freebsd-dev/sys/gnu/i386/fpemul/reg_ld_str.c

/*
 *  reg_ld_str.c
 *
 * All of the functions which transfer data between user memory and FPU_REGs.
 *
 *
 * Copyright (C) 1992,1993,1994
 *                       W. Metzenthen, 22 Parker St, Ormond, Vic 3163,
 *                       Australia.  E-mail   billm@vaxc.cc.monash.edu.au
 * All rights reserved.
 *
 * This copyright notice covers the redistribution and use of the
 * FPU emulator developed by W. Metzenthen. It covers only its use
 * in the 386BSD, FreeBSD and NetBSD operating systems. Any other
 * use is not permitted under this copyright.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must include information specifying
 *    that source code for the emulator is freely available and include
 *    either:
 *      a) an offer to provide the source code for a nominal distribution
 *         fee, or
 *      b) list at least two alternative methods whereby the source
 *         can be obtained, e.g. a publically accessible bulletin board
 *         and an anonymous ftp site from which the software can be
 *         downloaded.
 * 3. All advertising materials specifically mentioning features or use of
 *    this emulator must acknowledge that it was developed by W. Metzenthen.
 * 4. The name of W. Metzenthen may not be used to endorse or promote
 *    products derived from this software without specific prior written
 *    permission.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
 * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL
 * W. METZENTHEN BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 *
 * The purpose of this copyright, based upon the Berkeley copyright, is to
 * ensure that the covered software remains freely available to everyone.
 *
 * The software (with necessary differences) is also available, but under
 * the terms of the GNU copyleft, for the Linux operating system and for
 * the djgpp ms-dos extender.
 *
 * W. Metzenthen   June 1994.
 *
 *
 * $FreeBSD$
 *
 */


/*---------------------------------------------------------------------------+
 | Note:                                                                     |
 |    The file contains code which accesses user memory.                     |
 |    Emulator static data may change when user memory is accessed, due to   |
 |    other processes using the emulator while swapping is in progress.      |
 +---------------------------------------------------------------------------*/
#include <sys/param.h>
#include <sys/proc.h>
#include <sys/systm.h>
#include <machine/pcb.h>

#include <gnu/i386/fpemul/fpu_emu.h>
#include <gnu/i386/fpemul/fpu_system.h>
#include <gnu/i386/fpemul/exception.h>
#include <gnu/i386/fpemul/reg_constant.h>
#include <gnu/i386/fpemul/control_w.h>
#include <gnu/i386/fpemul/status_w.h>


#define EXTENDED_Emax 0x3fff	/* largest valid exponent */
#define EXTENDED_Ebias 0x3fff
#define EXTENDED_Emin (-0x3ffe)	/* smallest valid exponent */

#define DOUBLE_Emax 1023	/* largest valid exponent */
#define DOUBLE_Ebias 1023
#define DOUBLE_Emin (-1022)	/* smallest valid exponent */

#define SINGLE_Emax 127		/* largest valid exponent */
#define SINGLE_Ebias 127
#define SINGLE_Emin (-126)	/* smallest valid exponent */

#define LOST_UP    (EX_Precision | SW_C1)
#define LOST_DOWN  EX_Precision

FPU_REG FPU_loaded_data;


/* Get a long double from user memory */
void
reg_load_extended(void)
{
	long double *s = (long double *) FPU_data_address;
	unsigned long sigl, sigh, exp;

	REENTRANT_CHECK(OFF);
	/* Use temporary variables here because FPU_loaded data is static and
	 * hence re-entrancy problems can arise */
	sigl = fuword((unsigned long *) s);
	sigh = fuword(1 + (unsigned long *) s);
	exp = fusword(4 + (unsigned short *) s);
	REENTRANT_CHECK(ON);

	FPU_loaded_data.sigl = sigl;
	FPU_loaded_data.sigh = sigh;
	FPU_loaded_data.exp = exp;

	if (FPU_loaded_data.exp & 0x8000)
		FPU_loaded_data.sign = SIGN_NEG;
	else
		FPU_loaded_data.sign = SIGN_POS;
	if ((FPU_loaded_data.exp &= 0x7fff) == 0) {
		if (!(FPU_loaded_data.sigl | FPU_loaded_data.sigh)) {
			FPU_loaded_data.tag = TW_Zero;
			return;
		}
		/* The number is a de-normal or pseudodenormal. */
		/* The 80486 doesn't regard pseudodenormals as denormals here. */
		if (!(FPU_loaded_data.sigh & 0x80000000))
			EXCEPTION(EX_Denormal);
		FPU_loaded_data.exp++;

		/* The default behaviour will now take care of it. */
	} else
		if (FPU_loaded_data.exp == 0x7fff) {
			FPU_loaded_data.exp = EXTENDED_Emax;
			if ((FPU_loaded_data.sigh == 0x80000000)
			    && (FPU_loaded_data.sigl == 0)) {
				FPU_loaded_data.tag = TW_Infinity;
				return;
			} else
				if (!(FPU_loaded_data.sigh & 0x80000000)) {
					/* Unsupported NaN data type */
					EXCEPTION(EX_Invalid);
					FPU_loaded_data.tag = TW_NaN;
					return;
				}
			FPU_loaded_data.tag = TW_NaN;
			return;
		}
	FPU_loaded_data.exp = (FPU_loaded_data.exp & 0x7fff) - EXTENDED_Ebias
	    + EXP_BIAS;
	FPU_loaded_data.tag = TW_Valid;

	if (!(sigh & 0x80000000)) {
		/* Unsupported data type */
		EXCEPTION(EX_Invalid);
		normalize_nuo(&FPU_loaded_data);
	}
}


