prim_ops.c

/****************************************************************************
*
* Realmode X86 Emulator Library
*
* Copyright (c) 1996-1999 SciTech Software, Inc.
* Copyright (c) David Mosberger-Tang
* Copyright (c) 1999 Egbert Eich
* Copyright (c) 2007-2017 SUSE LINUX GmbH; Author: Steffen Winterfeldt
*
*  ========================================================================
*
*  Permission to use, copy, modify, distribute, and sell this software and
*  its documentation for any purpose is hereby granted without fee,
*  provided that the above copyright notice appear in all copies and that
*  both that copyright notice and this permission notice appear in
*  supporting documentation, and that the name of the authors not be used
*  in advertising or publicity pertaining to distribution of the software
*  without specific, written prior permission.  The authors makes no
*  representations about the suitability of this software for any purpose.
*  It is provided "as is" without express or implied warranty.
*
*  THE AUTHORS DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
*  INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
*  EVENT SHALL THE AUTHORS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
*  CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF
*  USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
*  OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
*  PERFORMANCE OF THIS SOFTWARE.
*
*  ========================================================================
*
* Description:
*   Implement the primitive machine operations used by the emulation code
*   in ops.c
*
*   Carry Chain Calculation
*
*   This represents a somewhat expensive calculation which is
*   apparently required to emulate the setting of the OF and AF flag.
*   The latter is not so important, but the former is.  The overflow
*   flag is the XOR of the top two bits of the carry chain for an
*   addition (similar for subtraction).  Since we do not want to
*   simulate the addition in a bitwise manner, we try to calculate the
*   carry chain given the two operands and the result.
*
*   So, given the following table, which represents the addition of two
*   bits, we can derive a formula for the carry chain.
*
*   a   b   cin   r     cout
*   0   0   0     0     0
*   0   0   1     1     0
*   0   1   0     1     0
*   0   1   1     0     1
*   1   0   0     1     0
*   1   0   1     0     1
*   1   1   0     0     1
*   1   1   1     1     1
*
*   Construction of table for cout:
*
*   ab
*   r  \  00   01   11  10
*   |------------------
*   0  |   0    1    1   1
*   1  |   0    0    1   0
*
*   By inspection, one gets:  cc = ab +  r'(a + b)
*
*   That represents alot of operations, but NO CHOICE....
*
*   Borrow Chain Calculation.
*
*   The following table represents the subtraction of two bits, from
*   which we can derive a formula for the borrow chain.
*
*   a   b   bin   r     bout
*   0   0   0     0     0
*   0   0   1     1     1
*   0   1   0     1     1
*   0   1   1     0     1
*   1   0   0     1     0
*   1   0   1     0     0
*   1   1   0     0     0
*   1   1   1     1     1
*
*   Construction of table for cout:
*
*   ab
*   r  \  00   01   11  10
*   |------------------
*   0  |   0    1    0   0
*   1  |   1    1    1   0
*
*   By inspection, one gets:  bc = a'b +  r(a' + b)
*
****************************************************************************/


#include "include/x86emu_int.h"

/*------------------------- Global Variables ------------------------------*/

u32 x86emu_parity_tab[8] =
{
	0x96696996,
	0x69969669,
	0x69969669,
	0x96696996,
	0x69969669,
	0x96696996,
	0x96696996,
	0x69969669,
};

#define XOR2(x) 	(((x) ^ ((x)>>1)) & 0x1)

/*----------------------------- Implementation ----------------------------*/

/****************************************************************************
REMARKS:
Implements the AAA instruction and side effects.
****************************************************************************/
u16 aaa_word(x86emu_t *emu, u16 d)
{
	u16	res;
	if ((d & 0xf) > 0x9 || ACCESS_FLAG(F_AF)) {
		d += 0x6;
		d += 0x100;
		SET_FLAG(F_AF);
		SET_FLAG(F_CF);
	} else {
		CLEAR_FLAG(F_CF);
		CLEAR_FLAG(F_AF);
	}
	res = (u16)(d & 0xFF0F);
	CLEAR_FLAG(F_SF);
	CONDITIONAL_SET_FLAG(res == 0, F_ZF);
	CONDITIONAL_SET_FLAG(PARITY(res & 0xff), F_PF);
	return res;
}

/****************************************************************************
REMARKS:
Implements the AAA instruction and side effects.
****************************************************************************/
u16 aas_word(x86emu_t *emu, u16 d)
{
	u16	res;
	if ((d & 0xf) > 0x9 || ACCESS_FLAG(F_AF)) {
		d -= 0x6;
		d -= 0x100;
		SET_FLAG(F_AF);
		SET_FLAG(F_CF);
	} else {
		CLEAR_FLAG(F_CF);
		CLEAR_FLAG(F_AF);
	}
	res = (u16)(d & 0xFF0F);
	CLEAR_FLAG(F_SF);
	CONDITIONAL_SET_FLAG(res == 0, F_ZF);
	CONDITIONAL_SET_FLAG(PARITY(res & 0xff), F_PF);
	return res;
}

/****************************************************************************
REMARKS:
Implements the AAD instruction and side effects.
****************************************************************************/
u16 aad_word(x86emu_t *emu, u16 d, u8 base)
{
	u16 l;
	u8 hb, lb;

	hb = (u8)((d >> 8) & 0xff);
	lb = (u8)((d & 0xff));
	l = (u16)((lb + base * hb) & 0xFF);

	CLEAR_FLAG(F_CF);
	CLEAR_FLAG(F_AF);
	CLEAR_FLAG(F_OF);
	CONDITIONAL_SET_FLAG(l & 0x80, F_SF);
	CONDITIONAL_SET_FLAG(l == 0, F_ZF);
	CONDITIONAL_SET_FLAG(PARITY(l & 0xff), F_PF);
	return l;
}

/****************************************************************************
REMARKS:
Implements the AAM instruction and side effects.
****************************************************************************/
u16 aam_word(x86emu_t *emu, u8 d, u8 base)
{
    u16 h, l;

	h = (u16)(d / base);
	l = (u16)(d % base);
	l |= (u16)(h << 8);

	CLEAR_FLAG(F_CF);
	CLEAR_FLAG(F_AF);
	CLEAR_FLAG(F_OF);
	CONDITIONAL_SET_FLAG(l & 0x80, F_SF);
	CONDITIONAL_SET_FLAG(l == 0, F_ZF);
	CONDITIONAL_SET_FLAG(PARITY(l & 0xff), F_PF);
    return l;
}

/****************************************************************************
REMARKS:
Implements the ADC instruction and side effects.
****************************************************************************/
u8 adc_byte(x86emu_t *emu, u8 d, u8 s)
{
	register u32 res;   /* all operands in native machine order */
	register u32 cc;

	if (ACCESS_FLAG(F_CF))
		res = 1 + d + s;
	else
		res = d + s;

	CONDITIONAL_SET_FLAG(res & 0x100, F_CF);
	CONDITIONAL_SET_FLAG((res & 0xff) == 0, F_ZF);
	CONDITIONAL_SET_FLAG(res & 0x80, F_SF);
	CONDITIONAL_SET_FLAG(PARITY(res & 0xff), F_PF);

	/* calculate the carry chain  SEE NOTE AT TOP. */
	cc = (s & d) | ((~res) & (s | d));
	CONDITIONAL_SET_FLAG(XOR2(cc >> 6), F_OF);
	CONDITIONAL_SET_FLAG(cc & 0x8, F_AF);
	return (u8)res;
}

/****************************************************************************
REMARKS:
Implements the ADC instruction and side effects.
****************************************************************************/
u16 adc_word(x86emu_t *emu, u16 d, u16 s)
{
	register u32 res;   /* all operands in native machine order */
	register u32 cc;

	if (ACCESS_FLAG(F_CF))
		res = 1 + d + s;
	else
		res = d + s;

	CONDITIONAL_SET_FLAG(res & 0x10000, F_CF);
	CONDITIONAL_SET_FLAG((res & 0xffff) == 0, F_ZF);
	CONDITIONAL_SET_FLAG(res & 0x8000, F_SF);
	CONDITIONAL_SET_FLAG(PARITY(res & 0xff), F_PF);

	/* calculate the carry chain  SEE NOTE AT TOP. */
	cc = (s & d) | ((~res) & (s | d));
	CONDITIONAL_SET_FLAG(XOR2(cc >> 14), F_OF);
	CONDITIONAL_SET_FLAG(cc & 0x8, F_AF);
	return (u16)res;
}

/****************************************************************************
REMARKS:
Implements the ADC instruction and side effects.
****************************************************************************/
u32 adc_long(x86emu_t *emu, u32 d, u32 s)
{
	register u32 lo;	/* all operands in native machine order */
	register u32 hi;
	register u32 res;
	register u32 cc;

	if (ACCESS_FLAG(F_CF)) {
		lo = 1 + (d & 0xFFFF) + (s & 0xFFFF);
		res = 1 + d + s;
		}
	else {
		lo = (d & 0xFFFF) + (s & 0xFFFF);
		res = d + s;
		}
	hi = (lo >> 16) + (d >> 16) + (s >> 16);

	CONDITIONAL_SET_FLAG(hi & 0x10000, F_CF);
	CONDITIONAL_SET_FLAG((res & 0xffffffff) == 0, F_ZF);
	CONDITIONAL_SET_FLAG(res & 0x80000000, F_SF);
	CONDITIONAL_SET_FLAG(PARITY(res & 0xff), F_PF);

	/* calculate the carry chain  SEE NOTE AT TOP. */
	cc = (s & d) | ((~res) & (s | d));
	CONDITIONAL_SET_FLAG(XOR2(cc >> 30), F_OF);
	CONDITIONAL_SET_FLAG(cc & 0x8, F_AF);
	return res;
}

/****************************************************************************
REMARKS:
Implements the ADD instruction and side effects.
****************************************************************************/
u8 add_byte(x86emu_t *emu, u8 d, u8 s)
{
	register u32 res;   /* all operands in native machine order */
	register u32 cc;

	res = d + s;
	CONDITIONAL_SET_FLAG(res & 0x100, F_CF);
	CONDITIONAL_SET_FLAG((res & 0xff) == 0, F_ZF);
	CONDITIONAL_SET_FLAG(res & 0x80, F_SF);
	CONDITIONAL_SET_FLAG(PARITY(res & 0xff), F_PF);

	/* calculate the carry chain  SEE NOTE AT TOP. */
	cc = (s & d) | ((~res) & (s | d));
	CONDITIONAL_SET_FLAG(XOR2(cc >> 6), F_OF);
	CONDITIONAL_SET_FLAG(cc & 0x8, F_AF);
	return (u8)res;
}

/****************************************************************************
REMARKS:
Implements the ADD instruction and side effects.
****************************************************************************/
u16 add_word(x86emu_t *emu, u16 d, u16 s)
{
	register u32 res;   /* all operands in native machine order */
	register u32 cc;

	res = d + s;
	CONDITIONAL_SET_FLAG(res & 0x10000, F_CF);
	CONDITIONAL_SET_FLAG((res & 0xffff) == 0, F_ZF);
	CONDITIONAL_SET_FLAG(res & 0x8000, F_SF);
	CONDITIONAL_SET_FLAG(PARITY(res & 0xff), F_PF);

