '\063', '\064', '\065', '\066', '\067',
37 	'\070', '\071', '\072', '\073', '\074', '\075', '\076', '\077',
38 	'\100', '\141', '\142', '\143', '\144', '\145', '\146', '\147',
39 	'\150', '\151', '\152', '\153', '\154', '\155', '\156', '\157',
40 	'\160', '\161', '\162', '\163', '\164', '\165', '\166', '\167',
41 	'\170', '\171', '\172', '\133', '\134', '\135', '\136', '\137',
42 	'\140', '\141', '\142', '\143', '\144', '\145', '\146', '\147',
43 	'\150', '\151', '\152', '\153', '\154', '\155', '\156', '\157',
44 	'\160', '\161', '\162', '\163', '\164', '\165', '\166', '\167',
45 	'\170', '\171', '\172', '\173', '\174', '\175', '\176', '\177',
46 	'\200', '\201', '\202', '\203', '\204', '\205', '\206', '\207',
47 	'\210', '\211', '\212', '\213', '\214', '\215', '\216', '\217',
48 	'\220', '\221', '\222', '\223', '\224', '\225', '\226', '\227',
49 	'\230', '\231', '\232', '\233', '\234', '\235', '\236', '\237',
50 	'\240', '\241', '\242', '\243', '\244', '\245', '\246', '\247',
51 	'\250', '\251', '\252', '\253', '\254', '\255', '\256', '\257',
52 	'\260', '\261', '\262', '\263', '\264', '\265', '\266', '\267',
53 	'\270', '\271', '\272', '\273', '\274', '\275', '\276', '\277',
54 	'\300', '\341', '\342', '\343', '\344', '\345', '\346', '\347',
55 	'\350', '\351', '\352', '\353', '\354', '\355', '\356', '\357',
56 	'\360', '\361', '\362', '\363', '\364', '\365', '\366', '\367',
57 	'\370', '\371', '\372', '\333', '\334', '\335', '\336', '\337',
58 	'\340', '\341', '\342', '\343', '\344', '\345', '\346', '\347',
59 	'\350', '\351', '\352', '\353', '\354', '\355', '\356', '\357',
60 	'\360', '\361', '\362', '\363', '\364', '\365', '\366', '\367',
61 	'\370', '\371', '\372', '\373', '\374', '\375', '\376', '\377',
62 };
63 
64 strcasecmp(s1, s2)
65 	char *s1, *s2;
66 {
67 	register u_char	*cm = charmap,
68 			*us1 = (u_char *)s1,
69 			*us2 = (u_char *)s2;
70 
71 	while (cm[*us1] == cm[*us2++])
72 		if (*us1++ == '\0')
73 			return(0);
74 	return(cm[*us1] - cm[*--us2]);
75 }
76 
77 strncasecmp(s1, s2, n)
78 	char *s1, *s2;
79 	register int n;
80 {
81 	register u_char	*cm = charmap,
82 			*us1 = (u_char *)s1,
83 			*us2 = (u_char *)s2;
84 
85 	while (--n >= 0 && cm[*us1] == cm[*us2++])
86 		if (*us1++ == '\0')
87 			return(0);
88 	return(n < 0 ? 0 : cm[*us1] - cm[*--us2]);
89 }
90