1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
|
/*
* nut_float.h - Network UPS Tools include files for floating point routines
* and ways to compare if non-integers are close enough to assume equal
*
* Copyright (C) 2020 Jim Klimov <jimklimov@gmail.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#ifndef NUT_FLOAT_H_SEEN
#define NUT_FLOAT_H_SEEN 1
/* "config.h" is generated by autotools and lacks a header guard, so
* we use an unambiguously named macro we know we must have, as one.
* It must be the first header: be sure to know all about system config.
*/
#ifndef NUT_NETVERSION
# include "config.h"
#endif
#if defined HAVE_FLOAT_H
# include <float.h>
#endif
#if defined HAVE_MATH_H
# include <math.h>
#endif
/* Modern compilers frown upon direct comparisons of floating point numbers
* since their imprecise internal representations can misfire, and really we
* care if they are indiscernably close. To aviod warnings like -Wfloat-equal
* we prefer to compare with methods defined below. Note: despite the "floating"
* name, fabs() seems to be defined over doubles or wider types, e.g.:
* double fabs(double x);
* float fabsf(float x);
* long double fabsl(long double x);
* To be on the safer side, we compare the difference to be smaller or equal to
* the Epsilon for the respective numeric type, in order to be equivalent to a
* zero for our needs. Various libs define it as "the next representable number
* after 1.0 which is not equal to 1.0" for the discrete maths involved; no talk
* about exactly comparing it to zero or whether it is the smallest representable
* non-zero value...
*/
#define f_equal(x, y) ( fabsf((float)(x) - (float)(y)) <= FLT_EPSILON )
#define d_equal(x, y) ( fabs((double)(x) - (double)(y)) <= DBL_EPSILON )
#define ld_equal(x, y) ( fabsl((long double)(x) - (long double)(y)) <= LDBL_EPSILON )
#ifndef HAVE_STRTOF
/* Use fallback from libcommon */
float strtof(const char *nptr, char **endptr);
#endif
#endif /* NUT_FLOAT_H_SEEN */
|
