Bochs/bochs/cpu/arith16.cc
Kevin Lawton 3c09fdb363 I updated code that was using !!get_CF() (or other arithmetic flag) to
use getB_CF() etc.  getB_CF() and friends are only for a relatively
  small number of cases where a true boolean/binary number (0 or 1) is required
  rather than 0 or non-0 as is returned by get_CF().
2002-09-24 18:33:38 +00:00

943 lines
20 KiB
C++

/////////////////////////////////////////////////////////////////////////
// $Id: arith16.cc,v 1.19 2002-09-24 18:33:37 kevinlawton 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
void
BX_CPU_C::INC_RX(bxInstruction_c *i)
{
#if (defined(__i386__) && defined(__GNUC__) && BX_SupportHostAsms)
Bit32u flags32;
asm (
"incw %1 \n\t"
"pushfl \n\t"
"popl %0"
: "=g" (flags32), "=r" (BX_CPU_THIS_PTR gen_reg[i->opcodeReg()].word.rx)
: "1" (BX_CPU_THIS_PTR gen_reg[i->opcodeReg()].word.rx)
: "cc"
);
BX_CPU_THIS_PTR eflags.val32 =
(BX_CPU_THIS_PTR eflags.val32 & ~0x000008d4) | (flags32 & 0x000008d4);
BX_CPU_THIS_PTR lf_flags_status &= 0x00000f;
#else
Bit16u rx;
rx = ++ BX_CPU_THIS_PTR gen_reg[i->opcodeReg()].word.rx;
SET_FLAGS_OSZAP_16(0, 0, rx, BX_INSTR_INC16);
#endif
}
void
BX_CPU_C::DEC_RX(bxInstruction_c *i)
{
#if (defined(__i386__) && defined(__GNUC__) && BX_SupportHostAsms)
Bit32u flags32;
asm (
"decw %1 \n\t"
"pushfl \n\t"
"popl %0"
: "=g" (flags32), "=r" (BX_CPU_THIS_PTR gen_reg[i->opcodeReg()].word.rx)
: "1" (BX_CPU_THIS_PTR gen_reg[i->opcodeReg()].word.rx)
: "cc"
);
BX_CPU_THIS_PTR eflags.val32 =
(BX_CPU_THIS_PTR eflags.val32 & ~0x000008d4) | (flags32 & 0x000008d4);
BX_CPU_THIS_PTR lf_flags_status &= 0x00000f;
#else
Bit16u rx;
rx = -- BX_CPU_THIS_PTR gen_reg[i->opcodeReg()].word.rx;
SET_FLAGS_OSZAP_16(0, 0, rx, BX_INSTR_DEC16);
#endif
}
void
BX_CPU_C::ADD_EwGw(bxInstruction_c *i)
{
Bit16u op2_16, op1_16, sum_16;
/* op2_16 is a register, RMAddr(i) is an index of a register */
op2_16 = BX_READ_16BIT_REG(i->nnn());
/* op1_16 is a register or memory reference */
if (i->modC0()) {
op1_16 = BX_READ_16BIT_REG(i->rm());
}
else {
/* pointer, segment address pair */
read_virtual_word(i->seg(), RMAddr(i), &op1_16);
}
sum_16 = op1_16 + op2_16;
/* now write sum back to destination */
if (i->modC0()) {
BX_WRITE_16BIT_REG(i->rm(), sum_16);
}
else {
write_virtual_word(i->seg(), RMAddr(i), &sum_16);
}
SET_FLAGS_OSZAPC_16(op1_16, op2_16, sum_16, BX_INSTR_ADD16);
}
void
BX_CPU_C::ADD_GwEw(bxInstruction_c *i)
{
Bit16u op1_16, op2_16, sum_16;
/* op1_16 is a register, RMAddr(i) is an index of a register */
op1_16 = BX_READ_16BIT_REG(i->nnn());
/* op2_16 is a register or memory reference */
if (i->modC0()) {
op2_16 = BX_READ_16BIT_REG(i->rm());
}
else {
/* pointer, segment address pair */
read_virtual_word(i->seg(), RMAddr(i), &op2_16);
}
#if (defined(__i386__) && defined(__GNUC__) && BX_SupportHostAsms)
Bit32u flags32;
asm (
"addw %3, %1 \n\t"
"pushfl \n\t"
"popl %0"
: "=g" (flags32), "=r" (sum_16)
