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28f540f4 | 1 | /* `NAN' constant for IEEE 754 machines. |
bfff8b1b | 2 | Copyright (C) 1992-2017 Free Software Foundation, Inc. |
54d79e99 UD |
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 | |
41bdb6e2 AJ |
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. | |
54d79e99 UD |
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 | |
41bdb6e2 | 13 | Lesser General Public License for more details. |
54d79e99 | 14 | |
41bdb6e2 | 15 | You should have received a copy of the GNU Lesser General Public |
59ba27a6 PE |
16 | License along with the GNU C Library; if not, see |
17 | <http://www.gnu.org/licenses/>. */ | |
28f540f4 | 18 | |
5107cf1d UD |
19 | #ifndef _MATH_H |
20 | # error "Never use <bits/nan.h> directly; include <math.h> instead." | |
21 | #endif | |
28f540f4 | 22 | |
28f540f4 RM |
23 | |
24 | /* IEEE Not A Number. */ | |
25 | ||
a86573f4 RH |
26 | #if __GNUC_PREREQ(3,3) |
27 | ||
943db9eb | 28 | # define NAN (__builtin_nanf ("")) |
a86573f4 | 29 | |
943db9eb | 30 | #elif defined __GNUC__ |
f671aeab | 31 | |
fe0ec73e | 32 | # define NAN \ |
943db9eb UD |
33 | (__extension__ \ |
34 | ((union { unsigned __l __attribute__ ((__mode__ (__SI__))); float __d; }) \ | |
e150fddc | 35 | { __l: 0x7fc00000UL }).__d) |
f671aeab UD |
36 | |
37 | #else | |
38 | ||
5107cf1d | 39 | # include <endian.h> |
28f540f4 | 40 | |
5107cf1d | 41 | # if __BYTE_ORDER == __BIG_ENDIAN |
67e971f1 | 42 | # define __qnan_bytes { 0x7f, 0xc0, 0, 0 } |
5107cf1d UD |
43 | # endif |
44 | # if __BYTE_ORDER == __LITTLE_ENDIAN | |
67e971f1 | 45 | # define __qnan_bytes { 0, 0, 0xc0, 0x7f } |
5107cf1d | 46 | # endif |
28f540f4 | 47 | |
67e971f1 TS |
48 | static union { unsigned char __c[4]; float __d; } __qnan_union |
49 | __attribute__ ((__unused__)) = { __qnan_bytes }; | |
50 | # define NAN (__qnan_union.__d) | |
f671aeab | 51 | |
28f540f4 | 52 | #endif /* GCC. */ |