1/* mpfr_d_sub -- subtract a multiple precision floating-point number
2                 from a machine double precision float
3
4Copyright 2007-2023 Free Software Foundation, Inc.
5Contributed by the AriC and Caramba projects, INRIA.
6
7This file is part of the GNU MPFR Library.
8
9The GNU MPFR Library is free software; you can redistribute it and/or modify
10it under the terms of the GNU Lesser General Public License as published by
11the Free Software Foundation; either version 3 of the License, or (at your
12option) any later version.
13
14The GNU MPFR Library is distributed in the hope that it will be useful, but
15WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
16or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
17License for more details.
18
19You should have received a copy of the GNU Lesser General Public License
20along with the GNU MPFR Library; see the file COPYING.LESSER.  If not, see
21https://www.gnu.org/licenses/ or write to the Free Software Foundation, Inc.,
2251 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. */
23
24#include "mpfr-impl.h"
25
26int
27mpfr_d_sub (mpfr_ptr a, double b, mpfr_srcptr c, mpfr_rnd_t rnd_mode)
28{
29  int inexact;
30  mpfr_t d;
31  mp_limb_t tmp_man[MPFR_LIMBS_PER_DOUBLE];
32  MPFR_SAVE_EXPO_DECL (expo);
33
34  MPFR_LOG_FUNC (
35    ("b=%.20g c[%Pu]=%.*Rg rnd=%d", b, mpfr_get_prec (c), mpfr_log_prec, c, rnd_mode),
36    ("a[%Pu]=%.*Rg", mpfr_get_prec (a), mpfr_log_prec, a));
37
38  MPFR_SAVE_EXPO_MARK (expo);
39
40  MPFR_TMP_INIT1(tmp_man, d, IEEE_DBL_MANT_DIG);
41  inexact = mpfr_set_d (d, b, rnd_mode);
42  MPFR_ASSERTD (inexact == 0);
43
44  MPFR_CLEAR_FLAGS ();
45  inexact = mpfr_sub (a, d, c, rnd_mode);
46  MPFR_SAVE_EXPO_UPDATE_FLAGS (expo, __gmpfr_flags);
47
48  MPFR_SAVE_EXPO_FREE (expo);
49  return mpfr_check_range (a, inexact, rnd_mode);
50}
51