1 /* `HUGE_VAL' constant for IEEE 754 machines (where it is infinity).
2 Used by <stdlib.h> and <math.h> functions for overflow.
3 Copyright (C) 1992, 1995, 1996, 1997, 1999, 2000, 2004
4 Free Software Foundation, Inc.
5 This file is part of the GNU C Library.
6
7 The GNU C Library is free software; you can redistribute it and/or
8 modify it under the terms of the GNU Lesser General Public
9 License as published by the Free Software Foundation; either
10 version 2.1 of the License, or (at your option) any later version.
11
12 The GNU C Library is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 Lesser General Public License for more details.
16
17 You should have received a copy of the GNU Lesser General Public
18 License along with the GNU C Library; if not, write to the Free
19 Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
20 02111-1307 USA. */
21
22 #ifndef _MATH_H
23 # error "Never use <bits/huge_val.h> directly; include <math.h> instead."
24 #endif
25
26 /* IEEE positive infinity (-HUGE_VAL is negative infinity). */
27
28 #if __GNUC_PREREQ(3,3)
29 # define HUGE_VAL (__builtin_huge_val())
30 #elif __GNUC_PREREQ(2,96)
31 # define HUGE_VAL (__extension__ 0x1.0p2047)
32 #elif defined __GNUC__
33
34 # define HUGE_VAL \
35 (__extension__ \
36 ((union { unsigned __l __attribute__((__mode__(__DI__))); double __d; }) \
37 { __l: 0x7ff0000000000000ULL }).__d)
38
39 #else /* not GCC */
40
41 # include <endian.h>
42
43 typedef union { unsigned char __c[8]; double __d; } __huge_val_t;
44
45 # if __BYTE_ORDER == __BIG_ENDIAN
46 # define __HUGE_VAL_bytes { 0x7f, 0xf0, 0, 0, 0, 0, 0, 0 }
47 # endif
48 # if __BYTE_ORDER == __LITTLE_ENDIAN
49 # define __HUGE_VAL_bytes { 0, 0, 0, 0, 0, 0, 0xf0, 0x7f }
50 # endif
51
52 static __huge_val_t __huge_val = { __HUGE_VAL_bytes };
53 # define HUGE_VAL (__huge_val.__d)
54
55 #endif /* GCC. */
56