sdcc/device/lib/r2k/memcpy.s

   1 ;--------------------------------------------------------------------------
   2 ;  memcpy.s
   3 ;
   4 ;  Copyright (C) 2020, Sergey Belyashov, Philipp Klaus Krause
   5 ;
   6 ;  This library is free software; you can redistribute it and/or modify it
   7 ;  under the terms of the GNU General Public License as published by the
   8 ;  Free Software Foundation; either version 2, or (at your option) any
   9 ;  later version.
  10 ;
  11 ;  This library is distributed in the hope that it will be useful,
  12 ;  but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 ;  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  14 ;  GNU General Public License for more details.
  15 ;
  16 ;  You should have received a copy of the GNU General Public License
  17 ;  along with this library; see the file COPYING. If not, write to the
  18 ;  Free Software Foundation, 51 Franklin Street, Fifth Floor, Boston,
  19 ;   MA 02110-1301, USA.
  20 ;
  21 ;  As a special exception, if you link this library with other files,
  22 ;  some of which are compiled with SDCC, to produce an executable,
  23 ;  this library does not by itself cause the resulting executable to
  24 ;  be covered by the GNU General Public License. This exception does
  25 ;  not however invalidate any other reasons why the executable file
  26 ;   might be covered by the GNU General Public License.
  27 ;--------------------------------------------------------------------------
  28
  29         .area   _CODE
  30
  31         .globl _memcpy
  32         .globl ___memcpy
  33
  34 ; The Z80 has the ldir instruction, which is perfect for implementing memcpy(). Unfortunately, it is quite broken on early Rabbits, so we use ldi.
  35 _memcpy:
  36 ___memcpy:
  37         ex      de, hl
  38         pop     iy
  39         pop     hl
  40         pop     bc
  41         push    de
  42         ld      a, c
  43         or      a, b
  44         jr      Z, end
  45 loop:
  46         ldi
  47         jp      LO, loop
  48 end:
  49         pop     hl
  50         jp      (iy)
  51