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/*
* reg_mul.c
*
* Multiply one FPU_REG by another, put the result in a destination FPU_REG.
*
*
* 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.
*
*
* $FreeBSD$
*
*/
/*---------------------------------------------------------------------------+
| The destination may be any FPU_REG, including one of the source FPU_REGs. |
+---------------------------------------------------------------------------*/
#include <gnu/i386/fpemul/exception.h>
#include <gnu/i386/fpemul/reg_constant.h>
#include <gnu/i386/fpemul/fpu_emu.h>
#include <gnu/i386/fpemul/fpu_system.h>
/* This routine must be called with non-empty source registers */
void
reg_mul(FPU_REG * a, FPU_REG * b, FPU_REG * dest, unsigned int control_w)
{
char sign = (a->sign ^ b->sign);
if (!(a->tag | b->tag)) {
/* This should be the most common case */
reg_u_mul(a, b, dest, control_w);
dest->sign = sign;
return;
} else
if ((a->tag <= TW_Zero) && (b->tag <= TW_Zero)) {
#ifdef DENORM_OPERAND
if (((b->tag == TW_Valid) && (b->exp <= EXP_UNDER)) ||
((a->tag == TW_Valid) && (a->exp <= EXP_UNDER))) {
if (denormal_operand())
return;
}
#endif /* DENORM_OPERAND */
/* Must have either both arguments == zero, or one
* valid and the other zero. The result is therefore
* zero. */
reg_move(&CONST_Z, dest);
#ifdef PECULIAR_486
/* The 80486 book says that the answer is +0, but a
* real 80486 appears to behave this way... */
dest->sign = sign;
#endif /* PECULIAR_486 */
return;
}
#if 0 /* TW_Denormal is not used yet... perhaps
* never will be. */
else
if ((a->tag <= TW_Denormal) && (b->tag <= TW_Denormal)) {
/* One or both arguments are de-normalized */
/* Internal de-normalized numbers are not
* supported yet */
EXCEPTION(EX_INTERNAL | 0x105);
reg_move(&CONST_Z, dest);
}
#endif
else {
/* Must have infinities, NaNs, etc */
if ((a->tag == TW_NaN) || (b->tag == TW_NaN)) {
real_2op_NaN(a, b, dest);
return;
} else
if (a->tag == TW_Infinity) {
if (b->tag == TW_Zero) {
arith_invalid(dest);
return;
}
/* Zero*Infinity is invalid */
else {
#ifdef DENORM_OPERAND
if ((b->tag == TW_Valid) && (b->exp <= EXP_UNDER) &&
denormal_operand())
return;
#endif /* DENORM_OPERAND */
reg_move(a, dest);
dest->sign = sign;
}
return;
} else
if (b->tag == TW_Infinity) {
if (a->tag == TW_Zero) {
arith_invalid(dest);
return;
}
/* Zero*Infinity is
* invalid */
else {
#ifdef DENORM_OPERAND
if ((a->tag == TW_Valid) && (a->exp <= EXP_UNDER) &&
denormal_operand())
return;
#endif /* DENORM_OPERAND */
reg_move(b, dest);
dest->sign = sign;
}
return;
}
#ifdef PARANOID
else {
EXCEPTION(EX_INTERNAL | 0x102);
}
#endif /* PARANOID */
}
}
|
