memmove2.c

Vovida 社区开源的 SIP 协议源码

/*
 * Program:	Memory move when no bcopy()
 *
 * Author:	Mark Crispin
 *		Networks and Distributed Computing
 *		Computing & Communications
 *		University of Washington
 *		Administration Building, AG-44
 *		Seattle, WA  98195
 *		Internet: [e-mail]
 *
 * Date:	11 May 1989
 * Last Edited:	7 June 1995
 *
 * Copyright 1995 by the University of Washington
 *
 *  Permission to use, copy, modify, and distribute this software and its
 * documentation for any purpose and without fee is hereby granted, provided
 * that the above copyright notice appears in all copies and that both the
 * above copyright notice and this permission notice appear in supporting
 * documentation, and that the name of the University of Washington not be
 * used in advertising or publicity pertaining to distribution of the software
 * without specific, written prior permission.  This software is made
 * available "as is", and
 * THE UNIVERSITY OF WASHINGTON DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED,
 * WITH REGARD TO THIS SOFTWARE, INCLUDING WITHOUT LIMITATION ALL IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, AND IN
 * NO EVENT SHALL THE UNIVERSITY OF WASHINGTON BE LIABLE FOR ANY SPECIAL,
 * INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
 * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, TORT
 * (INCLUDING NEGLIGENCE) OR STRICT LIABILITY, ARISING OUT OF OR IN CONNECTION
 * WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 *
 */

/* Copy memory block
 * Accepts: destination pointer
 *	    source pointer
 *	    length
 * Returns: destination pointer
 */

void *memmove (void *s,void *ct,size_t n)
{
  char *dp,*sp;
  int i;
  unsigned long dest = (unsigned long) s;
  unsigned long src = (unsigned long) ct;
  if (((dest < src) && ((dest + n) < src)) ||
      ((dest > src) && ((src + n) < dest))) return (void *) memcpy (s,ct,n);
  dp = (char *) s;
  sp = (char *) ct;
  if (dest < src) for (i = 0; i < n; ++i) dp[i] = sp[i];
  else if (dest > src) for (i = n - 1; i >= 0; --i) dp[i] = sp[i];
  return s;
}