/* Get a double from user memory */
void
reg_load_double(void)
{
	double *dfloat = (double *) FPU_data_address;
	int     exp;
	unsigned m64, l64;

	REENTRANT_CHECK(OFF);
	m64 = fuword(1 + (unsigned long *) dfloat);
	l64 = fuword((unsigned long *) dfloat);
	REENTRANT_CHECK(ON);

	if (m64 & 0x80000000)
		FPU_loaded_data.sign = SIGN_NEG;
	else
		FPU_loaded_data.sign = SIGN_POS;
	exp = ((m64 & 0x7ff00000) >> 20) - DOUBLE_Ebias;
	m64 &= 0xfffff;
	if (exp > DOUBLE_Emax) {
		/* Infinity or NaN */
		if ((m64 == 0) && (l64 == 0)) {
			/* +- infinity */
			FPU_loaded_data.exp = EXTENDED_Emax;
			FPU_loaded_data.tag = TW_Infinity;
			return;
		} else {
			/* Must be a signaling or quiet NaN */
			FPU_loaded_data.exp = EXTENDED_Emax;
			FPU_loaded_data.tag = TW_NaN;
			FPU_loaded_data.sigh = (m64 << 11) | 0x80000000;
			FPU_loaded_data.sigh |= l64 >> 21;
			FPU_loaded_data.sigl = l64 << 11;
			return;
		}
	} else
		if (exp < DOUBLE_Emin) {
			/* Zero or de-normal */
			if ((m64 == 0) && (l64 == 0)) {
				/* Zero */
				int     c = FPU_loaded_data.sign;
				reg_move(&CONST_Z, &FPU_loaded_data);
				FPU_loaded_data.sign = c;
				return;
			} else {
				/* De-normal */
				EXCEPTION(EX_Denormal);
				FPU_loaded_data.exp = DOUBLE_Emin + EXP_BIAS;
				FPU_loaded_data.tag = TW_Valid;
				FPU_loaded_data.sigh = m64 << 11;
				FPU_loaded_data.sigh |= l64 >> 21;
				FPU_loaded_data.sigl = l64 << 11;
				normalize_nuo(&FPU_loaded_data);
				return;
			}
		} else {
			FPU_loaded_data.exp = exp + EXP_BIAS;
			FPU_loaded_data.tag = TW_Valid;
			FPU_loaded_data.sigh = (m64 << 11) | 0x80000000;
			FPU_loaded_data.sigh |= l64 >> 21;
			FPU_loaded_data.sigl = l64 << 11;

			return;
		}
}


/* Get a float from user memory */
void
reg_load_single(void)
{
	float  *single = (float *) FPU_data_address;
	unsigned m32;
	int     exp;

	REENTRANT_CHECK(OFF);
	m32 = fuword((unsigned long *) single);
	REENTRANT_CHECK(ON);

	if (m32 & 0x80000000)
		FPU_loaded_data.sign = SIGN_NEG;
	else
		FPU_loaded_data.sign = SIGN_POS;
	if (!(m32 & 0x7fffffff)) {
		/* Zero */
		int     c = FPU_loaded_data.sign;
		reg_move(&CONST_Z, &FPU_loaded_data);
		FPU_loaded_data.sign = c;
		return;
	}
	exp = ((m32 & 0x7f800000) >> 23) - SINGLE_Ebias;
	m32 = (m32 & 0x7fffff) << 8;
	if (exp < SINGLE_Emin) {
		/* De-normals */
		EXCEPTION(EX_Denormal);
		FPU_loaded_data.exp = SINGLE_Emin + EXP_BIAS;
		FPU_loaded_data.tag = TW_Valid;
		FPU_loaded_data.sigh = m32;
		FPU_loaded_data.sigl = 0;
		normalize_nuo(&FPU_loaded_data);
		return;
	} else
		if (exp > SINGLE_Emax) {
			/* Infinity or NaN */
			if (m32 == 0) {
				/* +- infinity */
				FPU_loaded_data.exp = EXTENDED_Emax;
				FPU_loaded_data.tag = TW_Infinity;
				return;
			} else {
				/* Must be a signaling or quiet NaN */
				FPU_loaded_data.exp = EXTENDED_Emax;
				FPU_loaded_data.tag = TW_NaN;
				FPU_loaded_data.sigh = m32 | 0x80000000;
				FPU_loaded_data.sigl = 0;
				return;
			}
		} else {
			FPU_loaded_data.exp = exp + EXP_BIAS;
			FPU_loaded_data.sigh = m32 | 0x80000000;
			FPU_loaded_data.sigl = 0;
			FPU_loaded_data.tag = TW_Valid;
		}
}


/* Get a long long from user memory */
void
reg_load_int64(void)
{
	long long *_s = (long long *) FPU_data_address;
	int     e;
	long long s;

	REENTRANT_CHECK(OFF);
	((unsigned long *) &s)[0] = fuword((unsigned long *) _s);
	((unsigned long *) &s)[1] = fuword(1 + (unsigned long *) _s);
	REENTRANT_CHECK(ON);

	if (s == 0) {
		reg_move(&CONST_Z, &FPU_loaded_data);
		return;
	}
	if (s > 0)
		FPU_loaded_data.sign = SIGN_POS;
	else {
		s = -s;
		FPU_loaded_data.sign = SIGN_NEG;
	}

	e = EXP_BIAS + 63;
	*((long long *) &FPU_loaded_data.sigl) = s;
	FPU_loaded_data.exp = e;
	FPU_loaded_data.tag = TW_Valid;
	normalize_nuo(&FPU_loaded_data);
}


/* Get a long from user memory */
void
reg_load_int32(void)
{
	long   *_s = (long *) FPU_data_address;
	long    s;
	int     e;

