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  *
   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
  29 ieee754dp 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
  73 ieee754dp 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 }