sdcc/device/lib/_decdptr.c

   1 /*-------------------------------------------------------------------------
   2    _decdptr.c - decrement dptr by 1
   3
   4    Copyright (C) 1999, Jean-Louis Vern <jlvern AT gmail.com>
   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 static void
  30 dummy (void) __naked
  31 {
  32 // void _decdptr (char *gptr)
  33 /* the return value is already in dph/dpl */
  34         __asm
  35         .globl  __decdptr
  36 __decdptr:
  37
  38 #ifdef __SDCC_ds390
  39         orl     dps, #0xc0
  40         inc     dptr
  41         anl     dps, #0x3f
  42 #else
  43         xch     a,dpl
  44         jnz     00001$
  45         dec     dph
  46 00001$:
  47         dec     a
  48         xch     a,dpl
  49 #endif
  50         ret
  51         __endasm;
  52 }