usr/src/lib/libast/common/comp/memmove.c

   1 /***********************************************************************
   2 *                                                                      *
   3 *               This software is part of the ast package               *
   4 *          Copyright (c) 1985-2010 AT&T Intellectual Property          *
   5 *                      and is licensed under the                       *
   6 *                  Common Public License, Version 1.0                  *
   7 *                    by AT&T Intellectual Property                     *
   8 *                                                                      *
   9 *                A copy of the License is available at                 *
  10 *            http://www.opensource.org/licenses/cpl1.0.txt             *
  11 *         (with md5 checksum 059e8cd6165cb4c31e351f2b69388fd9)         *
  12 *                                                                      *
  13 *              Information and Software Systems Research               *
  14 *                            AT&T Research                             *
  15 *                           Florham Park NJ                            *
  16 *                                                                      *
  17 *                 Glenn Fowler <gsf@research.att.com>                  *
  18 *                  David Korn <dgk@research.att.com>                   *
  19 *                   Phong Vo <kpv@research.att.com>                    *
  20 *                                                                      *
  21 ***********************************************************************/
  22 #pragma prototyped
  23
  24 #include <ast.h>
  25
  26 #if _lib_memmove
  27
  28 NoN(memmove)
  29
  30 #else
  31
  32 void*
  33 memmove(void* to, const void* from, register size_t n)
  34 {
  35         register char*  out = (char*)to;
  36         register char*  in = (char*)from;
  37
  38         if (n <= 0)     /* works if size_t is signed or not */
  39                 ;
  40         else if (in + n <= out || out + n <= in)
  41                 return(memcpy(to, from, n));    /* hope it's fast*/
  42         else if (out < in)
  43                 do *out++ = *in++; while (--n > 0);
  44         else
  45         {
  46                 out += n;
  47                 in += n;
  48                 do *--out = *--in; while(--n > 0);
  49         }
  50         return(to);
  51 }
  52
  53 #endif