sysdeps/libm-ieee754/s_lroundf.c

   1 /* Round float value to long int.
   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 Library General Public License as
   8    published by the Free Software Foundation; either version 2 of the
   9    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    Library General Public License for more details.
  15
  16    You should have received a copy of the GNU Library General Public
  17    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  18    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  19    Boston, MA 02111-1307, USA.  */
  20
  21 #include <math.h>
  22
  23 #include "math_private.h"
  24
  25
  26 long int
  27 __lroundf (float x)
  28 {
  29   int32_t j0;
  30   u_int32_t i;
  31   long int result;
  32   int sign;
  33
  34   GET_FLOAT_WORD (i, x);
  35   j0 = ((i >> 23) & 0xff) - 0x7f;
  36   sign = (i & 0x80000000) != 0 ? -1 : 1;
  37   i &= 0x7fffff;
  38   i |= 0x800000;
  39
  40   if (j0 < (int32_t) (8 * sizeof (long int)))
  41     {
  42       if (j0 < 0)
  43         return j0 < -1 ? 0 : sign;
  44       else if (j0 >= 23)
  45         result = (long int) i << (j0 - 23);
  46       else
  47         {
  48           i += 0x400000 >> j0;
  49
  50           result = i >> (23 - j0);
  51         }
  52     }
  53   else
  54     {
  55       /* The number is too large.  It is left implementation defined
  56          what happens.  */
  57       return (long int) x;
  58     }
  59
  60   return sign * result;
  61 }
  62
  63 weak_alias (__lroundf, lroundf)