sysdeps/ieee754/ldbl-96/s_lroundl.c

   1 /* Round long double value to long int.
   2    Copyright (C) 1997, 2004 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, write to the Free
  18    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19    02111-1307 USA.  */
  20
  21 #include <math.h>
  22
  23 #include "math_private.h"
  24
  25
  26 long int
  27 __lroundl (long double x)
  28 {
  29   int32_t j0;
  30   u_int32_t se, i1, i0;
  31   long int result;
  32   int sign;
  33
  34   GET_LDOUBLE_WORDS (se, i0, i1, x);
  35   j0 = (se & 0x7fff) - 0x3fff;
  36   sign = (se & 0x8000) != 0 ? -1 : 1;
  37
  38   if (j0 < 31)
  39     {
  40       if (j0 < 0)
  41         return j0 < -1 ? 0 : sign;
  42       else
  43         {
  44           u_int32_t j = i0 + (0x40000000 >> j0);
  45           if (j < i0)
  46             {
  47               j >>= 1;
  48               j |= 0x80000000;
  49               ++j0;
  50             }
  51
  52           result = j >> (31 - j0);
  53         }
  54     }
  55   else if (j0 < (int32_t) (8 * sizeof (long int)) - 1)
  56     {
  57       if (j0 >= 63)
  58         result = ((long int) i0 << (j0 - 31)) | (i1 << (j0 - 63));
  59       else
  60         {
  61           u_int32_t j = i1 + (0x80000000 >> (j0 - 31));
  62           if (j < i1)
  63             ++i0;
  64
  65           if (j0 == 31)
  66             result = (long int) i0;
  67           else
  68             result = ((long int) i0 << (j0 - 31)) | (j >> (63 - j0));
  69         }
  70     }
  71   else
  72     {
  73       /* The number is too large.  It is left implementation defined
  74          what happens.  */
  75       return (long int) x;
  76     }
  77
  78   return sign * result;
  79 }
  80
  81 weak_alias (__lroundl, lroundl)