fake86_cpu.cpp

/*
  Fake86: A portable, open-source 8086 PC emulator.
  Copyright (C)2010-2012 Mike Chambers

  This program is free software; you can redistribute it and/or
  modify it under the terms of the GNU General Public License
  as published by the Free Software Foundation; either version 2
  of the License, or (at your option) any later version.

  This program 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 General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with this program; if not, write to the Free Software
  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
*/

/* cpu.c: functions to emulate the 8086/V20 CPU in software. the heart of Fake86. */

#include <stdint.h>
#include <stdio.h>

#define CPU_V20
static int x86_cpu_v20;

extern void write_log(const char*,...);


#define regax 0
#define regcx 1
#define regdx 2
#define regbx 3
#define regsp 4
#define regbp 5
#define regsi 6
#define regdi 7
#define reges 0
#define regcs 1
#define regss 2
#define regds 3

#ifdef __BIG_ENDIAN__
#define regal 1
#define regah 0
#define regcl 3
#define regch 2
#define regdl 5
#define regdh 4
#define regbl 7
#define regbh 6
#else
#define regal 0
#define regah 1
#define regcl 2
#define regch 3
#define regdl 4
#define regdh 5
#define regbl 6
#define regbh 7
#endif

union _bytewordregs_ {
	uint16_t wordregs[8];
	uint8_t byteregs[8];
};

#define StepIP(x)	ip += x
#define getmem8(x, y)	read86(segbase(x) + y)
#define getmem16(x, y)	readw86(segbase(x) + y)
#define putmem8(x, y, z)	write86(segbase(x) + y, z)
#define putmem16(x, y, z)	writew86(segbase(x) + y, z)
#define signext(value)	(int16_t)(int8_t)(value)
#define signext32(value)	(int32_t)(int16_t)(value)
#define getreg16(regid)	regs.wordregs[regid]
#define getreg8(regid)	regs.byteregs[byteregtable[regid]]
#define putreg16(regid, writeval)	regs.wordregs[regid] = writeval
#define putreg8(regid, writeval)	regs.byteregs[byteregtable[regid]] = writeval
#define getsegreg(regid)	segregs[regid]
#define putsegreg(regid, writeval)	segregs[regid] = writeval
#define segbase(x)	((uint32_t) x << 4)

#if 0
#include "config.h"
#include <stdint.h>
#include <stdio.h>
#include "cpu.h"
#include "i8259.h"
#include "i8253.h"

extern struct i8253_s i8253;

extern struct structpic i8259;
#endif

uint64_t curtimer, lasttimer, timerfreq;

static uint8_t byteregtable[8] = { regal, regcl, regdl, regbl, regah, regch, regdh, regbh };

static const uint8_t parity[0x100] = {
	1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1, 0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0,
	0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0, 1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1,
	0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0, 1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1,
	1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1, 0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0,
	0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0, 1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1,
	1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1, 0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0,
	1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1, 0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0,
	0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0, 1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1
};

#if 0
uint8_t	RAM[0x100000], readonly[0x100000];
#endif
static uint8_t	opcode, segoverride, reptype, bootdrive = 0, hdcount = 0;
static uint16_t segregs[4], savecs, saveip, ip, useseg, oldsp;
static uint8_t	tempcf, oldcf, cf, pf, af, zf, sf, tf, ifl, df, of, mode, reg, rm;
static uint16_t oper1, oper2, res16, disp16, temp16, dummy, stacksize, frametemp;
static uint8_t	oper1b, oper2b, res8, disp8, temp8, nestlev, addrbyte;
static uint32_t temp1, temp2, temp3, temp4, temp5, temp32, tempaddr32, ea;
static int32_t	result;
static uint64_t totalexec;

#if 0
extern uint16_t	VGA_SC[0x100], VGA_CRTC[0x100], VGA_ATTR[0x100], VGA_GC[0x100];
extern uint8_t updatedscreen;
#endif

static union _bytewordregs_ regs;

#if 0
uint8_t	portram[0x10000];
uint8_t	running = 0, debugmode, showcsip, verbose;
uint8_t	ethif;
#endif
static int verbose = 1;
static int running = 1;

#if 0
extern uint8_t	vidmode;
extern uint8_t verbose;

extern void vidinterrupt();

extern uint8_t readVGA (uint32_t addr32);
#endif

void intcall86 (uint8_t intnum);

#define makeflagsword() \
	( \
	2 | (uint16_t) cf | ((uint16_t) pf << 2) | ((uint16_t) af << 4) | ((uint16_t) zf << 6) | ((uint16_t) sf << 7) | \
	((uint16_t) tf << 8) | ((uint16_t) ifl << 9) | ((uint16_t) df << 10) | ((uint16_t) of << 11) \
	)

#define decodeflagsword(x) { \
	temp16 = x; \
	cf = temp16 & 1; \
	pf = (temp16 >> 2) & 1; \
	af = (temp16 >> 4) & 1; \
	zf = (temp16 >> 6) & 1; \
	sf = (temp16 >> 7) & 1; \
	tf = (temp16 >> 8) & 1; \
	ifl = (temp16 >> 9) & 1; \
	df = (temp16 >> 10) & 1; \
	of = (temp16 >> 11) & 1; \
	}

#if 0
extern void	writeVGA (uint32_t addr32, uint8_t value);
#endif
extern void	portout (uint16_t portnum, uint8_t value);
extern void	portout16 (uint16_t portnum, uint16_t value);
extern uint8_t	portin (uint16_t portnum);
extern uint16_t portin16 (uint16_t portnum);

void write86(uint32_t addr32, uint8_t value);
void writew86(uint32_t addr32, uint16_t value);
uint8_t read86(uint32_t addr32);
uint16_t readw86(uint32_t addr32);

void flag_szp8 (uint8_t value) {
	if (!value) {
			zf = 1;
		}
	else {
			zf = 0;	/* set or clear zero flag */
		}

	if (value & 0x80) {
			sf = 1;
		}
	else {
			sf = 0;	/* set or clear sign flag */
		}

	pf = parity[value]; /* retrieve parity state from lookup table */
}

void flag_szp16 (uint16_t value) {
	if (!value) {
			zf = 1;
		}
	else {
			zf = 0;	/* set or clear zero flag */
		}

	if (value & 0x8000) {
			sf = 1;
		}
	else {
			sf = 0;	/* set or clear sign flag */
		}

	pf = parity[value & 255];	/* retrieve parity state from lookup table */
}

void flag_log8 (uint8_t value) {
	flag_szp8 (value);
	cf = 0;
	of = 0; /* bitwise logic ops always clear carry and overflow */
}

void flag_log16 (uint16_t value) {
	flag_szp16 (value);
	cf = 0;
	of = 0; /* bitwise logic ops always clear carry and overflow */
}

void flag_adc8 (uint8_t v1, uint8_t v2, uint8_t v3) {

	/* v1 = destination operand, v2 = source operand, v3 = carry flag */
	uint16_t	dst;

	dst = (uint16_t) v1 + (uint16_t) v2 + (uint16_t) v3;
	flag_szp8 ( (uint8_t) dst);
	if ( ( (dst ^ v1) & (dst ^ v2) & 0x80) == 0x80) {
			of = 1;
		}
	else {
			of = 0; /* set or clear overflow flag */
		}

	if (dst & 0xFF00) {
			cf = 1;
		}
	else {
			cf = 0; /* set or clear carry flag */
		}

	if ( ( (v1 ^ v2 ^ dst) & 0x10) == 0x10) {
			af = 1;
		}
	else {
			af = 0; /* set or clear auxilliary flag */
		}
}

void flag_adc16 (uint16_t v1, uint16_t v2, uint16_t v3) {

	uint32_t	dst;

	dst = (uint32_t) v1 + (uint32_t) v2 + (uint32_t) v3;
	flag_szp16 ( (uint16_t) dst);
	if ( ( ( (dst ^ v1) & (dst ^ v2) ) & 0x8000) == 0x8000) {
			of = 1;
		}
	else {
			of = 0;
		}

	if (dst & 0xFFFF0000) {
			cf = 1;
		}
	else {
			cf = 0;
		}

	if ( ( (v1 ^ v2 ^ dst) & 0x10) == 0x10) {
			af = 1;
		}
	else {
			af = 0;
		}
}

void flag_add8 (uint8_t v1, uint8_t v2) {
	/* v1 = destination operand, v2 = source operand */
	uint16_t	dst;

	dst = (uint16_t) v1 + (uint16_t) v2;
	flag_szp8 ( (uint8_t) dst);
	if (dst & 0xFF00) {
			cf = 1;
		}
	else {
			cf = 0;
		}

	if ( ( (dst ^ v1) & (dst ^ v2) & 0x80) == 0x80) {
			of = 1;
		}
	else {
			of = 0;
		}

	if ( ( (v1 ^ v2 ^ dst) & 0x10) == 0x10) {
			af = 1;
		}
	else {
			af = 0;
		}
}

void flag_add16 (uint16_t v1, uint16_t v2) {
	/* v1 = destination operand, v2 = source operand */
	uint32_t	dst;

	dst = (uint32_t) v1 + (uint32_t) v2;
	flag_szp16 ( (uint16_t) dst);
	if (dst & 0xFFFF0000) {
			cf = 1;
		}
	else {
			cf = 0;
		}

	if ( ( (dst ^ v1) & (dst ^ v2) & 0x8000) == 0x8000) {
			of = 1;
		}
	else {
			of = 0;
		}

	if ( ( (v1 ^ v2 ^ dst) & 0x10) == 0x10) {
			af = 1;
		}
	else {
			af = 0;
		}
}

void flag_sbb8 (uint8_t v1, uint8_t v2, uint8_t v3) {

	/* v1 = destination operand, v2 = source operand, v3 = carry flag */
	uint16_t	dst;

	v2 += v3;
	dst = (uint16_t) v1 - (uint16_t) v2;
	flag_szp8 ( (uint8_t) dst);
	if (dst & 0xFF00) {
			cf = 1;
		}
	else {
			cf = 0;
		}

	if ( (dst ^ v1) & (v1 ^ v2) & 0x80) {
			of = 1;
		}
	else {
			of = 0;
		}

	if ( (v1 ^ v2 ^ dst) & 0x10) {
			af = 1;
		}
	else {
			af = 0;
		}
}

void flag_sbb16 (uint16_t v1, uint16_t v2, uint16_t v3) {

	/* v1 = destination operand, v2 = source operand, v3 = carry flag */
	uint32_t	dst;

	v2 += v3;
	dst = (uint32_t) v1 - (uint32_t) v2;
	flag_szp16 ( (uint16_t) dst);
	if (dst & 0xFFFF0000) {
			cf = 1;
		}
	else {
			cf = 0;
		}

	if ( (dst ^ v1) & (v1 ^ v2) & 0x8000) {
			of = 1;
		}
	else {
			of = 0;
		}

	if ( (v1 ^ v2 ^ dst) & 0x10) {
			af = 1;
		}
	else {
			af = 0;
		}
}

void flag_sub8 (uint8_t v1, uint8_t v2) {

	/* v1 = destination operand, v2 = source operand */
	uint16_t	dst;

	dst = (uint16_t) v1 - (uint16_t) v2;
	flag_szp8 ( (uint8_t) dst);
	if (dst & 0xFF00) {
			cf = 1;
		}
	else {
			cf = 0;
		}

	if ( (dst ^ v1) & (v1 ^ v2) & 0x80) {
			of = 1;
		}
	else {
			of = 0;
		}

	if ( (v1 ^ v2 ^ dst) & 0x10) {
			af = 1;
		}
	else {
			af = 0;
		}
}

void flag_sub16 (uint16_t v1, uint16_t v2) {

	/* v1 = destination operand, v2 = source operand */
	uint32_t	dst;

	dst = (uint32_t) v1 - (uint32_t) v2;
	flag_szp16 ( (uint16_t) dst);
	if (dst & 0xFFFF0000) {
			cf = 1;
		}
	else {
			cf = 0;
		}

	if ( (dst ^ v1) & (v1 ^ v2) & 0x8000) {
			of = 1;
		}
	else {
			of = 0;
		}

	if ( (v1 ^ v2 ^ dst) & 0x10) {
			af = 1;
		}
	else {
			af = 0;
		}
}

void op_adc8() {
	res8 = oper1b + oper2b + cf;
	flag_adc8 (oper1b, oper2b, cf);
}

void op_adc16() {
	res16 = oper1 + oper2 + cf;
	flag_adc16 (oper1, oper2, cf);
}

void op_add8() {
	res8 = oper1b + oper2b;
	flag_add8 (oper1b, oper2b);
}

void op_add16() {
	res16 = oper1 + oper2;
	flag_add16 (oper1, oper2);
}

void op_and8() {
	res8 = oper1b & oper2b;
	flag_log8 (res8);
}

void op_and16() {
	res16 = oper1 & oper2;
	flag_log16 (res16);
}

void op_or8() {
	res8 = oper1b | oper2b;
	flag_log8 (res8);
}

void op_or16() {
	res16 = oper1 | oper2;
	flag_log16 (res16);
}

void op_xor8() {
	res8 = oper1b ^ oper2b;
	flag_log8 (res8);
}

void op_xor16() {
	res16 = oper1 ^ oper2;
	flag_log16 (res16);
}

void op_sub8() {
	res8 = oper1b - oper2b;
	flag_sub8 (oper1b, oper2b);
}

void op_sub16() {
	res16 = oper1 - oper2;
	flag_sub16 (oper1, oper2);
}

void op_sbb8() {
	res8 = oper1b - (oper2b + cf);
	flag_sbb8 (oper1b, oper2b, cf);
}

void op_sbb16() {
	res16 = oper1 - (oper2 + cf);
	flag_sbb16 (oper1, oper2, cf);
}