	/* calculate the carry chain  SEE NOTE AT TOP. */
	cc = (s & d) | ((~res) & (s | d));
	CONDITIONAL_SET_FLAG(XOR2(cc >> 14), F_OF);
	CONDITIONAL_SET_FLAG(cc & 0x8, F_AF);
	return (u16)res;
}

/****************************************************************************
REMARKS:
Implements the ADD instruction and side effects.
****************************************************************************/
u32 add_long(x86emu_t *emu, u32 d, u32 s)
{
	register u32 lo;	/* all operands in native machine order */
	register u32 hi;
	register u32 res;
	register u32 cc;

	lo = (d & 0xFFFF) + (s & 0xFFFF);
	res = d + s;
	hi = (lo >> 16) + (d >> 16) + (s >> 16);

	CONDITIONAL_SET_FLAG(hi & 0x10000, F_CF);
	CONDITIONAL_SET_FLAG((res & 0xffffffff) == 0, F_ZF);
	CONDITIONAL_SET_FLAG(res & 0x80000000, F_SF);
	CONDITIONAL_SET_FLAG(PARITY(res & 0xff), F_PF);

    /* calculate the carry chain  SEE NOTE AT TOP. */
    cc = (s & d) | ((~res) & (s | d));
	CONDITIONAL_SET_FLAG(XOR2(cc >> 30), F_OF);
	CONDITIONAL_SET_FLAG(cc & 0x8, F_AF);

    return res;
}

/****************************************************************************
REMARKS:
Implements the AND instruction and side effects.
****************************************************************************/
u8 and_byte(x86emu_t *emu, u8 d, u8 s)
{
	register u8 res;    /* all operands in native machine order */

	res = d & s;

	/* set the flags  */
	CLEAR_FLAG(F_OF);
	CLEAR_FLAG(F_CF);
	CLEAR_FLAG(F_AF);
	CONDITIONAL_SET_FLAG(res & 0x80, F_SF);
	CONDITIONAL_SET_FLAG(res == 0, F_ZF);
	CONDITIONAL_SET_FLAG(PARITY(res), F_PF);
	return res;
}

/****************************************************************************
REMARKS:
Implements the AND instruction and side effects.
****************************************************************************/
u16 and_word(x86emu_t *emu, u16 d, u16 s)
{
    register u16 res;   /* all operands in native machine order */

    res = d & s;

    /* set the flags  */
	CLEAR_FLAG(F_OF);
	CLEAR_FLAG(F_CF);
	CLEAR_FLAG(F_AF);
	CONDITIONAL_SET_FLAG(res & 0x8000, F_SF);
	CONDITIONAL_SET_FLAG(res == 0, F_ZF);
	CONDITIONAL_SET_FLAG(PARITY(res & 0xff), F_PF);
    return res;
}

/****************************************************************************
REMARKS:
Implements the AND instruction and side effects.
****************************************************************************/
u32 and_long(x86emu_t *emu, u32 d, u32 s)
{
	register u32 res;   /* all operands in native machine order */

	res = d & s;

	/* set the flags  */
	CLEAR_FLAG(F_OF);
	CLEAR_FLAG(F_CF);
	CLEAR_FLAG(F_AF);
	CONDITIONAL_SET_FLAG(res & 0x80000000, F_SF);
	CONDITIONAL_SET_FLAG(res == 0, F_ZF);
	CONDITIONAL_SET_FLAG(PARITY(res & 0xff), F_PF);
	return res;
}

/****************************************************************************
REMARKS:
Implements the CMP instruction and side effects.
****************************************************************************/
u8 cmp_byte(x86emu_t *emu, u8 d, u8 s)
{
	register u32 res;   /* all operands in native machine order */
	register u32 bc;

	res = d - s;
	CLEAR_FLAG(F_CF);
	CONDITIONAL_SET_FLAG(res & 0x80, F_SF);
	CONDITIONAL_SET_FLAG((res & 0xff) == 0, F_ZF);
	CONDITIONAL_SET_FLAG(PARITY(res & 0xff), F_PF);

	/* calculate the borrow chain.  See note at top */
	bc = (res & (~d | s)) | (~d & s);
	CONDITIONAL_SET_FLAG(bc & 0x80, F_CF);
	CONDITIONAL_SET_FLAG(XOR2(bc >> 6), F_OF);
	CONDITIONAL_SET_FLAG(bc & 0x8, F_AF);
	return d;
}

/****************************************************************************
REMARKS:
Implements the CMP instruction and side effects.
****************************************************************************/
u16 cmp_word(x86emu_t *emu, u16 d, u16 s)
{
	register u32 res;   /* all operands in native machine order */
	register u32 bc;

	res = d - s;
	CONDITIONAL_SET_FLAG(res & 0x8000, F_SF);
	CONDITIONAL_SET_FLAG((res & 0xffff) == 0, F_ZF);
	CONDITIONAL_SET_FLAG(PARITY(res & 0xff), F_PF);

	/* calculate the borrow chain.  See note at top */
    bc = (res & (~d | s)) | (~d & s);
	CONDITIONAL_SET_FLAG(bc & 0x8000, F_CF);
	CONDITIONAL_SET_FLAG(XOR2(bc >> 14), F_OF);
	CONDITIONAL_SET_FLAG(bc & 0x8, F_AF);
	return d;
}

/****************************************************************************
REMARKS:
Implements the CMP instruction and side effects.
****************************************************************************/
u32 cmp_long(x86emu_t *emu, u32 d, u32 s)
{
	register u32 res;   /* all operands in native machine order */
	register u32 bc;

	res = d - s;
	CONDITIONAL_SET_FLAG(res & 0x80000000, F_SF);
	CONDITIONAL_SET_FLAG((res & 0xffffffff) == 0, F_ZF);
	CONDITIONAL_SET_FLAG(PARITY(res & 0xff), F_PF);

	/* calculate the borrow chain.  See note at top */
	bc = (res & (~d | s)) | (~d & s);
	CONDITIONAL_SET_FLAG(bc & 0x80000000, F_CF);
	CONDITIONAL_SET_FLAG(XOR2(bc >> 30), F_OF);
	CONDITIONAL_SET_FLAG(bc & 0x8, F_AF);
	return d;
}

/****************************************************************************
REMARKS:
Implements the DAA instruction and side effects.
****************************************************************************/
u8 daa_byte(x86emu_t *emu, u8 d)
{
	u32 res = d;
	if ((d & 0xf) > 9 || ACCESS_FLAG(F_AF)) {
		res += 6;
		SET_FLAG(F_AF);
	}
	if (res > 0x9F || ACCESS_FLAG(F_CF)) {
		res += 0x60;
		SET_FLAG(F_CF);
	}
	CONDITIONAL_SET_FLAG(res & 0x80, F_SF);
	CONDITIONAL_SET_FLAG((res & 0xFF) == 0, F_ZF);
	CONDITIONAL_SET_FLAG(PARITY(res & 0xff), F_PF);
	return (u8)res;
}

/****************************************************************************
REMARKS:
Implements the DAS instruction and side effects.
****************************************************************************/
u8 das_byte(x86emu_t *emu, u8 d)
{
	if ((d & 0xf) > 9 || ACCESS_FLAG(F_AF)) {
		d -= 6;
		SET_FLAG(F_AF);
	}
	if (d > 0x9F || ACCESS_FLAG(F_CF)) {
		d -= 0x60;
		SET_FLAG(F_CF);
	}
	CONDITIONAL_SET_FLAG(d & 0x80, F_SF);
	CONDITIONAL_SET_FLAG(d == 0, F_ZF);
	CONDITIONAL_SET_FLAG(PARITY(d & 0xff), F_PF);
	return d;
}

/****************************************************************************
REMARKS:
Implements the DEC instruction and side effects.
****************************************************************************/
u8 dec_byte(x86emu_t *emu, u8 d)
{
    register u32 res;   /* all operands in native machine order */
    register u32 bc;

    res = d - 1;
	CONDITIONAL_SET_FLAG(res & 0x80, F_SF);
	CONDITIONAL_SET_FLAG((res & 0xff) == 0, F_ZF);
	CONDITIONAL_SET_FLAG(PARITY(res & 0xff), F_PF);

	/* calculate the borrow chain.  See note at top */
	/* based on sub_byte, uses s==1.  */
	bc = (res & (~d | 1)) | (~d & 1);
	/* carry flag unchanged */
	CONDITIONAL_SET_FLAG(XOR2(bc >> 6), F_OF);
	CONDITIONAL_SET_FLAG(bc & 0x8, F_AF);
	return (u8)res;
}

/****************************************************************************
REMARKS:
Implements the DEC instruction and side effects.
****************************************************************************/
u16 dec_word(x86emu_t *emu, u16 d)
{
    register u32 res;   /* all operands in native machine order */
    register u32 bc;

    res = d - 1;
	CONDITIONAL_SET_FLAG(res & 0x8000, F_SF);
	CONDITIONAL_SET_FLAG((res & 0xffff) == 0, F_ZF);
	CONDITIONAL_SET_FLAG(PARITY(res & 0xff), F_PF);

    /* calculate the borrow chain.  See note at top */
    /* based on the sub_byte routine, with s==1 */
    bc = (res & (~d | 1)) | (~d & 1);
    /* carry flag unchanged */
	CONDITIONAL_SET_FLAG(XOR2(bc >> 14), F_OF);
	CONDITIONAL_SET_FLAG(bc & 0x8, F_AF);
	return (u16)res;
}

/****************************************************************************
REMARKS:
Implements the DEC instruction and side effects.
****************************************************************************/
u32 dec_long(x86emu_t *emu, u32 d)
{
    register u32 res;   /* all operands in native machine order */
    register u32 bc;

    res = d - 1;

	CONDITIONAL_SET_FLAG(res & 0x80000000, F_SF);
	CONDITIONAL_SET_FLAG((res & 0xffffffff) == 0, F_ZF);
	CONDITIONAL_SET_FLAG(PARITY(res & 0xff), F_PF);

    /* calculate the borrow chain.  See note at top */
	bc = (res & (~d | 1)) | (~d & 1);
	/* carry flag unchanged */
	CONDITIONAL_SET_FLAG(XOR2(bc >> 30), F_OF);
	CONDITIONAL_SET_FLAG(bc & 0x8, F_AF);
	return res;
}

/****************************************************************************
REMARKS:
Implements the INC instruction and side effects.
****************************************************************************/
u8 inc_byte(x86emu_t *emu, u8 d)
{
	register u32 res;   /* all operands in native machine order */
	register u32 cc;

	res = d + 1;
	CONDITIONAL_SET_FLAG((res & 0xff) == 0, F_ZF);
	CONDITIONAL_SET_FLAG(res & 0x80, F_SF);
	CONDITIONAL_SET_FLAG(PARITY(res & 0xff), F_PF);

	/* calculate the carry chain  SEE NOTE AT TOP. */
	cc = ((1 & d) | (~res)) & (1 | d);
	CONDITIONAL_SET_FLAG(XOR2(cc >> 6), F_OF);
	CONDITIONAL_SET_FLAG(cc & 0x8, F_AF);
	return (u8)res;
}

