sysdeps/ieee754/ldbl-128/s_roundl.c

   1 /* Round long double to integer away from zero.
   2    Copyright (C) 1997-2018 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 #include <libm-alias-ldouble.h>
  25
  26
  27 _Float128
  28 __roundl (_Float128 x)
  29 {
  30   int32_t j0;
  31   uint64_t i1, i0;
  32
  33   GET_LDOUBLE_WORDS64 (i0, i1, x);
  34   j0 = ((i0 >> 48) & 0x7fff) - 0x3fff;
  35   if (j0 < 48)
  36     {
  37       if (j0 < 0)
  38         {
  39           i0 &= 0x8000000000000000ULL;
  40           if (j0 == -1)
  41             i0 |= 0x3fff000000000000LL;
  42           i1 = 0;
  43         }
  44       else
  45         {
  46           uint64_t i = 0x0000ffffffffffffLL >> j0;
  47           if (((i0 & i) | i1) == 0)
  48             /* X is integral.  */
  49             return x;
  50
  51           i0 += 0x0000800000000000LL >> j0;
  52           i0 &= ~i;
  53           i1 = 0;
  54         }
  55     }
  56   else if (j0 > 111)
  57     {
  58       if (j0 == 0x4000)
  59         /* Inf or NaN.  */
  60         return x + x;
  61       else
  62         return x;
  63     }
  64   else
  65     {
  66       uint64_t i = -1ULL >> (j0 - 48);
  67       if ((i1 & i) == 0)
  68         /* X is integral.  */
  69         return x;
  70
  71       uint64_t j = i1 + (1LL << (111 - j0));
  72       if (j < i1)
  73         i0 += 1;
  74       i1 = j;
  75       i1 &= ~i;
  76     }
  77
  78   SET_LDOUBLE_WORDS64 (x, i0, i1);
  79   return x;
  80 }
  81 libm_alias_ldouble (__round, round)