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cpu8086.ino
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cpu8086.ino
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/*
Fake86: A portable, open-source 8086 PC emulator.
Copyright (C)2010-2013 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.
*/
/*
The author of the port for Arduino Corax (Rabetsky Igor)
*/
#include <stdint.h>
#include <stdio.h>
//#define DEBUG
//#define CPU_8086
#define RAM_LENGTH 512
#define STACK_LENGTH 16
#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
#define regal 0
#define regah 1
#define regcl 2
#define regch 3
#define regdl 4
#define regdh 5
#define regbl 6
#define regbh 7
#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)
#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) \
)
union _bytewordregs_ {
uint16_t wordregs[8];
uint8_t byteregs[8];
};
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
};
//brainfuck
uint8_t RAM[RAM_LENGTH]={
0xbb, 0xb6, 0x01, 0xb8, 0xb6, 0x01, 0x05, 0x20, 0x00, 0xc6, 0x07, 0x00,
0x43, 0x3b, 0xd8, 0x75, 0xf8, 0xb4, 0x02, 0xb2, 0x0d, 0xcd, 0x21, 0xb2,
0x0a, 0xcd, 0x21, 0xb2, 0x23, 0xcd, 0x21, 0xb4, 0x0a, 0xba, 0xd9, 0x01,
0xcd, 0x21, 0xb4, 0x02, 0xb2, 0x0d, 0xcd, 0x21, 0xb2, 0x0a, 0xcd, 0x21,
0xbb, 0xda, 0x01, 0xbe, 0xb6, 0x01, 0xb5, 0x00, 0x43, 0x8a, 0x07, 0x3c,
0x00, 0x74, 0xc1, 0x3c, 0x3e, 0x74, 0x1b, 0x3c, 0x3c, 0x74, 0x1a, 0x3c,
0x2b, 0x74, 0x19, 0x3c, 0x2d, 0x74, 0x19, 0x3c, 0x2e, 0x74, 0x19, 0x3c,
0x5b, 0x74, 0x1d, 0x3c, 0x5d, 0x74, 0x3e, 0xeb, 0xdb, 0xc3, 0x46, 0xeb,
0xd7, 0x4e, 0xeb, 0xd4, 0xfe, 0x04, 0xeb, 0xd0, 0xfe, 0x0c, 0xeb, 0xcc,
0x8a, 0x14, 0xb4, 0x02, 0xcd, 0x21, 0xeb, 0xc4, 0x80, 0x3c, 0x00, 0x74,
0x02, 0xeb, 0xbd, 0x80, 0x3f, 0x5b, 0x74, 0x0f, 0x80, 0x3f, 0x5d, 0x74,
0x0f, 0x43, 0x80, 0xfd, 0x00, 0x75, 0xf0, 0x4b, 0x4b, 0xeb, 0xa9, 0xfe,
0xc5, 0x43, 0xeb, 0xe7, 0xfe, 0xcd, 0x43, 0xeb, 0xe2, 0x80, 0x3f, 0x5d,
0x74, 0x0e, 0x80, 0x3f, 0x5b, 0x74, 0x0e, 0x4b, 0x80, 0xfd, 0x00, 0x75,
0xf0, 0x43, 0xeb, 0x8c, 0xfe, 0xc5, 0x4b, 0xeb, 0xe8, 0xfe, 0xcd, 0x4b,
0xeb, 0xe3, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0xff, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x90
};
uint8_t STACK[STACK_LENGTH];
uint8_t opcode, segoverride, reptype, bootdrive = 0, hdcount = 0, hltstate = 0;
uint16_t segregs[4], savecs, saveip, ip, useseg, oldsp;
uint8_t tempcf, oldcf, cf, pf, af, zf, sf, tf, ifl, df, of, mode, reg, rm;
uint16_t oper1, oper2, res16, disp16, temp16, dummy, stacksize, frametemp;
uint8_t oper1b, oper2b, res8, disp8, temp8, nestlev, addrbyte;
uint32_t temp1, temp2, temp3, temp4, temp5, temp32, tempaddr32, ea;
int32_t result;
uint64_t totalexec;
union _bytewordregs_ regs;
uint8_t running = 0, didbootstrap = 0;
uint8_t vidmode;
void decodeflagsword( uint16_t 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;
}
void 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 write86 (uint32_t addr32, uint8_t value) {
if(addr32 > 0xFFFF - STACK_LENGTH){
STACK[tempaddr32] = value;
}
else if(addr32 >= 0x7100 && addr32 < RAM_LENGTH + 0x7100){
tempaddr32 = (addr32 & 0xFFFFF) - 0x7100;
RAM[tempaddr32] = value;
}
}
void writew86 (uint32_t addr32, uint16_t value) {
write86 (addr32, (uint8_t) value);
write86 (addr32 + 1, (uint8_t) (value >> 8) );
}
uint8_t read86 (uint32_t addr32) {
if(addr32 > 0xFFFF - STACK_LENGTH){
return STACK[tempaddr32];
}
else if(addr32 >= 0x7100 && addr32 < RAM_LENGTH + 0x7100){
addr32 &= 0xFFFFF;
addr32 -= 0x7100;
return (RAM[addr32]);
}
return 0x90;
}
uint16_t readw86 (uint32_t addr32) {
return ( (uint16_t) read86 (addr32) | (uint16_t) (read86 (addr32 + 1) << 8) );
}
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);
}
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) {
regs.wordregs[regsp] = regs.wordregs[regsp] - 2;
putmem16 (segregs[regss], regs.wordregs[regsp], pushval);
}
uint16_t pop() {
uint16_t tempval;
tempval = getmem16 (segregs[regss], regs.wordregs[regsp]);
regs.wordregs[regsp] = regs.wordregs[regsp] + 2;
return tempval;
}
void reset86() {
segregs[regcs] = 0xFFFF;
ip = 0x0100;
hltstate = 0;
}
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);
}
}
void intcall86 (uint8_t intnum) {
static uint16_t lastint10ax;
uint16_t oldregax;
if (intnum == 0x19) didbootstrap = 1;
switch (intnum) {
case 0x10:
videoBIOSinterupt();
break;
case 0x16:
keyBIOSinterupt();
break;
case 0x21:
DOSinterupt();
break;
default:
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;
}
}
uint8_t op_grp2_8 (uint8_t cnt) {
uint16_t s;
uint16_t shift;
uint16_t oldcf;
uint16_t msb;
s = oper1b;
oldcf = cf;
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);
if ((s & 0x80) && cf) of = 1; else of = 0;
} else of = 0;
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;
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);