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, write to the Free
  19    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  20    02111-1307 USA.  */
  21
  22 #include <math.h>
  23
  24 #include "math_private.h"
  25
  26 static const long double two63[2] =
  27 {
  28   9.223372036854775808000000e+18, /* 0x403E, 0x00000000, 0x00000000 */
  29  -9.223372036854775808000000e+18  /* 0xC03E, 0x00000000, 0x00000000 */
  30 };
  31
  32
  33 long long int
  34 __llrintl (long double x)
  35 {
  36   int32_t se,j0;
  37   u_int32_t i0, i1;
  38   long long int result;
  39   volatile long double w;
  40   long double t;
  41   int sx;
  42
  43   GET_LDOUBLE_WORDS (se, i0, i1, x);
  44
  45   sx = (se >> 15) & 1;
  46   j0 = (se & 0x7fff) - 0x3fff;
  47
  48   if (j0 < (int32_t) (8 * sizeof (long long int)) - 1)
  49     {
  50       if (j0 >= 63)
  51         result = (((long long int) i0 << 32) | i1) << (j0 - 63);
  52       else
  53         {
  54           w = two63[sx] + x;
  55           t = w - two63[sx];
  56           GET_LDOUBLE_WORDS (se, i0, i1, t);
  57           j0 = (se & 0x7fff) - 0x3fff;
  58
  59           if (j0 < 0)
  60             result = 0;
  61           else if (j0 <= 31)
  62             result = i0 >> (31 - j0);
  63           else
  64             result = ((long long int) i0 << (j0 - 31)) | (i1 >> (63 - j0));
  65         }
  66     }
  67   else
  68     {
  69       /* The number is too large.  It is left implementation defined
  70          what happens.  */
  71       return (long long int) x;
  72     }
  73
  74   return sx ? -result : result;
  75 }
  76
  77 weak_alias (__llrintl, llrintl)