xref: /illumos-gate/usr/src/common/util/memcmp.c (revision 9164a50bf932130cbb5097a16f6986873ce0e6e5)
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 2008 Sun Microsystems, Inc.  All rights reserved.
24  * Use is subject to license terms.
25  */
26 
27 /*	Copyright (c) 1988 AT&T	*/
28 /*	  All Rights Reserved  	*/
29 
30 #if !defined(_KMDB) && !defined(_BOOT) && !defined(_KERNEL)
31 
32 #pragma weak _memcmp = memcmp
33 
34 #include "lint.h"
35 #endif /* !_KMDB && !_BOOT && !_KERNEL */
36 
37 #include <sys/types.h>
38 #if defined(_KERNEL)
39 #include <sys/systm.h>
40 #else
41 #include <string.h>
42 #include <stddef.h>
43 #endif
44 
45 /*
46  * Compare n bytes:  s1>s2: >0  s1==s2: 0  s1<s2: <0
47  */
48 int
49 memcmp(const void *s1, const void *s2, size_t n)
50 {
51 	if (s1 != s2 && n != 0) {
52 		const unsigned char *ps1 = s1;
53 		const unsigned char *ps2 = s2;
54 
55 		do {
56 			if (*ps1++ != *ps2++)
57 				return (ps1[-1] - ps2[-1]);
58 		} while (--n != 0);
59 	}
60 
61 	return (0);
62 }
63