niceSOFT/mpfr | Gitverse

src/cmp_ld.c
55 строк2 KB
Vincent Lefèvre
03 янв 2018, 13:53
03 янв 2018, 13:532fce388
/* mpfr_cmp_d -- compare a floating-point number with a long double

Copyright 2004, 2006-2018 Free Software Foundation, Inc.
Contributed by the AriC and Caramba projects, INRIA.

This file is part of the GNU MPFR Library.

The GNU MPFR Library is free software; you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 3 of the License, or (at your
option) any later version.

The GNU MPFR Library is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
License for more details.

You should have received a copy of the GNU Lesser General Public License
along with the GNU MPFR Library; see the file COPYING.LESSER.  If not, see
http://www.gnu.org/licenses/ or write to the Free Software Foundation, Inc.,
51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. */

#include <float.h> /* needed so that MPFR_LDBL_MANT_DIG is correctly defined */

#include "mpfr-impl.h"

int
mpfr_cmp_ld (mpfr_srcptr b, long double d)
{
  mpfr_t tmp;
  int res;
  MPFR_SAVE_EXPO_DECL (expo);

  MPFR_SAVE_EXPO_MARK (expo);

  mpfr_init2 (tmp, MPFR_LDBL_MANT_DIG);
  res = mpfr_set_ld (tmp, d, MPFR_RNDN);
  if (res != 0) /* can happen when "long double" is double-double */
    {
      /* since the smallest value is 2^(-1074) and the largest is
         < 2^1024, every double-double is exactly representable with
         1024 + 1074 bits */
      mpfr_set_prec (tmp, 1024 + 1074);
      res = mpfr_set_ld (tmp, d, MPFR_RNDN);
    }
  MPFR_ASSERTD (res == 0);

  MPFR_CLEAR_FLAGS ();
  res = mpfr_cmp (b, tmp);
  MPFR_SAVE_EXPO_UPDATE_FLAGS (expo, __gmpfr_flags);

  mpfr_clear (tmp);
  MPFR_SAVE_EXPO_FREE (expo);
  return res;
}