sys/platform/pc32/gnu/fpemul/reg_mul.c

   1 /*
   2  *  reg_mul.c
   3  *
   4  * Multiply one FPU_REG by another, put the result in a destination FPU_REG.
   5  *
   6  *
   7  * Copyright (C) 1992,1993,1994
   8  *                       W. Metzenthen, 22 Parker St, Ormond, Vic 3163,
   9  *                       Australia.  E-mail   billm@vaxc.cc.monash.edu.au
  10  * All rights reserved.
  11  *
  12  * This copyright notice covers the redistribution and use of the
  13  * FPU emulator developed by W. Metzenthen. It covers only its use
  14  * in the 386BSD, FreeBSD and NetBSD operating systems. Any other
  15  * use is not permitted under this copyright.
  16  *
  17  * Redistribution and use in source and binary forms, with or without
  18  * modification, are permitted provided that the following conditions
  19  * are met:
  20  * 1. Redistributions of source code must retain the above copyright
  21  *    notice, this list of conditions and the following disclaimer.
  22  * 2. Redistributions in binary form must include information specifying
  23  *    that source code for the emulator is freely available and include
  24  *    either:
  25  *      a) an offer to provide the source code for a nominal distribution
  26  *         fee, or
  27  *      b) list at least two alternative methods whereby the source
  28  *         can be obtained, e.g. a publically accessible bulletin board
  29  *         and an anonymous ftp site from which the software can be
  30  *         downloaded.
  31  * 3. All advertising materials specifically mentioning features or use of
  32  *    this emulator must acknowledge that it was developed by W. Metzenthen.
  33  * 4. The name of W. Metzenthen may not be used to endorse or promote
  34  *    products derived from this software without specific prior written
  35  *    permission.
  36  *
  37  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
  38  * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
  39  * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL
  40  * W. METZENTHEN BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  41  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  42  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  43  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
  44  * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
  45  * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
  46  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  47  *
  48  *
  49  * The purpose of this copyright, based upon the Berkeley copyright, is to
  50  * ensure that the covered software remains freely available to everyone.
  51  *
  52  * The software (with necessary differences) is also available, but under
  53  * the terms of the GNU copyleft, for the Linux operating system and for
  54  * the djgpp ms-dos extender.
  55  *
  56  * W. Metzenthen   June 1994.
  57  *
  58  *
  59  * $FreeBSD: src/sys/gnu/i386/fpemul/reg_mul.c,v 1.8 1999/08/28 00:42:56 peter Exp $
  60  *
  61  */
  62
  63 /*---------------------------------------------------------------------------+
  64  | The destination may be any FPU_REG, including one of the source FPU_REGs. |
  65  +---------------------------------------------------------------------------*/
  66
  67 #include <gnu/i386/fpemul/reg_constant.h>
  68
  69
  70 /* This routine must be called with non-empty source registers */
  71 void
  72 reg_mul(FPU_REG * a, FPU_REG * b, FPU_REG * dest, unsigned int control_w)
  73 {
  74         char    sign = (a->sign ^ b->sign);
  75
  76         if (!(a->tag | b->tag)) {
  77                 /* This should be the most common case */
  78                 reg_u_mul(a, b, dest, control_w);
  79                 dest->sign = sign;
  80                 return;
  81         } else
  82                 if ((a->tag <= TW_Zero) && (b->tag <= TW_Zero)) {
  83 #ifdef DENORM_OPERAND
  84                         if (((b->tag == TW_Valid) && (b->exp <= EXP_UNDER)) ||
  85                             ((a->tag == TW_Valid) && (a->exp <= EXP_UNDER))) {
  86                                 if (denormal_operand())
  87                                         return;
  88                         }
  89 #endif                          /* DENORM_OPERAND */
  90                         /* Must have either both arguments == zero, or one
  91                          * valid and the other zero. The result is therefore
  92                          * zero. */
  93                         reg_move(&CONST_Z, dest);
  94 #ifdef PECULIAR_486
  95                         /* The 80486 book says that the answer is +0, but a
  96                          * real 80486 appears to behave this way... */
  97                         dest->sign = sign;
  98 #endif                          /* PECULIAR_486 */
  99                         return;
 100                 }
 101 #if 0                           /* TW_Denormal is not used yet... perhaps
 102                                  * never will be. */
 103                 else
 104                         if ((a->tag <= TW_Denormal) && (b->tag <= TW_Denormal)) {
 105                                 /* One or both arguments are de-normalized */
 106                                 /* Internal de-normalized numbers are not
 107                                  * supported yet */
 108                                 EXCEPTION(EX_INTERNAL | 0x105);
 109                                 reg_move(&CONST_Z, dest);
 110                         }
 111 #endif
 112                         else {
 113                                 /* Must have infinities, NaNs, etc */
 114                                 if ((a->tag == TW_NaN) || (b->tag == TW_NaN)) {
 115                                         real_2op_NaN(a, b, dest);
 116                                         return;
 117                                 } else
 118                                         if (a->tag == TW_Infinity) {
 119                                                 if (b->tag == TW_Zero) {
 120                                                         arith_invalid(dest);
 121                                                         return;
 122                                                 }
 123                                                 /* Zero*Infinity is invalid */
 124                                                 else {
 125 #ifdef DENORM_OPERAND
 126                                                         if ((b->tag == TW_Valid) && (b->exp <= EXP_UNDER) &&
 127                                                             denormal_operand())
 128                                                                 return;
 129 #endif                          /* DENORM_OPERAND */
 130                                                         reg_move(a, dest);
 131                                                         dest->sign = sign;
 132                                                 }
 133                                                 return;
 134                                         } else
 135                                                 if (b->tag == TW_Infinity) {
 136                                                         if (a->tag == TW_Zero) {
 137                                                                 arith_invalid(dest);
 138                                                                 return;
 139                                                         }
 140                                                         /* Zero*Infinity is
 141                                                          * invalid */
 142                                                         else {
 143 #ifdef DENORM_OPERAND
 144                                                                 if ((a->tag == TW_Valid) && (a->exp <= EXP_UNDER) &&
 145                                                                     denormal_operand())
 146                                                                         return;
 147 #endif                          /* DENORM_OPERAND */
 148                                                                 reg_move(b, dest);
 149                                                                 dest->sign = sign;
 150                                                         }
 151                                                         return;
 152                                                 }
 153 #ifdef PARANOID
 154                                                 else {
 155                                                         EXCEPTION(EX_INTERNAL | 0x102);
 156                                                 }
 157 #endif                          /* PARANOID */
 158                         }
 159 }