: "1" (op1_16), "g" (op2_16)
: "cc"
);
BX_CPU_THIS_PTR eflags.val32 =
(BX_CPU_THIS_PTR eflags.val32 & ~0x000008d5) | (flags32 & 0x000008d5);
BX_CPU_THIS_PTR lf_flags_status = 0;
#else
sum_16 = op1_16 + op2_16;
#endif
BX_WRITE_16BIT_REG(i->nnn(), sum_16);
#if !(defined(__i386__) && defined(__GNUC__) && BX_SupportHostAsms)
SET_FLAGS_OSZAPC_16(op1_16, op2_16, sum_16, BX_INSTR_ADD16);
#endif
}
void
BX_CPU_C::ADD_AXIw(bxInstruction_c *i)
{
Bit16u op1_16, op2_16, sum_16;
op1_16 = AX;
op2_16 = i->Iw();
sum_16 = op1_16 + op2_16;
/* now write sum back to destination */
AX = sum_16;
SET_FLAGS_OSZAPC_16(op1_16, op2_16, sum_16, BX_INSTR_ADD16);
}
void
BX_CPU_C::ADC_EwGw(bxInstruction_c *i)
{
Boolean temp_CF;
Bit16u op2_16, op1_16, sum_16;
temp_CF = getB_CF();
/* op2_16 is a register, RMAddr(i) is an index of a register */
op2_16 = BX_READ_16BIT_REG(i->nnn());
/* op1_16 is a register or memory reference */
if (i->modC0()) {
op1_16 = BX_READ_16BIT_REG(i->rm());
}
else {
/* pointer, segment address pair */
read_RMW_virtual_word(i->seg(), RMAddr(i), &op1_16);
}
sum_16 = op1_16 + op2_16 + temp_CF;
/* now write sum back to destination */
if (i->modC0()) {
BX_WRITE_16BIT_REG(i->rm(), sum_16);
}
else {
Write_RMW_virtual_word(sum_16);
}
SET_FLAGS_OSZAPC_16_CF(op1_16, op2_16, sum_16, BX_INSTR_ADC16,
temp_CF);
}
void
BX_CPU_C::ADC_GwEw(bxInstruction_c *i)
{
Boolean temp_CF;
Bit16u op1_16, op2_16, sum_16;
temp_CF = getB_CF();
/* op1_16 is a register, RMAddr(i) is an index of a register */
op1_16 = BX_READ_16BIT_REG(i->nnn());
/* op2_16 is a register or memory reference */
if (i->modC0()) {
op2_16 = BX_READ_16BIT_REG(i->rm());
}
else {
/* pointer, segment address pair */
read_virtual_word(i->seg(), RMAddr(i), &op2_16);
}
sum_16 = op1_16 + op2_16 + temp_CF;
/* now write sum back to destination */
BX_WRITE_16BIT_REG(i->nnn(), sum_16);
SET_FLAGS_OSZAPC_16_CF(op1_16, op2_16, sum_16, BX_INSTR_ADC16,
temp_CF);
}
void
BX_CPU_C::ADC_AXIw(bxInstruction_c *i)
{
Boolean temp_CF;
Bit16u op1_16, op2_16, sum_16;
temp_CF = getB_CF();
op1_16 = AX;
op2_16 = i->Iw();
sum_16 = op1_16 + op2_16 + temp_CF;
/* now write sum back to destination */
AX = sum_16;
SET_FLAGS_OSZAPC_16_CF(op1_16, op2_16, sum_16, BX_INSTR_ADC16,
temp_CF);
}
void
BX_CPU_C::SBB_EwGw(bxInstruction_c *i)
{
Boolean temp_CF;
Bit16u op2_16, op1_16, diff_16;
temp_CF = getB_CF();
/* op2_16 is a register, RMAddr(i) is an index of a register */
op2_16 = BX_READ_16BIT_REG(i->nnn());
/* op1_16 is a register or memory reference */
if (i->modC0()) {
op1_16 = BX_READ_16BIT_REG(i->rm());
}
else {
/* pointer, segment address pair */
read_RMW_virtual_word(i->seg(), RMAddr(i), &op1_16);
}
diff_16 = op1_16 - (op2_16 + temp_CF);
/* now write diff back to destination */
if (i->modC0()) {
BX_WRITE_16BIT_REG(i->rm(), diff_16);
}
else {
Write_RMW_virtual_word(diff_16);
}
SET_FLAGS_OSZAPC_16_CF(op1_16, op2_16, diff_16, BX_INSTR_SBB16,
temp_CF);
}
void
