121 lines
2.8 KiB
C++
121 lines
2.8 KiB
C++
/////////////////////////////////////////////////////////////////////////
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// $Id: decode16.cc,v 1.5 2001-10-03 13:10:37 bdenney Exp $
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/////////////////////////////////////////////////////////////////////////
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//
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// Copyright (C) 2001 MandrakeSoft S.A.
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//
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// MandrakeSoft S.A.
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// 43, rue d'Aboukir
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// 75002 Paris - France
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// http://www.linux-mandrake.com/
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// http://www.mandrakesoft.com/
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//
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// This library is free software; you can redistribute it and/or
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// modify it under the terms of the GNU Lesser General Public
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// License as published by the Free Software Foundation; either
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// version 2 of the License, or (at your option) any later version.
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//
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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// Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public
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// License along with this library; if not, write to the Free Software
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// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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#define NEED_CPU_REG_SHORTCUTS 1
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#include "bochs.h"
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#define LOG_THIS BX_CPU_THIS_PTR
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static Bit16u *aaa[8] = {
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& BX,
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& BX,
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& BP,
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& BP,
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& SI,
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& DI,
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& BP,
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& BX,
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};
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static Bit16u *bbb[8] = {
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& SI,
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& DI,
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& SI,
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& DI,
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(Bit16u *) & BX_CPU_THIS_PTR empty_register,
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(Bit16u *) & BX_CPU_THIS_PTR empty_register,
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(Bit16u *) & BX_CPU_THIS_PTR empty_register,
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(Bit16u *) & BX_CPU_THIS_PTR empty_register
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};
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void
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BX_CPU_C::decode_exgx16(unsigned modrm)
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{
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Bit8u displ8;
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Bit16u displ16;
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unsigned mod, rm;
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#if BX_WEIRDISMS
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i->seg_reg = NULL;
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#endif
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// | 76 | 543 | 210
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// | mod | ttt | rm
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BX_INSTR_MODRM16(modrm);
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i->nnn = (modrm>>3) & 0x07;
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mod = modrm & 0xc0;
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rm = modrm & 0x07;
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if (mod == 0xc0) {
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i->rm_addr = rm;
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BX_CPU_THIS_PTR rm_type = BX_REGISTER_REF;
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return;
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}
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else { // mod != 3
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BX_CPU_THIS_PTR rm_type = BX_MEMORY_REF;
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if (mod == 0x40) {
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displ8 = fetch_next_byte();
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i->rm_addr = (Bit16u) (*aaa[rm] + *bbb[rm] + (Bit8s) displ8);
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if (i->seg_reg == NULL)
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i->seg_reg = BX_CPU_THIS_PTR sreg_mod01_rm16[rm];
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else
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i->seg_reg = i->seg_reg;
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return;
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}
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if (mod == 0x80) {
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displ16 = fetch_next_word();
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i->rm_addr = (Bit16u) (*aaa[rm] + *bbb[rm] + (Bit16s) displ16);
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if (i->seg_reg == NULL)
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i->seg_reg = BX_CPU_THIS_PTR sreg_mod10_rm16[rm];
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else
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i->seg_reg = i->seg_reg;
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return;
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}
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// mod == 0x00
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if (rm==6)
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i->rm_addr = fetch_next_word();
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else
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i->rm_addr = (Bit16u) (*aaa[rm] + *bbb[rm]);
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if (i->seg_reg == NULL)
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i->seg_reg = BX_CPU_THIS_PTR sreg_mod00_rm16[rm];
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else
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i->seg_reg = i->seg_reg;
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return;
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}
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}
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