Bochs/bochs/cpu/mult64.cc
Stanislav Shwartsman 400b7094c6 Commit patch by kuma neko [yuubyou@gmail.com]
64-bit IDIV uses unsigned overflow test
2005-05-13 14:15:35 +00:00

418 lines
9.4 KiB
C++

/////////////////////////////////////////////////////////////////////////
// $Id: mult64.cc,v 1.16 2005-05-13 14:15:35 sshwarts Exp $
/////////////////////////////////////////////////////////////////////////
//
// Copyright (C) 2001 MandrakeSoft S.A.
//
// MandrakeSoft S.A.
// 43, rue d'Aboukir
// 75002 Paris - France
// http://www.linux-mandrake.com/
// http://www.mandrakesoft.com/
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2 of the License, or (at your option) any later version.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
#define NEED_CPU_REG_SHORTCUTS 1
#include "bochs.h"
#define LOG_THIS BX_CPU_THIS_PTR
#if BX_SUPPORT_X86_64
static unsigned partial_add(Bit32u *sum,Bit32u b)
{
Bit32u t = *sum;
*sum += b;
return (*sum < t);
}
void long_mul(Bit128u *product, Bit64u op1, Bit64u op2)
{
Bit32u op_1[2],op_2[2];
Bit32u result[5];
Bit64u nn;
unsigned c;
int i,j,k;
op_1[0] = op1 & 0xffffffff;
op_1[1] = op1 >> 32;
op_2[0] = op2 & 0xffffffff;
op_2[1] = op2 >> 32;
for (i = 0; i < 4; i++) result[i] = 0;
for (i = 0; i < 2; i++) {
for (j = 0; j < 2; j++) {
nn = (Bit64u) op_1[i] * (Bit64u) op_2[j];
k = i + j;
c = partial_add(&result[k++],nn & 0xffffffff);
c = partial_add(&result[k++],(nn >> 32) + c);
while (k < 4 && c != 0) {
c = partial_add(&result[k++],c);
}
}
}
product->lo = result[0] + ((Bit64u) result[1] << 32);
product->hi = result[2] + ((Bit64u) result[3] << 32);
}
void long_neg(Bit128s *n)
{
Bit64u t = n->lo;
n->lo = -n->lo;
if (t - 1 > t) --n->hi;
n->hi = ~n->hi;
}
void long_imul(Bit128s *product, Bit64s op1, Bit64s op2)
{
unsigned s1,s2;
if ((s1 = (op1 < 0))) op1 = -op1;
if ((s2 = (op2 < 0))) op2 = -op2;
long_mul((Bit128u*)product,(Bit64u)op1,(Bit64u)op2);
if (s1 ^ s2)
long_neg(product);
}
void long_shl(Bit128u *a)
{
Bit64u c;
c = a->lo >> 63;
a->lo <<= 1;
a->hi <<= 1;
a->hi |= c;
}
void long_shr(Bit128u *a)
{
Bit64u c;
c = a->hi << 63;
a->hi >>= 1;
a->lo >>= 1;
a->lo |= c;
}
unsigned long_sub(Bit128u *a,Bit128u *b)
{
Bit64u t = a->lo;
a->lo -= b->lo;
int c = (a->lo > t);
t = a -> hi;
a->hi -= b->hi + c;
return(a->hi > t);
}
int long_le(Bit128u *a,Bit128u *b)
{
if (a->hi == b->hi) {
return(a->lo <= b->lo);
} else {
return(a->hi <= b->hi);
}
}
void long_div(Bit128u *quotient,Bit64u *remainder,Bit128u *dividend,Bit64u divisor)
{
/*
n := 0;
while (divisor <= dividend) do
inc(n);
divisor := divisor * 2;
end;
quotient := 0;
while n > 0 do
divisor := divisor div 2;
quotient := quotient * 2;
temp := dividend;
dividend := dividend - divisor;
if temp > dividend then
dividend := temp;
else
inc(quotient);
end;
dec(n);
end;
remainder := dividend;
*/
Bit128u d,acc,q,temp;
int n,c;