#define modregrm() { \
	addrbyte = getmem8(segregs[regcs], ip); \
	StepIP(1); \
	mode = addrbyte >> 6; \
	reg = (addrbyte >> 3) & 7; \
	rm = addrbyte & 7; \
	switch(mode) \
	{ \
	case 0: \
	if(rm == 6) { \
	disp16 = getmem16(segregs[regcs], ip); \
	StepIP(2); \
	} \
	if(((rm == 2) || (rm == 3)) && !segoverride) { \
	useseg = segregs[regss]; \
	} \
	break; \
 \
	case 1: \
	disp16 = signext(getmem8(segregs[regcs], ip)); \
	StepIP(1); \
	if(((rm == 2) || (rm == 3) || (rm == 6)) && !segoverride) { \
	useseg = segregs[regss]; \
	} \
	break; \
 \
	case 2: \
	disp16 = getmem16(segregs[regcs], ip); \
	StepIP(2); \
	if(((rm == 2) || (rm == 3) || (rm == 6)) && !segoverride) { \
	useseg = segregs[regss]; \
	} \
	break; \
 \
	default: \
	disp8 = 0; \
	disp16 = 0; \
	} \
	}

void getea (uint8_t rmval) {
	uint32_t	tempea;

	tempea = 0;
	switch (mode) {
			case 0:
				switch (rmval) {
						case 0:
							tempea = regs.wordregs[regbx] + regs.wordregs[regsi];
							break;
						case 1:
							tempea = regs.wordregs[regbx] + regs.wordregs[regdi];
							break;
						case 2:
							tempea = regs.wordregs[regbp] + regs.wordregs[regsi];
							break;
						case 3:
							tempea = regs.wordregs[regbp] + regs.wordregs[regdi];
							break;
						case 4:
							tempea = regs.wordregs[regsi];
							break;
						case 5:
							tempea = regs.wordregs[regdi];
							break;
						case 6:
							tempea = disp16;
							break;
						case 7:
							tempea = regs.wordregs[regbx];
							break;
					}
				break;

			case 1:
			case 2:
				switch (rmval) {
						case 0:
							tempea = regs.wordregs[regbx] + regs.wordregs[regsi] + disp16;
							break;
						case 1:
							tempea = regs.wordregs[regbx] + regs.wordregs[regdi] + disp16;
							break;
						case 2:
							tempea = regs.wordregs[regbp] + regs.wordregs[regsi] + disp16;
							break;
						case 3:
							tempea = regs.wordregs[regbp] + regs.wordregs[regdi] + disp16;
							break;
						case 4:
							tempea = regs.wordregs[regsi] + disp16;
							break;
						case 5:
							tempea = regs.wordregs[regdi] + disp16;
							break;
						case 6:
							tempea = regs.wordregs[regbp] + disp16;
							break;
						case 7:
							tempea = regs.wordregs[regbx] + disp16;
							break;
					}
				break;
		}

	ea = (tempea & 0xFFFF) + (useseg << 4);
}

void push (uint16_t pushval) {
	putreg16 (regsp, getreg16 (regsp) - 2);
	putmem16 (segregs[regss], getreg16 (regsp), pushval);
}

uint16_t pop() {

	uint16_t	tempval;

	tempval = getmem16 (segregs[regss], getreg16 (regsp) );
	putreg16 (regsp, getreg16 (regsp) + 2);
	return tempval;
}

void reset86(int v20) {
	segregs[regcs] = 0xFFFF;
	ip = 0x0000;
	x86_cpu_v20 = v20;
	//regs.wordregs[regsp] = 0xFFFE;
}

uint16_t readrm16 (uint8_t rmval) {
	if (mode < 3) {
			getea (rmval);
			return read86 (ea) | ( (uint16_t) read86 (ea + 1) << 8);
		}
	else {
			return getreg16 (rmval);
		}
}

uint8_t readrm8 (uint8_t rmval) {
	if (mode < 3) {
			getea (rmval);
			return read86 (ea);
		}
	else {
			return getreg8 (rmval);
		}
}

void writerm16 (uint8_t rmval, uint16_t value) {
	if (mode < 3) {
			getea (rmval);
			write86 (ea, value & 0xFF);
			write86 (ea + 1, value >> 8);
		}
	else {
			putreg16 (rmval, value);
		}
}

void writerm8 (uint8_t rmval, uint8_t value) {
	if (mode < 3) {
			getea (rmval);
			write86 (ea, value);
		}
	else {
			putreg8 (rmval, value);
		}
}

uint8_t op_grp2_8 (uint8_t cnt) {

	uint16_t	s;
	uint16_t	shift;
	uint16_t	oldcf;
	uint16_t	msb;

	s = oper1b;
	oldcf = cf;
	if (x86_cpu_v20)
		cnt &= 0x1F;
	switch (reg) {
			case 0: /* ROL r/m8 */
				for (shift = 1; shift <= cnt; shift++) {
						if (s & 0x80) {
								cf = 1;
							}
						else {
								cf = 0;
							}

						s = s << 1;
						s = s | cf;
					}

				if (cnt == 1) {
						of = cf ^ ( (s >> 7) & 1);
					}
				break;

			case 1: /* ROR r/m8 */
				for (shift = 1; shift <= cnt; shift++) {
						cf = s & 1;
						s = (s >> 1) | (cf << 7);
					}

				if (cnt == 1) {
						of = (s >> 7) ^ ( (s >> 6) & 1);
					}
				break;

			case 2: /* RCL r/m8 */
				for (shift = 1; shift <= cnt; shift++) {
						oldcf = cf;
						if (s & 0x80) {
								cf = 1;
							}
						else {
								cf = 0;
							}

						s = s << 1;
						s = s | oldcf;
					}

				if (cnt == 1) {
						of = cf ^ ( (s >> 7) & 1);
					}
				break;

			case 3: /* RCR r/m8 */
				for (shift = 1; shift <= cnt; shift++) {
						oldcf = cf;
						cf = s & 1;
						s = (s >> 1) | (oldcf << 7);
					}

				if (cnt == 1) {
						of = (s >> 7) ^ ( (s >> 6) & 1);
					}
				break;

			case 4:
			case 6: /* SHL r/m8 */
				for (shift = 1; shift <= cnt; shift++) {
						if (s & 0x80) {
								cf = 1;
							}
						else {
								cf = 0;
							}

						s = (s << 1) & 0xFF;
					}

				if ( (cnt == 1) && (cf == (s >> 7) ) ) {
						of = 0;
					}
				else {
						of = 1;
					}

				flag_szp8 ( (uint8_t) s);
				break;

			case 5: /* SHR r/m8 */
				if ( (cnt == 1) && (s & 0x80) ) {
						of = 1;
					}
				else {
						of = 0;
					}

				for (shift = 1; shift <= cnt; shift++) {
						cf = s & 1;
						s = s >> 1;
					}

				flag_szp8 ( (uint8_t) s);
				break;

			case 7: /* SAR r/m8 */
				for (shift = 1; shift <= cnt; shift++) {
						msb = s & 0x80;
						cf = s & 1;
						s = (s >> 1) | msb;
					}

				of = 0;
				flag_szp8 ( (uint8_t) s);
				break;
		}

	return s & 0xFF;
}

uint16_t op_grp2_16 (uint8_t cnt) {

	uint32_t	s;
	uint32_t	shift;
	uint32_t	oldcf;
	uint32_t	msb;

	s = oper1;
	oldcf = cf;
	if (x86_cpu_v20)
		cnt &= 0x1F;
	switch (reg) {
			case 0: /* ROL r/m8 */
				for (shift = 1; shift <= cnt; shift++) {
						if (s & 0x8000) {
								cf = 1;
							}
						else {
								cf = 0;
							}

						s = s << 1;
						s = s | cf;
					}

				if (cnt == 1) {
						of = cf ^ ( (s >> 15) & 1);
					}
				break;

			case 1: /* ROR r/m8 */
				for (shift = 1; shift <= cnt; shift++) {
						cf = s & 1;
						s = (s >> 1) | (cf << 15);
					}

				if (cnt == 1) {
						of = (s >> 15) ^ ( (s >> 14) & 1);
					}
				break;

			case 2: /* RCL r/m8 */
				for (shift = 1; shift <= cnt; shift++) {
						oldcf = cf;
						if (s & 0x8000) {
								cf = 1;
							}
						else {
								cf = 0;
							}

						s = s << 1;
						s = s | oldcf;
					}

				if (cnt == 1) {
						of = cf ^ ( (s >> 15) & 1);
					}
				break;

			case 3: /* RCR r/m8 */
				for (shift = 1; shift <= cnt; shift++) {
						oldcf = cf;
						cf = s & 1;
						s = (s >> 1) | (oldcf << 15);
					}

				if (cnt == 1) {
						of = (s >> 15) ^ ( (s >> 14) & 1);
					}
				break;

			case 4:
			case 6: /* SHL r/m8 */
				for (shift = 1; shift <= cnt; shift++) {
						if (s & 0x8000) {
								cf = 1;
							}
						else {
								cf = 0;
							}

						s = (s << 1) & 0xFFFF;
					}

				if ( (cnt == 1) && (cf == (s >> 15) ) ) {
						of = 0;
					}
				else {
						of = 1;
					}

				flag_szp16 ( (uint16_t) s);
				break;

			case 5: /* SHR r/m8 */
				if ( (cnt == 1) && (s & 0x8000) ) {
						of = 1;
					}
				else {
						of = 0;
					}

				for (shift = 1; shift <= cnt; shift++) {
						cf = s & 1;
						s = s >> 1;
					}

				flag_szp16 ( (uint16_t) s);
				break;

			case 7: /* SAR r/m8 */
				for (shift = 1; shift <= cnt; shift++) {
						msb = s & 0x8000;
						cf = s & 1;
						s = (s >> 1) | msb;
					}

				of = 0;
				flag_szp16 ( (uint16_t) s);
				break;
		}

	return (uint16_t) s & 0xFFFF;
}

void op_div8 (uint16_t valdiv, uint8_t divisor) {
	if (divisor == 0) {
			intcall86 (0);
			return;
		}

	if ( (valdiv / (uint16_t) divisor) > 0xFF) {
			intcall86 (0);
			return;
		}

	regs.byteregs[regah] = valdiv % (uint16_t) divisor;
	regs.byteregs[regal] = valdiv / (uint16_t) divisor;
}

void op_idiv8 (uint16_t valdiv, uint8_t divisor) {

	uint16_t	s1;
	uint16_t	s2;
	uint16_t	d1;
	uint16_t	d2;
	int	sign;