/****************************************************************************
REMARKS:
Implements the INC instruction and side effects.
****************************************************************************/
u16 inc_word(x86emu_t *emu, u16 d)
{
	register u32 res;   /* all operands in native machine order */
	register u32 cc;

	res = d + 1;
	CONDITIONAL_SET_FLAG((res & 0xffff) == 0, F_ZF);
	CONDITIONAL_SET_FLAG(res & 0x8000, F_SF);
	CONDITIONAL_SET_FLAG(PARITY(res & 0xff), F_PF);

	/* calculate the carry chain  SEE NOTE AT TOP. */
	cc = (1 & d) | ((~res) & (1 | d));
	CONDITIONAL_SET_FLAG(XOR2(cc >> 14), F_OF);
	CONDITIONAL_SET_FLAG(cc & 0x8, F_AF);
	return (u16)res;
}

/****************************************************************************
REMARKS:
Implements the INC instruction and side effects.
****************************************************************************/
u32 inc_long(x86emu_t *emu, u32 d)
{
	register u32 res;   /* all operands in native machine order */
	register u32 cc;

	res = d + 1;
	CONDITIONAL_SET_FLAG((res & 0xffffffff) == 0, F_ZF);
	CONDITIONAL_SET_FLAG(res & 0x80000000, F_SF);
	CONDITIONAL_SET_FLAG(PARITY(res & 0xff), F_PF);

	/* calculate the carry chain  SEE NOTE AT TOP. */
	cc = (1 & d) | ((~res) & (1 | d));
	CONDITIONAL_SET_FLAG(XOR2(cc >> 30), F_OF);
	CONDITIONAL_SET_FLAG(cc & 0x8, F_AF);
	return res;
}

/****************************************************************************
REMARKS:
Implements the OR instruction and side effects.
****************************************************************************/
u8 or_byte(x86emu_t *emu, u8 d, u8 s)
{
	register u8 res;    /* all operands in native machine order */

	res = d | s;
	CLEAR_FLAG(F_OF);
	CLEAR_FLAG(F_CF);
	CLEAR_FLAG(F_AF);
	CONDITIONAL_SET_FLAG(res & 0x80, F_SF);
	CONDITIONAL_SET_FLAG(res == 0, F_ZF);
	CONDITIONAL_SET_FLAG(PARITY(res), F_PF);
	return res;
}

/****************************************************************************
REMARKS:
Implements the OR instruction and side effects.
****************************************************************************/
u16 or_word(x86emu_t *emu, u16 d, u16 s)
{
	register u16 res;   /* all operands in native machine order */

	res = d | s;
	/* set the carry flag to be bit 8 */
	CLEAR_FLAG(F_OF);
	CLEAR_FLAG(F_CF);
	CLEAR_FLAG(F_AF);
	CONDITIONAL_SET_FLAG(res & 0x8000, F_SF);
	CONDITIONAL_SET_FLAG(res == 0, F_ZF);
	CONDITIONAL_SET_FLAG(PARITY(res & 0xff), F_PF);
	return res;
}

/****************************************************************************
REMARKS:
Implements the OR instruction and side effects.
****************************************************************************/
u32 or_long(x86emu_t *emu, u32 d, u32 s)
{
	register u32 res;   /* all operands in native machine order */

	res = d | s;

	/* set the carry flag to be bit 8 */
	CLEAR_FLAG(F_OF);
	CLEAR_FLAG(F_CF);
	CLEAR_FLAG(F_AF);
	CONDITIONAL_SET_FLAG(res & 0x80000000, F_SF);
	CONDITIONAL_SET_FLAG(res == 0, F_ZF);
	CONDITIONAL_SET_FLAG(PARITY(res & 0xff), F_PF);
	return res;
}

/****************************************************************************
REMARKS:
Implements the NEG instruction and side effects.
****************************************************************************/
u8 neg_byte(x86emu_t *emu, u8 s)
{
    register u8 res;
    register u8 bc;

	CONDITIONAL_SET_FLAG(s != 0, F_CF);
	res = (u8)-s;
	CONDITIONAL_SET_FLAG((res & 0xff) == 0, F_ZF);
	CONDITIONAL_SET_FLAG(res & 0x80, F_SF);
	CONDITIONAL_SET_FLAG(PARITY(res), F_PF);
	/* calculate the borrow chain --- modified such that d=0.
	   substitutiing d=0 into     bc= res&(~d|s)|(~d&s);
	   (the one used for sub) and simplifying, since ~d=0xff...,
	   ~d|s == 0xffff..., and res&0xfff... == res.  Similarly
	   ~d&s == s.  So the simplified result is: */
	bc = res | s;
	CONDITIONAL_SET_FLAG(XOR2(bc >> 6), F_OF);
	CONDITIONAL_SET_FLAG(bc & 0x8, F_AF);
	return res;
}

/****************************************************************************
REMARKS:
Implements the NEG instruction and side effects.
****************************************************************************/
u16 neg_word(x86emu_t *emu, u16 s)
{
	register u16 res;
	register u16 bc;

	CONDITIONAL_SET_FLAG(s != 0, F_CF);
	res = (u16)-s;
	CONDITIONAL_SET_FLAG((res & 0xffff) == 0, F_ZF);
	CONDITIONAL_SET_FLAG(res & 0x8000, F_SF);
	CONDITIONAL_SET_FLAG(PARITY(res & 0xff), F_PF);

	/* calculate the borrow chain --- modified such that d=0.
	   substitutiing d=0 into     bc= res&(~d|s)|(~d&s);
	   (the one used for sub) and simplifying, since ~d=0xff...,
	   ~d|s == 0xffff..., and res&0xfff... == res.  Similarly
	   ~d&s == s.  So the simplified result is: */
	bc = res | s;
	CONDITIONAL_SET_FLAG(XOR2(bc >> 14), F_OF);
	CONDITIONAL_SET_FLAG(bc & 0x8, F_AF);
	return res;
}

/****************************************************************************
REMARKS:
Implements the NEG instruction and side effects.
****************************************************************************/
u32 neg_long(x86emu_t *emu, u32 s)
{
	register u32 res;
	register u32 bc;

	CONDITIONAL_SET_FLAG(s != 0, F_CF);
	res = (u32)-s;
	CONDITIONAL_SET_FLAG((res & 0xffffffff) == 0, F_ZF);
	CONDITIONAL_SET_FLAG(res & 0x80000000, F_SF);
	CONDITIONAL_SET_FLAG(PARITY(res & 0xff), F_PF);

	/* calculate the borrow chain --- modified such that d=0.
	   substitutiing d=0 into     bc= res&(~d|s)|(~d&s);
	   (the one used for sub) and simplifying, since ~d=0xff...,
	   ~d|s == 0xffff..., and res&0xfff... == res.  Similarly
	   ~d&s == s.  So the simplified result is: */
	bc = res | s;
	CONDITIONAL_SET_FLAG(XOR2(bc >> 30), F_OF);
	CONDITIONAL_SET_FLAG(bc & 0x8, F_AF);
	return res;
}

/****************************************************************************
REMARKS:
Implements the NOT instruction and side effects.
****************************************************************************/
u8 not_byte(x86emu_t *emu, u8 s)
{
	return ~s;
}

/****************************************************************************
REMARKS:
Implements the NOT instruction and side effects.
****************************************************************************/
u16 not_word(x86emu_t *emu, u16 s)
{
	return ~s;
}

/****************************************************************************
REMARKS:
Implements the NOT instruction and side effects.
****************************************************************************/
u32 not_long(x86emu_t *emu, u32 s)
{
	return ~s;
}

/****************************************************************************
REMARKS:
Implements the RCL instruction and side effects.
****************************************************************************/
u8 rcl_byte(x86emu_t *emu, u8 d, u8 s)
{
    register unsigned int res, cnt, mask, cf;

    /* s is the rotate distance.  It varies from 0 - 8. */
	/* have

       CF  B_7 B_6 B_5 B_4 B_3 B_2 B_1 B_0 

       want to rotate through the carry by "s" bits.  We could 
       loop, but that's inefficient.  So the width is 9,
       and we split into three parts:

       The new carry flag   (was B_n)
       the stuff in B_n-1 .. B_0
       the stuff in B_7 .. B_n+1

       The new rotate is done mod 9, and given this,
       for a rotation of n bits (mod 9) the new carry flag is
       then located n bits from the MSB.  The low part is 
       then shifted up cnt bits, and the high part is or'd
       in.  Using CAPS for new values, and lowercase for the 
       original values, this can be expressed as:

       IF n > 0 
       1) CF <-  b_(8-n)
       2) B_(7) .. B_(n)  <-  b_(8-(n+1)) .. b_0
       3) B_(n-1) <- cf
       4) B_(n-2) .. B_0 <-  b_7 .. b_(8-(n-1))
	 */
	res = d;
	if ((cnt = s % 9) != 0) {
        /* extract the new CARRY FLAG. */
        /* CF <-  b_(8-n)             */
        cf = (d >> (8 - cnt)) & 0x1;

        /* get the low stuff which rotated 
           into the range B_7 .. B_cnt */
        /* B_(7) .. B_(n)  <-  b_(8-(n+1)) .. b_0  */
        /* note that the right hand side done by the mask */
		res = (d << cnt) & 0xff;

        /* now the high stuff which rotated around 
           into the positions B_cnt-2 .. B_0 */
        /* B_(n-2) .. B_0 <-  b_7 .. b_(8-(n-1)) */
        /* shift it downward, 7-(n-2) = 9-n positions. 
           and mask off the result before or'ing in. 
         */
        mask = (1 << (cnt - 1)) - 1;
        res |= (d >> (9 - cnt)) & mask;

        /* if the carry flag was set, or it in.  */
		if (ACCESS_FLAG(F_CF)) {     /* carry flag is set */
            /*  B_(n-1) <- cf */
            res |= 1 << (cnt - 1);
        }
        /* set the new carry flag, based on the variable "cf" */
		CONDITIONAL_SET_FLAG(cf, F_CF);
        /* OVERFLOW is set *IFF* cnt==1, then it is the 
           xor of CF and the most significant bit.  Blecck. */
        /* parenthesized this expression since it appears to
           be causing OF to be misset */
        CONDITIONAL_SET_FLAG(cnt == 1 && XOR2(cf + ((res >> 6) & 0x2)),
							 F_OF);

    }
	return (u8)res;
}

/****************************************************************************
REMARKS:
Implements the RCL instruction and side effects.
****************************************************************************/
u16 rcl_word(x86emu_t *emu, u16 d, u8 s)
{
	register unsigned int res, cnt, mask, cf;

	res = d;
	if ((cnt = s % 17) != 0) {
		cf = (d >> (16 - cnt)) & 0x1;
		res = (d << cnt) & 0xffff;
		mask = (1 << (cnt - 1)) - 1;
		res |= (d >> (17 - cnt)) & mask;
		if (ACCESS_FLAG(F_CF)) {
			res |= 1 << (cnt - 1);
		}
		CONDITIONAL_SET_FLAG(cf, F_CF);
		CONDITIONAL_SET_FLAG(cnt == 1 && XOR2(cf + ((res >> 14) & 0x2)),
							 F_OF);
	}
	return (u16)res;
}