d.lo = divisor;
d.hi = 0;
acc.lo = dividend->lo;
acc.hi = dividend->hi;
q.lo = 0;
q.hi = 0;
n = 0;
while (long_le(&d,&acc) && n < 128) {
long_shl(&d);
n++;
}
while (n > 0) {
long_shr(&d);
long_shl(&q);
temp.lo = acc.lo;
temp.hi = acc.hi;
c = long_sub(&acc,&d);
if (c) {
acc.lo = temp.lo;
acc.hi = temp.hi;
} else {
q.lo++;
}
n--;
}
*remainder = acc.lo;
quotient->lo = q.lo;
quotient->hi = q.hi;
}
void long_idiv(Bit128s *quotient,Bit64s *remainder,Bit128s *dividend,Bit64s divisor)
{
unsigned s1,s2;
Bit128s temp;
temp = *dividend;
if ((s1 = (temp.hi < 0))) {
long_neg(&temp);
}
if ((s2 = (divisor < 0))) divisor = -divisor;
long_div((Bit128u*)quotient,(Bit64u*)remainder,(Bit128u*)&temp,divisor);
if (s1 ^ s2) {
long_neg(quotient);
}
if (s2) {
*remainder = -*remainder;
}
}
void BX_CPU_C::MUL_RAXEq(bxInstruction_c *i)
{
Bit64u op1_64, op2_64;
Bit128u product_128;
op1_64 = RAX;
/* op2 is a register or memory reference */
if (i->modC0()) {
op2_64 = BX_READ_64BIT_REG(i->rm());
}
else {
/* pointer, segment address pair */
read_virtual_qword(i->seg(), RMAddr(i), &op2_64);
}
// product_128 = ((Bit128u) op1_64) * ((Bit128u) op2_64);
// product_64l = (Bit64u) (product_128 & 0xFFFFFFFFFFFFFFFF);
// product_64h = (Bit64u) (product_128 >> 64);
long_mul(&product_128,op1_64,op2_64);
/* set EFLAGS */
SET_FLAGS_OSZAPC_S1S2_64(product_128.lo, product_128.hi, BX_INSTR_MUL64);
/* now write product back to destination */
RAX = product_128.lo;
RDX = product_128.hi;
}
void BX_CPU_C::IMUL_RAXEq(bxInstruction_c *i)
{
Bit64s op1_64, op2_64;
Bit128s product_128;
op1_64 = RAX;
/* op2 is a register or memory reference */
if (i->modC0()) {
op2_64 = BX_READ_64BIT_REG(i->rm());
}
else {
/* pointer, segment address pair */
read_virtual_qword(i->seg(), RMAddr(i), (Bit64u *) &op2_64);
}
// product_128 = ((Bit128s) op1_64) * ((Bit128s) op2_64);
// product_64l = (Bit64u) (product_128 & 0xFFFFFFFFFFFFFFFF);
// product_64h = (Bit64u) (product_128 >> 64);
long_imul(&product_128,op1_64,op2_64);
/* now write product back to destination */
RAX = product_128.lo;
RDX = product_128.hi;
/* set eflags:
* IMUL r/m64: condition for clearing CF & OF:
* RDX:RAX = sign-extend of RAX
*/
SET_FLAGS_OSZAPC_S1S2_64(product_128.lo, product_128.hi, BX_INSTR_IMUL64);
}
void BX_CPU_C::DIV_RAXEq(bxInstruction_c *i)
{
Bit64u op2_64, remainder_64, quotient_64l;
Bit128u op1_128, quotient_128;
op1_128.lo = RAX;
op1_128.hi = RDX;
/* op2 is a register or memory reference */
if (i->modC0()) {
op2_64 = BX_READ_64BIT_REG(i->rm());
}
else {
/* pointer, segment address pair */
read_virtual_qword(i->seg(), RMAddr(i), &op2_64);
}
if (op2_64 == 0) {
exception(BX_DE_EXCEPTION, 0, 0);
}
// quotient_128 = op1_128 / op2_64;
// remainder_64 = (Bit64u) (op1_128 % op2_64);
// quotient_64l = (Bit64u) (quotient_128 & 0xFFFFFFFFFFFFFFFF);
