xref: /original-bsd/lib/libc/string/strcasecmp.c (revision 540a81df)
1 /*
2  * Copyright (c) 1987 Regents of the University of California.
3  * All rights reserved.
4  *
5  * %sccs.include.redist.c%
6  */
7 
8 #include <sys/stdc.h>
9 #include <string.h>
10 
11 #if defined(LIBC_SCCS) && !defined(lint)
12 static const char sccsid[] = "@(#)strcasecmp.c	5.9 (Berkeley) 06/01/90";
13 #endif /* LIBC_SCCS and not lint */
14 
15 typedef unsigned char u_char;
16 
17 /*
18  * This array is designed for mapping upper and lower case letter
19  * together for a case independent comparison.  The mappings are
20  * based upon ascii character sequences.
21  */
22 static const u_char charmap[] = {
23 	'\000', '\001', '\002', '\003', '\004', '\005', '\006', '\007',
24 	'\010', '\011', '\012', '\013', '\014', '\015', '\016', '\017',
25 	'\020', '\021', '\022', '\023', '\024', '\025', '\026', '\027',
26 	'\030', '\031', '\032', '\033', '\034', '\035', '\036', '\037',
27 	'\040', '\041', '\042', '\043', '\044', '\045', '\046', '\047',
28 	'\050', '\051', '\052', '\053', '\054', '\055', '\056', '\057',
29 	'\060', '\061', '\062', '\063', '\064', '\065', '\066', '\067',
30 	'\070', '\071', '\072', '\073', '\074', '\075', '\076', '\077',
31 	'\100', '\141', '\142', '\143', '\144', '\145', '\146', '\147',
32 	'\150', '\151', '\152', '\153', '\154', '\155', '\156', '\157',
33 	'\160', '\161', '\162', '\163', '\164', '\165', '\166', '\167',
34 	'\170', '\171', '\172', '\133', '\134', '\135', '\136', '\137',
35 	'\140', '\141', '\142', '\143', '\144', '\145', '\146', '\147',
36 	'\150', '\151', '\152', '\153', '\154', '\155', '\156', '\157',
37 	'\160', '\161', '\162', '\163', '\164', '\165', '\166', '\167',
38 	'\170', '\171', '\172', '\173', '\174', '\175', '\176', '\177',
39 	'\200', '\201', '\202', '\203', '\204', '\205', '\206', '\207',
40 	'\210', '\211', '\212', '\213', '\214', '\215', '\216', '\217',
41 	'\220', '\221', '\222', '\223', '\224', '\225', '\226', '\227',
42 	'\230', '\231', '\232', '\233', '\234', '\235', '\236', '\237',
43 	'\240', '\241', '\242', '\243', '\244', '\245', '\246', '\247',
44 	'\250', '\251', '\252', '\253', '\254', '\255', '\256', '\257',
45 	'\260', '\261', '\262', '\263', '\264', '\265', '\266', '\267',
46 	'\270', '\271', '\272', '\273', '\274', '\275', '\276', '\277',
47 	'\300', '\301', '\302', '\303', '\304', '\305', '\306', '\307',
48 	'\310', '\311', '\312', '\313', '\314', '\315', '\316', '\317',
49 	'\320', '\321', '\322', '\323', '\324', '\325', '\326', '\327',
50 	'\330', '\331', '\332', '\333', '\334', '\335', '\336', '\337',
51 	'\340', '\341', '\342', '\343', '\344', '\345', '\346', '\347',
52 	'\350', '\351', '\352', '\353', '\354', '\355', '\356', '\357',
53 	'\360', '\361', '\362', '\363', '\364', '\365', '\366', '\367',
54 	'\370', '\371', '\372', '\373', '\374', '\375', '\376', '\377',
55 };
56 
57 int
58 strcasecmp(s1, s2)
59 	const char *s1, *s2;
60 {
61 	register const u_char *cm = charmap,
62 			*us1 = (const u_char *)s1,
63 			*us2 = (const u_char *)s2;
64 
65 	while (cm[*us1] == cm[*us2++])
66 		if (*us1++ == '\0')
67 			return (0);
68 	return (cm[*us1] - cm[*--us2]);
69 }
70 
71 int
72 strncasecmp(s1, s2, n)
73 	const char *s1, *s2;
74 	register size_t n;
75 {
76 	if (n != 0) {
77 		register const u_char *cm = charmap,
78 				*us1 = (const u_char *)s1,
79 				*us2 = (const u_char *)s2;
80 
81 		do {
82 			if (cm[*us1] != cm[*us2++])
83 				return (cm[*us1] - cm[*--us2]);
84 			if (*us1++ == '\0')
85 				break;
86 		} while (--n != 0);
87 	}
88 	return (0);
89 }
90