sysdeps/ieee754/flt-32/s_roundf.c

   1 /* Round float to integer away from zero.
   2    Copyright (C) 1997 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, write to the Free
  18    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19    02111-1307 USA.  */
  20
  21 #include <math.h>
  22
  23 #include "math_private.h"
  24
  25
  26 static const float huge = 1.0e30;
  27
  28
  29 float
  30 __roundf (float x)
  31 {
  32   int32_t i0, j0;
  33
  34   GET_FLOAT_WORD (i0, x);
  35   j0 = ((i0 >> 23) & 0xff) - 0x7f;
  36   if (j0 < 23)
  37     {
  38       if (j0 < 0)
  39         {
  40           if (huge + x > 0.0F)
  41             {
  42               i0 &= 0x80000000;
  43               if (j0 == -1)
  44                 i0 |= 0x3f800000;
  45             }
  46         }
  47       else
  48         {
  49           u_int32_t i = 0x007fffff >> j0;
  50           if ((i0 & i) == 0)
  51             /* X is integral.  */
  52             return x;
  53           if (huge + x > 0.0F)
  54             {
  55               /* Raise inexact if x != 0.  */
  56               i0 += 0x00400000 >> j0;
  57               i0 &= ~i;
  58             }
  59         }
  60     }
  61   else
  62     {
  63       if (j0 == 0x80)
  64         /* Inf or NaN.  */
  65         return x + x;
  66       else
  67         return x;
  68     }
  69
  70   SET_FLOAT_WORD (x, i0);
  71   return x;
  72 }
  73 weak_alias (__roundf, roundf)