long_div(&quotient_128,&remainder_64,&op1_128,op2_64);
quotient_64l = quotient_128.lo;
if (quotient_128.hi != 0)
exception(BX_DE_EXCEPTION, 0, 0);
/* set EFLAGS:
* DIV affects the following flags: O,S,Z,A,P,C are undefined
*/
/* now write quotient back to destination */
RAX = quotient_64l;
RDX = remainder_64;
}
void BX_CPU_C::IDIV_RAXEq(bxInstruction_c *i)
{
Bit64s op2_64, remainder_64, quotient_64l;
Bit128s op1_128, quotient_128;
op1_128.lo = RAX;
op1_128.hi = RDX;
/* op2 is a register or memory reference */
if (i->modC0()) {
op2_64 = BX_READ_64BIT_REG(i->rm());
}
else {
/* pointer, segment address pair */
read_virtual_qword(i->seg(), RMAddr(i), (Bit64u *) &op2_64);
}
if (op2_64 == 0) {
exception(BX_DE_EXCEPTION, 0, 0);
}
/* check MIN_INT divided by -1 case */
if (op2_64 == -1)
{
if ((op1_128.hi == BX_CONST64(0x8000000000000000)) && (!op1_128.lo))
exception(BX_DE_EXCEPTION, 0, 0);
}
// quotient_128 = op1_128 / op2_64;
// remainder_64 = (Bit64s) (op1_128 % op2_64);
// quotient_64l = (Bit64s) (quotient_128 & 0xFFFFFFFFFFFFFFFF);
long_idiv(&quotient_128,&remainder_64,&op1_128,op2_64);
quotient_64l = quotient_128.lo;
if ((!(quotient_128.lo & BX_CONST64(0x8000000000000000)) && quotient_128.hi != 0) ||
(quotient_128.lo & BX_CONST64(0x8000000000000000)) && quotient_128.hi != BX_CONST64(0xffffffffffffffff))
{
exception(BX_DE_EXCEPTION, 0, 0);
}
/* set EFLAGS:
* IDIV affects the following flags: O,S,Z,A,P,C are undefined
*/
/* now write quotient back to destination */
RAX = quotient_64l;
RDX = remainder_64;
}
void BX_CPU_C::IMUL_GqEqId(bxInstruction_c *i)
{
Bit64s op2_64, op3_64;
Bit128s product_128;
op3_64 = (Bit32s) i->Id();
/* op2 is a register or memory reference */
if (i->modC0()) {
op2_64 = BX_READ_64BIT_REG(i->rm());
}
else {
/* pointer, segment address pair */
read_virtual_qword(i->seg(), RMAddr(i), (Bit64u *) &op2_64);
}
long_imul(&product_128,op2_64,op3_64);
/* now write product back to destination */
BX_WRITE_64BIT_REG(i->nnn(), product_128.lo);
/* set eflags:
* IMUL r64,r/m64,imm64: condition for clearing CF & OF:
* result exactly fits within r64
*/
SET_FLAGS_OSZAPC_S1S2_64(product_128.lo, product_128.hi, BX_INSTR_IMUL64);
}
void BX_CPU_C::IMUL_GqEq(bxInstruction_c *i)
{
Bit64s op1_64, op2_64;
Bit128s product_128;
/* op2 is a register or memory reference */
if (i->modC0()) {
op2_64 = BX_READ_64BIT_REG(i->rm());
}
else {
/* pointer, segment address pair */
read_virtual_qword(i->seg(), RMAddr(i), (Bit64u *) &op2_64);
}
op1_64 = BX_READ_64BIT_REG(i->nnn());
long_imul(&product_128,op1_64,op2_64);
/* now write product back to destination */
BX_WRITE_64BIT_REG(i->nnn(), product_128.lo);
/* set eflags:
* IMUL r64,r/m64,imm64: condition for clearing CF & OF:
* result exactly fits within r64
*/
SET_FLAGS_OSZAPC_S1S2_64(product_128.lo, product_128.hi, BX_INSTR_IMUL64);
}
#endif /* if BX_SUPPORT_X86_64 */