BX_CPU_C::SBB_GwEw(bxInstruction_c *i)
{
Boolean temp_CF;
temp_CF = getB_CF();
Bit16u op1_16, op2_16, diff_16;
/* op1_16 is a register, RMAddr(i) is an index of a register */
op1_16 = BX_READ_16BIT_REG(i->nnn());
/* op2_16 is a register or memory reference */
if (i->modC0()) {
op2_16 = BX_READ_16BIT_REG(i->rm());
}
else {
/* pointer, segment address pair */
read_virtual_word(i->seg(), RMAddr(i), &op2_16);
}
diff_16 = op1_16 - (op2_16 + temp_CF);
/* now write diff back to destination */
BX_WRITE_16BIT_REG(i->nnn(), diff_16);
SET_FLAGS_OSZAPC_16_CF(op1_16, op2_16, diff_16, BX_INSTR_SBB16,
temp_CF);
}
void
BX_CPU_C::SBB_AXIw(bxInstruction_c *i)
{
Boolean temp_CF;
Bit16u op1_16, op2_16, diff_16;
temp_CF = getB_CF();
op1_16 = AX;
op2_16 = i->Iw();
diff_16 = op1_16 - (op2_16 + temp_CF);
/* now write diff back to destination */
AX = diff_16;
SET_FLAGS_OSZAPC_16_CF(op1_16, op2_16, diff_16, BX_INSTR_SBB16,
temp_CF);
}
void
BX_CPU_C::SBB_EwIw(bxInstruction_c *i)
{
Boolean temp_CF;
Bit16u op2_16, op1_16, diff_16;
temp_CF = getB_CF();
op2_16 = i->Iw();
/* op1_16 is a register or memory reference */
if (i->modC0()) {
op1_16 = BX_READ_16BIT_REG(i->rm());
}
else {
/* pointer, segment address pair */
read_RMW_virtual_word(i->seg(), RMAddr(i), &op1_16);
}
diff_16 = op1_16 - (op2_16 + temp_CF);
/* now write diff back to destination */
if (i->modC0()) {
BX_WRITE_16BIT_REG(i->rm(), diff_16);
}
else {
Write_RMW_virtual_word(diff_16);
}
SET_FLAGS_OSZAPC_16_CF(op1_16, op2_16, diff_16, BX_INSTR_SBB16,
temp_CF);
}
void
BX_CPU_C::SUB_EwGw(bxInstruction_c *i)
{
Bit16u op2_16, op1_16, diff_16;
/* op2_16 is a register, RMAddr(i) is an index of a register */
op2_16 = BX_READ_16BIT_REG(i->nnn());
/* op1_16 is a register or memory reference */
if (i->modC0()) {
op1_16 = BX_READ_16BIT_REG(i->rm());
}
else {
/* pointer, segment address pair */
read_RMW_virtual_word(i->seg(), RMAddr(i), &op1_16);
}
diff_16 = op1_16 - op2_16;
/* now write diff back to destination */
if (i->modC0()) {
BX_WRITE_16BIT_REG(i->rm(), diff_16);
}
else {
Write_RMW_virtual_word(diff_16);
}
SET_FLAGS_OSZAPC_16(op1_16, op2_16, diff_16, BX_INSTR_SUB16);
}
void
BX_CPU_C::SUB_GwEw(bxInstruction_c *i)
{
Bit16u op1_16, op2_16, diff_16;
/* op1_16 is a register, RMAddr(i) is an index of a register */
op1_16 = BX_READ_16BIT_REG(i->nnn());
/* op2_16 is a register or memory reference */
if (i->modC0()) {
op2_16 = BX_READ_16BIT_REG(i->rm());
}
else {
/* pointer, segment address pair */
read_virtual_word(i->seg(), RMAddr(i), &op2_16);
}
diff_16 = op1_16 - op2_16;
/* now write diff back to destination */
BX_WRITE_16BIT_REG(i->nnn(), diff_16);
SET_FLAGS_OSZAPC_16(op1_16, op2_16, diff_16, BX_INSTR_SUB16);
}
void
BX_CPU_C::SUB_AXIw(bxInstruction_c *i)
{
Bit16u op1_16, op2_16, diff_16;
op1_16 = AX;
op2_16 = i->Iw();
diff_16 = op1_16 - op2_16;
/* now write diff back to destination */
AX = diff_16;
SET_FLAGS_OSZAPC_16(op1_16, op2_16, diff_16, BX_INSTR_SUB16);