	REENTRANT_CHECK(OFF);
	s = (long) fuword((unsigned long *) _s);
	REENTRANT_CHECK(ON);

	if (s == 0) {
		reg_move(&CONST_Z, &FPU_loaded_data);
		return;
	}
	if (s > 0)
		FPU_loaded_data.sign = SIGN_POS;
	else {
		s = -s;
		FPU_loaded_data.sign = SIGN_NEG;
	}

	e = EXP_BIAS + 31;
	FPU_loaded_data.sigh = s;
	FPU_loaded_data.sigl = 0;
	FPU_loaded_data.exp = e;
	FPU_loaded_data.tag = TW_Valid;
	normalize_nuo(&FPU_loaded_data);
}


/* Get a short from user memory */
void
reg_load_int16(void)
{
	short  *_s = (short *) FPU_data_address;
	int     s, e;

	REENTRANT_CHECK(OFF);
	/* Cast as short to get the sign extended. */
	s = (short) fusword((unsigned short *) _s);
	REENTRANT_CHECK(ON);

	if (s == 0) {
		reg_move(&CONST_Z, &FPU_loaded_data);
		return;
	}
	if (s > 0)
		FPU_loaded_data.sign = SIGN_POS;
	else {
		s = -s;
		FPU_loaded_data.sign = SIGN_NEG;
	}

	e = EXP_BIAS + 15;
	FPU_loaded_data.sigh = s << 16;

	FPU_loaded_data.sigl = 0;
	FPU_loaded_data.exp = e;
	FPU_loaded_data.tag = TW_Valid;
	normalize_nuo(&FPU_loaded_data);
}


/* Get a packed bcd array from user memory */
void
reg_load_bcd(void)
{
	char   *s = (char *) FPU_data_address;
	int     pos;
	unsigned char bcd;
	long long l = 0;

	for (pos = 8; pos >= 0; pos--) {
		l *= 10;
		REENTRANT_CHECK(OFF);
		bcd = (unsigned char) fubyte((unsigned char *) s + pos);
		REENTRANT_CHECK(ON);
		l += bcd >> 4;
		l *= 10;
		l += bcd & 0x0f;
	}

	/* Finish all access to user memory before putting stuff into the
	 * static FPU_loaded_data */
	REENTRANT_CHECK(OFF);
	FPU_loaded_data.sign =
	    ((unsigned char) fubyte((unsigned char *) s + 9)) & 0x80 ?
	    SIGN_NEG : SIGN_POS;
	REENTRANT_CHECK(ON);

	if (l == 0) {
		char    sign = FPU_loaded_data.sign;
		reg_move(&CONST_Z, &FPU_loaded_data);
		FPU_loaded_data.sign = sign;
	} else {
		*((long long *) &FPU_loaded_data.sigl) = l;
		FPU_loaded_data.exp = EXP_BIAS + 63;
		FPU_loaded_data.tag = TW_Valid;
		normalize_nuo(&FPU_loaded_data);
	}
}
/*===========================================================================*/

/* Put a long double into user memory */
int
reg_store_extended(void)
{
	long double *d = (long double *) FPU_data_address;
	long    e = FPU_st0_ptr->exp - EXP_BIAS + EXTENDED_Ebias;
	unsigned short sign = FPU_st0_ptr->sign * 0x8000;
	unsigned long ls, ms;


	if (FPU_st0_tag == TW_Valid) {
		if (e >= 0x7fff) {
			EXCEPTION(EX_Overflow);	/* Overflow */
			/* This is a special case: see sec 16.2.5.1 of the
			 * 80486 book */
			if (control_word & EX_Overflow) {
				/* Overflow to infinity */
				ls = 0;
				ms = 0x80000000;
				e = 0x7fff;
			} else
				return 0;
		} else
			if (e <= 0) {
				if (e > -63) {
					/* Correctly format the de-normal */
					int     precision_loss;
					FPU_REG tmp;

					EXCEPTION(EX_Denormal);
					reg_move(FPU_st0_ptr, &tmp);
					tmp.exp += -EXTENDED_Emin + 63;	/* largest exp to be 62 */
					if ((precision_loss = round_to_int(&tmp))) {
						EXCEPTION(EX_Underflow | precision_loss);
						/* This is a special case: see
						 * sec 16.2.5.1 of the 80486
						 * book */
						if (!(control_word & EX_Underflow))
							return 0;
					}
					e = 0;
					ls = tmp.sigl;
					ms = tmp.sigh;
				} else {
					/* ****** ??? This should not be
					 * possible */
					EXCEPTION(EX_Underflow);	/* Underflow */
					/* This is a special case: see sec
					 * 16.2.5.1 of the 80486 book */
					if (control_word & EX_Underflow) {
						/* Underflow to zero */
						ls = 0;
						ms = 0;
						e = FPU_st0_ptr->sign == SIGN_POS ? 0x7fff : 0xffff;
					} else
						return 0;
				}
			} else {
				ls = FPU_st0_ptr->sigl;
				ms = FPU_st0_ptr->sigh;
			}
	} else
		if (FPU_st0_tag == TW_Zero) {
			ls = ms = 0;
			e = 0;
		} else
			if (FPU_st0_tag == TW_Infinity) {
				ls = 0;
				ms = 0x80000000;
				e = 0x7fff;
			} else
				if (FPU_st0_tag == TW_NaN) {
					ls = FPU_st0_ptr->sigl;
					ms = FPU_st0_ptr->sigh;
					e = 0x7fff;
				} else
					if (FPU_st0_tag == TW_Empty) {
						/* Empty register (stack
						 * underflow) */
						EXCEPTION(EX_StackUnder);
						if (control_word & EX_Invalid) {
							/* The masked response */
							/* Put out the QNaN
							 * indefinite */
							ls = 0;
							ms = 0xc0000000;
							e = 0xffff;
						} else
							return 0;
					} else {
						/* We don't use TW_Denormal
						 * yet ... perhaps never! */
						EXCEPTION(EX_Invalid);
						/* Store a NaN */
						e = 0x7fff;
						ls = 1;
						ms = 0x80000000;
					}
	REENTRANT_CHECK(OFF);
/*	    verify_area(VERIFY_WRITE, d, 10); */
	suword((unsigned long *) d, ls);
	suword(1 + (unsigned long *) d, ms);
	susword(4 + (short *) d, (unsigned short) e | sign);
	REENTRANT_CHECK(ON);

	return 1;