/****************************************************************************
REMARKS:
Implements the RCL instruction and side effects.
****************************************************************************/
u32 rcl_long(x86emu_t *emu, u32 d, u8 s)
{
	register u32 res, cnt, mask, cf;

	res = d;
	if ((cnt = s % 33) != 0) {
		cf = (d >> (32 - cnt)) & 0x1;
		res = (d << cnt) & 0xffffffff;
		mask = (1 << (cnt - 1)) - 1;
		res |= (d >> (33 - cnt)) & mask;
		if (ACCESS_FLAG(F_CF)) {     /* carry flag is set */
			res |= 1 << (cnt - 1);
		}
		CONDITIONAL_SET_FLAG(cf, F_CF);
		CONDITIONAL_SET_FLAG(cnt == 1 && XOR2(cf + ((res >> 30) & 0x2)),
							 F_OF);
	}
	return res;
}

/****************************************************************************
REMARKS:
Implements the RCR instruction and side effects.
****************************************************************************/
u8 rcr_byte(x86emu_t *emu, u8 d, u8 s)
{
	u32	res, cnt;
	u32	mask, cf, ocf = 0;

	/* rotate right through carry */
    /* 
       s is the rotate distance.  It varies from 0 - 8.
       d is the byte object rotated.  

       have 

       CF  B_7 B_6 B_5 B_4 B_3 B_2 B_1 B_0 

       The new rotate is done mod 9, and given this,
       for a rotation of n bits (mod 9) the new carry flag is
       then located n bits from the LSB.  The low part is 
       then shifted up cnt bits, and the high part is or'd
       in.  Using CAPS for new values, and lowercase for the 
       original values, this can be expressed as:

       IF n > 0 
       1) CF <-  b_(n-1)
       2) B_(8-(n+1)) .. B_(0)  <-  b_(7) .. b_(n)
       3) B_(8-n) <- cf
       4) B_(7) .. B_(8-(n-1)) <-  b_(n-2) .. b_(0)
	 */
	res = d;
	if ((cnt = s % 9) != 0) {
        /* extract the new CARRY FLAG. */
        /* CF <-  b_(n-1)              */
        if (cnt == 1) {
            cf = d & 0x1;
            /* note hackery here.  Access_flag(..) evaluates to either
               0 if flag not set
               non-zero if flag is set.
               doing access_flag(..) != 0 casts that into either 
			   0..1 in any representation of the flags register
               (i.e. packed bit array or unpacked.)
             */
			ocf = ACCESS_FLAG(F_CF) != 0;
        } else
            cf = (d >> (cnt - 1)) & 0x1;

        /* B_(8-(n+1)) .. B_(0)  <-  b_(7) .. b_n  */
        /* note that the right hand side done by the mask
           This is effectively done by shifting the 
           object to the right.  The result must be masked,
           in case the object came in and was treated 
           as a negative number.  Needed??? */

        mask = (1 << (8 - cnt)) - 1;
        res = (d >> cnt) & mask;

        /* now the high stuff which rotated around 
           into the positions B_cnt-2 .. B_0 */
        /* B_(7) .. B_(8-(n-1)) <-  b_(n-2) .. b_(0) */
        /* shift it downward, 7-(n-2) = 9-n positions. 
           and mask off the result before or'ing in. 
         */
        res |= (d << (9 - cnt));

        /* if the carry flag was set, or it in.  */
		if (ACCESS_FLAG(F_CF)) {     /* carry flag is set */
            /*  B_(8-n) <- cf */
            res |= 1 << (8 - cnt);
        }
        /* set the new carry flag, based on the variable "cf" */
		CONDITIONAL_SET_FLAG(cf, F_CF);
        /* OVERFLOW is set *IFF* cnt==1, then it is the 
           xor of CF and the most significant bit.  Blecck. */
        /* parenthesized... */
		if (cnt == 1) {
			CONDITIONAL_SET_FLAG(XOR2(ocf + ((d >> 6) & 0x2)),
								 F_OF);
		}
	}
	return (u8)res;
}

/****************************************************************************
REMARKS:
Implements the RCR instruction and side effects.
****************************************************************************/
u16 rcr_word(x86emu_t *emu, u16 d, u8 s)
{
	u32 res, cnt;
	u32	mask, cf, ocf = 0;

	/* rotate right through carry */
	res = d;
	if ((cnt = s % 17) != 0) {
		if (cnt == 1) {
			cf = d & 0x1;
			ocf = ACCESS_FLAG(F_CF) != 0;
		} else
			cf = (d >> (cnt - 1)) & 0x1;
		mask = (1 << (16 - cnt)) - 1;
		res = (d >> cnt) & mask;
		res |= (d << (17 - cnt));
		if (ACCESS_FLAG(F_CF)) {
			res |= 1 << (16 - cnt);
		}
		CONDITIONAL_SET_FLAG(cf, F_CF);
		if (cnt == 1) {
			CONDITIONAL_SET_FLAG(XOR2(ocf + ((d >> 14) & 0x2)),
								 F_OF);
		}
	}
	return (u16)res;
}

/****************************************************************************
REMARKS:
Implements the RCR instruction and side effects.
****************************************************************************/
u32 rcr_long(x86emu_t *emu, u32 d, u8 s)
{
	u32 res, cnt;
	u32 mask, cf, ocf = 0;

	/* rotate right through carry */
	res = d;
	if ((cnt = s % 33) != 0) {
		if (cnt == 1) {
			cf = d & 0x1;
			ocf = ACCESS_FLAG(F_CF) != 0;
		} else
			cf = (d >> (cnt - 1)) & 0x1;
		mask = (1 << (32 - cnt)) - 1;
		res = (d >> cnt) & mask;
		if (cnt != 1)
			res |= (d << (33 - cnt));
		if (ACCESS_FLAG(F_CF)) {     /* carry flag is set */
			res |= 1 << (32 - cnt);
		}
		CONDITIONAL_SET_FLAG(cf, F_CF);
		if (cnt == 1) {
			CONDITIONAL_SET_FLAG(XOR2(ocf + ((d >> 30) & 0x2)),
								 F_OF);
		}
	}
	return res;
}

/****************************************************************************
REMARKS:
Implements the ROL instruction and side effects.
****************************************************************************/
u8 rol_byte(x86emu_t *emu, u8 d, u8 s)
{
  unsigned cnt;

  if(!s) return d;

  if((cnt = s % 8) != 0) {
    d = (d << cnt) + ((d >> (8 - cnt)) & ((1 << cnt) - 1));
  }

  /* OF flag is set if s == 1; OF = CF _XOR_ MSB of result */
  if(s == 1) {
    CONDITIONAL_SET_FLAG((d + (d >> 7)) & 1, F_OF);
  }

  /* set new CF; note that it is the LSB of the result */
  CONDITIONAL_SET_FLAG(d & 0x1, F_CF);

  return d;
}

/****************************************************************************
REMARKS:
Implements the ROL instruction and side effects.
****************************************************************************/
u16 rol_word(x86emu_t *emu, u16 d, u8 s)
{
  unsigned cnt;

  if(!s) return d;

  if((cnt = s % 16) != 0) {
    d = (d << cnt) + ((d >> (16 - cnt)) & ((1 << cnt) - 1));
  }

  /* OF flag is set if s == 1; OF = CF _XOR_ MSB of result */
  if(s == 1) {
    CONDITIONAL_SET_FLAG((d + (d >> 15)) & 1, F_OF);
  }

  /* set new CF; note that it is the LSB of the result */
  CONDITIONAL_SET_FLAG(d & 0x1, F_CF);

  return d;
}

/****************************************************************************
REMARKS:
Implements the ROL instruction and side effects.
****************************************************************************/
u32 rol_long(x86emu_t *emu, u32 d, u8 s)
{
  unsigned cnt;

  if(!s) return d;

  if((cnt = s % 32) != 0) {
    d = (d << cnt) + ((d >> (32 - cnt)) & ((1 << cnt) - 1));
  }

  /* OF flag is set if s == 1; OF = CF _XOR_ MSB of result */
  if(s == 1) {
    CONDITIONAL_SET_FLAG((d + (d >> 31)) & 1, F_OF);
  }

  /* set new CF; note that it is the LSB of the result */
  CONDITIONAL_SET_FLAG(d & 0x1, F_CF);

  return d;
}

/****************************************************************************
REMARKS:
Implements the ROR instruction and side effects.
****************************************************************************/
u8 ror_byte(x86emu_t *emu, u8 d, u8 s)
{
  unsigned cnt;

  if(!s) return d;

  if((cnt = s % 8) != 0) {
    d = (d << (8 - cnt)) + ((d >> (cnt)) & ((1 << (8 - cnt)) - 1));
  }

  /* OF flag is set if s == 1; OF = MSB _XOR_ (M-1)SB of result */
  if(s == 1) {
    CONDITIONAL_SET_FLAG(XOR2(d >> 6), F_OF);
  }

  /* set new CF; note that it is the MSB of the result */
  CONDITIONAL_SET_FLAG(d & (1 << 7), F_CF);

  return d;
}

/****************************************************************************
REMARKS:
Implements the ROR instruction and side effects.
****************************************************************************/
u16 ror_word(x86emu_t *emu, u16 d, u8 s)
{
  unsigned cnt;

  if(!s) return d;

  if((cnt = s % 16) != 0) {
    d = (d << (16 - cnt)) + ((d >> (cnt)) & ((1 << (16 - cnt)) - 1));
  }

  /* OF flag is set if s == 1; OF = MSB _XOR_ (M-1)SB of result */
  if(s == 1) {
    CONDITIONAL_SET_FLAG(XOR2(d >> 14), F_OF);
  }

  /* set new CF; note that it is the MSB of the result */
  CONDITIONAL_SET_FLAG(d & (1 << 15), F_CF);

  return d;
}

/****************************************************************************
REMARKS:
Implements the ROR instruction and side effects.
****************************************************************************/
u32 ror_long(x86emu_t *emu, u32 d, u8 s)
{
  unsigned cnt;

  if(!s) return d;

  if((cnt = s % 32) != 0) {
    d = (d << (32 - cnt)) + ((d >> (cnt)) & ((1 << (32 - cnt)) - 1));
  }

  /* OF flag is set if s == 1; OF = MSB _XOR_ (M-1)SB of result */
  if(s == 1) {
    CONDITIONAL_SET_FLAG(XOR2(d >> 30), F_OF);
  }

  /* set new CF; note that it is the MSB of the result */
  CONDITIONAL_SET_FLAG(d & (1 << 31), F_CF);

  return d;
}

/****************************************************************************
REMARKS:
Implements the SHL instruction and side effects.
****************************************************************************/
u8 shl_byte(x86emu_t *emu, u8 d, u8 s)
{
	unsigned int cnt, res, cf;

	if (s < 8) {
		cnt = s % 8;