}
void
BX_CPU_C::CMP_EwGw(bxInstruction_c *i)
{
Bit16u op2_16, op1_16;
op2_16 = BX_READ_16BIT_REG(i->nnn());
if (i->modC0()) {
op1_16 = BX_READ_16BIT_REG(i->rm());
}
else {
read_virtual_word(i->seg(), RMAddr(i), &op1_16);
}
#if (defined(__i386__) && defined(__GNUC__) && BX_SupportHostAsms)
Bit32u flags32;
asm (
"cmpw %2, %1\n\t"
"pushfl \n\t"
"popl %0"
: "=g" (flags32)
: "r" (op1_16), "g" (op2_16)
: "cc"
);
BX_CPU_THIS_PTR eflags.val32 =
(BX_CPU_THIS_PTR eflags.val32 & ~0x000008d5) | (flags32 & 0x000008d5);
BX_CPU_THIS_PTR lf_flags_status = 0;
#else
Bit16u diff_16;
diff_16 = op1_16 - op2_16;
SET_FLAGS_OSZAPC_16(op1_16, op2_16, diff_16, BX_INSTR_CMP16);
#endif
}
void
BX_CPU_C::CMP_GwEw(bxInstruction_c *i)
{
Bit16u op1_16, op2_16;
op1_16 = BX_READ_16BIT_REG(i->nnn());
if (i->modC0()) {
op2_16 = BX_READ_16BIT_REG(i->rm());
}
else {
read_virtual_word(i->seg(), RMAddr(i), &op2_16);
}
#if (defined(__i386__) && defined(__GNUC__) && BX_SupportHostAsms)
Bit32u flags32;
asm (
"cmpw %2, %1\n\t"
"pushfl \n\t"
"popl %0"
: "=g" (flags32)
: "r" (op1_16), "g" (op2_16)
: "cc"
);
BX_CPU_THIS_PTR eflags.val32 =
(BX_CPU_THIS_PTR eflags.val32 & ~0x000008d5) | (flags32 & 0x000008d5);
BX_CPU_THIS_PTR lf_flags_status = 0;
#else
Bit16u diff_16;
diff_16 = op1_16 - op2_16;
SET_FLAGS_OSZAPC_16(op1_16, op2_16, diff_16, BX_INSTR_CMP16);
#endif
}
void
BX_CPU_C::CMP_AXIw(bxInstruction_c *i)
{
Bit16u op1_16, op2_16;
op1_16 = AX;
op2_16 = i->Iw();
#if (defined(__i386__) && defined(__GNUC__) && BX_SupportHostAsms)
Bit32u flags32;
asm (
"cmpw %2, %1\n\t"
"pushfl \n\t"
"popl %0"
: "=g" (flags32)
: "r" (op1_16), "g" (op2_16)
: "cc"
);
BX_CPU_THIS_PTR eflags.val32 =
(BX_CPU_THIS_PTR eflags.val32 & ~0x000008d5) | (flags32 & 0x000008d5);
BX_CPU_THIS_PTR lf_flags_status = 0;
#else
Bit16u diff_16;
diff_16 = op1_16 - op2_16;
SET_FLAGS_OSZAPC_16(op1_16, op2_16, diff_16, BX_INSTR_CMP16);
#endif
}
void
BX_CPU_C::CBW(bxInstruction_c *i)
{
/* CBW: no flags are effected */
AX = (Bit8s) AL;
}
void
BX_CPU_C::CWD(bxInstruction_c *i)
{
/* CWD: no flags are affected */
if (AX & 0x8000) {
DX = 0xFFFF;
}
else {
DX = 0x0000;
}
}
void
BX_CPU_C::XADD_EwGw(bxInstruction_c *i)
{
#if (BX_CPU_LEVEL >= 4) || (BX_CPU_LEVEL_HACKED >= 4)
Bit16u op2_16, op1_16, sum_16;
/* XADD dst(r/m), src(r)
* temp <-- src + dst | sum = op2 + op1
* src <-- dst | op2 = op1
* dst <-- tmp | op1 = sum
*/
/* op2 is a register, RMAddr(i) is an index of a register */
op2_16 = BX_READ_16BIT_REG(i->nnn());
/* op1 is a register or memory reference */
if (i->modC0()) {
op1_16 = BX_READ_16BIT_REG(i->rm());
}
else {
/* pointer, segment address pair */
read_RMW_virtual_word(i->seg(), RMAddr(i), &op1_16);
}
sum_16 = op1_16 + op2_16;
/* now write sum back to destination */
if (i->modC0()) {
// and write destination into source
// Note: if both op1 & op2 are registers, the last one written
// should be the sum, as op1 & op2 may be the same register.