	if (divisor == 0) {
			intcall86 (0);
			return;
		}

	s1 = valdiv;
	s2 = divisor;
	sign = ( ( (s1 ^ s2) & 0x8000) != 0);
	s1 = (s1 < 0x8000) ? s1 : ( (~s1 + 1) & 0xffff);
	s2 = (s2 < 0x8000) ? s2 : ( (~s2 + 1) & 0xffff);
	d1 = s1 / s2;
	d2 = s1 % s2;
	if (d1 & 0xFF00) {
			intcall86 (0);
			return;
		}

	if (sign) {
			d1 = (~d1 + 1) & 0xff;
			d2 = (~d2 + 1) & 0xff;
		}

	regs.byteregs[regah] = (uint8_t) d2;
	regs.byteregs[regal] = (uint8_t) d1;
}

void op_grp3_8() {
	oper1 = signext (oper1b);
	oper2 = signext (oper2b);
	switch (reg) {
			case 0:
			case 1: /* TEST */
				flag_log8 (oper1b & getmem8 (segregs[regcs], ip) );
				StepIP (1);
				break;

			case 2: /* NOT */
				res8 = ~oper1b;
				break;

			case 3: /* NEG */
				res8 = (~oper1b) + 1;
				flag_sub8 (0, oper1b);
				if (res8 == 0) {
						cf = 0;
					}
				else {
						cf = 1;
					}
				break;

			case 4: /* MUL */
				temp1 = (uint32_t) oper1b * (uint32_t) regs.byteregs[regal];
				putreg16 (regax, temp1 & 0xFFFF);
				flag_szp8 ( (uint8_t) temp1);
				if (regs.byteregs[regah]) {
						cf = 1;
						of = 1;
					}
				else {
						cf = 0;
						of = 0;
					}

				if (!x86_cpu_v20)
					zf = 0;
				break;

			case 5: /* IMUL */
				oper1 = signext (oper1b);
				temp1 = signext (regs.byteregs[regal]);
				temp2 = oper1;
				if ( (temp1 & 0x80) == 0x80) {
						temp1 = temp1 | 0xFFFFFF00;
					}

				if ( (temp2 & 0x80) == 0x80) {
						temp2 = temp2 | 0xFFFFFF00;
					}

				temp3 = (temp1 * temp2) & 0xFFFF;
				putreg16 (regax, temp3 & 0xFFFF);
				if (regs.byteregs[regah]) {
						cf = 1;
						of = 1;
					}
				else {
						cf = 0;
						of = 0;
					}
				if (!x86_cpu_v20)
					zf = 0;
				break;

			case 6: /* DIV */
				op_div8 (getreg16 (regax), oper1b);
				break;

			case 7: /* IDIV */
				op_idiv8 (getreg16 (regax), oper1b);
				break;
		}
}

void op_div16 (uint32_t valdiv, uint16_t divisor) {
	if (divisor == 0) {
			intcall86 (0);
			return;
		}

	if ( (valdiv / (uint32_t) divisor) > 0xFFFF) {
			intcall86 (0);
			return;
		}

	putreg16 (regdx, valdiv % (uint32_t) divisor);
	putreg16 (regax, valdiv / (uint32_t) divisor);
}

void op_idiv16 (uint32_t valdiv, uint16_t divisor) {

	uint32_t	d1;
	uint32_t	d2;
	uint32_t	s1;
	uint32_t	s2;
	int	sign;

	if (divisor == 0) {
			intcall86 (0);
			return;
		}

	s1 = valdiv;
	s2 = divisor;
	s2 = (s2 & 0x8000) ? (s2 | 0xffff0000) : s2;
	sign = ( ( (s1 ^ s2) & 0x80000000) != 0);
	s1 = (s1 < 0x80000000) ? s1 : ( (~s1 + 1) & 0xffffffff);
	s2 = (s2 < 0x80000000) ? s2 : ( (~s2 + 1) & 0xffffffff);
	d1 = s1 / s2;
	d2 = s1 % s2;
	if (d1 & 0xFFFF0000) {
			intcall86 (0);
			return;
		}

	if (sign) {
			d1 = (~d1 + 1) & 0xffff;
			d2 = (~d2 + 1) & 0xffff;
		}

	putreg16 (regax, d1);
	putreg16 (regdx, d2);
}

void op_grp3_16() {
	switch (reg) {
			case 0:
			case 1: /* TEST */
				flag_log16 (oper1 & getmem16 (segregs[regcs], ip) );
				StepIP (2);
				break;

			case 2: /* NOT */
				res16 = ~oper1;
				break;

			case 3: /* NEG */
				res16 = (~oper1) + 1;
				flag_sub16 (0, oper1);
				if (res16) {
						cf = 1;
					}
				else {
						cf = 0;
					}
				break;

			case 4: /* MUL */
				temp1 = (uint32_t) oper1 * (uint32_t) getreg16 (regax);
				putreg16 (regax, temp1 & 0xFFFF);
				putreg16 (regdx, temp1 >> 16);
				flag_szp16 ( (uint16_t) temp1);
				if (getreg16 (regdx) ) {
						cf = 1;
						of = 1;
					}
				else {
						cf = 0;
						of = 0;
					}
				if (!x86_cpu_v20)
					zf = 0;
				break;

			case 5: /* IMUL */
				temp1 = getreg16 (regax);
				temp2 = oper1;
				if (temp1 & 0x8000) {
						temp1 |= 0xFFFF0000;
					}

				if (temp2 & 0x8000) {
						temp2 |= 0xFFFF0000;
					}

				temp3 = temp1 * temp2;
				putreg16 (regax, temp3 & 0xFFFF);	/* into register ax */
				putreg16 (regdx, temp3 >> 16);	/* into register dx */
				if (getreg16 (regdx) ) {
						cf = 1;
						of = 1;
					}
				else {
						cf = 0;
						of = 0;
					}
				if (!x86_cpu_v20)
					zf = 0;
				break;

			case 6: /* DIV */
				op_div16 ( ( (uint32_t) getreg16 (regdx) << 16) + getreg16 (regax), oper1);
				break;

			case 7: /* DIV */
				op_idiv16 ( ( (uint32_t) getreg16 (regdx) << 16) + getreg16 (regax), oper1);
				break;
		}
}

void op_grp5() {
	switch (reg) {
			case 0: /* INC Ev */
				oper2 = 1;
				tempcf = cf;
				op_add16();
				cf = tempcf;
				writerm16 (rm, res16);
				break;

			case 1: /* DEC Ev */
				oper2 = 1;
				tempcf = cf;
				op_sub16();
				cf = tempcf;
				writerm16 (rm, res16);
				break;

			case 2: /* CALL Ev */
				push (ip);
				ip = oper1;
				break;

			case 3: /* CALL Mp */
				push (segregs[regcs]);
				push (ip);
				getea (rm);
				ip = (uint16_t) read86 (ea) + (uint16_t) read86 (ea + 1) * 256;
				segregs[regcs] = (uint16_t) read86 (ea + 2) + (uint16_t) read86 (ea + 3) * 256;
				break;

			case 4: /* JMP Ev */
				ip = oper1;
				break;

			case 5: /* JMP Mp */
				getea (rm);
				ip = (uint16_t) read86 (ea) + (uint16_t) read86 (ea + 1) * 256;
				segregs[regcs] = (uint16_t) read86 (ea + 2) + (uint16_t) read86 (ea + 3) * 256;
				break;

			case 6: /* PUSH Ev */
				push (oper1);
				break;
		}
}

#if 0
uint8_t dolog = 0, didintr = 0;
FILE	*logout;
uint8_t printops = 0;
#endif

#ifdef NETWORKING_ENABLED
extern void nethandler();
#endif
#if 0
extern void diskhandler();
extern void readdisk(uint8_t drivenum, uint16_t dstseg, uint16_t dstoff, uint16_t cyl, uint16_t sect, uint16_t head, uint16_t sectcount);
#endif

void intcall86(uint8_t intnum)
{
#if 0
	static uint16_t lastint10ax;
	uint16_t oldregax;

	didintr = 1;

	if (intnum == 0x19) didbootstrap = 1;

	switch (intnum) {
		case 0x10:
		updatedscreen = 1;
		if ((regs.byteregs[regah] == 0x00) || (regs.byteregs[regah] == 0x10)) {
			oldregax = regs.wordregs[regax];
			vidinterrupt();
			regs.wordregs[regax] = oldregax;
			if (regs.byteregs[regah] == 0x10) return;
			if (vidmode == 9) return;
		}
		if ((regs.byteregs[regah] == 0x1A) && (lastint10ax != 0x0100)) { //the 0x0100 is a cheap hack to make it not do this if DOS EDIT/QBASIC
			regs.byteregs[regal] = 0x1A;
			regs.byteregs[regbl] = 0x8;
			return;
		}
		lastint10ax = regs.wordregs[regax];
		break;
#ifndef DISK_CONTROLLER_ATA
		case 0x19: //bootstrap
		if (bootdrive<255) { //read first sector of boot drive into 07C0:0000 and execute it
			regs.byteregs[regdl] = bootdrive;
			readdisk(regs.byteregs[regdl], 0x07C0, 0x0000, 0, 1, 0, 1);
			segregs[regcs] = 0x0000;
			ip = 0x7C00;
		} else {
			segregs[regcs] = 0xF600;	//start ROM BASIC at bootstrap if requested
			ip = 0x0000;
		}
		return;

		case 0x13:
		case 0xFD:
		diskhandler();
		return;
#endif
#ifdef NETWORKING_OLDCARD
		case 0xFC:
#ifdef NETWORKING_ENABLED
		nethandler();
#endif
		return;
#endif
	}
#endif

	push(makeflagsword());
	push(segregs[regcs]);
	push(ip);
	segregs[regcs] = getmem16(0, (uint16_t)intnum * 4 + 2);
	ip = getmem16(0, (uint16_t)intnum * 4);
	ifl = 0;
	tf = 0;
}


#if defined(NETWORKING_ENABLED)
extern struct netstruct {
	uint8_t	enabled;
	uint8_t	canrecv;
	uint16_t	pktlen;
} net;
#endif
#if 0
uint64_t	frametimer = 0, didwhen = 0, didticks = 0;
uint32_t	makeupticks = 0;
extern float	timercomp;
uint64_t	timerticks = 0, realticks = 0;
#endif
uint64_t	lastcountertimer = 0, counterticks = 10000;
//extern uint8_t	nextintr();
//extern void	timing();

extern void check_x86_irq(void);

void exec86 (uint32_t execloops) {

	uint32_t	loopcount;
	uint8_t	docontinue;
	static uint16_t firstip;
	static uint16_t trap_toggle = 0;

	counterticks = (uint64_t) ( (double) timerfreq / (double) 65536.0);

	for (loopcount = 0; loopcount < execloops; loopcount++) {

			//if ( (totalexec & 31) == 0) timing();

			if (trap_toggle) {
					intcall86 (1);
				}

			if (tf) {
					trap_toggle = 1;
				}
			else {
					trap_toggle = 0;
				}

			if (!trap_toggle && ifl)
				check_x86_irq();

			reptype = 0;
			segoverride = 0;
			useseg = segregs[regds];
			docontinue = 0;
			firstip = ip;

#if 0
			if ( (segregs[regcs] == 0xF000) && (ip == 0xE066) ) didbootstrap = 0; //detect if we hit the BIOS entry point to clear didbootstrap because we've rebooted
#endif

			while (!docontinue) {
					segregs[regcs] = segregs[regcs] & 0xFFFF;
					ip = ip & 0xFFFF;
					savecs = segregs[regcs];
					saveip = ip;
					opcode = getmem8 (segregs[regcs], ip);
					StepIP (1);

					switch (opcode) {
								/* segment prefix check */
							case 0x2E:	/* segment segregs[regcs] */
								useseg = segregs[regcs];
								segoverride = 1;
								break;

							case 0x3E:	/* segment segregs[regds] */
								useseg = segregs[regds];
								segoverride = 1;
								break;

							case 0x26:	/* segment segregs[reges] */
								useseg = segregs[reges];
								segoverride = 1;
								break;

							case 0x36:	/* segment segregs[regss] */
								useseg = segregs[regss];
								segoverride = 1;
								break;

