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