sysdeps/ieee754/flt-32/s_llroundf.c

   1 /* Round float value to long 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 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, see
  18    <http://www.gnu.org/licenses/>.  */
  19
  20 #include <math.h>
  21
  22 #include <math_private.h>
  23
  24
  25 long long int
  26 __llroundf (float x)
  27 {
  28   int32_t j0;
  29   u_int32_t i;
  30   long long int result;
  31   int sign;
  32
  33   GET_FLOAT_WORD (i, x);
  34   j0 = ((i >> 23) & 0xff) - 0x7f;
  35   sign = (i & 0x80000000) != 0 ? -1 : 1;
  36   i &= 0x7fffff;
  37   i |= 0x800000;
  38
  39   if (j0 < (int32_t) (8 * sizeof (long long int)) - 1)
  40     {
  41       if (j0 < 0)
  42         return j0 < -1 ? 0 : sign;
  43       else if (j0 >= 23)
  44         result = (long long int) i << (j0 - 23);
  45       else
  46         {
  47           i += 0x400000 >> j0;
  48
  49           result = i >> (23 - j0);
  50         }
  51     }
  52   else
  53     {
  54       /* The number is too large.  It is left implementation defined
  55          what happens.  */
  56       return (long long int) x;
  57     }
  58
  59   return sign * result;
  60 }
  61
  62 weak_alias (__llroundf, llroundf)