usr/src/common/util/memcmp.c

   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 #pragma ident   "%Z%%M% %I%     %E% SMI"
  31
  32 #if !defined(_KMDB) && !defined(_BOOT) && !defined(_KERNEL)
  33
  34 #pragma weak _memcmp = memcmp
  35
  36 #include "lint.h"
  37 #endif /* !_KMDB && !_BOOT && !_KERNEL */
  38
  39 #include <sys/types.h>
  40 #if defined(_KERNEL)
  41 #include <sys/systm.h>
  42 #else
  43 #include <string.h>
  44 #include <stddef.h>
  45 #endif
  46
  47 /*
  48  * Compare n bytes:  s1>s2: >0  s1==s2: 0  s1<s2: <0
  49  */
  50 int
  51 memcmp(const void *s1, const void *s2, size_t n)
  52 {
  53         if (s1 != s2 && n != 0) {
  54                 const unsigned char *ps1 = s1;
  55                 const unsigned char *ps2 = s2;
  56
  57                 do {
  58                         if (*ps1++ != *ps2++)
  59                                 return (ps1[-1] - ps2[-1]);
  60                 } while (--n != 0);
  61         }
  62
  63         return (0);
  64 }