usr/src/common/util/memmove.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 (c) 1988, 2010, Oracle and/or its affiliates. All rights reserved.
  24  */
  25
  26 /*      Copyright (c) 1988 AT&T */
  27 /*        All Rights Reserved   */
  28
  29 #if !defined(_KMDB) && !defined(_KERNEL)
  30
  31 #include "lint.h"
  32
  33 #endif /* !_KMDB && !_KERNEL */
  34
  35 /*
  36  * The SunStudio compiler may generate calls to _memmove; So we
  37  * need to make sure that the correct symbol exists for these calls.
  38  */
  39 #pragma weak _memmove = memmove
  40
  41 #include <sys/types.h>
  42
  43 #if defined(_KERNEL)
  44 #include <sys/systm.h>
  45 #else
  46 #include <string.h>
  47 #include <memory.h>
  48 #endif
  49
  50 /*
  51  * Copy s0 to s, always copy n bytes.
  52  * Return s
  53  * Copying between objects that overlap will take place correctly
  54  */
  55 void *
  56 memmove(void *s, const void *s0, size_t n)
  57 {
  58         if (n != 0) {
  59                 char *s1 = s;
  60                 const char *s2 = s0;
  61
  62                 if (s1 <= s2) {
  63                         do {
  64                                 *s1++ = *s2++;
  65                         } while (--n != 0);
  66                 } else {
  67                         s2 += n;
  68                         s1 += n;
  69                         do {
  70                                 *--s1 = *--s2;
  71                         } while (--n != 0);
  72                 }
  73         }
  74         return (s);
  75 }