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
|
/* `NAN' constant for IEEE 754 machines.
Copyright (C) 1992, 1996, 1997, 1999, 2002, 2004
Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C 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 2.1 of the License, or (at your option) any later version.
The GNU C 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 C Library. If not, see
<http://www.gnu.org/licenses/>. */
#ifndef _MATH_H
# error "Never use <bits/nan.h> directly; include <math.h> instead."
#endif
/* IEEE Not A Number (QNaN). Note that MIPS has the QNaN and SNaN patterns
reversed compared to most other architectures. The IEEE spec left
the definition of this open to implementations, and for MIPS the top
bit of the mantissa must be SET to indicate a SNaN. */
#if __GNUC_PREREQ(3,3)
# define NAN (__builtin_nanf(""))
#elif defined __GNUC__
# define NAN \
(__extension__ \
((union { unsigned __l __attribute__((__mode__(__SI__))); float __d; }) \
{ __l: 0x7fbfffffUL }).__d)
#else
# include <endian.h>
# if __BYTE_ORDER == __BIG_ENDIAN
# define __nan_bytes { 0x7f, 0xbf, 0xff, 0xff }
# endif
# if __BYTE_ORDER == __LITTLE_ENDIAN
# define __nan_bytes { 0xff, 0xff, 0xbf, 0x7f }
# endif
static union { unsigned char __c[4]; float __d; } __nan_union = { __nan_bytes };
# define NAN (__nan_union.__d)
#endif /* GCC. */
|
