sysdeps/ieee754/ldbl-96/s_llrintl.c

   1 /* Round argument to nearest integral value according to current rounding
   2    direction.
   3    Copyright (C) 1997, 2004, 2006 Free Software Foundation, Inc.
   4    This file is part of the GNU C Library.
   5    Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
   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 static const long double two63[2] =
  26 {
  27   9.223372036854775808000000e+18, /* 0x403E, 0x00000000, 0x00000000 */
  28  -9.223372036854775808000000e+18  /* 0xC03E, 0x00000000, 0x00000000 */
  29 };
  30
  31
  32 long long int
  33 __llrintl (long double x)
  34 {
  35   int32_t se,j0;
  36   u_int32_t i0, i1;
  37   long long int result;
  38   volatile long double w;
  39   long double t;
  40   int sx;
  41
  42   GET_LDOUBLE_WORDS (se, i0, i1, x);
  43
  44   sx = (se >> 15) & 1;
  45   j0 = (se & 0x7fff) - 0x3fff;
  46
  47   if (j0 < (int32_t) (8 * sizeof (long long int)) - 1)
  48     {
  49       if (j0 >= 63)
  50         result = (((long long int) i0 << 32) | i1) << (j0 - 63);
  51       else
  52         {
  53           w = two63[sx] + x;
  54           t = w - two63[sx];
  55           GET_LDOUBLE_WORDS (se, i0, i1, t);
  56           j0 = (se & 0x7fff) - 0x3fff;
  57
  58           if (j0 < 0)
  59             result = 0;
  60           else if (j0 <= 31)
  61             result = i0 >> (31 - j0);
  62           else
  63             result = ((long long int) i0 << (j0 - 31)) | (i1 >> (63 - j0));
  64         }
  65     }
  66   else
  67     {
  68       /* The number is too large.  It is left implementation defined
  69          what happens.  */
  70       return (long long int) x;
  71     }
  72
  73   return sx ? -result : result;
  74 }
  75
  76 weak_alias (__llrintl, llrintl)