libchill/memmove.c

   1 /* Implement string-related runtime actions for CHILL.
   2    Copyright (C) 1992,1993 Free Software Foundation, Inc.
   3    Author: Bill Cox
   4
   5 This file is part of GNU CC.
   6
   7 GNU CC is free software; you can redistribute it and/or modify
   8 it under the terms of the GNU General Public License as published by
   9 the Free Software Foundation; either version 2, or (at your option)
  10 any later version.
  11
  12 GNU CC is distributed in the hope that it will be useful,
  13 but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 GNU General Public License for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with GNU CC; see the file COPYING.  If not, write to
  19 the Free Software Foundation, 59 Temple Place - Suite 330,
  20 Boston, MA 02111-1307, USA.  */
  21
  22 /* As a special exception, if you link this library with other files,
  23    some of which are compiled with GCC, to produce an executable,
  24    this library does not by itself cause the resulting executable
  25    to be covered by the GNU General Public License.
  26    This exception does not however invalidate any other reasons why
  27    the executable file might be covered by the GNU General Public License.  */
  28
  29 #ifdef __STDC__
  30 #include <stddef.h>
  31 #else
  32 #define size_t unsigned long
  33 #endif
  34
  35
  36 /*
  37  * function memmove
  38  *
  39  * parameters:
  40  *     S1 - pointer to destination string
  41  *     S2 - pointer to source string
  42  *     LEN - length of string
  43  *
  44  * returns:
  45  *     pointer to destination string
  46  *
  47  * exceptions:
  48  *     none
  49  *
  50  * abstract:
  51  *     copies a string safely, where the source and dest areas may overlap.
  52  *
  53  */
  54
  55 void *
  56 memmove (s1, s2, n)
  57      void *s1;
  58      const void *s2;
  59      size_t n;
  60 {
  61   char *sc1 = s1;
  62   const char *sc2 = s2;
  63
  64   if (sc2 < sc1 && (sc1 < sc2 + n))
  65     for (sc1 += n, sc2 += n; 0 < n; --n)
  66       *--sc1 = *--sc2;
  67   else
  68 #if 0
  69     for (; 0 < n; --n)
  70       *sc1++ = *sc2++;
  71 #else
  72     memcpy (sc1, sc2, n);
  73 #endif
  74   return s1;
  75 }