}


/* Put a double into user memory */
int
reg_store_double(void)
{
	double *dfloat = (double *) FPU_data_address;
	unsigned long l[2];
	if (FPU_st0_tag == TW_Valid) {
		int     exp;
		FPU_REG tmp;

		reg_move(FPU_st0_ptr, &tmp);
		exp = tmp.exp - EXP_BIAS;

		if (exp < DOUBLE_Emin) {	/* It may be a denormal */
			/* Make a de-normal */
			int     precision_loss;

			if (exp <= -EXTENDED_Ebias)
				EXCEPTION(EX_Denormal);

			tmp.exp += -DOUBLE_Emin + 52;	/* largest exp to be 51 */

			if ((precision_loss = round_to_int(&tmp))) {
#ifdef PECULIAR_486
				/* Did it round to a non-denormal ? */
				/* This behaviour might be regarded as
				 * peculiar, it appears that the 80486 rounds
				 * to the dest precision, then converts to
				 * decide underflow. */
				if ((tmp.sigh == 0x00100000) && (tmp.sigl == 0) &&
				    (FPU_st0_ptr->sigl & 0x000007ff))
					EXCEPTION(precision_loss);
				else
#endif				/* PECULIAR_486 */
				{
					EXCEPTION(EX_Underflow | precision_loss);
					/* This is a special case: see sec
					 * 16.2.5.1 of the 80486 book */
					if (!(control_word & EX_Underflow))
						return 0;
				}
			}
			l[0] = tmp.sigl;
			l[1] = tmp.sigh;
		} else {
			if (tmp.sigl & 0x000007ff) {
				unsigned long increment = 0;	/* avoid gcc warnings */

				switch (control_word & CW_RC) {
				case RC_RND:
					/* Rounding can get a little messy.. */
					increment = ((tmp.sigl & 0x7ff) > 0x400) |	/* nearest */
					    ((tmp.sigl & 0xc00) == 0xc00);	/* odd -> even */
					break;
				case RC_DOWN:	/* towards -infinity */
					increment = (tmp.sign == SIGN_POS) ? 0 : tmp.sigl & 0x7ff;
					break;
				case RC_UP:	/* towards +infinity */
					increment = (tmp.sign == SIGN_POS) ? tmp.sigl & 0x7ff : 0;
					break;
				case RC_CHOP:
					increment = 0;
					break;
				}

				/* Truncate the mantissa */
				tmp.sigl &= 0xfffff800;

				if (increment) {
					set_precision_flag_up();

					if (tmp.sigl >= 0xfffff800) {
						/* the sigl part overflows */
						if (tmp.sigh == 0xffffffff) {
							/* The sigh part
							 * overflows */
							tmp.sigh = 0x80000000;
							exp++;
							if (exp >= EXP_OVER)
								goto overflow;
						} else {
							tmp.sigh++;
						}
						tmp.sigl = 0x00000000;
					} else {
						/* We only need to increment
						 * sigl */
						tmp.sigl += 0x00000800;
					}
				} else
					set_precision_flag_down();
			}
			l[0] = (tmp.sigl >> 11) | (tmp.sigh << 21);
			l[1] = ((tmp.sigh >> 11) & 0xfffff);

			if (exp > DOUBLE_Emax) {
		overflow:
				EXCEPTION(EX_Overflow);
				/* This is a special case: see sec 16.2.5.1 of
				 * the 80486 book */
				if (control_word & EX_Overflow) {
					/* Overflow to infinity */
					l[0] = 0x00000000;	/* Set to */
					l[1] = 0x7ff00000;	/* + INF */
				} else
					return 0;
			} else {
				/* Add the exponent */
				l[1] |= (((exp + DOUBLE_Ebias) & 0x7ff) << 20);
			}
		}
	} else
		if (FPU_st0_tag == TW_Zero) {
			/* Number is zero */
			l[0] = 0;
			l[1] = 0;
		} else
			if (FPU_st0_tag == TW_Infinity) {
				l[0] = 0;
				l[1] = 0x7ff00000;
			} else
				if (FPU_st0_tag == TW_NaN) {
					/* See if we can get a valid NaN from
					 * the FPU_REG */
					l[0] = (FPU_st0_ptr->sigl >> 11) | (FPU_st0_ptr->sigh << 21);
					l[1] = ((FPU_st0_ptr->sigh >> 11) & 0xfffff);
					if (!(l[0] | l[1])) {
						/* This case does not seem to
						 * be handled by the 80486
						 * specs */
						EXCEPTION(EX_Invalid);
						/* Make the quiet NaN "real
						 * indefinite" */
						goto put_indefinite;
					}
					l[1] |= 0x7ff00000;
				} else
					if (FPU_st0_tag == TW_Empty) {
						/* Empty register (stack
						 * underflow) */
						EXCEPTION(EX_StackUnder);
						if (control_word & EX_Invalid) {
							/* The masked response */
							/* Put out the QNaN
							 * indefinite */
					put_indefinite:
							REENTRANT_CHECK(OFF);
							/* verify_area(VERIFY_W
							 * RITE, (void *)
							 * dfloat, 8); */
							suword((unsigned long *) dfloat, 0);
							suword(1 + (unsigned long *) dfloat, 0xfff80000);
							REENTRANT_CHECK(ON);
							return 1;
						} else
							return 0;
					}
#if 0				/* TW_Denormal is not used yet, and probably
				 * won't be */
					else
						if (FPU_st0_tag == TW_Denormal) {
							/* Extended real ->
							 * double real will
							 * always underflow */
							l[0] = l[1] = 0;
							EXCEPTION(EX_Underflow);
						}
#endif
	if (FPU_st0_ptr->sign)
		l[1] |= 0x80000000;