		/* last bit shifted out goes into carry flag */
		if (cnt > 0) {
			res = d << cnt;
			cf = d & (1 << (8 - cnt));
			CONDITIONAL_SET_FLAG(cf, F_CF);
			CONDITIONAL_SET_FLAG((res & 0xff) == 0, F_ZF);
			CONDITIONAL_SET_FLAG(res & 0x80, F_SF);
			CONDITIONAL_SET_FLAG(PARITY(res & 0xff), F_PF);
		} else {
			res = (u8) d;
		}

		if (cnt == 1) {
			/* Needs simplification. */
			CONDITIONAL_SET_FLAG(
									(((res & 0x80) == 0x80) ^
									 (ACCESS_FLAG(F_CF) != 0)),
			/* was (emu->x86.R_FLG&F_CF)==F_CF)), */
									F_OF);
		} else {
			CLEAR_FLAG(F_OF);
		}
	} else {
		res = 0;
		CONDITIONAL_SET_FLAG((d << (s-1)) & 0x80, F_CF);
		CLEAR_FLAG(F_OF);
		CLEAR_FLAG(F_SF);
		SET_FLAG(F_PF);
		SET_FLAG(F_ZF);
    }
	return (u8)res;
}

/****************************************************************************
REMARKS:
Implements the SHL instruction and side effects.
****************************************************************************/
u16 shl_word(x86emu_t *emu, u16 d, u8 s)
{
    unsigned int cnt, res, cf;

	if (s < 16) {
		cnt = s % 16;
		if (cnt > 0) {
			res = d << cnt;
			cf = d & (1 << (16 - cnt));
			CONDITIONAL_SET_FLAG(cf, F_CF);
			CONDITIONAL_SET_FLAG((res & 0xffff) == 0, F_ZF);
			CONDITIONAL_SET_FLAG(res & 0x8000, F_SF);
			CONDITIONAL_SET_FLAG(PARITY(res & 0xff), F_PF);
		} else {
			res = (u16) d;
		}

		if (cnt == 1) {
			CONDITIONAL_SET_FLAG(
									(((res & 0x8000) == 0x8000) ^
									 (ACCESS_FLAG(F_CF) != 0)),
									F_OF);
        } else {
			CLEAR_FLAG(F_OF);
        }
    } else {
		res = 0;
		CONDITIONAL_SET_FLAG((d << (s-1)) & 0x8000, F_CF);
		CLEAR_FLAG(F_OF);
		CLEAR_FLAG(F_SF);
		SET_FLAG(F_PF);
		SET_FLAG(F_ZF);
	}
	return (u16)res;
}

/****************************************************************************
REMARKS:
Implements the SHL instruction and side effects.
****************************************************************************/
u32 shl_long(x86emu_t *emu, u32 d, u8 s)
{
	unsigned int cnt, res, cf;

	if (s < 32) {
		cnt = s % 32;
		if (cnt > 0) {
			res = d << cnt;
			cf = d & (1 << (32 - cnt));
			CONDITIONAL_SET_FLAG(cf, F_CF);
			CONDITIONAL_SET_FLAG((res & 0xffffffff) == 0, F_ZF);
			CONDITIONAL_SET_FLAG(res & 0x80000000, F_SF);
			CONDITIONAL_SET_FLAG(PARITY(res & 0xff), F_PF);
		} else {
			res = d;
		}
		if (cnt == 1) {
			CONDITIONAL_SET_FLAG((((res & 0x80000000) == 0x80000000) ^
								  (ACCESS_FLAG(F_CF) != 0)), F_OF);
		} else {
			CLEAR_FLAG(F_OF);
		}
	} else {
		res = 0;
		CONDITIONAL_SET_FLAG((d << (s-1)) & 0x80000000, F_CF);
		CLEAR_FLAG(F_OF);
		CLEAR_FLAG(F_SF);
		SET_FLAG(F_PF);
		SET_FLAG(F_ZF);
	}
	return res;
}

/****************************************************************************
REMARKS:
Implements the SHR instruction and side effects.
****************************************************************************/
u8 shr_byte(x86emu_t *emu, u8 d, u8 s)
{
	unsigned int cnt, res, cf;

	if (s < 8) {
		cnt = s % 8;
		if (cnt > 0) {
			cf = d & (1 << (cnt - 1));
			res = d >> cnt;
			CONDITIONAL_SET_FLAG(cf, F_CF);
			CONDITIONAL_SET_FLAG((res & 0xff) == 0, F_ZF);
			CONDITIONAL_SET_FLAG(res & 0x80, F_SF);
			CONDITIONAL_SET_FLAG(PARITY(res & 0xff), F_PF);
		} else {
			res = (u8) d;
		}

		if (cnt == 1) {
			CONDITIONAL_SET_FLAG(XOR2(res >> 6), F_OF);
		} else {
			CLEAR_FLAG(F_OF);
		}
	} else {
		res = 0;
		CONDITIONAL_SET_FLAG((d >> (s-1)) & 0x1, F_CF);
		CLEAR_FLAG(F_OF);
		CLEAR_FLAG(F_SF);
		SET_FLAG(F_PF);
		SET_FLAG(F_ZF);
	}
	return (u8)res;
}

/****************************************************************************
REMARKS:
Implements the SHR instruction and side effects.
****************************************************************************/
u16 shr_word(x86emu_t *emu, u16 d, u8 s)
{
	unsigned int cnt, res, cf;

	if (s < 16) {
		cnt = s % 16;
		if (cnt > 0) {
			cf = d & (1 << (cnt - 1));
			res = d >> cnt;
			CONDITIONAL_SET_FLAG(cf, F_CF);
			CONDITIONAL_SET_FLAG((res & 0xffff) == 0, F_ZF);
			CONDITIONAL_SET_FLAG(res & 0x8000, F_SF);
			CONDITIONAL_SET_FLAG(PARITY(res & 0xff), F_PF);
		} else {
			res = d;
		}

		if (cnt == 1) {
			CONDITIONAL_SET_FLAG(XOR2(res >> 14), F_OF);
        } else {
			CLEAR_FLAG(F_OF);
        }
	} else {
		res = 0;
		CLEAR_FLAG(F_CF);
		CLEAR_FLAG(F_OF);
		SET_FLAG(F_ZF);
		CLEAR_FLAG(F_SF);
		CLEAR_FLAG(F_PF);
    }
	return (u16)res;
}

/****************************************************************************
REMARKS:
Implements the SHR instruction and side effects.
****************************************************************************/
u32 shr_long(x86emu_t *emu, u32 d, u8 s)
{
	unsigned int cnt, res, cf;

	if (s < 32) {
		cnt = s % 32;
		if (cnt > 0) {
			cf = d & (1 << (cnt - 1));
			res = d >> cnt;
			CONDITIONAL_SET_FLAG(cf, F_CF);
			CONDITIONAL_SET_FLAG((res & 0xffffffff) == 0, F_ZF);
			CONDITIONAL_SET_FLAG(res & 0x80000000, F_SF);
			CONDITIONAL_SET_FLAG(PARITY(res & 0xff), F_PF);
        } else {
            res = d;
        }
        if (cnt == 1) {
			CONDITIONAL_SET_FLAG(XOR2(res >> 30), F_OF);
        } else {
			CLEAR_FLAG(F_OF);
        }
    } else {
        res = 0;
		CLEAR_FLAG(F_CF);
		CLEAR_FLAG(F_OF);
		SET_FLAG(F_ZF);
		CLEAR_FLAG(F_SF);
		CLEAR_FLAG(F_PF);
    }
    return res;
}

/****************************************************************************
REMARKS:
Implements the SAR instruction and side effects.
****************************************************************************/
u8 sar_byte(x86emu_t *emu, u8 d, u8 s)
{
	unsigned int cnt, res, cf, mask, sf;

	res = d;
	sf = d & 0x80;
    cnt = s % 8;
	if (cnt > 0 && cnt < 8) {
		mask = (1 << (8 - cnt)) - 1;
		cf = d & (1 << (cnt - 1));
		res = (d >> cnt) & mask;
		CONDITIONAL_SET_FLAG(cf, F_CF);
		if (sf) {
			res |= ~mask;
		}
		CONDITIONAL_SET_FLAG((res & 0xff) == 0, F_ZF);
		CONDITIONAL_SET_FLAG(PARITY(res & 0xff), F_PF);
		CONDITIONAL_SET_FLAG(res & 0x80, F_SF);
    } else if (cnt >= 8) {
        if (sf) {
            res = 0xff;
			SET_FLAG(F_CF);
			CLEAR_FLAG(F_ZF);
			SET_FLAG(F_SF);
			SET_FLAG(F_PF);
		} else {
			res = 0;
			CLEAR_FLAG(F_CF);
			SET_FLAG(F_ZF);
			CLEAR_FLAG(F_SF);
			CLEAR_FLAG(F_PF);
		}
	}
	return (u8)res;
}

/****************************************************************************
REMARKS:
Implements the SAR instruction and side effects.
****************************************************************************/
u16 sar_word(x86emu_t *emu, u16 d, u8 s)
{
    unsigned int cnt, res, cf, mask, sf;

    sf = d & 0x8000;
    cnt = s % 16;
	res = d;
	if (cnt > 0 && cnt < 16) {
        mask = (1 << (16 - cnt)) - 1;
        cf = d & (1 << (cnt - 1));
        res = (d >> cnt) & mask;
		CONDITIONAL_SET_FLAG(cf, F_CF);
        if (sf) {
            res |= ~mask;
        }
		CONDITIONAL_SET_FLAG((res & 0xffff) == 0, F_ZF);
		CONDITIONAL_SET_FLAG(res & 0x8000, F_SF);
		CONDITIONAL_SET_FLAG(PARITY(res & 0xff), F_PF);
    } else if (cnt >= 16) {
        if (sf) {
            res = 0xffff;
			SET_FLAG(F_CF);
			CLEAR_FLAG(F_ZF);
			SET_FLAG(F_SF);
			SET_FLAG(F_PF);
        } else {
            res = 0;
			CLEAR_FLAG(F_CF);
			SET_FLAG(F_ZF);
			CLEAR_FLAG(F_SF);
			CLEAR_FLAG(F_PF);
        }
    }
	return (u16)res;
}

/****************************************************************************
REMARKS:
Implements the SAR instruction and side effects.
****************************************************************************/
u32 sar_long(x86emu_t *emu, u32 d, u8 s)
{
    u32 cnt, res, cf, mask, sf;

    sf = d & 0x80000000;
    cnt = s % 32;
	res = d;
	if (cnt > 0 && cnt < 32) {
        mask = (1 << (32 - cnt)) - 1;
		cf = d & (1 << (cnt - 1));
        res = (d >> cnt) & mask;
		CONDITIONAL_SET_FLAG(cf, F_CF);
        if (sf) {
            res |= ~mask;
        }
		CONDITIONAL_SET_FLAG((res & 0xffffffff) == 0, F_ZF);
		CONDITIONAL_SET_FLAG(res & 0x80000000, F_SF);
		CONDITIONAL_SET_FLAG(PARITY(res & 0xff), F_PF);
    } else if (cnt >= 32) {
        if (sf) {
            res = 0xffffffff;
			SET_FLAG(F_CF);
			CLEAR_FLAG(F_ZF);
			SET_FLAG(F_SF);
			SET_FLAG(F_PF);
		} else {
			res = 0;
			CLEAR_FLAG(F_CF);
			SET_FLAG(F_ZF);
			CLEAR_FLAG(F_SF);
			CLEAR_FLAG(F_PF);
		}
	}
	return res;
}

