arch/mips/math-emu/dp_flong.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  *  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
  24 union ieee754dp ieee754dp_flong(s64 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 == (1ULL << 63))
  42                         xm = (1ULL << 63);      /* max neg can't be safely negated */
  43                 else
  44                         xm = -x;
  45         } else {
  46                 xm = x;
  47         }
  48
  49         /* normalize */
  50         xe = DP_FBITS + 3;
  51         if (xm >> (DP_FBITS + 1 + 3)) {
  52                 /* shunt out overflow bits */
  53                 while (xm >> (DP_FBITS + 1 + 3)) {
  54                         XDPSRSX1();
  55                 }
  56         } else {
  57                 /* normalize in grs extended double precision */
  58                 while ((xm >> (DP_FBITS + 3)) == 0) {
  59                         xm <<= 1;
  60                         xe--;
  61                 }
  62         }
  63
  64         return ieee754dp_format(xs, xe, xm);
  65 }