sdcc/device/lib/_memmove.c

   1 /*-------------------------------------------------------------------------
   2         _memmove.c - part of string library functions
   3
   4         Copyright (C) 1999, Sandeep Dutta . sandeep.dutta@usa.net
   5         Copyright (C) 2022, Sebastian 'basxto' Riedel . sdcc@basxto.de
   6         Adapted By -  Erik Petrich  . epetrich@users.sourceforge.net
   7         from _memcpy.c which was originally
   8
   9         This library is free software; you can redistribute it and/or modify it
  10         under the terms of the GNU General Public License as published by the
  11         Free Software Foundation; either version 2, or (at your option) any
  12         later version.
  13
  14         This library is distributed in the hope that it will be useful,
  15         but WITHOUT ANY WARRANTY; without even the implied warranty of
  16         MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17         GNU General Public License for more details.
  18
  19         You should have received a copy of the GNU General Public License
  20         along with this library; see the file COPYING. If not, write to the
  21         Free Software Foundation, 51 Franklin Street, Fifth Floor, Boston,
  22         MA 02110-1301, USA.
  23
  24         As a special exception, if you link this library with other files,
  25         some of which are compiled with SDCC, to produce an executable,
  26         this library does not by itself cause the resulting executable to
  27         be covered by the GNU General Public License. This exception does
  28         not however invalidate any other reasons why the executable file
  29         might be covered by the GNU General Public License.
  30 -------------------------------------------------------------------------*/
  31 #include <string.h>
  32 #include <stdint.h>
  33 #include <sdcc-lib.h>
  34
  35 void *memmove (void *dst, const void *src, size_t size)
  36 {
  37         size_t c = size;
  38         if (c == 0 || dst == src)
  39                 return dst;
  40
  41         char *d = dst;
  42         const char *s = src;
  43         if (s < d) {
  44 #if !defined (_SDCC_NO_ASM_LIB_FUNCS) && defined(__SDCC_sm83)
  45                 if (s + c < d) { // no overlap
  46                         // sm83 asm memcpy copies ascending (and faster than this)
  47                         return memcpy(d, s, c);
  48                 }
  49 #endif
  50                 s += c;
  51                 d += c;
  52                 do {
  53                         *--d = *--s;
  54                 } while (--c);
  55         } else {
  56 #if !defined (_SDCC_NO_ASM_LIB_FUNCS) && defined(__SDCC_sm83)
  57                 return memcpy(d, s, c);
  58 #else
  59                 do {
  60                         *d++ = *s++;
  61                 } while (--c);
  62 #endif
  63         }
  64
  65         return dst;
  66 }