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 "ieee754dp.h"
  23
  24union ieee754dp ieee754dp_fint(int x)
  25{
  26        u64 xm;
  27        int xe;
  28        int xs;
  29
  30        ieee754_clearcx();
  31
  32        if (x == 0)
  33                return ieee754dp_zero(0);
  34        if (x == 1 || x == -1)
  35                return ieee754dp_one(x < 0);
  36        if (x == 10 || x == -10)
  37                return ieee754dp_ten(x < 0);
  38
  39        xs = (x < 0);
  40        if (xs) {
  41                if (x == (1 << 31))
  42                        xm = ((unsigned) 1 << 31);      /* max neg can't be safely negated */
  43                else
  44                        xm = -x;
  45        } else {
  46                xm = x;
  47        }
  48
  49        /* normalize - result can never be inexact or overflow */
  50        xe = DP_FBITS;
  51        while ((xm >> DP_FBITS) == 0) {
  52                xm <<= 1;
  53                xe--;
  54        }
  55        return builddp(xs, xe + DP_EBIAS, xm & ~DP_HIDDEN_BIT);
  56}
  57