arch/mips/math-emu/sp_div.c

   1 /* IEEE754 floating point arithmetic
   2  * single precision
   3  */
   4 /*
   5  * MIPS floating point support
   6  * Copyright (C) 1994-2000 Algorithmics Ltd.
   7  *
   8  *  This program is free software; you can distribute it and/or modify it
   9  *  under the terms of the GNU General Public License (Version 2) as
  10  *  published by the Free Software Foundation.
  11  *
  12  *  This program is distributed in the hope it will be useful, but WITHOUT
  13  *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  14  *  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  15  *  for more details.
  16  *
  17  *  You should have received a copy of the GNU General Public License along
  18  *  with this program; if not, write to the Free Software Foundation, Inc.,
  19  *  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA.
  20  */
  21
  22 #include "ieee754sp.h"
  23
  24 union ieee754sp ieee754sp_div(union ieee754sp x, union ieee754sp y)
  25 {
  26         unsigned rm;
  27         int re;
  28         unsigned bm;
  29
  30         COMPXSP;
  31         COMPYSP;
  32
  33         EXPLODEXSP;
  34         EXPLODEYSP;
  35
  36         ieee754_clearcx();
  37
  38         FLUSHXSP;
  39         FLUSHYSP;
  40
  41         switch (CLPAIR(xc, yc)) {
  42         case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_QNAN):
  43         case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_SNAN):
  44         case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_SNAN):
  45         case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_SNAN):
  46         case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_SNAN):
  47         case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_SNAN):
  48         case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_SNAN):
  49         case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_ZERO):
  50         case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_NORM):
  51         case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_DNORM):
  52         case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_INF):
  53                 ieee754_setcx(IEEE754_INVALID_OPERATION);
  54                 return ieee754sp_nanxcpt(ieee754sp_indef());
  55
  56         case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_QNAN):
  57         case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_QNAN):
  58         case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_QNAN):
  59         case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_QNAN):
  60                 return y;
  61
  62         case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_QNAN):
  63         case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_ZERO):
  64         case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_NORM):
  65         case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_DNORM):
  66         case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_INF):
  67                 return x;
  68
  69
  70         /*
  71          * Infinity handling
  72          */
  73         case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_INF):
  74                 ieee754_setcx(IEEE754_INVALID_OPERATION);
  75                 return ieee754sp_indef();
  76
  77         case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_INF):
  78         case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_INF):
  79         case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_INF):
  80                 return ieee754sp_zero(xs ^ ys);
  81
  82         case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_ZERO):
  83         case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_NORM):
  84         case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_DNORM):
  85                 return ieee754sp_inf(xs ^ ys);
  86
  87         /*
  88          * Zero handling
  89          */
  90         case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO):
  91                 ieee754_setcx(IEEE754_INVALID_OPERATION);
  92                 return ieee754sp_indef();
  93
  94         case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_ZERO):
  95         case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO):
  96                 ieee754_setcx(IEEE754_ZERO_DIVIDE);
  97                 return ieee754sp_inf(xs ^ ys);
  98
  99         case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_NORM):
 100         case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_DNORM):
 101                 return ieee754sp_zero(xs == ys ? 0 : 1);
 102
 103         case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM):
 104                 SPDNORMX;
 105
 106         case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM):
 107                 SPDNORMY;
 108                 break;
 109
 110         case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM):
 111                 SPDNORMX;
 112                 break;
 113
 114         case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_NORM):
 115                 break;
 116         }
 117         assert(xm & SP_HIDDEN_BIT);
 118         assert(ym & SP_HIDDEN_BIT);
 119
 120         /* provide rounding space */
 121         xm <<= 3;
 122         ym <<= 3;
 123
 124         /* now the dirty work */
 125
 126         rm = 0;
 127         re = xe - ye;
 128
 129         for (bm = SP_MBIT(SP_FBITS + 2); bm; bm >>= 1) {
 130                 if (xm >= ym) {
 131                         xm -= ym;
 132                         rm |= bm;
 133                         if (xm == 0)
 134                                 break;
 135                 }
 136                 xm <<= 1;
 137         }
 138
 139         rm <<= 1;
 140         if (xm)
 141                 rm |= 1;        /* have remainder, set sticky */
 142
 143         assert(rm);
 144
 145         /* normalise rm to rounding precision ?
 146          */
 147         while ((rm >> (SP_FBITS + 3)) == 0) {
 148                 rm <<= 1;
 149                 re--;
 150         }
 151
 152         return ieee754sp_format(xs == ys ? 0 : 1, re, rm);
 153 }