// For example: XADD AL, AL
BX_WRITE_16BIT_REG(i->nnn(), op1_16);
BX_WRITE_16BIT_REG(i->rm(), sum_16);
}
else {
Write_RMW_virtual_word(sum_16);
/* and write destination into source */
BX_WRITE_16BIT_REG(i->nnn(), op1_16);
}
SET_FLAGS_OSZAPC_16(op1_16, op2_16, sum_16, BX_INSTR_XADD16);
#else
BX_PANIC(("XADD_EvGv: not supported on < 80486"));
#endif
}
void
BX_CPU_C::ADD_EwIw(bxInstruction_c *i)
{
Bit16u op2_16, op1_16, sum_16;
op2_16 = i->Iw();
/* op1_16 is a register or memory reference */
if (i->modC0()) {
op1_16 = BX_READ_16BIT_REG(i->rm());
#if (defined(__i386__) && defined(__GNUC__) && BX_SupportHostAsms)
Bit32u flags32;
asm (
"addw %3, %1 \n\t"
"pushfl \n\t"
"popl %0"
: "=g" (flags32), "=r" (sum_16)
: "1" (op1_16), "g" (op2_16)
: "cc"
);
BX_CPU_THIS_PTR eflags.val32 =
(BX_CPU_THIS_PTR eflags.val32 & ~0x000008d5) | (flags32 & 0x000008d5);
BX_CPU_THIS_PTR lf_flags_status = 0;
#else
sum_16 = op1_16 + op2_16;
#endif
BX_WRITE_16BIT_REG(i->rm(), sum_16);
}
else {
/* pointer, segment address pair */
read_RMW_virtual_word(i->seg(), RMAddr(i), &op1_16);
#if (defined(__i386__) && defined(__GNUC__) && BX_SupportHostAsms)
Bit32u flags32;
asm (
"addw %3, %1 \n\t"
"pushfl \n\t"
"popl %0"
: "=g" (flags32), "=r" (sum_16)
: "1" (op1_16), "g" (op2_16)
: "cc"
);
BX_CPU_THIS_PTR eflags.val32 =
(BX_CPU_THIS_PTR eflags.val32 & ~0x000008d5) | (flags32 & 0x000008d5);
BX_CPU_THIS_PTR lf_flags_status = 0;
#else
sum_16 = op1_16 + op2_16;
#endif
Write_RMW_virtual_word(sum_16);
}
#if !(defined(__i386__) && defined(__GNUC__) && BX_SupportHostAsms)
SET_FLAGS_OSZAPC_16(op1_16, op2_16, sum_16, BX_INSTR_ADD16);
#endif
}
void
BX_CPU_C::ADC_EwIw(bxInstruction_c *i)
{
Boolean temp_CF;
Bit16u op2_16, op1_16, sum_16;
temp_CF = getB_CF();
op2_16 = i->Iw();
/* op1_16 is a register or memory reference */
if (i->modC0()) {
op1_16 = BX_READ_16BIT_REG(i->rm());
}
else {
/* pointer, segment address pair */
read_RMW_virtual_word(i->seg(), RMAddr(i), &op1_16);
}
sum_16 = op1_16 + op2_16 + temp_CF;
/* now write sum back to destination */
if (i->modC0()) {
BX_WRITE_16BIT_REG(i->rm(), sum_16);
}
else {
Write_RMW_virtual_word(sum_16);
}
SET_FLAGS_OSZAPC_16_CF(op1_16, op2_16, sum_16, BX_INSTR_ADC16,
temp_CF);
}
void
BX_CPU_C::SUB_EwIw(bxInstruction_c *i)
{
Bit16u op2_16, op1_16, diff_16;
op2_16 = i->Iw();
/* op1_16 is a register or memory reference */
if (i->modC0()) {
op1_16 = BX_READ_16BIT_REG(i->rm());
}
else {
/* pointer, segment address pair */
read_RMW_virtual_word(i->seg(), RMAddr(i), &op1_16);
}
diff_16 = op1_16 - op2_16;
/* now write diff back to destination */
if (i->modC0()) {
BX_WRITE_16BIT_REG(i->rm(), diff_16);
}
else {
Write_RMW_virtual_word(diff_16);
}
SET_FLAGS_OSZAPC_16(op1_16, op2_16, diff_16, BX_INSTR_SUB16);
}
void
BX_CPU_C::CMP_EwIw(bxInstruction_c *i)
