sysdeps/ieee754/ldbl-128/s_lrintl.c

   1 /* Round argument to nearest integral value according to current rounding
   2    direction.
   3    Copyright (C) 1997-2015 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, see
  20    <http://www.gnu.org/licenses/>.  */
  21
  22 #include <math.h>
  23
  24 #include <math_private.h>
  25
  26 static const long double two112[2] =
  27 {
  28   5.19229685853482762853049632922009600E+33L, /* 0x406F000000000000, 0 */
  29  -5.19229685853482762853049632922009600E+33L  /* 0xC06F000000000000, 0 */
  30 };
  31
  32 long int
  33 __lrintl (long double x)
  34 {
  35   int32_t j0;
  36   u_int64_t i0,i1;
  37   volatile long double w;
  38   long double t;
  39   long int result;
  40   int sx;
  41
  42   GET_LDOUBLE_WORDS64 (i0, i1, x);
  43   j0 = ((i0 >> 48) & 0x7fff) - 0x3fff;
  44   sx = i0 >> 63;
  45   i0 &= 0x0000ffffffffffffLL;
  46   i0 |= 0x0001000000000000LL;
  47
  48   if (j0 < 48)
  49     {
  50       w = two112[sx] + x;
  51       t = w - two112[sx];
  52       GET_LDOUBLE_WORDS64 (i0, i1, t);
  53       j0 = ((i0 >> 48) & 0x7fff) - 0x3fff;
  54       i0 &= 0x0000ffffffffffffLL;
  55       i0 |= 0x0001000000000000LL;
  56
  57       result = (j0 < 0 ? 0 : i0 >> (48 - j0));
  58     }
  59   else if (j0 < (int32_t) (8 * sizeof (long int)) - 1)
  60     {
  61       if (j0 >= 112)
  62         result = ((long int) i0 << (j0 - 48)) | (i1 << (j0 - 112));
  63       else
  64         {
  65           w = two112[sx] + x;
  66           t = w - two112[sx];
  67           GET_LDOUBLE_WORDS64 (i0, i1, t);
  68           j0 = ((i0 >> 48) & 0x7fff) - 0x3fff;
  69           i0 &= 0x0000ffffffffffffLL;
  70           i0 |= 0x0001000000000000LL;
  71
  72           if (j0 == 48)
  73             result = (long int) i0;
  74           else
  75             result = ((long int) i0 << (j0 - 48)) | (i1 >> (112 - j0));
  76         }
  77     }
  78   else
  79     {
  80       /* The number is too large.  It is left implementation defined
  81          what happens.  */
  82       return (long int) x;
  83     }
  84
  85   return sx ? -result : result;
  86 }
  87
  88 weak_alias (__lrintl, lrintl)