sysdeps/ieee754/ldbl-128/s_roundl.c

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