xref: /netbsd-src/external/lgpl3/mpfr/dist/src/cmp_ld.c (revision 33881f779a77dce6440bdc44610d94de75bebefe)
1 /* mpfr_cmp_d -- compare a floating-point number with a long double
2 
3 Copyright 2004, 2006-2018 Free Software Foundation, Inc.
4 Contributed by the AriC and Caramba projects, INRIA.
5 
6 This file is part of the GNU MPFR Library.
7 
8 The GNU MPFR Library is free software; you can redistribute it and/or modify
9 it under the terms of the GNU Lesser General Public License as published by
10 the Free Software Foundation; either version 3 of the License, or (at your
11 option) any later version.
12 
13 The GNU MPFR Library is distributed in the hope that it will be useful, but
14 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
15 or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
16 License for more details.
17 
18 You should have received a copy of the GNU Lesser General Public License
19 along with the GNU MPFR Library; see the file COPYING.LESSER.  If not, see
20 http://www.gnu.org/licenses/ or write to the Free Software Foundation, Inc.,
21 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. */
22 
23 #include <float.h> /* needed so that MPFR_LDBL_MANT_DIG is correctly defined */
24 
25 #include "mpfr-impl.h"
26 
27 int
28 mpfr_cmp_ld (mpfr_srcptr b, long double d)
29 {
30   mpfr_t tmp;
31   int res;
32   MPFR_SAVE_EXPO_DECL (expo);
33 
34   MPFR_SAVE_EXPO_MARK (expo);
35 
36   mpfr_init2 (tmp, MPFR_LDBL_MANT_DIG);
37   res = mpfr_set_ld (tmp, d, MPFR_RNDN);
38   if (res != 0) /* can happen when "long double" is double-double */
39     {
40       /* since the smallest value is 2^(-1074) and the largest is
41          < 2^1024, every double-double is exactly representable with
42          1024 + 1074 bits */
43       mpfr_set_prec (tmp, 1024 + 1074);
44       res = mpfr_set_ld (tmp, d, MPFR_RNDN);
45     }
46   MPFR_ASSERTD (res == 0);
47 
48   MPFR_CLEAR_FLAGS ();
49   res = mpfr_cmp (b, tmp);
50   MPFR_SAVE_EXPO_UPDATE_FLAGS (expo, __gmpfr_flags);
51 
52   mpfr_clear (tmp);
53   MPFR_SAVE_EXPO_FREE (expo);
54   return res;
55 }
56