sysdeps/ieee754/ldbl-128/s_llrintl.c

   1 /* Round argument to nearest integral value according to current rounding
   2    direction.
   3    Copyright (C) 1997, 1999, 2006 Free Software Foundation, Inc.
   4    This file is part of the GNU C Library.
   5    Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997 and
   6                   Jakub Jelinek <jj@ultra.linux.cz>, 1999.
   7
   8    The GNU C Library is free software; you can redistribute it and/or
   9    modify it under the terms of the GNU Lesser General Public
  10    License as published by the Free Software Foundation; either
  11    version 2.1 of the License, or (at your option) any later version.
  12
  13    The GNU C Library is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16    Lesser General Public License for more details.
  17
  18    You should have received a copy of the GNU Lesser General Public
  19    License along with the GNU C Library; if not, write to the Free
  20    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  21    02111-1307 USA.  */
  22
  23 #include <math.h>
  24
  25 #include "math_private.h"
  26
  27 static const long double two112[2] =
  28 {
  29   5.19229685853482762853049632922009600E+33L, /* 0x406F000000000000, 0 */
  30  -5.19229685853482762853049632922009600E+33L  /* 0xC06F000000000000, 0 */
  31 };
  32
  33 long long int
  34 __llrintl (long double x)
  35 {
  36   int32_t j0;
  37   u_int64_t i0,i1;
  38   volatile long double w;
  39   long double t;
  40   long long int result;
  41   int sx;
  42
  43   GET_LDOUBLE_WORDS64 (i0, i1, x);
  44   j0 = ((i0 >> 48) & 0x7fff) - 0x3fff;
  45   sx = i0 >> 63;
  46   i0 &= 0x0000ffffffffffffLL;
  47   i0 |= 0x0001000000000000LL;
  48
  49   if (j0 < (int32_t) (8 * sizeof (long long int)) - 1)
  50     {
  51       w = two112[sx] + x;
  52       t = w - two112[sx];
  53       GET_LDOUBLE_WORDS64 (i0, i1, t);
  54       j0 = ((i0 >> 48) & 0x7fff) - 0x3fff;
  55       i0 &= 0x0000ffffffffffffLL;
  56       i0 |= 0x0001000000000000LL;
  57
  58       if (j0 < 0)
  59         result = 0;
  60       else if (j0 <= 48)
  61         result = i0 >> (48 - j0);
  62       else
  63         result = ((long long int) i0 << (j0 - 48)) | (i1 >> (112 - j0));
  64     }
  65   else
  66     {
  67       /* The number is too large.  It is left implementation defined
  68          what happens.  */
  69       return (long long int) x;
  70     }
  71
  72   return sx ? -result : result;
  73 }
  74
  75 weak_alias (__llrintl, llrintl)