arch/mips/math-emu/dp_fint.c

   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  * http://www.algor.co.uk
   8  *
   9  * ########################################################################
  10  *
  11  *  This program is free software; you can distribute it and/or modify it
  12  *  under the terms of the GNU General Public License (Version 2) as
  13  *  published by the Free Software Foundation.
  14  *
  15  *  This program is distributed in the hope it will be useful, but WITHOUT
  16  *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  17  *  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  18  *  for more details.
  19  *
  20  *  You should have received a copy of the GNU General Public License along
  21  *  with this program; if not, write to the Free Software Foundation, Inc.,
  22  *  59 Temple Place - Suite 330, Boston MA 02111-1307, USA.
  23  *
  24  * ########################################################################
  25  */
  26
  27
  28 #include "ieee754dp.h"
  29
  30 ieee754dp ieee754dp_fint(int x)
  31 {
  32         u64 xm;
  33         int xe;
  34         int xs;
  35
  36         CLEARCX;
  37
  38         if (x == 0)
  39                 return ieee754dp_zero(0);
  40         if (x == 1 || x == -1)
  41                 return ieee754dp_one(x < 0);
  42         if (x == 10 || x == -10)
  43                 return ieee754dp_ten(x < 0);
  44
  45         xs = (x < 0);
  46         if (xs) {
  47                 if (x == (1 << 31))
  48                         xm = ((unsigned) 1 << 31);      /* max neg can't be safely negated */
  49                 else
  50                         xm = -x;
  51         } else {
  52                 xm = x;
  53         }
  54
  55 #if 1
  56         /* normalize - result can never be inexact or overflow */
  57         xe = DP_MBITS;
  58         while ((xm >> DP_MBITS) == 0) {
  59                 xm <<= 1;
  60                 xe--;
  61         }
  62         return builddp(xs, xe + DP_EBIAS, xm & ~DP_HIDDEN_BIT);
  63 #else
  64         /* normalize */
  65         xe = DP_MBITS + 3;
  66         while ((xm >> (DP_MBITS + 3)) == 0) {
  67                 xm <<= 1;
  68                 xe--;
  69         }
  70         DPNORMRET1(xs, xe, xm, "fint", x);
  71 #endif
  72 }
  73
  74 ieee754dp ieee754dp_funs(unsigned int u)
  75 {
  76         if ((int) u < 0)
  77                 return ieee754dp_add(ieee754dp_1e31(),
  78                                      ieee754dp_fint(u & ~(1 << 31)));
  79         return ieee754dp_fint(u);
  80 }