153 lines
5.0 KiB
C
153 lines
5.0 KiB
C
/*
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* reg_mul.c
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*
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* Multiply one FPU_REG by another, put the result in a destination FPU_REG.
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*
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*
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* Copyright (C) 1992, 1993 W. Metzenthen, 22 Parker St, Ormond,
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* Vic 3163, Australia.
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* E-mail apm233m@vaxc.cc.monash.edu.au
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* All rights reserved.
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*
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* This copyright notice covers the redistribution and use of the
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* FPU emulator developed by W. Metzenthen. It covers only its use
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* in the 386BSD operating system. Any other use is not permitted
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* under this copyright.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must include information specifying
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* that source code for the emulator is freely available and include
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* either:
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* a) an offer to provide the source code for a nominal distribution
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* fee, or
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* b) list at least two alternative methods whereby the source
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* can be obtained, e.g. a publically accessible bulletin board
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* and an anonymous ftp site from which the software can be
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* downloaded.
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* 3. All advertising materials specifically mentioning features or use of
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* this emulator must acknowledge that it was developed by W. Metzenthen.
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* 4. The name of W. Metzenthen may not be used to endorse or promote
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* products derived from this software without specific prior written
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* permission.
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*
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* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
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* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
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* AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
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* W. METZENTHEN BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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*
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* $Id:$
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*
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*/
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/*---------------------------------------------------------------------------+
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| The destination may be any FPU_REG, including one of the source FPU_REGs. |
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+---------------------------------------------------------------------------*/
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#include "exception.h"
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#include "reg_constant.h"
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#include "fpu_emu.h"
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#include "fpu_system.h"
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/* This routine must be called with non-empty source registers */
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void
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reg_mul(FPU_REG * a, FPU_REG * b, FPU_REG * dest, unsigned int control_w)
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{
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char sign = (a->sign ^ b->sign);
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if (!(a->tag | b->tag)) {
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/* This should be the most common case */
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reg_u_mul(a, b, dest, control_w);
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dest->sign = sign;
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return;
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} else
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if ((a->tag <= TW_Zero) && (b->tag <= TW_Zero)) {
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#ifdef DENORM_OPERAND
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if (((b->tag == TW_Valid) && (b->exp <= EXP_UNDER)) ||
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((a->tag == TW_Valid) && (a->exp <= EXP_UNDER))) {
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if (denormal_operand())
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return;
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}
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#endif /* DENORM_OPERAND */
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/* Must have either both arguments == zero, or one
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* valid and the other zero. The result is therefore
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* zero. */
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reg_move(&CONST_Z, dest);
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#ifdef PECULIAR_486
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/* The 80486 book says that the answer is +0, but a
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* real 80486 appears to behave this way... */
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dest->sign = sign;
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#endif /* PECULIAR_486 */
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return;
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}
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#if 0 /* TW_Denormal is not used yet... perhaps
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* never will be. */
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else
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if ((a->tag <= TW_Denormal) && (b->tag <= TW_Denormal)) {
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/* One or both arguments are de-normalized */
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/* Internal de-normalized numbers are not
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* supported yet */
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EXCEPTION(EX_INTERNAL | 0x105);
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reg_move(&CONST_Z, dest);
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}
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#endif
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else {
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/* Must have infinities, NaNs, etc */
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if ((a->tag == TW_NaN) || (b->tag == TW_NaN)) {
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real_2op_NaN(a, b, dest);
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return;
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} else
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if (a->tag == TW_Infinity) {
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if (b->tag == TW_Zero) {
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arith_invalid(dest);
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return;
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}
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/* Zero*Infinity is invalid */
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else {
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#ifdef DENORM_OPERAND
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if ((b->tag == TW_Valid) && (b->exp <= EXP_UNDER) &&
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denormal_operand())
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return;
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#endif /* DENORM_OPERAND */
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reg_move(a, dest);
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dest->sign = sign;
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}
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return;
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} else
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if (b->tag == TW_Infinity) {
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if (a->tag == TW_Zero) {
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arith_invalid(dest);
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return;
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}
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/* Zero*Infinity is
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* invalid */
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else {
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#ifdef DENORM_OPERAND
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if ((a->tag == TW_Valid) && (a->exp <= EXP_UNDER) &&
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denormal_operand())
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return;
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#endif /* DENORM_OPERAND */
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reg_move(b, dest);
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dest->sign = sign;
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}
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return;
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}
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#ifdef PARANOID
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else {
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EXCEPTION(EX_INTERNAL | 0x102);
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}
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#endif /* PARANOID */
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}
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}
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