								/* repetition prefix check */
							case 0xF3:	/* REP/REPE/REPZ */
								reptype = 1;
								break;

							case 0xF2:	/* REPNE/REPNZ */
								reptype = 2;
								break;

							default:
								docontinue = 1;
								break;
						}
				}

			totalexec++;

			/*
			 * if (printops == 1) { printf("%04X:%04X - %s\n", savecs, saveip, oplist[opcode]);
			 * }
			 */
			switch (opcode) {
					case 0x0:	/* 00 ADD Eb Gb */
						modregrm();
						oper1b = readrm8 (rm);
						oper2b = getreg8 (reg);
						op_add8();
						writerm8 (rm, res8);
						break;

					case 0x1:	/* 01 ADD Ev Gv */
						modregrm();
						oper1 = readrm16 (rm);
						oper2 = getreg16 (reg);
						op_add16();
						writerm16 (rm, res16);
						break;

					case 0x2:	/* 02 ADD Gb Eb */
						modregrm();
						oper1b = getreg8 (reg);
						oper2b = readrm8 (rm);
						op_add8();
						putreg8 (reg, res8);
						break;

					case 0x3:	/* 03 ADD Gv Ev */
						modregrm();
						oper1 = getreg16 (reg);
						oper2 = readrm16 (rm);
						op_add16();
						putreg16 (reg, res16);
						break;

					case 0x4:	/* 04 ADD regs.byteregs[regal] Ib */
						oper1b = regs.byteregs[regal];
						oper2b = getmem8 (segregs[regcs], ip);
						StepIP (1);
						op_add8();
						regs.byteregs[regal] = res8;
						break;

					case 0x5:	/* 05 ADD eAX Iv */
						oper1 = (getreg16 (regax) );
						oper2 = getmem16 (segregs[regcs], ip);
						StepIP (2);
						op_add16();
						putreg16 (regax, res16);
						break;

					case 0x6:	/* 06 PUSH segregs[reges] */
						push (segregs[reges]);
						break;

					case 0x7:	/* 07 POP segregs[reges] */
						segregs[reges] = pop();
						break;

					case 0x8:	/* 08 OR Eb Gb */
						modregrm();
						oper1b = readrm8 (rm);
						oper2b = getreg8 (reg);
						op_or8();
						writerm8 (rm, res8);
						break;

					case 0x9:	/* 09 OR Ev Gv */
						modregrm();
						oper1 = readrm16 (rm);
						oper2 = getreg16 (reg);
						op_or16();
						writerm16 (rm, res16);
						break;

					case 0xA:	/* 0A OR Gb Eb */
						modregrm();
						oper1b = getreg8 (reg);
						oper2b = readrm8 (rm);
						op_or8();
						putreg8 (reg, res8);
						break;

					case 0xB:	/* 0B OR Gv Ev */
						modregrm();
						oper1 = getreg16 (reg);
						oper2 = readrm16 (rm);
						op_or16();
						if ( (oper1 == 0xF802) && (oper2 == 0xF802) ) {
								sf = 0;	/* cheap hack to make Wolf 3D think we're a 286 so it plays */
							}

						putreg16 (reg, res16);
						break;

					case 0xC:	/* 0C OR regs.byteregs[regal] Ib */
						oper1b = regs.byteregs[regal];
						oper2b = getmem8 (segregs[regcs], ip);
						StepIP (1);
						op_or8();
						regs.byteregs[regal] = res8;
						break;

					case 0xD:	/* 0D OR eAX Iv */
						oper1 = getreg16 (regax);
						oper2 = getmem16 (segregs[regcs], ip);
						StepIP (2);
						op_or16();
						putreg16 (regax, res16);
						break;

					case 0xE:	/* 0E PUSH segregs[regcs] */
						push (segregs[regcs]);
						break;

					case 0xF: //0F POP CS
						if (!x86_cpu_v20)
							segregs[regcs] = pop();
						break;

					case 0x10:	/* 10 ADC Eb Gb */
						modregrm();
						oper1b = readrm8 (rm);
						oper2b = getreg8 (reg);
						op_adc8();
						writerm8 (rm, res8);
						break;

					case 0x11:	/* 11 ADC Ev Gv */
						modregrm();
						oper1 = readrm16 (rm);
						oper2 = getreg16 (reg);
						op_adc16();
						writerm16 (rm, res16);
						break;

					case 0x12:	/* 12 ADC Gb Eb */
						modregrm();
						oper1b = getreg8 (reg);
						oper2b = readrm8 (rm);
						op_adc8();
						putreg8 (reg, res8);
						break;

					case 0x13:	/* 13 ADC Gv Ev */
						modregrm();
						oper1 = getreg16 (reg);
						oper2 = readrm16 (rm);
						op_adc16();
						putreg16 (reg, res16);
						break;

					case 0x14:	/* 14 ADC regs.byteregs[regal] Ib */
						oper1b = regs.byteregs[regal];
						oper2b = getmem8 (segregs[regcs], ip);
						StepIP (1);
						op_adc8();
						regs.byteregs[regal] = res8;
						break;

					case 0x15:	/* 15 ADC eAX Iv */
						oper1 = getreg16 (regax);
						oper2 = getmem16 (segregs[regcs], ip);
						StepIP (2);
						op_adc16();
						putreg16 (regax, res16);
						break;

					case 0x16:	/* 16 PUSH segregs[regss] */
						push (segregs[regss]);
						break;

					case 0x17:	/* 17 POP segregs[regss] */
						segregs[regss] = pop();
						break;

					case 0x18:	/* 18 SBB Eb Gb */
						modregrm();
						oper1b = readrm8 (rm);
						oper2b = getreg8 (reg);
						op_sbb8();
						writerm8 (rm, res8);
						break;

					case 0x19:	/* 19 SBB Ev Gv */
						modregrm();
						oper1 = readrm16 (rm);
						oper2 = getreg16 (reg);
						op_sbb16();
						writerm16 (rm, res16);
						break;

					case 0x1A:	/* 1A SBB Gb Eb */
						modregrm();
						oper1b = getreg8 (reg);
						oper2b = readrm8 (rm);
						op_sbb8();
						putreg8 (reg, res8);
						break;

					case 0x1B:	/* 1B SBB Gv Ev */
						modregrm();
						oper1 = getreg16 (reg);
						oper2 = readrm16 (rm);
						op_sbb16();
						putreg16 (reg, res16);
						break;

					case 0x1C:	/* 1C SBB regs.byteregs[regal] Ib */
						oper1b = regs.byteregs[regal];
						oper2b = getmem8 (segregs[regcs], ip);
						StepIP (1);
						op_sbb8();
						regs.byteregs[regal] = res8;
						break;

					case 0x1D:	/* 1D SBB eAX Iv */
						oper1 = getreg16 (regax);
						oper2 = getmem16 (segregs[regcs], ip);
						StepIP (2);
						op_sbb16();
						putreg16 (regax, res16);
						break;

					case 0x1E:	/* 1E PUSH segregs[regds] */
						push (segregs[regds]);
						break;

					case 0x1F:	/* 1F POP segregs[regds] */
						segregs[regds] = pop();
						break;

					case 0x20:	/* 20 AND Eb Gb */
						modregrm();
						oper1b = readrm8 (rm);
						oper2b = getreg8 (reg);
						op_and8();
						writerm8 (rm, res8);
						break;

					case 0x21:	/* 21 AND Ev Gv */
						modregrm();
						oper1 = readrm16 (rm);
						oper2 = getreg16 (reg);
						op_and16();
						writerm16 (rm, res16);
						break;

					case 0x22:	/* 22 AND Gb Eb */
						modregrm();
						oper1b = getreg8 (reg);
						oper2b = readrm8 (rm);
						op_and8();
						putreg8 (reg, res8);
						break;

					case 0x23:	/* 23 AND Gv Ev */
						modregrm();
						oper1 = getreg16 (reg);
						oper2 = readrm16 (rm);
						op_and16();
						putreg16 (reg, res16);
						break;

					case 0x24:	/* 24 AND regs.byteregs[regal] Ib */
						oper1b = regs.byteregs[regal];
						oper2b = getmem8 (segregs[regcs], ip);
						StepIP (1);
						op_and8();
						regs.byteregs[regal] = res8;
						break;

					case 0x25:	/* 25 AND eAX Iv */
						oper1 = getreg16 (regax);
						oper2 = getmem16 (segregs[regcs], ip);
						StepIP (2);
						op_and16();
						putreg16 (regax, res16);
						break;

					case 0x27:	/* 27 DAA */
						if ( ( (regs.byteregs[regal] & 0xF) > 9) || (af == 1) ) {
								oper1 = regs.byteregs[regal] + 6;
								regs.byteregs[regal] = oper1 & 255;
								if (oper1 & 0xFF00) {
										cf = 1;
									}
								else {
										cf = 0;
									}

								af = 1;
							}
						else {
								af = 0;
							}

						if ( ( (regs.byteregs[regal] & 0xF0) > 0x90) || (cf == 1) ) {
								regs.byteregs[regal] = regs.byteregs[regal] + 0x60;
								cf = 1;
							}
						else {
								cf = 0;
							}

						regs.byteregs[regal] = regs.byteregs[regal] & 255;
						flag_szp8 (regs.byteregs[regal]);
						break;

					case 0x28:	/* 28 SUB Eb Gb */
						modregrm();
						oper1b = readrm8 (rm);
						oper2b = getreg8 (reg);
						op_sub8();
						writerm8 (rm, res8);
						break;

					case 0x29:	/* 29 SUB Ev Gv */
						modregrm();
						oper1 = readrm16 (rm);
						oper2 = getreg16 (reg);
						op_sub16();
						writerm16 (rm, res16);
						break;

					case 0x2A:	/* 2A SUB Gb Eb */
						modregrm();
						oper1b = getreg8 (reg);
						oper2b = readrm8 (rm);
						op_sub8();
						putreg8 (reg, res8);
						break;

					case 0x2B:	/* 2B SUB Gv Ev */
						modregrm();
						oper1 = getreg16 (reg);
						oper2 = readrm16 (rm);
						op_sub16();
						putreg16 (reg, res16);
						break;

					case 0x2C:	/* 2C SUB regs.byteregs[regal] Ib */
						oper1b = regs.byteregs[regal];
						oper2b = getmem8 (segregs[regcs], ip);
						StepIP (1);
						op_sub8();
						regs.byteregs[regal] = res8;
						break;

					case 0x2D:	/* 2D SUB eAX Iv */
						oper1 = getreg16 (regax);
						oper2 = getmem16 (segregs[regcs], ip);
						StepIP (2);
						op_sub16();
						putreg16 (regax, res16);
						break;

					case 0x2F:	/* 2F DAS */
						if ( ( (regs.byteregs[regal] & 15) > 9) || (af == 1) ) {
								oper1 = regs.byteregs[regal] - 6;
								regs.byteregs[regal] = oper1 & 255;
								if (oper1 & 0xFF00) {
										cf = 1;
									}
								else {
										cf = 0;
									}

								af = 1;
							}
						else {
								af = 0;
							}

						if ( ( (regs.byteregs[regal] & 0xF0) > 0x90) || (cf == 1) ) {
								regs.byteregs[regal] = regs.byteregs[regal] - 0x60;
								cf = 1;
							}
						else {
								cf = 0;
							}

						flag_szp8 (regs.byteregs[regal]);
						break;

					case 0x30:	/* 30 XOR Eb Gb */
						modregrm();
						oper1b = readrm8 (rm);
						oper2b = getreg8 (reg);
						op_xor8();
						writerm8 (rm, res8);
						break;

					case 0x31:	/* 31 XOR Ev Gv */
						modregrm();
						oper1 = readrm16 (rm);
						oper2 = getreg16 (reg);
						op_xor16();
						writerm16 (rm, res16);
						break;

					case 0x32:	/* 32 XOR Gb Eb */
						modregrm();
						oper1b = getreg8 (reg);
						oper2b = readrm8 (rm);
						op_xor8();
						putreg8 (reg, res8);
						break;

					case 0x33:	/* 33 XOR Gv Ev */
						modregrm();
						oper1 = getreg16 (reg);
						oper2 = readrm16 (rm);
						op_xor16();
						putreg16 (reg, res16);
						break;

