LXR linux/arch/mips/math-emu/dp

   1/* IEEE754 floating point arithmetic
   2 * double precision: common utilities
   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#include "ieee754dp.h"
  24
  25static inline union ieee754dp ieee754dp_nan_fsp(int xs, u64 xm)
  26{
  27        return builddp(xs, DP_EMAX + 1 + DP_EBIAS,
  28                       xm << (DP_FBITS - SP_FBITS));
  29}
  30
  31union ieee754dp ieee754dp_fsp(union ieee754sp x)
  32{
  33        COMPXSP;
  34
  35        EXPLODEXSP;
  36
  37        ieee754_clearcx();
  38
  39        FLUSHXSP;
  40
  41        switch (xc) {
  42        case IEEE754_CLASS_SNAN:
  43                return ieee754dp_nanxcpt(ieee754dp_nan_fsp(xs, xm));
  44
  45        case IEEE754_CLASS_QNAN:
  46                return ieee754dp_nan_fsp(xs, xm);
  47
  48        case IEEE754_CLASS_INF:
  49                return ieee754dp_inf(xs);
  50
  51        case IEEE754_CLASS_ZERO:
  52                return ieee754dp_zero(xs);
  53
  54        case IEEE754_CLASS_DNORM:
  55                /* normalize */
  56                while ((xm >> SP_FBITS) == 0) {
  57                        xm <<= 1;
  58                        xe--;
  59                }
  60                break;
  61
  62        case IEEE754_CLASS_NORM:
  63                break;
  64        }
  65
  66        /*
  67         * Can't possibly overflow,underflow, or need rounding
  68         */
  69
  70        /* drop the hidden bit */
  71        xm &= ~SP_HIDDEN_BIT;
  72
  73        return builddp(xs, xe + DP_EBIAS,
  74                       (u64) xm << (DP_FBITS - SP_FBITS));
  75}
  76