sysdeps/ieee754/flt-32/s_llroundf.c

   1 /* Round float value to long long int.
   2    Copyright (C) 1997-2018 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 <fenv_private.h>
  26 #include <libm-alias-float.h>
  27 #include <fix-fp-int-convert-overflow.h>
  28
  29
  30 long long int
  31 __llroundf (float x)
  32 {
  33   int32_t j0;
  34   uint32_t i;
  35   long long int result;
  36   int sign;
  37
  38   GET_FLOAT_WORD (i, x);
  39   j0 = ((i >> 23) & 0xff) - 0x7f;
  40   sign = (i & 0x80000000) != 0 ? -1 : 1;
  41   i &= 0x7fffff;
  42   i |= 0x800000;
  43
  44   if (j0 < (int32_t) (8 * sizeof (long long int)) - 1)
  45     {
  46       if (j0 < 0)
  47         return j0 < -1 ? 0 : sign;
  48       else if (j0 >= 23)
  49         result = (long long int) i << (j0 - 23);
  50       else
  51         {
  52           i += 0x400000 >> j0;
  53
  54           result = i >> (23 - j0);
  55         }
  56     }
  57   else
  58     {
  59 #ifdef FE_INVALID
  60       /* The number is too large.  Unless it rounds to LLONG_MIN,
  61          FE_INVALID must be raised and the return value is
  62          unspecified.  */
  63       if (FIX_FLT_LLONG_CONVERT_OVERFLOW && x != (float) LLONG_MIN)
  64         {
  65           feraiseexcept (FE_INVALID);
  66           return sign == 1 ? LLONG_MAX : LLONG_MIN;
  67         }
  68 #endif
  69       return (long long int) x;
  70     }
  71
  72   return sign * result;
  73 }
  74
  75 libm_alias_float (__llround, llround)