/****************************************************************************
REMARKS:
Implements the SHLD instruction and side effects.
****************************************************************************/
u16 shld_word (x86emu_t *emu, u16 d, u16 fill, u8 s)
{
	unsigned int cnt, res, cf;

	if (s < 16) {
		cnt = s % 16;
		if (cnt > 0) {
			res = (d << cnt) | (fill >> (16-cnt));
			cf = d & (1 << (16 - cnt));
			CONDITIONAL_SET_FLAG(cf, F_CF);
			CONDITIONAL_SET_FLAG((res & 0xffff) == 0, F_ZF);
			CONDITIONAL_SET_FLAG(res & 0x8000, F_SF);
			CONDITIONAL_SET_FLAG(PARITY(res & 0xff), F_PF);
		} else {
			res = d;
		}
		if (cnt == 1) {
			CONDITIONAL_SET_FLAG((((res & 0x8000) == 0x8000) ^
								  (ACCESS_FLAG(F_CF) != 0)), F_OF);
		} else {
			CLEAR_FLAG(F_OF);
		}
	} else {
		res = 0;
		CONDITIONAL_SET_FLAG((d << (s-1)) & 0x8000, F_CF);
		CLEAR_FLAG(F_OF);
		CLEAR_FLAG(F_SF);
		SET_FLAG(F_PF);
		SET_FLAG(F_ZF);
	}
	return (u16)res;
}

/****************************************************************************
REMARKS:
Implements the SHLD instruction and side effects.
****************************************************************************/
u32 shld_long (x86emu_t *emu, u32 d, u32 fill, u8 s)
{
	unsigned int cnt, res, cf;

	if (s < 32) {
		cnt = s % 32;
		if (cnt > 0) {
			res = (d << cnt) | (fill >> (32-cnt));
			cf = d & (1 << (32 - cnt));
			CONDITIONAL_SET_FLAG(cf, F_CF);
			CONDITIONAL_SET_FLAG((res & 0xffffffff) == 0, F_ZF);
			CONDITIONAL_SET_FLAG(res & 0x80000000, F_SF);
			CONDITIONAL_SET_FLAG(PARITY(res & 0xff), F_PF);
		} else {
			res = d;
		}
		if (cnt == 1) {
			CONDITIONAL_SET_FLAG((((res & 0x80000000) == 0x80000000) ^
								  (ACCESS_FLAG(F_CF) != 0)), F_OF);
		} else {
			CLEAR_FLAG(F_OF);
		}
	} else {
		res = 0;
		CONDITIONAL_SET_FLAG((d << (s-1)) & 0x80000000, F_CF);
		CLEAR_FLAG(F_OF);
		CLEAR_FLAG(F_SF);
		SET_FLAG(F_PF);
		SET_FLAG(F_ZF);
	}
	return res;
}

/****************************************************************************
REMARKS:
Implements the SHRD instruction and side effects.
****************************************************************************/
u16 shrd_word (x86emu_t *emu, u16 d, u16 fill, u8 s)
{
	unsigned int cnt, res, cf;

	if (s < 16) {
		cnt = s % 16;
		if (cnt > 0) {
			cf = d & (1 << (cnt - 1));
			res = (d >> cnt) | (fill << (16 - cnt));
			CONDITIONAL_SET_FLAG(cf, F_CF);
			CONDITIONAL_SET_FLAG((res & 0xffff) == 0, F_ZF);
			CONDITIONAL_SET_FLAG(res & 0x8000, F_SF);
			CONDITIONAL_SET_FLAG(PARITY(res & 0xff), F_PF);
		} else {
			res = d;
		}

		if (cnt == 1) {
			CONDITIONAL_SET_FLAG(XOR2(res >> 14), F_OF);
        } else {
			CLEAR_FLAG(F_OF);
        }
	} else {
		res = 0;
		CLEAR_FLAG(F_CF);
		CLEAR_FLAG(F_OF);
		SET_FLAG(F_ZF);
		CLEAR_FLAG(F_SF);
		CLEAR_FLAG(F_PF);
    }
	return (u16)res;
}

/****************************************************************************
REMARKS:
Implements the SHRD instruction and side effects.
****************************************************************************/
u32 shrd_long (x86emu_t *emu, u32 d, u32 fill, u8 s)
{
	unsigned int cnt, res, cf;

	if (s < 32) {
		cnt = s % 32;
		if (cnt > 0) {
			cf = d & (1 << (cnt - 1));
			res = (d >> cnt) | (fill << (32 - cnt));
			CONDITIONAL_SET_FLAG(cf, F_CF);
			CONDITIONAL_SET_FLAG((res & 0xffffffff) == 0, F_ZF);
			CONDITIONAL_SET_FLAG(res & 0x80000000, F_SF);
			CONDITIONAL_SET_FLAG(PARITY(res & 0xff), F_PF);
		} else {
			res = d;
		}
		if (cnt == 1) {
			CONDITIONAL_SET_FLAG(XOR2(res >> 30), F_OF);
        } else {
			CLEAR_FLAG(F_OF);
        }
	} else {
		res = 0;
		CLEAR_FLAG(F_CF);
		CLEAR_FLAG(F_OF);
		SET_FLAG(F_ZF);
		CLEAR_FLAG(F_SF);
		CLEAR_FLAG(F_PF);
    }
	return res;
}

/****************************************************************************
REMARKS:
Implements the SBB instruction and side effects.
****************************************************************************/
u8 sbb_byte(x86emu_t *emu, u8 d, u8 s)
{
    register u32 res;   /* all operands in native machine order */
    register u32 bc;

	if (ACCESS_FLAG(F_CF))
		res = d - s - 1;
	else
		res = d - s;
	CONDITIONAL_SET_FLAG(res & 0x80, F_SF);
	CONDITIONAL_SET_FLAG((res & 0xff) == 0, F_ZF);
	CONDITIONAL_SET_FLAG(PARITY(res & 0xff), F_PF);

	/* calculate the borrow chain.  See note at top */
	bc = (res & (~d | s)) | (~d & s);
	CONDITIONAL_SET_FLAG(bc & 0x80, F_CF);
	CONDITIONAL_SET_FLAG(XOR2(bc >> 6), F_OF);
	CONDITIONAL_SET_FLAG(bc & 0x8, F_AF);
	return (u8)res;
}

/****************************************************************************
REMARKS:
Implements the SBB instruction and side effects.
****************************************************************************/
u16 sbb_word(x86emu_t *emu, u16 d, u16 s)
{
    register u32 res;   /* all operands in native machine order */
    register u32 bc;

	if (ACCESS_FLAG(F_CF))
		res = d - s - 1;
	else
		res = d - s;

	CONDITIONAL_SET_FLAG(res & 0x8000, F_SF);
	CONDITIONAL_SET_FLAG((res & 0xffff) == 0, F_ZF);
	CONDITIONAL_SET_FLAG(PARITY(res & 0xff), F_PF);

	/* calculate the borrow chain.  See note at top */
	bc = (res & (~d | s)) | (~d & s);
	CONDITIONAL_SET_FLAG(bc & 0x8000, F_CF);
	CONDITIONAL_SET_FLAG(XOR2(bc >> 14), F_OF);
	CONDITIONAL_SET_FLAG(bc & 0x8, F_AF);
	return (u16)res;
}

/****************************************************************************
REMARKS:
Implements the SBB instruction and side effects.
****************************************************************************/
u32 sbb_long(x86emu_t *emu, u32 d, u32 s)
{
	register u32 res;   /* all operands in native machine order */
	register u32 bc;

	if (ACCESS_FLAG(F_CF))
		res = d - s - 1;
	else
		res = d - s;
	CONDITIONAL_SET_FLAG(res & 0x80000000, F_SF);
	CONDITIONAL_SET_FLAG((res & 0xffffffff) == 0, F_ZF);
	CONDITIONAL_SET_FLAG(PARITY(res & 0xff), F_PF);

	/* calculate the borrow chain.  See note at top */
	bc = (res & (~d | s)) | (~d & s);
	CONDITIONAL_SET_FLAG(bc & 0x80000000, F_CF);
	CONDITIONAL_SET_FLAG(XOR2(bc >> 30), F_OF);
	CONDITIONAL_SET_FLAG(bc & 0x8, F_AF);
	return res;
}

/****************************************************************************
REMARKS:
Implements the SUB instruction and side effects.
****************************************************************************/
u8 sub_byte(x86emu_t *emu, u8 d, u8 s)
{
	register u32 res;   /* all operands in native machine order */
	register u32 bc;

	res = d - s;
	CONDITIONAL_SET_FLAG(res & 0x80, F_SF);
	CONDITIONAL_SET_FLAG((res & 0xff) == 0, F_ZF);
	CONDITIONAL_SET_FLAG(PARITY(res & 0xff), F_PF);

	/* calculate the borrow chain.  See note at top */
	bc = (res & (~d | s)) | (~d & s);
	CONDITIONAL_SET_FLAG(bc & 0x80, F_CF);
	CONDITIONAL_SET_FLAG(XOR2(bc >> 6), F_OF);
	CONDITIONAL_SET_FLAG(bc & 0x8, F_AF);
	return (u8)res;
}

/****************************************************************************
REMARKS:
Implements the SUB instruction and side effects.
****************************************************************************/
u16 sub_word(x86emu_t *emu, u16 d, u16 s)
{
    register u32 res;   /* all operands in native machine order */
    register u32 bc;

    res = d - s;
	CONDITIONAL_SET_FLAG(res & 0x8000, F_SF);
	CONDITIONAL_SET_FLAG((res & 0xffff) == 0, F_ZF);
	CONDITIONAL_SET_FLAG(PARITY(res & 0xff), F_PF);

	/* calculate the borrow chain.  See note at top */
	bc = (res & (~d | s)) | (~d & s);
	CONDITIONAL_SET_FLAG(bc & 0x8000, F_CF);
	CONDITIONAL_SET_FLAG(XOR2(bc >> 14), F_OF);
	CONDITIONAL_SET_FLAG(bc & 0x8, F_AF);
	return (u16)res;
}

/****************************************************************************
REMARKS:
Implements the SUB instruction and side effects.
****************************************************************************/
u32 sub_long(x86emu_t *emu, u32 d, u32 s)
{
	register u32 res;   /* all operands in native machine order */
	register u32 bc;

	res = d - s;
	CONDITIONAL_SET_FLAG(res & 0x80000000, F_SF);
	CONDITIONAL_SET_FLAG((res & 0xffffffff) == 0, F_ZF);
	CONDITIONAL_SET_FLAG(PARITY(res & 0xff), F_PF);

	/* calculate the borrow chain.  See note at top */
	bc = (res & (~d | s)) | (~d & s);
	CONDITIONAL_SET_FLAG(bc & 0x80000000, F_CF);
	CONDITIONAL_SET_FLAG(XOR2(bc >> 30), F_OF);
	CONDITIONAL_SET_FLAG(bc & 0x8, F_AF);
	return res;
}

