sysdeps/ieee754/ldbl-128/s_roundl.c

   1 /* Round long double to integer away from zero.
   2    Copyright (C) 1997-2014 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997 and
   5                   Jakub Jelinek <jj@ultra.linux.cz>, 1999.
   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
  26 static const long double huge = 1.0E4930L;
  27
  28
  29 long double
  30 __roundl (long double x)
  31 {
  32   int32_t j0;
  33   u_int64_t i1, i0;
  34
  35   GET_LDOUBLE_WORDS64 (i0, i1, x);
  36   j0 = ((i0 >> 48) & 0x7fff) - 0x3fff;
  37   if (j0 < 31)
  38     {
  39       if (j0 < 0)
  40         {
  41           if (huge + x > 0.0)
  42             {
  43               i0 &= 0x8000000000000000ULL;
  44               if (j0 == -1)
  45                 i0 |= 0x3fff000000000000LL;
  46               i1 = 0;
  47             }
  48         }
  49       else
  50         {
  51           u_int64_t i = 0x0000ffffffffffffLL >> j0;
  52           if (((i0 & i) | i1) == 0)
  53             /* X is integral.  */
  54             return x;
  55           if (huge + x > 0.0)
  56             {
  57               /* Raise inexact if x != 0.  */
  58               i0 += 0x0000800000000000LL >> j0;
  59               i0 &= ~i;
  60               i1 = 0;
  61             }
  62         }
  63     }
  64   else if (j0 > 111)
  65     {
  66       if (j0 == 0x4000)
  67         /* Inf or NaN.  */
  68         return x + x;
  69       else
  70         return x;
  71     }
  72   else
  73     {
  74       u_int64_t i = -1ULL >> (j0 - 48);
  75       if ((i1 & i) == 0)
  76         /* X is integral.  */
  77         return x;
  78
  79       if (huge + x > 0.0)
  80         {
  81           /* Raise inexact if x != 0.  */
  82           u_int64_t j = i1 + (1LL << (111 - j0));
  83           if (j < i1)
  84             i0 += 1;
  85           i1 = j;
  86         }
  87       i1 &= ~i;
  88     }
  89
  90   SET_LDOUBLE_WORDS64 (x, i0, i1);
  91   return x;
  92 }
  93 weak_alias (__roundl, roundl)