xref: /illumos-gate/usr/src/lib/libc/port/gen/ascii_strncasecmp.c (revision 08855964b9970604433f7b19dcd71cf5af5e5f14)
1 /*
2  * CDDL HEADER START
3  *
4  * The contents of this file are subject to the terms of the
5  * Common Development and Distribution License (the "License").
6  * You may not use this file except in compliance with the License.
7  *
8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9  * or http://www.opensolaris.org/os/licensing.
10  * See the License for the specific language governing permissions
11  * and limitations under the License.
12  *
13  * When distributing Covered Code, include this CDDL HEADER in each
14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15  * If applicable, add the following below this CDDL HEADER, with the
16  * fields enclosed by brackets "[]" replaced with your own identifying
17  * information: Portions Copyright [yyyy] [name of copyright owner]
18  *
19  * CDDL HEADER END
20  */
21 
22 /*
23  * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved.
24  */
25 
26 /*	Copyright (c) 1983, 1984, 1985, 1986, 1987, 1988, 1989 AT&T	*/
27 /*	  All Rights Reserved  	*/
28 
29 /*
30  * Portions of this source code were derived from Berkeley 4.3 BSD
31  * under license from the Regents of the University of California.
32  */
33 
34 #include "lint.h"
35 #include <sys/types.h>
36 #include <strings.h>
37 
38 /*
39  * This array is designed for mapping upper and lower case letter
40  * together for a case independent comparison.  The mappings are
41  * based upon ascii character sequences.
42  */
43 
44 extern const char strcase_charmap[];
45 
46 int
47 ascii_strncasecmp(const char *s1, const char *s2, size_t n)
48 {
49 	const unsigned char	*cm = (const unsigned char *)strcase_charmap;
50 	const unsigned char	*us1 = (const unsigned char *)s1;
51 	const unsigned char	*us2 = (const unsigned char *)s2;
52 
53 	while (n != 0 && cm[*us1] == cm[*us2++]) {
54 		if (*us1++ == '\0')
55 			return (0);
56 		n--;
57 	}
58 	return (n == 0 ? 0 : cm[*us1] - cm[*(us2 - 1)]);
59 }
60