	REENTRANT_CHECK(OFF);
/*	    verify_area(VERIFY_WRITE, (void *) dfloat, 8);*/
	suword((u_long *) dfloat, l[0]);
	suword((u_long *) dfloat + 1, l[1]);
/*
	suword(l[0], (unsigned long *) dfloat);
	suword(l[1], 1 + (unsigned long *) dfloat);*/
	REENTRANT_CHECK(ON);

	return 1;
}


/* Put a float into user memory */
int
reg_store_single(void)
{
	float  *single = (float *) FPU_data_address;
	long    templ = 0;

	if (FPU_st0_tag == TW_Valid) {
		int     exp;
		FPU_REG tmp;

		reg_move(FPU_st0_ptr, &tmp);
		exp = tmp.exp - EXP_BIAS;

		if (exp < SINGLE_Emin) {
			/* Make a de-normal */
			int     precision_loss;

			if (exp <= -EXTENDED_Ebias)
				EXCEPTION(EX_Denormal);

			tmp.exp += -SINGLE_Emin + 23;	/* largest exp to be 22 */

			if ((precision_loss = round_to_int(&tmp))) {
#ifdef PECULIAR_486
				/* Did it round to a non-denormal ? */
				/* This behaviour might be regarded as
				 * peculiar, it appears that the 80486 rounds
				 * to the dest precision, then converts to
				 * decide underflow. */
				if ((tmp.sigl == 0x00800000) &&
				    ((FPU_st0_ptr->sigh & 0x000000ff) || FPU_st0_ptr->sigl))
					EXCEPTION(precision_loss);
				else
#endif				/* PECULIAR_486 */
				{
					EXCEPTION(EX_Underflow | precision_loss);
					/* This is a special case: see sec
					 * 16.2.5.1 of the 80486 book */
					if (!(control_word & EX_Underflow))
						return 0;
				}
			}
			templ = tmp.sigl;
		} else {
			if (tmp.sigl | (tmp.sigh & 0x000000ff)) {
				unsigned long increment = 0;	/* avoid gcc warnings */
				unsigned long sigh = tmp.sigh;
				unsigned long sigl = tmp.sigl;

				switch (control_word & CW_RC) {
				case RC_RND:
					increment = ((sigh & 0xff) > 0x80)	/* more than half */
					    ||(((sigh & 0xff) == 0x80) && sigl)	/* more than half */
					    ||((sigh & 0x180) == 0x180);	/* round to even */
					break;
				case RC_DOWN:	/* towards -infinity */
					increment = (tmp.sign == SIGN_POS)
					    ? 0 : (sigl | (sigh & 0xff));
					break;
				case RC_UP:	/* towards +infinity */
					increment = (tmp.sign == SIGN_POS)
					    ? (sigl | (sigh & 0xff)) : 0;
					break;
				case RC_CHOP:
					increment = 0;
					break;
				}

				/* Truncate part of the mantissa */
				tmp.sigl = 0;

				if (increment) {
					set_precision_flag_up();

					if (sigh >= 0xffffff00) {
						/* The sigh part overflows */
						tmp.sigh = 0x80000000;
						exp++;
						if (exp >= EXP_OVER)
							goto overflow;
					} else {
						tmp.sigh &= 0xffffff00;
						tmp.sigh += 0x100;
					}
				} else {
					set_precision_flag_down();
					tmp.sigh &= 0xffffff00;	/* Finish the truncation */
				}
			}
			templ = (tmp.sigh >> 8) & 0x007fffff;

			if (exp > SINGLE_Emax) {
		overflow:
				EXCEPTION(EX_Overflow);
				/* This is a special case: see sec 16.2.5.1 of
				 * the 80486 book */
				if (control_word & EX_Overflow) {
					/* Overflow to infinity */
					templ = 0x7f800000;
				} else
					return 0;
			} else
				templ |= ((exp + SINGLE_Ebias) & 0xff) << 23;
		}
	} else
		if (FPU_st0_tag == TW_Zero) {
			templ = 0;
		} else
			if (FPU_st0_tag == TW_Infinity) {
				templ = 0x7f800000;
			} else
				if (FPU_st0_tag == TW_NaN) {
					/* See if we can get a valid NaN from
					 * the FPU_REG */
					templ = FPU_st0_ptr->sigh >> 8;
					if (!(templ & 0x3fffff)) {
						/* This case does not seem to
						 * be handled by the 80486
						 * specs */
						EXCEPTION(EX_Invalid);
						/* Make the quiet NaN "real
						 * indefinite" */
						goto put_indefinite;
					}
					templ |= 0x7f800000;
				} else
					if (FPU_st0_tag == TW_Empty) {
						/* Empty register (stack
						 * underflow) */
						EXCEPTION(EX_StackUnder);
						if (control_word & EX_Invalid) {
							/* The masked response */
							/* Put out the QNaN
							 * indefinite */
					put_indefinite:
							REENTRANT_CHECK(OFF);
/*							    verify_area(VERIFY_WRITE, (void *) single, 4); */
							suword((unsigned long *) single, 0xffc00000);
							REENTRANT_CHECK(ON);
							return 1;
						} else
							return 0;
					}
#if 0				/* TW_Denormal is not used yet, and probably
				 * won't be */
					else
						if (FPU_st0_tag == TW_Denormal) {
							/* Extended real ->
							 * real will always
							 * underflow */
							templ = 0;
							EXCEPTION(EX_Underflow);
						}
#endif
#ifdef PARANOID
						else {
							EXCEPTION(EX_INTERNAL | 0x106);
							return 0;
						}
#endif
	if (FPU_st0_ptr->sign)
		templ |= 0x80000000;