{
Bit16u op2_16, op1_16;
op2_16 = i->Iw();
if (i->modC0()) {
op1_16 = BX_READ_16BIT_REG(i->rm());
}
else {
read_virtual_word(i->seg(), RMAddr(i), &op1_16);
}
#if (defined(__i386__) && defined(__GNUC__) && BX_SupportHostAsms)
Bit32u flags32;
asm (
"cmpw %2, %1\n\t"
"pushfl \n\t"
"popl %0"
: "=g" (flags32)
: "r" (op1_16), "g" (op2_16)
: "cc"
);
BX_CPU_THIS_PTR eflags.val32 =
(BX_CPU_THIS_PTR eflags.val32 & ~0x000008d5) | (flags32 & 0x000008d5);
BX_CPU_THIS_PTR lf_flags_status = 0;
#else
Bit16u diff_16;
diff_16 = op1_16 - op2_16;
SET_FLAGS_OSZAPC_16(op1_16, op2_16, diff_16, BX_INSTR_CMP16);
#endif
}
void
BX_CPU_C::NEG_Ew(bxInstruction_c *i)
{
Bit16u op1_16, diff_16;
/* op1_16 is a register or memory reference */
if (i->modC0()) {
op1_16 = BX_READ_16BIT_REG(i->rm());
}
else {
/* pointer, segment address pair */
read_RMW_virtual_word(i->seg(), RMAddr(i), &op1_16);
}
diff_16 = 0 - op1_16;
/* now write diff back to destination */
if (i->modC0()) {
BX_WRITE_16BIT_REG(i->rm(), diff_16);
}
else {
Write_RMW_virtual_word(diff_16);
}
SET_FLAGS_OSZAPC_16(op1_16, 0, diff_16, BX_INSTR_NEG16);
}
void
BX_CPU_C::INC_Ew(bxInstruction_c *i)
{
Bit16u op1_16;
/* op1_16 is a register or memory reference */
if (i->modC0()) {
op1_16 = BX_READ_16BIT_REG(i->rm());
}
else {
/* pointer, segment address pair */
read_RMW_virtual_word(i->seg(), RMAddr(i), &op1_16);
}
op1_16++;
/* now write sum back to destination */
if (i->modC0()) {
BX_WRITE_16BIT_REG(i->rm(), op1_16);
}
else {
Write_RMW_virtual_word(op1_16);
}
SET_FLAGS_OSZAP_16(0, 0, op1_16, BX_INSTR_INC16);
}
void
BX_CPU_C::DEC_Ew(bxInstruction_c *i)
{
Bit16u op1_16;
/* op1_16 is a register or memory reference */
if (i->modC0()) {
op1_16 = BX_READ_16BIT_REG(i->rm());
}
else {
/* pointer, segment address pair */
read_RMW_virtual_word(i->seg(), RMAddr(i), &op1_16);
}
op1_16--;
/* now write sum back to destination */
if (i->modC0()) {
BX_WRITE_16BIT_REG(i->rm(), op1_16);
}
else {
Write_RMW_virtual_word(op1_16);
}
SET_FLAGS_OSZAP_16(0, 0, op1_16, BX_INSTR_DEC16);
}
void
BX_CPU_C::CMPXCHG_EwGw(bxInstruction_c *i)
{
#if (BX_CPU_LEVEL >= 4) || (BX_CPU_LEVEL_HACKED >= 4)
Bit16u op2_16, op1_16, diff_16;
/* op1_16 is a register or memory reference */
if (i->modC0()) {
op1_16 = BX_READ_16BIT_REG(i->rm());
}
else {
/* pointer, segment address pair */
read_RMW_virtual_word(i->seg(), RMAddr(i), &op1_16);
}
diff_16 = AX - op1_16;
SET_FLAGS_OSZAPC_16(AX, op1_16, diff_16, BX_INSTR_CMP16);
if (diff_16 == 0) { // if accumulator == dest
// ZF = 1
set_ZF(1);
// dest <-- src
op2_16 = BX_READ_16BIT_REG(i->nnn());
if (i->modC0()) {
BX_WRITE_16BIT_REG(i->rm(), op2_16);
}
else {
Write_RMW_virtual_word(op2_16);
}
}
else {
// ZF = 0
set_ZF(0);
// accumulator <-- dest
AX = op1_16;
}
#else
BX_PANIC(("CMPXCHG_EwGw:"));
#endif
}