/****************************************************************************
REMARKS:
Implements the TEST instruction and side effects.
****************************************************************************/
void test_byte(x86emu_t *emu, u8 d, u8 s)
{
    register u32 res;   /* all operands in native machine order */

    res = d & s;

	CLEAR_FLAG(F_OF);
	CONDITIONAL_SET_FLAG(res & 0x80, F_SF);
	CONDITIONAL_SET_FLAG(res == 0, F_ZF);
	CONDITIONAL_SET_FLAG(PARITY(res & 0xff), F_PF);
    /* AF == dont care */
	CLEAR_FLAG(F_CF);
}

/****************************************************************************
REMARKS:
Implements the TEST instruction and side effects.
****************************************************************************/
void test_word(x86emu_t *emu, u16 d, u16 s)
{
	register u32 res;   /* all operands in native machine order */

	res = d & s;

	CLEAR_FLAG(F_OF);
	CONDITIONAL_SET_FLAG(res & 0x8000, F_SF);
	CONDITIONAL_SET_FLAG(res == 0, F_ZF);
	CONDITIONAL_SET_FLAG(PARITY(res & 0xff), F_PF);
	/* AF == dont care */
	CLEAR_FLAG(F_CF);
}

/****************************************************************************
REMARKS:
Implements the TEST instruction and side effects.
****************************************************************************/
void test_long(x86emu_t *emu, u32 d, u32 s)
{
	register u32 res;   /* all operands in native machine order */

	res = d & s;

	CLEAR_FLAG(F_OF);
	CONDITIONAL_SET_FLAG(res & 0x80000000, F_SF);
	CONDITIONAL_SET_FLAG(res == 0, F_ZF);
	CONDITIONAL_SET_FLAG(PARITY(res & 0xff), F_PF);
	/* AF == dont care */
	CLEAR_FLAG(F_CF);
}

/****************************************************************************
REMARKS:
Implements the XOR instruction and side effects.
****************************************************************************/
u8 xor_byte(x86emu_t *emu, u8 d, u8 s)
{
	register u8 res;    /* all operands in native machine order */

	res = d ^ s;
	CLEAR_FLAG(F_OF);
	CONDITIONAL_SET_FLAG(res & 0x80, F_SF);
	CONDITIONAL_SET_FLAG(res == 0, F_ZF);
	CONDITIONAL_SET_FLAG(PARITY(res), F_PF);
	CLEAR_FLAG(F_CF);
	CLEAR_FLAG(F_AF);
	return res;
}

/****************************************************************************
REMARKS:
Implements the XOR instruction and side effects.
****************************************************************************/
u16 xor_word(x86emu_t *emu, u16 d, u16 s)
{
	register u16 res;   /* all operands in native machine order */

	res = d ^ s;
	CLEAR_FLAG(F_OF);
	CONDITIONAL_SET_FLAG(res & 0x8000, F_SF);
	CONDITIONAL_SET_FLAG(res == 0, F_ZF);
	CONDITIONAL_SET_FLAG(PARITY(res & 0xff), F_PF);
	CLEAR_FLAG(F_CF);
	CLEAR_FLAG(F_AF);
	return res;
}

/****************************************************************************
REMARKS:
Implements the XOR instruction and side effects.
****************************************************************************/
u32 xor_long(x86emu_t *emu, u32 d, u32 s)
{
	register u32 res;   /* all operands in native machine order */

	res = d ^ s;
	CLEAR_FLAG(F_OF);
	CONDITIONAL_SET_FLAG(res & 0x80000000, F_SF);
	CONDITIONAL_SET_FLAG(res == 0, F_ZF);
	CONDITIONAL_SET_FLAG(PARITY(res & 0xff), F_PF);
	CLEAR_FLAG(F_CF);
	CLEAR_FLAG(F_AF);
	return res;
}

/****************************************************************************
REMARKS:
Implements the IMUL instruction and side effects.
****************************************************************************/
void imul_byte(x86emu_t *emu, u8 s)
{
  s16 res = (s16) (s8) emu->x86.R_AL * (s16) (s8) s;

  emu->x86.R_AX = res;

  if(res >> 7 != 0 && res >> 7 != -1) {
    SET_FLAG(F_CF);
    SET_FLAG(F_OF);
  }
  else {
    CLEAR_FLAG(F_CF);
    CLEAR_FLAG(F_OF);
  }

  SET_FLAGS_FOR_MUL(res, emu->x86.R_AL, 8);
}

/****************************************************************************
REMARKS:
Implements the IMUL instruction and side effects.

return 1 if result overflows
****************************************************************************/
int imul_word_direct(u16 *res_lo, u16* res_hi, u16 d, u16 s)
{
  s32 res = (s32) (s16) d * (s32) (s16) s;

  *res_lo = res;
  *res_hi = res >> 16;

  return res >> 15 != 0 && res >> 15 != -1;
}

/****************************************************************************
REMARKS:
Implements the IMUL instruction and side effects.

return 1 if result overflows
****************************************************************************/
int imul_long_direct(u32 *res_lo, u32* res_hi, u32 d, u32 s)
{
  s64 res = (s64) (s32) d * (s64) (s32) s;

  *res_lo = res;
  *res_hi = res >> 32;

  return res >> 31 != 0 && res >> 31 != -1;
}

/****************************************************************************
REMARKS:
Implements the IMUL instruction and side effects.
****************************************************************************/
void imul_word(x86emu_t *emu, u16 s)
{
  if(imul_word_direct(&emu->x86.R_AX, &emu->x86.R_DX, emu->x86.R_AX, s)) {
    SET_FLAG(F_CF);
    SET_FLAG(F_OF);
  }
  else {
    CLEAR_FLAG(F_CF);
    CLEAR_FLAG(F_OF);
  }

  SET_FLAGS_FOR_MUL(emu->x86.R_AX | emu->x86.R_DX, emu->x86.R_AX, 16);
}

/****************************************************************************
REMARKS:
Implements the IMUL instruction and side effects.
****************************************************************************/
void imul_long(x86emu_t *emu, u32 s)
{
  if(imul_long_direct(&emu->x86.R_EAX, &emu->x86.R_EDX, emu->x86.R_EAX, s)) {
    SET_FLAG(F_CF);
    SET_FLAG(F_OF);
  }
  else {
    CLEAR_FLAG(F_CF);
    CLEAR_FLAG(F_OF);
  }

  SET_FLAGS_FOR_MUL(emu->x86.R_EAX | emu->x86.R_EDX, emu->x86.R_EAX, 32);
}

/****************************************************************************
REMARKS:
Implements the MUL instruction and side effects.
****************************************************************************/
void mul_byte(x86emu_t *emu, u8 s)
{
  u16 res = (u16) emu->x86.R_AL * (u16) s;

  emu->x86.R_AX = res;

  if(emu->x86.R_AH == 0) {
    CLEAR_FLAG(F_CF);
    CLEAR_FLAG(F_OF);
  }
  else {
    SET_FLAG(F_CF);
    SET_FLAG(F_OF);
  }

  SET_FLAGS_FOR_MUL(res, emu->x86.R_AL, 8);
}

/****************************************************************************
REMARKS:
Implements the MUL instruction and side effects.
****************************************************************************/
void mul_word(x86emu_t *emu, u16 s)
{
  u32 res = (u32) emu->x86.R_AX * (u32) s;

  emu->x86.R_AX = res;
  emu->x86.R_DX = res >> 16;

  if(emu->x86.R_DX == 0) {
    CLEAR_FLAG(F_CF);
    CLEAR_FLAG(F_OF);
  }
  else {
    SET_FLAG(F_CF);
    SET_FLAG(F_OF);
  }

  SET_FLAGS_FOR_MUL(res, emu->x86.R_AX, 16);
}

/****************************************************************************
REMARKS:
Implements the MUL instruction and side effects.
****************************************************************************/
void mul_long(x86emu_t *emu, u32 s)
{
  u64 res = (u64) emu->x86.R_EAX * (u64) s;

  emu->x86.R_EAX = res;
  emu->x86.R_EDX = res >> 32;

  if(emu->x86.R_EDX == 0) {
    CLEAR_FLAG(F_CF);
    CLEAR_FLAG(F_OF);
  }
  else {
    SET_FLAG(F_CF);
    SET_FLAG(F_OF);
  }

  SET_FLAGS_FOR_MUL(res, emu->x86.R_EAX, 32);
}

/****************************************************************************
REMARKS:
Implements the IDIV instruction and side effects.
****************************************************************************/
void idiv_byte(x86emu_t *emu, u8 s)
{
	s32 dvd, div, mod;

	dvd = (s16)emu->x86.R_AX;
	if (s == 0) {
		INTR_RAISE_DIV0(emu);
		return;
	}
	div = dvd / (s8)s;
	mod = dvd % (s8)s;
	if (div >> 7 != 0 && div >> 7 != -1) {
		INTR_RAISE_DIV0(emu);
		return;
	}

	emu->x86.R_AL = (s8) div;
	emu->x86.R_AH = (s8) mod;
}

/****************************************************************************
REMARKS:
Implements the IDIV instruction and side effects.
****************************************************************************/
void idiv_word(x86emu_t *emu, u16 s)
{
	s32 dvd, div, mod;

	dvd = ((u32) emu->x86.R_DX << 16) + (u32) emu->x86.R_AX;
	if (s == 0) {
		INTR_RAISE_DIV0(emu);
		return;
	}
	div = dvd / (s16)s;
	mod = dvd % (s16)s;
	if (div >> 15 != 0 && div >> 15 != -1) {
		INTR_RAISE_DIV0(emu);
		return;
	}

	emu->x86.R_AX = (u16)div;
	emu->x86.R_DX = (u16)mod;
}

/****************************************************************************
REMARKS:
Implements the IDIV instruction and side effects.
****************************************************************************/
void idiv_long(x86emu_t *emu, u32 s)
{
	s64 dvd, div, mod;

	dvd = ((u64) emu->x86.R_EDX << 32) + (u64) emu->x86.R_EAX;
	if (s == 0) {
		INTR_RAISE_DIV0(emu);
		return;
	}
	div = dvd / (s32)s;
	mod = dvd % (s32)s;
	if (div >> 31 != 0 && div >> 31 != -1) {
		INTR_RAISE_DIV0(emu);
		return;
	}

	emu->x86.R_EAX = div;
	emu->x86.R_EDX = mod;
}

/****************************************************************************
REMARKS:
Implements the DIV instruction and side effects.
****************************************************************************/
void div_byte(x86emu_t *emu, u8 s)
{
	u32 dvd, div, mod;

	dvd = emu->x86.R_AX;
        if (s == 0) {
		INTR_RAISE_DIV0(emu);
		return;
        }
	div = dvd / (u8)s;
	mod = dvd % (u8)s;
	if (div > 0xff) {
		INTR_RAISE_DIV0(emu);
		return;
	}

	emu->x86.R_AL = div;
	emu->x86.R_AH = mod;
}

/****************************************************************************
REMARKS:
Implements the DIV instruction and side effects.
****************************************************************************/
void div_word(x86emu_t *emu, u16 s)
{
	u32 dvd, div, mod;