					case 0x34:	/* 34 XOR regs.byteregs[regal] Ib */
						oper1b = regs.byteregs[regal];
						oper2b = getmem8 (segregs[regcs], ip);
						StepIP (1);
						op_xor8();
						regs.byteregs[regal] = res8;
						break;

					case 0x35:	/* 35 XOR eAX Iv */
						oper1 = getreg16 (regax);
						oper2 = getmem16 (segregs[regcs], ip);
						StepIP (2);
						op_xor16();
						putreg16 (regax, res16);
						break;

					case 0x37:	/* 37 AAA ASCII */
						if ( ( (regs.byteregs[regal] & 0xF) > 9) || (af == 1) ) {
								regs.byteregs[regal] = regs.byteregs[regal] + 6;
								regs.byteregs[regah] = regs.byteregs[regah] + 1;
								af = 1;
								cf = 1;
							}
						else {
								af = 0;
								cf = 0;
							}

						regs.byteregs[regal] = regs.byteregs[regal] & 0xF;
						break;

					case 0x38:	/* 38 CMP Eb Gb */
						modregrm();
						oper1b = readrm8 (rm);
						oper2b = getreg8 (reg);
						flag_sub8 (oper1b, oper2b);
						break;

					case 0x39:	/* 39 CMP Ev Gv */
						modregrm();
						oper1 = readrm16 (rm);
						oper2 = getreg16 (reg);
						flag_sub16 (oper1, oper2);
						break;

					case 0x3A:	/* 3A CMP Gb Eb */
						modregrm();
						oper1b = getreg8 (reg);
						oper2b = readrm8 (rm);
						flag_sub8 (oper1b, oper2b);
						break;

					case 0x3B:	/* 3B CMP Gv Ev */
						modregrm();
						oper1 = getreg16 (reg);
						oper2 = readrm16 (rm);
						flag_sub16 (oper1, oper2);
						break;

					case 0x3C:	/* 3C CMP regs.byteregs[regal] Ib */
						oper1b = regs.byteregs[regal];
						oper2b = getmem8 (segregs[regcs], ip);
						StepIP (1);
						flag_sub8 (oper1b, oper2b);
						break;

					case 0x3D:	/* 3D CMP eAX Iv */
						oper1 = getreg16 (regax);
						oper2 = getmem16 (segregs[regcs], ip);
						StepIP (2);
						flag_sub16 (oper1, oper2);
						break;

					case 0x3F:	/* 3F AAS ASCII */
						if ( ( (regs.byteregs[regal] & 0xF) > 9) || (af == 1) ) {
								regs.byteregs[regal] = regs.byteregs[regal] - 6;
								regs.byteregs[regah] = regs.byteregs[regah] - 1;
								af = 1;
								cf = 1;
							}
						else {
								af = 0;
								cf = 0;
							}

						regs.byteregs[regal] = regs.byteregs[regal] & 0xF;
						break;

					case 0x40:	/* 40 INC eAX */
						oldcf = cf;
						oper1 = getreg16 (regax);
						oper2 = 1;
						op_add16();
						cf = oldcf;
						putreg16 (regax, res16);
						break;

					case 0x41:	/* 41 INC eCX */
						oldcf = cf;
						oper1 = getreg16 (regcx);
						oper2 = 1;
						op_add16();
						cf = oldcf;
						putreg16 (regcx, res16);
						break;

					case 0x42:	/* 42 INC eDX */
						oldcf = cf;
						oper1 = getreg16 (regdx);
						oper2 = 1;
						op_add16();
						cf = oldcf;
						putreg16 (regdx, res16);
						break;

					case 0x43:	/* 43 INC eBX */
						oldcf = cf;
						oper1 = getreg16 (regbx);
						oper2 = 1;
						op_add16();
						cf = oldcf;
						putreg16 (regbx, res16);
						break;

					case 0x44:	/* 44 INC eSP */
						oldcf = cf;
						oper1 = getreg16 (regsp);
						oper2 = 1;
						op_add16();
						cf = oldcf;
						putreg16 (regsp, res16);
						break;

					case 0x45:	/* 45 INC eBP */
						oldcf = cf;
						oper1 = getreg16 (regbp);
						oper2 = 1;
						op_add16();
						cf = oldcf;
						putreg16 (regbp, res16);
						break;

					case 0x46:	/* 46 INC eSI */
						oldcf = cf;
						oper1 = getreg16 (regsi);
						oper2 = 1;
						op_add16();
						cf = oldcf;
						putreg16 (regsi, res16);
						break;

					case 0x47:	/* 47 INC eDI */
						oldcf = cf;
						oper1 = getreg16 (regdi);
						oper2 = 1;
						op_add16();
						cf = oldcf;
						putreg16 (regdi, res16);
						break;

					case 0x48:	/* 48 DEC eAX */
						oldcf = cf;
						oper1 = getreg16 (regax);
						oper2 = 1;
						op_sub16();
						cf = oldcf;
						putreg16 (regax, res16);
						break;

					case 0x49:	/* 49 DEC eCX */
						oldcf = cf;
						oper1 = getreg16 (regcx);
						oper2 = 1;
						op_sub16();
						cf = oldcf;
						putreg16 (regcx, res16);
						break;

					case 0x4A:	/* 4A DEC eDX */
						oldcf = cf;
						oper1 = getreg16 (regdx);
						oper2 = 1;
						op_sub16();
						cf = oldcf;
						putreg16 (regdx, res16);
						break;

					case 0x4B:	/* 4B DEC eBX */
						oldcf = cf;
						oper1 = getreg16 (regbx);
						oper2 = 1;
						op_sub16();
						cf = oldcf;
						putreg16 (regbx, res16);
						break;

					case 0x4C:	/* 4C DEC eSP */
						oldcf = cf;
						oper1 = getreg16 (regsp);
						oper2 = 1;
						op_sub16();
						cf = oldcf;
						putreg16 (regsp, res16);
						break;

					case 0x4D:	/* 4D DEC eBP */
						oldcf = cf;
						oper1 = getreg16 (regbp);
						oper2 = 1;
						op_sub16();
						cf = oldcf;
						putreg16 (regbp, res16);
						break;

					case 0x4E:	/* 4E DEC eSI */
						oldcf = cf;
						oper1 = getreg16 (regsi);
						oper2 = 1;
						op_sub16();
						cf = oldcf;
						putreg16 (regsi, res16);
						break;

					case 0x4F:	/* 4F DEC eDI */
						oldcf = cf;
						oper1 = getreg16 (regdi);
						oper2 = 1;
						op_sub16();
						cf = oldcf;
						putreg16 (regdi, res16);
						break;

					case 0x50:	/* 50 PUSH eAX */
						push (getreg16 (regax) );
						break;

					case 0x51:	/* 51 PUSH eCX */
						push (getreg16 (regcx) );
						break;

					case 0x52:	/* 52 PUSH eDX */
						push (getreg16 (regdx) );
						break;

					case 0x53:	/* 53 PUSH eBX */
						push (getreg16 (regbx) );
						break;

					case 0x54:	/* 54 PUSH eSP */
						push (getreg16 (regsp) - 2);
						break;

					case 0x55:	/* 55 PUSH eBP */
						push (getreg16 (regbp) );
						break;

					case 0x56:	/* 56 PUSH eSI */
						push (getreg16 (regsi) );
						break;

					case 0x57:	/* 57 PUSH eDI */
						push (getreg16 (regdi) );
						break;

					case 0x58:	/* 58 POP eAX */
						putreg16 (regax, pop() );
						break;

					case 0x59:	/* 59 POP eCX */
						putreg16 (regcx, pop() );
						break;

					case 0x5A:	/* 5A POP eDX */
						putreg16 (regdx, pop() );
						break;

					case 0x5B:	/* 5B POP eBX */
						putreg16 (regbx, pop() );
						break;

					case 0x5C:	/* 5C POP eSP */
						putreg16 (regsp, pop() );
						break;

					case 0x5D:	/* 5D POP eBP */
						putreg16 (regbp, pop() );
						break;

					case 0x5E:	/* 5E POP eSI */
						putreg16 (regsi, pop() );
						break;

					case 0x5F:	/* 5F POP eDI */
						putreg16 (regdi, pop() );
						break;

					case 0x60:	/* 60 PUSHA (80186+) */
						if (!x86_cpu_v20)
							goto nov20;
						oldsp = getreg16 (regsp);
						push (getreg16 (regax) );
						push (getreg16 (regcx) );
						push (getreg16 (regdx) );
						push (getreg16 (regbx) );
						push (oldsp);
						push (getreg16 (regbp) );
						push (getreg16 (regsi) );
						push (getreg16 (regdi) );
						break;

					case 0x61:	/* 61 POPA (80186+) */
						if (!x86_cpu_v20)
							goto nov20;
						putreg16 (regdi, pop() );
						putreg16 (regsi, pop() );
						putreg16 (regbp, pop() );
						dummy = pop();
						putreg16 (regbx, pop() );
						putreg16 (regdx, pop() );
						putreg16 (regcx, pop() );
						putreg16 (regax, pop() );
						break;

					case 0x62: /* 62 BOUND Gv, Ev (80186+) */
						if (!x86_cpu_v20)
							goto nov20;
						modregrm();
						getea (rm);
						if (signext32 (getreg16 (reg) ) < signext32 ( getmem16 (ea >> 4, ea & 15) ) ) {
								intcall86 (5); //bounds check exception
							}
						else {
								ea += 2;
								if (signext32 (getreg16 (reg) ) > signext32 ( getmem16 (ea >> 4, ea & 15) ) ) {
										intcall86(5); //bounds check exception
									}
							}
						break;

					case 0x68:	/* 68 PUSH Iv (80186+) */
						if (!x86_cpu_v20)
							goto nov20;
						push (getmem16 (segregs[regcs], ip) );
						StepIP (2);
						break;

					case 0x69:	/* 69 IMUL Gv Ev Iv (80186+) */
						if (!x86_cpu_v20)
							goto nov20;
						modregrm();
						temp1 = readrm16 (rm);
						temp2 = getmem16 (segregs[regcs], ip);
						StepIP (2);
						if ( (temp1 & 0x8000L) == 0x8000L) {
								temp1 = temp1 | 0xFFFF0000L;
							}

						if ( (temp2 & 0x8000L) == 0x8000L) {
								temp2 = temp2 | 0xFFFF0000L;
							}

						temp3 = temp1 * temp2;
						putreg16 (reg, temp3 & 0xFFFFL);
						if (temp3 & 0xFFFF0000L) {
								cf = 1;
								of = 1;
							}
						else {
								cf = 0;
								of = 0;
							}
						break;

					case 0x6A:	/* 6A PUSH Ib (80186+) */
						if (!x86_cpu_v20)
							goto nov20;
						push (getmem8 (segregs[regcs], ip) );
						StepIP (1);
						break;

					case 0x6B:	/* 6B IMUL Gv Eb Ib (80186+) */
						if (!x86_cpu_v20)
							goto nov20;
						modregrm();
						temp1 = readrm16 (rm);
						temp2 = signext (getmem8 (segregs[regcs], ip) );
						StepIP (1);
						if ( (temp1 & 0x8000L) == 0x8000L) {
								temp1 = temp1 | 0xFFFF0000L;
							}

						if ( (temp2 & 0x8000L) == 0x8000L) {
								temp2 = temp2 | 0xFFFF0000L;
							}

						temp3 = temp1 * temp2;
						putreg16 (reg, temp3 & 0xFFFFL);
						if (temp3 & 0xFFFF0000L) {
								cf = 1;
								of = 1;
							}
						else {
								cf = 0;
								of = 0;
							}
						break;

					case 0x6C:	/* 6E INSB */
						if (!x86_cpu_v20)
							goto nov20;
						if (reptype && (getreg16 (regcx) == 0) ) {
								break;
							}

						putmem8 (useseg, getreg16 (regsi) , portin (regs.wordregs[regdx]) );
						if (df) {
								putreg16 (regsi, getreg16 (regsi) - 1);
								putreg16 (regdi, getreg16 (regdi) - 1);
							}
						else {
								putreg16 (regsi, getreg16 (regsi) + 1);
								putreg16 (regdi, getreg16 (regdi) + 1);
							}

