sysdeps/ieee754/ldbl-96/s_llroundl.c

   1 /* Round long double value to long long int.
   2    Copyright (C) 1997-2014 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, see
  18    <http://www.gnu.org/licenses/>.  */
  19
  20 #include <math.h>
  21
  22 #include <math_private.h>
  23
  24
  25 long long int
  26 __llroundl (long double x)
  27 {
  28   int32_t j0;
  29   u_int32_t se, i1, i0;
  30   long long int result;
  31   int sign;
  32
  33   GET_LDOUBLE_WORDS (se, i0, i1, x);
  34   j0 = (se & 0x7fff) - 0x3fff;
  35   sign = (se & 0x8000) != 0 ? -1 : 1;
  36
  37   if (j0 < 31)
  38     {
  39       if (j0 < 0)
  40         return j0 < -1 ? 0 : sign;
  41       else
  42         {
  43           u_int32_t j = i0 + (0x40000000 >> j0);
  44           if (j < i0)
  45             {
  46               j >>= 1;
  47               j |= 0x80000000;
  48               ++j0;
  49             }
  50
  51           result = j >> (31 - j0);
  52         }
  53     }
  54   else if (j0 < (int32_t) (8 * sizeof (long long int)) - 1)
  55     {
  56       if (j0 >= 63)
  57         result = (((long long int) i0 << 32) | i1) << (j0 - 63);
  58       else
  59         {
  60           u_int32_t j = i1 + (0x80000000 >> (j0 - 31));
  61
  62           result = (long long int) i0;
  63           if (j < i1)
  64             ++result;
  65
  66           if (j0 > 31)
  67             result = (result << (j0 - 31)) | (j >> (63 - j0));
  68         }
  69     }
  70   else
  71     {
  72       /* The number is too large.  It is left implementation defined
  73          what happens.  */
  74       return (long long int) x;
  75     }
  76
  77   return sign * result;
  78 }
  79
  80 weak_alias (__llroundl, llroundl)