	dvd = ((u32) emu->x86.R_DX << 16) + emu->x86.R_AX;
	if (s == 0) {
		INTR_RAISE_DIV0(emu);
		return;
        }
	div = dvd / (u16)s;
	mod = dvd % (u16)s;
	if (div > 0xffff) {
		INTR_RAISE_DIV0(emu);
		return;
	}

	emu->x86.R_AX = div;
	emu->x86.R_DX = mod;
}

/****************************************************************************
REMARKS:
Implements the DIV instruction and side effects.
****************************************************************************/
void div_long(x86emu_t *emu, u32 s)
{
	u64 dvd, div, mod;

	dvd = ((u64) emu->x86.R_EDX << 32) + emu->x86.R_EAX;
	if (s == 0) {
		INTR_RAISE_DIV0(emu);
		return;
	}
	div = dvd / (u32)s;
	mod = dvd % (u32)s;
	if (div > 0xffffffff) {
		INTR_RAISE_DIV0(emu);
		return;
	}

	emu->x86.R_EAX = div;
	emu->x86.R_EDX = mod;
}

/****************************************************************************
REMARKS:
Implements the IN string instruction and side effects.
****************************************************************************/
void ins(x86emu_t *emu, int size)
{
  s32 inc;
  u32 count;

  inc = ACCESS_FLAG(F_DF) ? -1 : 1;

  if(MODE_ADDR32) {
    if(MODE_REP) {
      count = emu->x86.R_ECX;
      emu->x86.R_ECX = 0;

      switch(size) {
        case 1:
          while(count--) {
            store_data_byte_abs(emu, emu->x86.seg + R_ES_INDEX, emu->x86.R_EDI, fetch_io_byte(emu, emu->x86.R_DX));
            emu->x86.R_EDI += inc;
          }
          break;
        case 2:
          while(count--) {
            store_data_word_abs(emu, emu->x86.seg + R_ES_INDEX, emu->x86.R_EDI, fetch_io_word(emu, emu->x86.R_DX));
            emu->x86.R_EDI += inc;
          }
          break;
        case 4:
          while(count--) {
            store_data_long_abs(emu, emu->x86.seg + R_ES_INDEX, emu->x86.R_EDI, fetch_io_long(emu, emu->x86.R_DX));
            emu->x86.R_EDI += inc;
          }
          break;
      }
    }
    else {
      switch(size) {
        case 1:
          store_data_byte_abs(emu, emu->x86.seg + R_ES_INDEX, emu->x86.R_EDI, fetch_io_byte(emu, emu->x86.R_DX));
          break;
        case 2:
          store_data_word_abs(emu, emu->x86.seg + R_ES_INDEX, emu->x86.R_EDI, fetch_io_word(emu, emu->x86.R_DX));
          break;
        case 4:
          store_data_long_abs(emu, emu->x86.seg + R_ES_INDEX, emu->x86.R_EDI, fetch_io_long(emu, emu->x86.R_DX));
          break;
      }
       emu->x86.R_EDI += inc;
    }
  }
  else {
    if(MODE_REP) {
      count = emu->x86.R_CX;
      emu->x86.R_CX = 0;

      switch(size) {
        case 1:
          while(count--) {
            store_data_byte_abs(emu, emu->x86.seg + R_ES_INDEX, emu->x86.R_DI, fetch_io_byte(emu, emu->x86.R_DX));
            emu->x86.R_DI += inc;
          }
          break;
        case 2:
          while(count--) {
            store_data_word_abs(emu, emu->x86.seg + R_ES_INDEX, emu->x86.R_DI, fetch_io_word(emu, emu->x86.R_DX));
            emu->x86.R_DI += inc;
          }
          break;
        case 4:
          while(count--) {
            store_data_long_abs(emu, emu->x86.seg + R_ES_INDEX, emu->x86.R_DI, fetch_io_long(emu, emu->x86.R_DX));
            emu->x86.R_DI += inc;
          }
          break;
      }
    }
    else {
      switch(size) {
        case 1:
          store_data_byte_abs(emu, emu->x86.seg + R_ES_INDEX, emu->x86.R_DI, fetch_io_byte(emu, emu->x86.R_DX));
          break;
        case 2:
          store_data_word_abs(emu, emu->x86.seg + R_ES_INDEX, emu->x86.R_DI, fetch_io_word(emu, emu->x86.R_DX));
          break;
        case 4:
          store_data_long_abs(emu, emu->x86.seg + R_ES_INDEX, emu->x86.R_DI, fetch_io_long(emu, emu->x86.R_DX));
          break;
      }
      emu->x86.R_DI += inc;
    }
  }
}

/****************************************************************************
REMARKS:
Implements the OUT string instruction and side effects.
****************************************************************************/
void outs(x86emu_t *emu, int size)
{
  s32 inc;
  u32 count;

  inc = ACCESS_FLAG(F_DF) ? -1 : 1;

  if(MODE_ADDR32) {
    if(MODE_REP) {
      count = emu->x86.R_ECX;
      emu->x86.R_ECX = 0;
   
      switch(size) {
        case 1:
          while(count--) {
            store_io_byte(emu, emu->x86.R_DX, fetch_data_byte_abs(emu, emu->x86.seg + R_ES_INDEX, emu->x86.R_ESI));
            emu->x86.R_ESI += inc;
          }
          break;
        case 2:
          while(count--) {
            store_io_word(emu, emu->x86.R_DX, fetch_data_word_abs(emu, emu->x86.seg + R_ES_INDEX, emu->x86.R_ESI));
            emu->x86.R_ESI += inc;
          }
          break;
        case 4:
          while(count--) {
            store_io_long(emu, emu->x86.R_DX, fetch_data_long_abs(emu, emu->x86.seg + R_ES_INDEX, emu->x86.R_ESI));
            emu->x86.R_ESI += inc;
          }
          break;
      }
    }
    else {
      switch(size) {
        case 1:
          store_io_byte(emu, emu->x86.R_DX, fetch_data_byte_abs(emu, emu->x86.seg + R_ES_INDEX, emu->x86.R_ESI));
          break;
        case 2:
          store_io_word(emu, emu->x86.R_DX, fetch_data_word_abs(emu, emu->x86.seg + R_ES_INDEX, emu->x86.R_ESI));
          break;
        case 4:
          store_io_long(emu, emu->x86.R_DX, fetch_data_long_abs(emu, emu->x86.seg + R_ES_INDEX, emu->x86.R_ESI));
          break;
      }
      emu->x86.R_SI += inc;
    }
  }
  else {
    if(MODE_REP) {
      count = emu->x86.R_CX;
      emu->x86.R_CX = 0;
   
      switch(size) {
        case 1:
          while(count--) {
            store_io_byte(emu, emu->x86.R_DX, fetch_data_byte_abs(emu, emu->x86.seg + R_ES_INDEX, emu->x86.R_SI));
            emu->x86.R_SI += inc;
          }
          break;
        case 2:
          while(count--) {
            store_io_word(emu, emu->x86.R_DX, fetch_data_word_abs(emu, emu->x86.seg + R_ES_INDEX, emu->x86.R_SI));
            emu->x86.R_SI += inc;
          }
          break;
        case 4:
          while(count--) {
            store_io_long(emu, emu->x86.R_DX, fetch_data_long_abs(emu, emu->x86.seg + R_ES_INDEX, emu->x86.R_SI));
            emu->x86.R_SI += inc;
          }
          break;
      }
    }
    else {
      switch(size) {
        case 1:
          store_io_byte(emu, emu->x86.R_DX, fetch_data_byte_abs(emu, emu->x86.seg + R_ES_INDEX, emu->x86.R_SI));
          break;
        case 2:
          store_io_word(emu, emu->x86.R_DX, fetch_data_word_abs(emu, emu->x86.seg + R_ES_INDEX, emu->x86.R_SI));
          break;
        case 4:
          store_io_long(emu, emu->x86.R_DX, fetch_data_long_abs(emu, emu->x86.seg + R_ES_INDEX, emu->x86.R_SI));
          break;
      }
      emu->x86.R_SI += inc;
    }
  }
}

/****************************************************************************
REMARKS:
Pushes a word onto the stack.
****************************************************************************/
void push_word(x86emu_t *emu, u16 w)
{
  if(MODE_STACK32) {
    emu->x86.R_ESP -= 2;
    store_data_word_abs(emu, emu->x86.seg + R_SS_INDEX, emu->x86.R_ESP, w);
  }
  else {
    emu->x86.R_SP -= 2;
    store_data_word_abs(emu, emu->x86.seg + R_SS_INDEX, emu->x86.R_SP, w);
  }
}

/****************************************************************************
REMARKS:
Pushes a long onto the stack.
****************************************************************************/
void push_long(x86emu_t *emu, u32 w)
{
  if(MODE_STACK32) {
    emu->x86.R_ESP -= 4;
    store_data_long_abs(emu, emu->x86.seg + R_SS_INDEX, emu->x86.R_ESP, w);
  }
  else {
    emu->x86.R_SP -= 4;
    store_data_long_abs(emu, emu->x86.seg + R_SS_INDEX, emu->x86.R_SP, w);
  }
}

/****************************************************************************
REMARKS:
Pops a word from the stack.
****************************************************************************/
u16 pop_word(x86emu_t *emu)
{
  u16 res;

  if(MODE_STACK32) {
    res = fetch_data_word_abs(emu, emu->x86.seg + R_SS_INDEX, emu->x86.R_ESP);
    emu->x86.R_ESP += 2;
  }
  else {
    res = fetch_data_word_abs(emu, emu->x86.seg + R_SS_INDEX, emu->x86.R_SP);
    emu->x86.R_SP += 2;
  }

  return res;
}

/****************************************************************************
REMARKS:
Pops a long from the stack.
****************************************************************************/
u32 pop_long(x86emu_t *emu)
{
  u32 res;

  if(MODE_STACK32) {
    res = fetch_data_long_abs(emu, emu->x86.seg + R_SS_INDEX, emu->x86.R_ESP);
    emu->x86.R_ESP += 4;
  }
  else {
    res = fetch_data_long_abs(emu, emu->x86.seg + R_SS_INDEX, emu->x86.R_SP);
    emu->x86.R_SP += 4;
  }

  return res;
}


int eval_condition(x86emu_t *emu, unsigned type)
{
  int cond = 0;
  unsigned flags = emu->x86.R_EFLG;

  switch(type >> 1) {
    case 0:	/* O */
      cond = flags & F_OF;
      break;

    case 1:	/* B */
      cond = flags & F_CF;
      break;

    case 3:	/* BE */
      cond = (flags & F_CF) != 0;
      /* fallthrough */

    case 2:	/* Z */
      cond |= (flags & F_ZF) != 0;
      break;

    case 4:	/* S */
      cond = flags & F_SF;
      break;

    case 5:	/* P */
      cond = flags & F_PF;
      break;

    case 7:	/* LE */
      cond = (flags & F_ZF) != 0;
      /* fallthrough */

    case 6:	/* L */
      cond |= ((flags & F_SF) != 0) ^ ((flags & F_OF) != 0);
      break;
  }

  return type & 1 ? !cond : cond;
}