						if (reptype) {
								putreg16 (regcx, getreg16 (regcx) - 1);
							}

						totalexec++;
						loopcount++;
						if (!reptype) {
								break;
							}

						ip = firstip;
						break;

					case 0x6D:	/* 6F INSW */
						if (!x86_cpu_v20)
							goto nov20;
						if (reptype && (getreg16 (regcx) == 0) ) {
								break;
							}

						putmem16 (useseg, getreg16 (regsi) , portin16 (regs.wordregs[regdx]) );
						if (df) {
								putreg16 (regsi, getreg16 (regsi) - 2);
								putreg16 (regdi, getreg16 (regdi) - 2);
							}
						else {
								putreg16 (regsi, getreg16 (regsi) + 2);
								putreg16 (regdi, getreg16 (regdi) + 2);
							}

						if (reptype) {
								putreg16 (regcx, getreg16 (regcx) - 1);
							}

						totalexec++;
						loopcount++;
						if (!reptype) {
								break;
							}

						ip = firstip;
						break;

					case 0x6E:	/* 6E OUTSB */
						if (!x86_cpu_v20)
							goto nov20;
						if (reptype && (getreg16 (regcx) == 0) ) {
								break;
							}

						portout (regs.wordregs[regdx], getmem8 (useseg, getreg16 (regsi) ) );
						if (df) {
								putreg16 (regsi, getreg16 (regsi) - 1);
								putreg16 (regdi, getreg16 (regdi) - 1);
							}
						else {
								putreg16 (regsi, getreg16 (regsi) + 1);
								putreg16 (regdi, getreg16 (regdi) + 1);
							}

						if (reptype) {
								putreg16 (regcx, getreg16 (regcx) - 1);
							}

						totalexec++;
						loopcount++;
						if (!reptype) {
								break;
							}

						ip = firstip;
						break;

					case 0x6F:	/* 6F OUTSW */
						if (!x86_cpu_v20)
							goto nov20;
						if (reptype && (getreg16 (regcx) == 0) ) {
								break;
							}

						portout16 (regs.wordregs[regdx], getmem16 (useseg, getreg16 (regsi) ) );
						if (df) {
								putreg16 (regsi, getreg16 (regsi) - 2);
								putreg16 (regdi, getreg16 (regdi) - 2);
							}
						else {
								putreg16 (regsi, getreg16 (regsi) + 2);
								putreg16 (regdi, getreg16 (regdi) + 2);
							}

						if (reptype) {
								putreg16 (regcx, getreg16 (regcx) - 1);
							}

						totalexec++;
						loopcount++;
						if (!reptype) {
								break;
							}

						ip = firstip;
						break;

					case 0x70:	/* 70 JO Jb */
						temp16 = signext (getmem8 (segregs[regcs], ip) );
						StepIP (1);
						if (of) {
								ip = ip + temp16;
							}
						break;

					case 0x71:	/* 71 JNO Jb */
						temp16 = signext (getmem8 (segregs[regcs], ip) );
						StepIP (1);
						if (!of) {
								ip = ip + temp16;
							}
						break;

					case 0x72:	/* 72 JB Jb */
						temp16 = signext (getmem8 (segregs[regcs], ip) );
						StepIP (1);
						if (cf) {
								ip = ip + temp16;
							}
						break;

					case 0x73:	/* 73 JNB Jb */
						temp16 = signext (getmem8 (segregs[regcs], ip) );
						StepIP (1);
						if (!cf) {
								ip = ip + temp16;
							}
						break;

					case 0x74:	/* 74 JZ Jb */
						temp16 = signext (getmem8 (segregs[regcs], ip) );
						StepIP (1);
						if (zf) {
								ip = ip + temp16;
							}
						break;

					case 0x75:	/* 75 JNZ Jb */
						temp16 = signext (getmem8 (segregs[regcs], ip) );
						StepIP (1);
						if (!zf) {
								ip = ip + temp16;
							}
						break;

					case 0x76:	/* 76 JBE Jb */
						temp16 = signext (getmem8 (segregs[regcs], ip) );
						StepIP (1);
						if (cf || zf) {
								ip = ip + temp16;
							}
						break;

					case 0x77:	/* 77 JA Jb */
						temp16 = signext (getmem8 (segregs[regcs], ip) );
						StepIP (1);
						if (!cf && !zf) {
								ip = ip + temp16;
							}
						break;

					case 0x78:	/* 78 JS Jb */
						temp16 = signext (getmem8 (segregs[regcs], ip) );
						StepIP (1);
						if (sf) {
								ip = ip + temp16;
							}
						break;

					case 0x79:	/* 79 JNS Jb */
						temp16 = signext (getmem8 (segregs[regcs], ip) );
						StepIP (1);
						if (!sf) {
								ip = ip + temp16;
							}
						break;

					case 0x7A:	/* 7A JPE Jb */
						temp16 = signext (getmem8 (segregs[regcs], ip) );
						StepIP (1);
						if (pf) {
								ip = ip + temp16;
							}
						break;

					case 0x7B:	/* 7B JPO Jb */
						temp16 = signext (getmem8 (segregs[regcs], ip) );
						StepIP (1);
						if (!pf) {
								ip = ip + temp16;
							}
						break;

					case 0x7C:	/* 7C JL Jb */
						temp16 = signext (getmem8 (segregs[regcs], ip) );
						StepIP (1);
						if (sf != of) {
								ip = ip + temp16;
							}
						break;

					case 0x7D:	/* 7D JGE Jb */
						temp16 = signext (getmem8 (segregs[regcs], ip) );
						StepIP (1);
						if (sf == of) {
								ip = ip + temp16;
							}
						break;

					case 0x7E:	/* 7E JLE Jb */
						temp16 = signext (getmem8 (segregs[regcs], ip) );
						StepIP (1);
						if ( (sf != of) || zf) {
								ip = ip + temp16;
							}
						break;

					case 0x7F:	/* 7F JG Jb */
						temp16 = signext (getmem8 (segregs[regcs], ip) );
						StepIP (1);
						if (!zf && (sf == of) ) {
								ip = ip + temp16;
							}
						break;

					case 0x80:
					case 0x82:	/* 80/82 GRP1 Eb Ib */
						modregrm();
						oper1b = readrm8 (rm);
						oper2b = getmem8 (segregs[regcs], ip);
						StepIP (1);
						switch (reg) {
								case 0:
									op_add8();
									break;
								case 1:
									op_or8();
									break;
								case 2:
									op_adc8();
									break;
								case 3:
									op_sbb8();
									break;
								case 4:
									op_and8();
									break;
								case 5:
									op_sub8();
									break;
								case 6:
									op_xor8();
									break;
								case 7:
									flag_sub8 (oper1b, oper2b);
									break;
								default:
									break;	/* to avoid compiler warnings */
							}

						if (reg < 7) {
								writerm8 (rm, res8);
							}
						break;

					case 0x81:	/* 81 GRP1 Ev Iv */
					case 0x83:	/* 83 GRP1 Ev Ib */
						modregrm();
						oper1 = readrm16 (rm);
						if (opcode == 0x81) {
								oper2 = getmem16 (segregs[regcs], ip);
								StepIP (2);
							}
						else {
								oper2 = signext (getmem8 (segregs[regcs], ip) );
								StepIP (1);
							}

						switch (reg) {
								case 0:
									op_add16();
									break;
								case 1:
									op_or16();
									break;
								case 2:
									op_adc16();
									break;
								case 3:
									op_sbb16();
									break;
								case 4:
									op_and16();
									break;
								case 5:
									op_sub16();
									break;
								case 6:
									op_xor16();
									break;
								case 7:
									flag_sub16 (oper1, oper2);
									break;
								default:
									break;	/* to avoid compiler warnings */
							}

						if (reg < 7) {
								writerm16 (rm, res16);
							}
						break;

					case 0x84:	/* 84 TEST Gb Eb */
						modregrm();
						oper1b = getreg8 (reg);
						oper2b = readrm8 (rm);
						flag_log8 (oper1b & oper2b);
						break;

					case 0x85:	/* 85 TEST Gv Ev */
						modregrm();
						oper1 = getreg16 (reg);
						oper2 = readrm16 (rm);
						flag_log16 (oper1 & oper2);
						break;

					case 0x86:	/* 86 XCHG Gb Eb */
						modregrm();
						oper1b = getreg8 (reg);
						putreg8 (reg, readrm8 (rm) );
						writerm8 (rm, oper1b);
						break;

					case 0x87:	/* 87 XCHG Gv Ev */
						modregrm();
						oper1 = getreg16 (reg);
						putreg16 (reg, readrm16 (rm) );
						writerm16 (rm, oper1);
						break;

					case 0x88:	/* 88 MOV Eb Gb */
						modregrm();
						writerm8 (rm, getreg8 (reg) );
						break;

					case 0x89:	/* 89 MOV Ev Gv */
						modregrm();
						writerm16 (rm, getreg16 (reg) );
						break;

					case 0x8A:	/* 8A MOV Gb Eb */
						modregrm();
						putreg8 (reg, readrm8 (rm) );
						break;

					case 0x8B:	/* 8B MOV Gv Ev */
						modregrm();
						putreg16 (reg, readrm16 (rm) );
						break;

					case 0x8C:	/* 8C MOV Ew Sw */
						modregrm();
						writerm16 (rm, getsegreg (reg) );
						break;

					case 0x8D:	/* 8D LEA Gv M */
						modregrm();
						getea (rm);
						putreg16 (reg, ea - segbase (useseg) );
						break;

					case 0x8E:	/* 8E MOV Sw Ew */
						modregrm();
						putsegreg (reg, readrm16 (rm) );
						break;

					case 0x8F:	/* 8F POP Ev */
						modregrm();
						writerm16 (rm, pop() );
						break;

					case 0x90:	/* 90 NOP */
						break;

					case 0x91:	/* 91 XCHG eCX eAX */
						oper1 = getreg16 (regcx);
						putreg16 (regcx, getreg16 (regax) );
						putreg16 (regax, oper1);
						break;

					case 0x92:	/* 92 XCHG eDX eAX */
						oper1 = getreg16 (regdx);
						putreg16 (regdx, getreg16 (regax) );
						putreg16 (regax, oper1);
						break;

					case 0x93:	/* 93 XCHG eBX eAX */
						oper1 = getreg16 (regbx);
						putreg16 (regbx, getreg16 (regax) );
						putreg16 (regax, oper1);
						break;

					case 0x94:	/* 94 XCHG eSP eAX */
						oper1 = getreg16 (regsp);
						putreg16 (regsp, getreg16 (regax) );
						putreg16 (regax, oper1);
						break;

					case 0x95:	/* 95 XCHG eBP eAX */
						oper1 = getreg16 (regbp);
						putreg16 (regbp, getreg16 (regax) );
						putreg16 (regax, oper1);
						break;

					case 0x96:	/* 96 XCHG eSI eAX */
						oper1 = getreg16 (regsi);
						putreg16 (regsi, getreg16 (regax) );
						putreg16 (regax, oper1);
						break;

					case 0x97:	/* 97 XCHG eDI eAX */
						oper1 = getreg16 (regdi);
						putreg16 (regdi, getreg16 (regax) );
						putreg16 (regax, oper1);
						break;

					case 0x98:	/* 98 CBW */
						if ( (regs.byteregs[regal] & 0x80) == 0x80) {
								regs.byteregs[regah] = 0xFF;
							}
						else {
								regs.byteregs[regah] = 0;
							}
						break;

					case 0x99:	/* 99 CWD */
						if ( (regs.byteregs[regah] & 0x80) == 0x80) {
								putreg16 (regdx, 0xFFFF);
							}
						else {
								putreg16 (regdx, 0);
							}
						break;

					case 0x9A:	/* 9A CALL Ap */
						oper1 = getmem16 (segregs[regcs], ip);
						StepIP (2);
						oper2 = getmem16 (segregs[regcs], ip);
						StepIP (2);
						push (segregs[regcs]);
						push (ip);
						ip = oper1;
						segregs[regcs] = oper2;
						break;

					case 0x9B:	/* 9B WAIT */
						break;