	REENTRANT_CHECK(OFF);
/*	    verify_area(VERIFY_WRITE, (void *) single, 4); */
	suword((unsigned long *) single, templ);
	REENTRANT_CHECK(ON);

	return 1;
}


/* Put a long long into user memory */
int
reg_store_int64(void)
{
	long long *d = (long long *) FPU_data_address;
	FPU_REG t;
	long long tll;

	if (FPU_st0_tag == TW_Empty) {
		/* Empty register (stack underflow) */
		EXCEPTION(EX_StackUnder);
		if (control_word & EX_Invalid) {
			/* The masked response */
			/* Put out the QNaN indefinite */
			goto put_indefinite;
		} else
			return 0;
	}
	reg_move(FPU_st0_ptr, &t);
	round_to_int(&t);
	((long *) &tll)[0] = t.sigl;
	((long *) &tll)[1] = t.sigh;
	if ((t.sigh & 0x80000000) &&
	    !((t.sigh == 0x80000000) && (t.sigl == 0) && (t.sign == SIGN_NEG))) {
		EXCEPTION(EX_Invalid);
		/* This is a special case: see sec 16.2.5.1 of the 80486 book */
		if (control_word & EX_Invalid) {
			/* Produce "indefinite" */
	put_indefinite:
			((long *) &tll)[1] = 0x80000000;
			((long *) &tll)[0] = 0;
		} else
			return 0;
	} else
		if (t.sign)
			tll = -tll;

	REENTRANT_CHECK(OFF);
/*	    verify_area(VERIFY_WRITE, (void *) d, 8); */
	suword((unsigned long *) d, ((long *) &tll)[0]);
	suword(1 + (unsigned long *) d, ((long *) &tll)[1]);
	REENTRANT_CHECK(ON);

	return 1;
}


/* Put a long into user memory */
int
reg_store_int32(void)
{
	long   *d = (long *) FPU_data_address;
	FPU_REG t;

	if (FPU_st0_tag == TW_Empty) {
		/* Empty register (stack underflow) */
		EXCEPTION(EX_StackUnder);
		if (control_word & EX_Invalid) {
			/* The masked response */
			/* Put out the QNaN indefinite */
			REENTRANT_CHECK(OFF);
/*			    verify_area(VERIFY_WRITE, d, 4);*/
			suword((unsigned long *) d, 0x80000000);
			REENTRANT_CHECK(ON);
			return 1;
		} else
			return 0;
	}
	reg_move(FPU_st0_ptr, &t);
	round_to_int(&t);
	if (t.sigh ||
	    ((t.sigl & 0x80000000) &&
		!((t.sigl == 0x80000000) && (t.sign == SIGN_NEG)))) {
		EXCEPTION(EX_Invalid);
		/* This is a special case: see sec 16.2.5.1 of the 80486 book */
		if (control_word & EX_Invalid) {
			/* Produce "indefinite" */
			t.sigl = 0x80000000;
		} else
			return 0;
	} else
		if (t.sign)
			t.sigl = -(long) t.sigl;

	REENTRANT_CHECK(OFF);
/*	    verify_area(VERIFY_WRITE, d, 4); */
	suword((unsigned long *) d, t.sigl);
	REENTRANT_CHECK(ON);

	return 1;
}


/* Put a short into user memory */
int
reg_store_int16(void)
{
	short  *d = (short *) FPU_data_address;
	FPU_REG t;
	short   ts;

	if (FPU_st0_tag == TW_Empty) {
		/* Empty register (stack underflow) */
		EXCEPTION(EX_StackUnder);
		if (control_word & EX_Invalid) {
			/* The masked response */
			/* Put out the QNaN indefinite */
			REENTRANT_CHECK(OFF);
/*			    verify_area(VERIFY_WRITE, d, 2);*/
			susword((unsigned short *) d, 0x8000);
			REENTRANT_CHECK(ON);
			return 1;
		} else
			return 0;
	}
	reg_move(FPU_st0_ptr, &t);
	round_to_int(&t);
	if (t.sigh ||
	    ((t.sigl & 0xffff8000) &&
		!((t.sigl == 0x8000) && (t.sign == SIGN_NEG)))) {
		EXCEPTION(EX_Invalid);
		/* This is a special case: see sec 16.2.5.1 of the 80486 book */
		if (control_word & EX_Invalid) {
			/* Produce "indefinite" */
			ts = 0x8000;
		} else
			return 0;
	} else
		if (t.sign)
			t.sigl = -t.sigl;

	REENTRANT_CHECK(OFF);
/*	    verify_area(VERIFY_WRITE, d, 2); */
	susword((short *) d, (short) t.sigl);
	REENTRANT_CHECK(ON);

	return 1;
}


/* Put a packed bcd array into user memory */
int
reg_store_bcd(void)
{
	char   *d = (char *) FPU_data_address;
	FPU_REG t;
	long long ll;
	unsigned char b;
	int     i;
	unsigned char sign = (FPU_st0_ptr->sign == SIGN_NEG) ? 0x80 : 0;

	if (FPU_st0_tag == TW_Empty) {
		/* Empty register (stack underflow) */
		EXCEPTION(EX_StackUnder);
		if (control_word & EX_Invalid) {
			/* The masked response */
			/* Put out the QNaN indefinite */
			goto put_indefinite;
		} else
			return 0;
	}
	reg_move(FPU_st0_ptr, &t);
	round_to_int(&t);
	ll = *(long long *) (&t.sigl);

