libquadmath/math/truncq.c

   1 /* Truncate argument to nearest integral value not larger than the argument.
   2    Copyright (C) 1997-2017 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997 and
   5                   Jakub Jelinek <jj@ultra.linux.cz>, 1999.
   6
   7    The GNU C Library is free software; you can redistribute it and/or
   8    modify it under the terms of the GNU Lesser General Public
   9    License as published by the Free Software Foundation; either
  10    version 2.1 of the License, or (at your option) any later version.
  11
  12    The GNU C Library is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15    Lesser General Public License for more details.
  16
  17    You should have received a copy of the GNU Lesser General Public
  18    License along with the GNU C Library; if not, write to the Free
  19    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  20    02111-1307 USA.  */
  21
  22 #include "quadmath-imp.h"
  23
  24
  25 __float128
  26 truncq (__float128 x)
  27 {
  28   int32_t j0;
  29   uint64_t i0, i1, sx;
  30
  31   GET_FLT128_WORDS64 (i0, i1, x);
  32   sx = i0 & 0x8000000000000000ULL;
  33   j0 = ((i0 >> 48) & 0x7fff) - 0x3fff;
  34   if (j0 < 48)
  35     {
  36       if (j0 < 0)
  37         /* The magnitude of the number is < 1 so the result is +-0.  */
  38         SET_FLT128_WORDS64 (x, sx, 0);
  39       else
  40         SET_FLT128_WORDS64 (x, i0 & ~(0x0000ffffffffffffLL >> j0), 0);
  41     }
  42   else if (j0 > 111)
  43     {
  44       if (j0 == 0x4000)
  45         /* x is inf or NaN.  */
  46         return x + x;
  47     }
  48   else
  49     {
  50       SET_FLT128_WORDS64 (x, i0, i1 & ~(0xffffffffffffffffULL >> (j0 - 48)));
  51     }
  52
  53   return x;
  54 }