1/* `NAN' constant for IEEE 754 machines.
2   Copyright (C) 1992,1996,1997,1999,2004,2006 Free Software Foundation, Inc.
3   This file is part of the GNU C Library.
4
5   The GNU C Library is free software; you can redistribute it and/or
6   modify it under the terms of the GNU Lesser General Public
7   License as published by the Free Software Foundation; either
8   version 2.1 of the License, or (at your option) any later version.
9
10   The GNU C Library is distributed in the hope that it will be useful,
11   but WITHOUT ANY WARRANTY; without even the implied warranty of
12   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
13   Lesser General Public License for more details.
14
15   You should have received a copy of the GNU Lesser General Public
16   License along with the GNU C Library; if not, see
17   <http://www.gnu.org/licenses/>.  */
18
19#ifndef _MATH_H
20# error "Never use <bits/nan.h> directly; include <math.h> instead."
21#endif
22
23
24/* IEEE Not A Number.  */
25
26#if __GNUC_PREREQ(3,3)
27
28# define NAN	(__builtin_nanf (""))
29
30#elif defined __GNUC__
31
32# define NAN \
33  (__extension__							      \
34   ((union { unsigned __l __attribute__ ((__mode__ (__SI__))); float __d; })  \
35    { __l: 0x7fc00000UL }).__d)
36
37#else
38
39# include <endian.h>
40
41# if __BYTE_ORDER == __BIG_ENDIAN
42#  define __nan_bytes		{ 0x7f, 0xc0, 0, 0 }
43# endif
44# if __BYTE_ORDER == __LITTLE_ENDIAN
45#  define __nan_bytes		{ 0, 0, 0xc0, 0x7f }
46# endif
47
48static union { unsigned char __c[4]; float __d; } __nan_union
49    __attribute_used__ = { __nan_bytes };
50# define NAN	(__nan_union.__d)
51
52#endif	/* GCC.  */
53