sysdeps/ieee754/flt-32/s_llroundf.c

   1 /* Round float value to long long int.
   2    Copyright (C) 1997-2016 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 <fenv.h>
  21 #include <limits.h>
  22 #include <math.h>
  23
  24 #include <math_private.h>
  25 #include <fix-fp-int-convert-overflow.h>
  26
  27
  28 long long int
  29 __llroundf (float x)
  30 {
  31   int32_t j0;
  32   u_int32_t i;
  33   long long int result;
  34   int sign;
  35
  36   GET_FLOAT_WORD (i, x);
  37   j0 = ((i >> 23) & 0xff) - 0x7f;
  38   sign = (i & 0x80000000) != 0 ? -1 : 1;
  39   i &= 0x7fffff;
  40   i |= 0x800000;
  41
  42   if (j0 < (int32_t) (8 * sizeof (long long int)) - 1)
  43     {
  44       if (j0 < 0)
  45         return j0 < -1 ? 0 : sign;
  46       else if (j0 >= 23)
  47         result = (long long int) i << (j0 - 23);
  48       else
  49         {
  50           i += 0x400000 >> j0;
  51
  52           result = i >> (23 - j0);
  53         }
  54     }
  55   else
  56     {
  57 #ifdef FE_INVALID
  58       /* The number is too large.  Unless it rounds to LLONG_MIN,
  59          FE_INVALID must be raised and the return value is
  60          unspecified.  */
  61       if (FIX_FLT_LLONG_CONVERT_OVERFLOW && x != (float) LLONG_MIN)
  62         {
  63           feraiseexcept (FE_INVALID);
  64           return sign == 1 ? LLONG_MAX : LLONG_MIN;
  65         }
  66 #endif
  67       return (long long int) x;
  68     }
  69
  70   return sign * result;
  71 }
  72
  73 weak_alias (__llroundf, llroundf)