					case 0x9C:	/* 9C PUSHF */
						push (makeflagsword() | 0xF800);
						break;

					case 0x9D:	/* 9D POPF */
						temp16 = pop();
						decodeflagsword (temp16);
						break;

					case 0x9E:	/* 9E SAHF */
						decodeflagsword ( (makeflagsword() & 0xFF00) | regs.byteregs[regah]);
						break;

					case 0x9F:	/* 9F LAHF */
						regs.byteregs[regah] = makeflagsword() & 0xFF;
						break;

					case 0xA0:	/* A0 MOV regs.byteregs[regal] Ob */
						regs.byteregs[regal] = getmem8 (useseg, getmem16 (segregs[regcs], ip) );
						StepIP (2);
						break;

					case 0xA1:	/* A1 MOV eAX Ov */
						oper1 = getmem16 (useseg, getmem16 (segregs[regcs], ip) );
						StepIP (2);
						putreg16 (regax, oper1);
						break;

					case 0xA2:	/* A2 MOV Ob regs.byteregs[regal] */
						putmem8 (useseg, getmem16 (segregs[regcs], ip), regs.byteregs[regal]);
						StepIP (2);
						break;

					case 0xA3:	/* A3 MOV Ov eAX */
						putmem16 (useseg, getmem16 (segregs[regcs], ip), getreg16 (regax) );
						StepIP (2);
						break;

					case 0xA4:	/* A4 MOVSB */
						if (reptype && (getreg16 (regcx) == 0) ) {
								break;
							}

						putmem8 (segregs[reges], getreg16 (regdi), getmem8 (useseg, getreg16 (regsi) ) );
						if (df) {
								putreg16 (regsi, getreg16 (regsi) - 1);
								putreg16 (regdi, getreg16 (regdi) - 1);
							}
						else {
								putreg16 (regsi, getreg16 (regsi) + 1);
								putreg16 (regdi, getreg16 (regdi) + 1);
							}

						if (reptype) {
								putreg16 (regcx, getreg16 (regcx) - 1);
							}

						totalexec++;
						loopcount++;
						if (!reptype) {
								break;
							}

						ip = firstip;
						break;

					case 0xA5:	/* A5 MOVSW */
						if (reptype && (getreg16 (regcx) == 0) ) {
								break;
							}

						putmem16 (segregs[reges], getreg16 (regdi), getmem16 (useseg, getreg16 (regsi) ) );
						if (df) {
								putreg16 (regsi, getreg16 (regsi) - 2);
								putreg16 (regdi, getreg16 (regdi) - 2);
							}
						else {
								putreg16 (regsi, getreg16 (regsi) + 2);
								putreg16 (regdi, getreg16 (regdi) + 2);
							}

						if (reptype) {
								putreg16 (regcx, getreg16 (regcx) - 1);
							}

						totalexec++;
						loopcount++;
						if (!reptype) {
								break;
							}

						ip = firstip;
						break;

					case 0xA6:	/* A6 CMPSB */
						if (reptype && (getreg16 (regcx) == 0) ) {
								break;
							}

						oper1b = getmem8 (useseg, getreg16 (regsi) );
						oper2b = getmem8 (segregs[reges], getreg16 (regdi) );
						if (df) {
								putreg16 (regsi, getreg16 (regsi) - 1);
								putreg16 (regdi, getreg16 (regdi) - 1);
							}
						else {
								putreg16 (regsi, getreg16 (regsi) + 1);
								putreg16 (regdi, getreg16 (regdi) + 1);
							}

						flag_sub8 (oper1b, oper2b);
						if (reptype) {
								putreg16 (regcx, getreg16 (regcx) - 1);
							}

						if ( (reptype == 1) && !zf) {
								break;
							}
						else if ( (reptype == 2) && (zf == 1) ) {
								break;
							}

						totalexec++;
						loopcount++;
						if (!reptype) {
								break;
							}

						ip = firstip;
						break;

					case 0xA7:	/* A7 CMPSW */
						if (reptype && (getreg16 (regcx) == 0) ) {
								break;
							}

						oper1 = getmem16 (useseg, getreg16 (regsi) );
						oper2 = getmem16 (segregs[reges], getreg16 (regdi) );
						if (df) {
								putreg16 (regsi, getreg16 (regsi) - 2);
								putreg16 (regdi, getreg16 (regdi) - 2);
							}
						else {
								putreg16 (regsi, getreg16 (regsi) + 2);
								putreg16 (regdi, getreg16 (regdi) + 2);
							}

						flag_sub16 (oper1, oper2);
						if (reptype) {
								putreg16 (regcx, getreg16 (regcx) - 1);
							}

						if ( (reptype == 1) && !zf) {
								break;
							}

						if ( (reptype == 2) && (zf == 1) ) {
								break;
							}

						totalexec++;
						loopcount++;
						if (!reptype) {
								break;
							}

						ip = firstip;
						break;

					case 0xA8:	/* A8 TEST regs.byteregs[regal] Ib */
						oper1b = regs.byteregs[regal];
						oper2b = getmem8 (segregs[regcs], ip);
						StepIP (1);
						flag_log8 (oper1b & oper2b);
						break;

					case 0xA9:	/* A9 TEST eAX Iv */
						oper1 = getreg16 (regax);
						oper2 = getmem16 (segregs[regcs], ip);
						StepIP (2);
						flag_log16 (oper1 & oper2);
						break;

					case 0xAA:	/* AA STOSB */
						if (reptype && (getreg16 (regcx) == 0) ) {
								break;
							}

						putmem8 (segregs[reges], getreg16 (regdi), regs.byteregs[regal]);
						if (df) {
								putreg16 (regdi, getreg16 (regdi) - 1);
							}
						else {
								putreg16 (regdi, getreg16 (regdi) + 1);
							}

						if (reptype) {
								putreg16 (regcx, getreg16 (regcx) - 1);
							}

						totalexec++;
						loopcount++;
						if (!reptype) {
								break;
							}

						ip = firstip;
						break;

					case 0xAB:	/* AB STOSW */
						if (reptype && (getreg16 (regcx) == 0) ) {
								break;
							}

						putmem16 (segregs[reges], getreg16 (regdi), getreg16 (regax) );
						if (df) {
								putreg16 (regdi, getreg16 (regdi) - 2);
							}
						else {
								putreg16 (regdi, getreg16 (regdi) + 2);
							}

						if (reptype) {
								putreg16 (regcx, getreg16 (regcx) - 1);
							}

						totalexec++;
						loopcount++;
						if (!reptype) {
								break;
							}

						ip = firstip;
						break;

					case 0xAC:	/* AC LODSB */
						if (reptype && (getreg16 (regcx) == 0) ) {
								break;
							}

						regs.byteregs[regal] = getmem8 (useseg, getreg16 (regsi) );
						if (df) {
								putreg16 (regsi, getreg16 (regsi) - 1);
							}
						else {
								putreg16 (regsi, getreg16 (regsi) + 1);
							}

						if (reptype) {
								putreg16 (regcx, getreg16 (regcx) - 1);
							}

						totalexec++;
						loopcount++;
						if (!reptype) {
								break;
							}

						ip = firstip;
						break;

					case 0xAD:	/* AD LODSW */
						if (reptype && (getreg16 (regcx) == 0) ) {
								break;
							}

						oper1 = getmem16 (useseg, getreg16 (regsi) );
						putreg16 (regax, oper1);
						if (df) {
								putreg16 (regsi, getreg16 (regsi) - 2);
							}
						else {
								putreg16 (regsi, getreg16 (regsi) + 2);
							}

						if (reptype) {
								putreg16 (regcx, getreg16 (regcx) - 1);
							}

						totalexec++;
						loopcount++;
						if (!reptype) {
								break;
							}

						ip = firstip;
						break;

					case 0xAE:	/* AE SCASB */
						if (reptype && (getreg16 (regcx) == 0) ) {
								break;
							}

						oper1b = getmem8 (segregs[reges], getreg16 (regdi) );
						oper2b = regs.byteregs[regal];
						flag_sub8 (oper1b, oper2b);
						if (df) {
								putreg16 (regdi, getreg16 (regdi) - 1);
							}
						else {
								putreg16 (regdi, getreg16 (regdi) + 1);
							}

						if (reptype) {
								putreg16 (regcx, getreg16 (regcx) - 1);
							}

						if ( (reptype == 1) && !zf) {
								break;
							}
						else if ( (reptype == 2) && (zf == 1) ) {
								break;
							}

						totalexec++;
						loopcount++;
						if (!reptype) {
								break;
							}

						ip = firstip;
						break;

					case 0xAF:	/* AF SCASW */
						if (reptype && (getreg16 (regcx) == 0) ) {
								break;
							}

						oper1 = getmem16 (segregs[reges], getreg16 (regdi) );
						oper2 = getreg16 (regax);
						flag_sub16 (oper1, oper2);
						if (df) {
								putreg16 (regdi, getreg16 (regdi) - 2);
							}
						else {
								putreg16 (regdi, getreg16 (regdi) + 2);
							}

						if (reptype) {
								putreg16 (regcx, getreg16 (regcx) - 1);
							}

						if ( (reptype == 1) && !zf) {
								break;
							}
						else if ( (reptype == 2) & (zf == 1) ) {
								break;
							}

						totalexec++;
						loopcount++;
						if (!reptype) {
								break;
							}

						ip = firstip;
						break;

					case 0xB0:	/* B0 MOV regs.byteregs[regal] Ib */
						regs.byteregs[regal] = getmem8 (segregs[regcs], ip);
						StepIP (1);
						break;

					case 0xB1:	/* B1 MOV regs.byteregs[regcl] Ib */
						regs.byteregs[regcl] = getmem8 (segregs[regcs], ip);
						StepIP (1);
						break;

					case 0xB2:	/* B2 MOV regs.byteregs[regdl] Ib */
						regs.byteregs[regdl] = getmem8 (segregs[regcs], ip);
						StepIP (1);
						break;

					case 0xB3:	/* B3 MOV regs.byteregs[regbl] Ib */
						regs.byteregs[regbl] = getmem8 (segregs[regcs], ip);
						StepIP (1);
						break;

					case 0xB4:	/* B4 MOV regs.byteregs[regah] Ib */
						regs.byteregs[regah] = getmem8 (segregs[regcs], ip);
						StepIP (1);
						break;

					case 0xB5:	/* B5 MOV regs.byteregs[regch] Ib */
						regs.byteregs[regch] = getmem8 (segregs[regcs], ip);
						StepIP (1);
						break;

					case 0xB6:	/* B6 MOV regs.byteregs[regdh] Ib */
						regs.byteregs[regdh] = getmem8 (segregs[regcs], ip);
						StepIP (1);
						break;

					case 0xB7:	/* B7 MOV regs.byteregs[regbh] Ib */
						regs.byteregs[regbh] = getmem8 (segregs[regcs], ip);
						StepIP (1);
						break;

					case 0xB8:	/* B8 MOV eAX Iv */
						oper1 = getmem16 (segregs[regcs], ip);
						StepIP (2);
						putreg16 (regax, oper1);
						break;

					case 0xB9:	/* B9 MOV eCX Iv */
						oper1 = getmem16 (segregs[regcs], ip);
						StepIP (2);
						putreg16 (regcx, oper1);
						break;

					case 0xBA:	/* BA MOV eDX Iv */
						oper1 = getmem16 (segregs[regcs], ip);
						StepIP (2);
						putreg16 (regdx, oper1);
						break;

					case 0xBB:	/* BB MOV eBX Iv */
						oper1 = getmem16 (segregs[regcs], ip);
						StepIP (2);
						putreg16 (regbx, oper1);
						break;

					case 0xBC:	/* BC MOV eSP Iv */
						putreg16 (regsp, getmem16 (segregs[regcs], ip) );
						StepIP (2);
						break;

					case 0xBD:	/* BD MOV eBP Iv */
						putreg16 (regbp, getmem16 (segregs[regcs], ip) );
						StepIP (2);
						break;

					case 0xBE:	/* BE MOV eSI Iv */
						putreg16 (regsi, getmem16 (segregs[regcs], ip) );
						StepIP (2);
						break;

					case 0xBF:	/* BF MOV eDI Iv */
						putreg16 (regdi, getmem16 (segregs[regcs], ip) );
						StepIP (2);
						break;