	/* Check for overflow, by comparing with 999999999999999999 decimal. */
	if ((t.sigh > 0x0de0b6b3) ||
	    ((t.sigh == 0x0de0b6b3) && (t.sigl > 0xa763ffff))) {
		EXCEPTION(EX_Invalid);
		/* This is a special case: see sec 16.2.5.1 of the 80486 book */
		if (control_word & EX_Invalid) {
	put_indefinite:
			/* Produce "indefinite" */
			REENTRANT_CHECK(OFF);
/*			    verify_area(VERIFY_WRITE, d, 10);*/
			subyte((unsigned char *) d + 7, 0xff);
			subyte((unsigned char *) d + 8, 0xff);
			subyte((unsigned char *) d + 9, 0xff);
			REENTRANT_CHECK(ON);
			return 1;
		} else
			return 0;
	}
/*	verify_area(VERIFY_WRITE, d, 10);*/
	for (i = 0; i < 9; i++) {
		b = div_small(&ll, 10);
		b |= (div_small(&ll, 10)) << 4;
		REENTRANT_CHECK(OFF);
		subyte((unsigned char *) d + i, b);
		REENTRANT_CHECK(ON);
	}
	REENTRANT_CHECK(OFF);
	subyte((unsigned char *) d + 9, sign);
	REENTRANT_CHECK(ON);

	return 1;
}
/*===========================================================================*/

/* r gets mangled such that sig is int, sign:
   it is NOT normalized */
/* The return value (in eax) is zero if the result is exact,
   if bits are changed due to rounding, truncation, etc, then
   a non-zero value is returned */
/* Overflow is signalled by a non-zero return value (in eax).
   In the case of overflow, the returned significand always has the
   the largest possible value */
/* The value returned in eax is never actually needed :-) */
int
round_to_int(FPU_REG * r)
{
	char    very_big;
	unsigned eax;

	if (r->tag == TW_Zero) {
		/* Make sure that zero is returned */
		*(long long *) &r->sigl = 0;
		return 0;	/* o.k. */
	}
	if (r->exp > EXP_BIAS + 63) {
		r->sigl = r->sigh = ~0;	/* The largest representable number */
		return 1;	/* overflow */
	}
	eax = shrxs(&r->sigl, EXP_BIAS + 63 - r->exp);
	very_big = !(~(r->sigh) | ~(r->sigl));	/* test for 0xfff...fff */
#define	half_or_more	(eax & 0x80000000)
#define	frac_part	(eax)
#define more_than_half  ((eax & 0x80000001) == 0x80000001)
	switch (control_word & CW_RC) {
	case RC_RND:
		if (more_than_half	/* nearest */
		    || (half_or_more && (r->sigl & 1))) {	/* odd -> even */
			if (very_big)
				return 1;	/* overflow */
			(*(long long *) (&r->sigl))++;
			return LOST_UP;
		}
		break;
	case RC_DOWN:
		if (frac_part && r->sign) {
			if (very_big)
				return 1;	/* overflow */
			(*(long long *) (&r->sigl))++;
			return LOST_UP;
		}
		break;
	case RC_UP:
		if (frac_part && !r->sign) {
			if (very_big)
				return 1;	/* overflow */
			(*(long long *) (&r->sigl))++;
			return LOST_UP;
		}
		break;
	case RC_CHOP:
		break;
	}

	return eax ? LOST_DOWN : 0;

}
/*===========================================================================*/

char   *
fldenv(void)
{
	char   *s = (char *) FPU_data_address;
	unsigned short tag_word = 0;
	unsigned char tag;
	int     i;

	REENTRANT_CHECK(OFF);
	control_word = fusword((unsigned short *) s);
	status_word = fusword((unsigned short *) (s + 4));
	tag_word = fusword((unsigned short *) (s + 8));
	ip_offset = fuword((unsigned long *) (s + 0x0c));
	cs_selector = fuword((unsigned long *) (s + 0x10));
	data_operand_offset = fuword((unsigned long *) (s + 0x14));
	operand_selector = fuword((unsigned long *) (s + 0x18));
	REENTRANT_CHECK(ON);

	top = (status_word >> SW_Top_Shift) & 7;

	for (i = 0; i < 8; i++) {
		tag = tag_word & 3;
		tag_word >>= 2;

		switch (tag) {
		case 0:
			regs[i].tag = TW_Valid;
			break;
		case 1:
			regs[i].tag = TW_Zero;
			break;
		case 2:
			regs[i].tag = TW_NaN;
			break;
		case 3:
			regs[i].tag = TW_Empty;
			break;
		}
	}

	/* We want no net effect: */
	FPU_data_address = (void *) (intptr_t) data_operand_offset;
	FPU_entry_eip = ip_offset;	/* We want no net effect */

	return s + 0x1c;
}


void
frstor(void)
{
	int     i, stnr;
	unsigned char tag;
	unsigned short saved_status, saved_control;
	char   *s = (char *) fldenv();

	saved_status = status_word;
	saved_control = control_word;
	control_word = 0x037f;	/* Mask all interrupts while we load. */
	for (i = 0; i < 8; i++) {
		/* load each register */
		FPU_data_address = (void *) (s + i * 10);
		reg_load_extended();
		stnr = (i + top) & 7;
		tag = regs[stnr].tag;	/* derived from the loaded tag word */
		reg_move(&FPU_loaded_data, &regs[stnr]);
		if (tag == TW_NaN) {
			/* The current data is a special, i.e. NaN,
			 * unsupported, infinity, or denormal */
			unsigned char t = regs[stnr].tag;	/* derived from the new
								 * data */
			if ( /* (t == TW_Valid) || *** */ (t == TW_Zero))
				regs[stnr].tag = TW_NaN;
		} else
			regs[stnr].tag = tag;
	}
	control_word = saved_control;
	status_word = saved_status;

