/* *  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: src/sys/gnu/i386/fpemul/reg_mul.c,v 1.4.2.1 1999/09/05 08:09:54 peter Exp $ * *//*---------------------------------------------------------------------------+ | 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 */voidreg_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 */			}}