					case 0xC0:	/* C0 GRP2 byte imm8 (80186+) */
						modregrm();
						oper1b = readrm8 (rm);
						oper2b = getmem8 (segregs[regcs], ip);
						StepIP (1);
						writerm8 (rm, op_grp2_8 (oper2b) );
						break;

					case 0xC1:	/* C1 GRP2 word imm8 (80186+) */
						modregrm();
						oper1 = readrm16 (rm);
						oper2 = getmem8 (segregs[regcs], ip);
						StepIP (1);
						writerm16 (rm, op_grp2_16 ( (uint8_t) oper2) );
						break;

					case 0xC2:	/* C2 RET Iw */
						oper1 = getmem16 (segregs[regcs], ip);
						ip = pop();
						putreg16 (regsp, getreg16 (regsp) + oper1);
						break;

					case 0xC3:	/* C3 RET */
						ip = pop();
						break;

					case 0xC4:	/* C4 LES Gv Mp */
						modregrm();
						getea (rm);
						putreg16 (reg, read86 (ea) + read86 (ea + 1) * 256);
						segregs[reges] = read86 (ea + 2) + read86 (ea + 3) * 256;
						break;

					case 0xC5:	/* C5 LDS Gv Mp */
						modregrm();
						getea (rm);
						putreg16 (reg, read86 (ea) + read86 (ea + 1) * 256);
						segregs[regds] = read86 (ea + 2) + read86 (ea + 3) * 256;
						break;

					case 0xC6:	/* C6 MOV Eb Ib */
						modregrm();
						writerm8 (rm, getmem8 (segregs[regcs], ip) );
						StepIP (1);
						break;

					case 0xC7:	/* C7 MOV Ev Iv */
						modregrm();
						writerm16 (rm, getmem16 (segregs[regcs], ip) );
						StepIP (2);
						break;

					case 0xC8:	/* C8 ENTER (80186+) */
						stacksize = getmem16 (segregs[regcs], ip);
						StepIP (2);
						nestlev = getmem8 (segregs[regcs], ip);
						StepIP (1);
						push (getreg16 (regbp) );
						frametemp = getreg16 (regsp);
						if (nestlev) {
								for (temp16 = 1; temp16 < nestlev; temp16++) {
										putreg16 (regbp, getreg16 (regbp) - 2);
										push (getreg16 (regbp) );
									}

								push (getreg16 (regsp) );
							}

						putreg16 (regbp, frametemp);
						putreg16 (regsp, getreg16 (regbp) - stacksize);

						break;

					case 0xC9:	/* C9 LEAVE (80186+) */
						putreg16 (regsp, getreg16 (regbp) );
						putreg16 (regbp, pop() );

						break;

					case 0xCA:	/* CA RETF Iw */
						oper1 = getmem16 (segregs[regcs], ip);
						ip = pop();
						segregs[regcs] = pop();
						putreg16 (regsp, getreg16 (regsp) + oper1);
						break;

					case 0xCB:	/* CB RETF */
						ip = pop();;
						segregs[regcs] = pop();
						break;

					case 0xCC:	/* CC INT 3 */
						intcall86 (3);
						break;

					case 0xCD:	/* CD INT Ib */
						oper1b = getmem8 (segregs[regcs], ip);
						StepIP (1);
						intcall86 (oper1b);
						break;

					case 0xCE:	/* CE INTO */
						if (of) {
								intcall86 (4);
							}
						break;

					case 0xCF:	/* CF IRET */
						ip = pop();
						segregs[regcs] = pop();
						decodeflagsword (pop() );

						/*
						 * if (net.enabled) net.canrecv = 1;
						 */
						break;

					case 0xD0:	/* D0 GRP2 Eb 1 */
						modregrm();
						oper1b = readrm8 (rm);
						writerm8 (rm, op_grp2_8 (1) );
						break;

					case 0xD1:	/* D1 GRP2 Ev 1 */
						modregrm();
						oper1 = readrm16 (rm);
						writerm16 (rm, op_grp2_16 (1) );
						break;

					case 0xD2:	/* D2 GRP2 Eb regs.byteregs[regcl] */
						modregrm();
						oper1b = readrm8 (rm);
						writerm8 (rm, op_grp2_8 (regs.byteregs[regcl]) );
						break;

					case 0xD3:	/* D3 GRP2 Ev regs.byteregs[regcl] */
						modregrm();
						oper1 = readrm16 (rm);
						writerm16 (rm, op_grp2_16 (regs.byteregs[regcl]) );
						break;

					case 0xD4:	/* D4 AAM I0 */
						oper1 = getmem8 (segregs[regcs], ip);
						StepIP (1);
						if (!oper1) {
								intcall86 (0);
								break;
							}	/* division by zero */

						regs.byteregs[regah] = (regs.byteregs[regal] / oper1) & 255;
						regs.byteregs[regal] = (regs.byteregs[regal] % oper1) & 255;
						flag_szp16 (getreg16 (regax) );
						break;

					case 0xD5:	/* D5 AAD I0 */
						oper1 = getmem8 (segregs[regcs], ip);
						StepIP (1);
						regs.byteregs[regal] = (regs.byteregs[regah] * oper1 + regs.byteregs[regal]) & 255;
						regs.byteregs[regah] = 0;
						flag_szp16 (regs.byteregs[regah] * oper1 + regs.byteregs[regal]);
						sf = 0;
						break;

					case 0xD6:	/* D6 XLAT on V20/V30, SALC on 8086/8088 */

					if (x86_cpu_v20)
						regs.byteregs[regal] = read86(useseg * 16 + (regs.wordregs[regbx]) + regs.byteregs[regal]);
					else
						regs.byteregs[regal] = cf ? 0xFF : 0x00;
					break;

					case 0xD7:	/* D7 XLAT */
						regs.byteregs[regal] = read86(useseg * 16 + (regs.wordregs[regbx]) + regs.byteregs[regal]);
						break;

					case 0xD8:
					case 0xD9:
					case 0xDA:
					case 0xDB:
					case 0xDC:
					case 0xDE:
					case 0xDD:
					case 0xDF:	/* escape to x87 FPU (unsupported) */
						modregrm();
						break;

					case 0xE0:	/* E0 LOOPNZ Jb */
						temp16 = signext (getmem8 (segregs[regcs], ip) );
						StepIP (1);
						putreg16 (regcx, getreg16 (regcx) - 1);
						if ( (getreg16 (regcx) ) && !zf) {
								ip = ip + temp16;
							}
						break;

					case 0xE1:	/* E1 LOOPZ Jb */
						temp16 = signext (getmem8 (segregs[regcs], ip) );
						StepIP (1);
						putreg16 (regcx, (getreg16 (regcx) ) - 1);
						if ( (getreg16 (regcx) ) && (zf == 1) ) {
								ip = ip + temp16;
							}
						break;

					case 0xE2:	/* E2 LOOP Jb */
						temp16 = signext (getmem8 (segregs[regcs], ip) );
						StepIP (1);
						putreg16 (regcx, (getreg16 (regcx) ) - 1);
						if (getreg16 (regcx) ) {
								ip = ip + temp16;
							}
						break;

					case 0xE3:	/* E3 JCXZ Jb */
						temp16 = signext (getmem8 (segregs[regcs], ip) );
						StepIP (1);
						if (! (getreg16 (regcx) ) ) {
								ip = ip + temp16;
							}
						break;

					case 0xE4:	/* E4 IN regs.byteregs[regal] Ib */
						oper1b = getmem8 (segregs[regcs], ip);
						StepIP (1);
						regs.byteregs[regal] = (uint8_t) portin (oper1b);
						break;

					case 0xE5:	/* E5 IN eAX Ib */
						oper1b = getmem8 (segregs[regcs], ip);
						StepIP (1);
						putreg16 (regax, portin16 (oper1b) );
						break;

					case 0xE6:	/* E6 OUT Ib regs.byteregs[regal] */
						oper1b = getmem8 (segregs[regcs], ip);
						StepIP (1);
						portout (oper1b, regs.byteregs[regal]);
						break;

					case 0xE7:	/* E7 OUT Ib eAX */
						oper1b = getmem8 (segregs[regcs], ip);
						StepIP (1);
						portout16 (oper1b, (getreg16 (regax) ) );
						break;

					case 0xE8:	/* E8 CALL Jv */
						oper1 = getmem16 (segregs[regcs], ip);
						StepIP (2);
						push (ip);
						ip = ip + oper1;
						break;

					case 0xE9:	/* E9 JMP Jv */
						oper1 = getmem16 (segregs[regcs], ip);
						StepIP (2);
						ip = ip + oper1;
						break;

					case 0xEA:	/* EA JMP Ap */
						oper1 = getmem16 (segregs[regcs], ip);
						StepIP (2);
						oper2 = getmem16 (segregs[regcs], ip);
						ip = oper1;
						segregs[regcs] = oper2;
						break;

					case 0xEB:	/* EB JMP Jb */
						oper1 = signext (getmem8 (segregs[regcs], ip) );
						StepIP (1);
						ip = ip + oper1;
						break;

					case 0xEC:	/* EC IN regs.byteregs[regal] regdx */
						oper1 = (getreg16 (regdx) );
						regs.byteregs[regal] = (uint8_t) portin (oper1);
						break;

					case 0xED:	/* ED IN eAX regdx */
						oper1 = (getreg16 (regdx) );
						putreg16 (regax, portin16 (oper1) );
						break;

					case 0xEE:	/* EE OUT regdx regs.byteregs[regal] */
						oper1 = (getreg16 (regdx) );
						portout (oper1, regs.byteregs[regal]);
						break;

					case 0xEF:	/* EF OUT regdx eAX */
						oper1 = (getreg16 (regdx) );
						portout16 (oper1, (getreg16 (regax) ) );
						break;

					case 0xF0:	/* F0 LOCK */
						break;

					case 0xF4:	/* F4 HLT */
						ip--;
						break;

					case 0xF5:	/* F5 CMC */
						if (!cf) {
								cf = 1;
							}
						else {
								cf = 0;
							}
						break;

					case 0xF6:	/* F6 GRP3a Eb */
						modregrm();
						oper1b = readrm8 (rm);
						op_grp3_8();
						if ( (reg > 1) && (reg < 4) ) {
								writerm8 (rm, res8);
							}
						break;

					case 0xF7:	/* F7 GRP3b Ev */
						modregrm();
						oper1 = readrm16 (rm);
						op_grp3_16();
						if ( (reg > 1) && (reg < 4) ) {
								writerm16 (rm, res16);
							}
						break;

					case 0xF8:	/* F8 CLC */
						cf = 0;
						break;

					case 0xF9:	/* F9 STC */
						cf = 1;
						break;

					case 0xFA:	/* FA CLI */
						ifl = 0;
						break;

					case 0xFB:	/* FB STI */
						ifl = 1;
						break;

					case 0xFC:	/* FC CLD */
						df = 0;
						break;

					case 0xFD:	/* FD STD */
						df = 1;
						break;

					case 0xFE:	/* FE GRP4 Eb */
						modregrm();
						oper1b = readrm8 (rm);
						oper2b = 1;
						if (!reg) {
								tempcf = cf;
								res8 = oper1b + oper2b;
								flag_add8 (oper1b, oper2b);
								cf = tempcf;
								writerm8 (rm, res8);
							}
						else {
								tempcf = cf;
								res8 = oper1b - oper2b;
								flag_sub8 (oper1b, oper2b);
								cf = tempcf;
								writerm8 (rm, res8);
							}
						break;

					case 0xFF:	/* FF GRP5 Ev */
						modregrm();
						oper1 = readrm16 (rm);
						op_grp5();
						break;

					default:
nov20:
					if (x86_cpu_v20)
						intcall86 (6); /* trip invalid opcode exception (this occurs on the 80186+, 8086/8088 CPUs treat them as NOPs. */
						               /* technically they aren't exactly like NOPs in most cases, but for our pursoses, that's accurate enough. */

						if (verbose) {
							write_log ("Illegal opcode: %02X @ %04X:%04X\n", opcode, savecs, saveip);
						}
						break;
				}

			if (!running) {
					return;
				}
		}
}