sysdeps/ieee754/ldbl-128/s_lroundl.c

   1 /* Round long double value to 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 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, see
  19    <http://www.gnu.org/licenses/>.  */
  20
  21 #include <math.h>
  22
  23 #include <math_private.h>
  24
  25
  26 long int
  27 __lroundl (long double x)
  28 {
  29   int64_t j0;
  30   u_int64_t i1, i0;
  31   long int result;
  32   int sign;
  33
  34   GET_LDOUBLE_WORDS64 (i0, i1, x);
  35   j0 = ((i0 >> 48) & 0x7fff) - 0x3fff;
  36   sign = (i0 & 0x8000000000000000ULL) != 0 ? -1 : 1;
  37   i0 &= 0x0000ffffffffffffLL;
  38   i0 |= 0x0001000000000000LL;
  39
  40   if (j0 < 48)
  41     {
  42       if (j0 < 0)
  43         return j0 < -1 ? 0 : sign;
  44       else
  45         {
  46           i0 += 0x0000800000000000LL >> j0;
  47           result = i0 >> (48 - j0);
  48         }
  49     }
  50   else if (j0 < (int32_t) (8 * sizeof (long int)) - 1)
  51     {
  52       if (j0 >= 112)
  53         result = ((long int) i0 << (j0 - 48)) | (i1 << (j0 - 112));
  54       else
  55         {
  56           u_int64_t j = i1 + (0x8000000000000000ULL >> (j0 - 48));
  57           if (j < i1)
  58             ++i0;
  59
  60           if (j0 == 48)
  61             result = (long int) i0;
  62           else
  63             result = ((long int) i0 << (j0 - 48)) | (j >> (112 - j0));
  64         }
  65     }
  66   else
  67     {
  68       /* The number is too large.  It is left implementation defined
  69          what happens.  */
  70       return (long int) x;
  71     }
  72
  73   return sign * result;
  74 }
  75
  76 weak_alias (__lroundl, lroundl)