	/* We want no net effect: */
	FPU_data_address = (void *) (intptr_t) data_operand_offset;
}


unsigned short
tag_word(void)
{
	unsigned short word = 0;
	unsigned char tag;
	int     i;

	for (i = 7; i >= 0; i--) {
		switch (tag = regs[i].tag) {
#if 0				/* TW_Denormal is not used yet, and probably
				 * won't be */
		case TW_Denormal:
#endif
		case TW_Valid:
			if (regs[i].exp <= (EXP_BIAS - EXTENDED_Ebias))
				tag = 2;
			break;
		case TW_Infinity:
		case TW_NaN:
			tag = 2;
			break;
		case TW_Empty:
			tag = 3;
			break;
			/* TW_Valid and TW_Zero already have the correct value */
		}
		word <<= 2;
		word |= tag;
	}
	return word;
}


char   *
fstenv(void)
{
	char   *d = (char *) FPU_data_address;

/*	verify_area(VERIFY_WRITE, d, 28);*/

#if 0				/****/
	*(unsigned short *) &cs_selector = fpu_cs;
	*(unsigned short *) &operand_selector = fpu_os;
#endif				/****/

	REENTRANT_CHECK(OFF);
	susword((unsigned short *) d, control_word);
	susword((unsigned short *) (d + 4), (status_word & ~SW_Top) | ((top & 7) << SW_Top_Shift));
	susword((unsigned short *) (d + 8), tag_word());
	suword((unsigned long *) (d + 0x0c), ip_offset);
	suword((unsigned long *) (d + 0x10), cs_selector);
	suword((unsigned long *) (d + 0x14), data_operand_offset);
	suword((unsigned long *) (d + 0x18), operand_selector);
	REENTRANT_CHECK(ON);

	return d + 0x1c;
}


void
fsave(void)
{
	char   *d;
	FPU_REG tmp, *rp;
	int     i;
	short   e;

	d = fstenv();
/*	verify_area(VERIFY_WRITE, d, 80);*/
	for (i = 0; i < 8; i++) {
		/* Store each register in the order: st(0), st(1), ... */
		rp = &regs[(top + i) & 7];

		e = rp->exp - EXP_BIAS + EXTENDED_Ebias;

		if (rp->tag == TW_Valid) {
			if (e >= 0x7fff) {
				/* Overflow to infinity */
				REENTRANT_CHECK(OFF);
				suword((unsigned long *) (d + i * 10), 0);
				suword((unsigned long *) (d + i * 10 + 4), 0);
				REENTRANT_CHECK(ON);
				e = 0x7fff;
			} else
				if (e <= 0) {
					if (e > -63) {
						/* Make a de-normal */
						reg_move(rp, &tmp);
						tmp.exp += -EXTENDED_Emin + 63;	/* largest exp to be 62 */
						round_to_int(&tmp);
						REENTRANT_CHECK(OFF);
						suword((unsigned long *) (d + i * 10), tmp.sigl);
						suword((unsigned long *) (d + i * 10 + 4), tmp.sigh);
						REENTRANT_CHECK(ON);
					} else {
						/* Underflow to zero */
						REENTRANT_CHECK(OFF);
						suword((unsigned long *) (d + i * 10), 0);
						suword((unsigned long *) (d + i * 10 + 4), 0);
						REENTRANT_CHECK(ON);
					}
					e = 0;
				} else {
					REENTRANT_CHECK(OFF);
					suword((unsigned long *) (d + i * 10), rp->sigl);
					suword((unsigned long *) (d + i * 10 + 4), rp->sigh);
					REENTRANT_CHECK(ON);
				}
		} else
			if (rp->tag == TW_Zero) {
				REENTRANT_CHECK(OFF);
				suword((unsigned long *) (d + i * 10), 0);
				suword((unsigned long *) (d + i * 10 + 4), 0);
				REENTRANT_CHECK(ON);
				e = 0;
			} else
				if (rp->tag == TW_Infinity) {
					REENTRANT_CHECK(OFF);
					suword((unsigned long *) (d + i * 10), 0);
					suword((unsigned long *) (d + i * 10 + 4), 0x80000000);
					REENTRANT_CHECK(ON);
					e = 0x7fff;
				} else
					if (rp->tag == TW_NaN) {
						REENTRANT_CHECK(OFF);
						suword((unsigned long *) (d + i * 10), rp->sigl);
						suword((unsigned long *) (d + i * 10 + 4), rp->sigh);
						REENTRANT_CHECK(ON);
						e = 0x7fff;
					} else
						if (rp->tag == TW_Empty) {
							/* just copy the reg */
							REENTRANT_CHECK(OFF);
							suword((unsigned long *) (d + i * 10), rp->sigl);
							suword((unsigned long *) (d + i * 10 + 4), rp->sigh);
							REENTRANT_CHECK(ON);
						}
		e |= rp->sign == SIGN_POS ? 0 : 0x8000;
		REENTRANT_CHECK(OFF);
		susword((unsigned short *) (d + i * 10 + 8), e);
		REENTRANT_CHECK(ON);
	}

	finit();

}
/*===========================================================================*/