72c8bf17b8
git-svn-id: https://svn.code.sf.net/p/freedos/svn/kernel/trunk@675 6ac86273-5f31-0410-b378-82cca8765d1b
73 lines
2.7 KiB
C
73 lines
2.7 KiB
C
/****************************************************************/
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/* */
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/* initoem.c */
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/* */
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/* OEM Initializattion Functions */
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/* */
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/* Copyright (c) 1995 */
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/* Pasquale J. Villani */
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/* All Rights Reserved */
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/* */
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/* This file is part of DOS-C. */
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/* */
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/* DOS-C is free software; you can redistribute it and/or */
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/* modify it under the terms of the GNU General Public License */
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/* as published by the Free Software Foundation; either version */
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/* 2, or (at your option) any later version. */
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/* */
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/* DOS-C is distributed in the hope that it will be useful, but */
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/* WITHOUT ANY WARRANTY; without even the implied warranty of */
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/* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See */
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/* the GNU General Public License for more details. */
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/* */
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/* You should have received a copy of the GNU General Public */
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/* License along with DOS-C; see the file COPYING. If not, */
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/* write to the Free Software Foundation, 675 Mass Ave, */
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/* Cambridge, MA 02139, USA. */
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/* */
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/****************************************************************/
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#include "portab.h"
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#include "init-mod.h"
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#ifdef VERSION_STRINGS
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static BYTE *RcsId =
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"$Id$";
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#endif
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#define EBDASEG 0x40e
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#define RAMSIZE 0x413
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unsigned init_oem(void)
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{
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iregs r;
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init_call_intr(0x12, &r);
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return r.a.x;
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}
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void movebda(size_t bytes, unsigned new_seg)
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{
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unsigned old_seg = peek(0, EBDASEG);
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fmemcpy(MK_FP(new_seg, 0), MK_FP(old_seg, 0), bytes);
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poke(0, EBDASEG, new_seg);
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poke(0, RAMSIZE, ram_top);
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}
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unsigned ebdasize(void)
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{
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unsigned ebdaseg = peek(0, EBDASEG);
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unsigned ramsize = ram_top;
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if (ramsize * 64 == ebdaseg && ramsize < 640 && peek(0, RAMSIZE) == ramsize)
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{
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unsigned ebdasz = peekb(ebdaseg, 0);
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/* sanity check: is there really no more than 63 KB?
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* must be at 640k (all other values never seen and are untested)
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*/
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if (ebdasz <= 63 && ramsize + ebdasz == 640)
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return ebdasz * 1024U;
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}
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return 0;
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}
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