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 * ########################################################################
   9 *
  10 *  This program is free software; you can distribute it and/or modify it
  11 *  under the terms of the GNU General Public License (Version 2) as
  12 *  published by the Free Software Foundation.
  13 *
  14 *  This program is distributed in the hope it will be useful, but WITHOUT
  15 *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  16 *  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  17 *  for more details.
  18 *
  19 *  You should have received a copy of the GNU General Public License along
  20 *  with this program; if not, write to the Free Software Foundation, Inc.,
  21 *  59 Temple Place - Suite 330, Boston MA 02111-1307, USA.
  22 *
  23 * ########################################################################
  24 */
  25
  26
  27#include "ieee754dp.h"
  28
  29ieee754dp ieee754dp_fint(int x)
  30{
  31        u64 xm;
  32        int xe;
  33        int xs;
  34
  35        CLEARCX;
  36
  37        if (x == 0)
  38                return ieee754dp_zero(0);
  39        if (x == 1 || x == -1)
  40                return ieee754dp_one(x < 0);
  41        if (x == 10 || x == -10)
  42                return ieee754dp_ten(x < 0);
  43
  44        xs = (x < 0);
  45        if (xs) {
  46                if (x == (1 << 31))
  47                        xm = ((unsigned) 1 << 31);      /* max neg can't be safely negated */
  48                else
  49                        xm = -x;
  50        } else {
  51                xm = x;
  52        }
  53
  54#if 1
  55        /* normalize - result can never be inexact or overflow */
  56        xe = DP_MBITS;
  57        while ((xm >> DP_MBITS) == 0) {
  58                xm <<= 1;
  59                xe--;
  60        }
  61        return builddp(xs, xe + DP_EBIAS, xm & ~DP_HIDDEN_BIT);
  62#else
  63        /* normalize */
  64        xe = DP_MBITS + 3;
  65        while ((xm >> (DP_MBITS + 3)) == 0) {
  66                xm <<= 1;
  67                xe--;
  68        }
  69        DPNORMRET1(xs, xe, xm, "fint", x);
  70#endif
  71}
  72
  73ieee754dp ieee754dp_funs(unsigned int u)
  74{
  75        if ((int) u < 0)
  76                return ieee754dp_add(ieee754dp_1e31(),
  77                                     ieee754dp_fint(u & ~(1 << 31)));
  78        return ieee754dp_fint(u);
  79}
  80