/* `NAN' constant for IEEE 754 machines. Copyright (C) 1992,1996,1997,1999,2004,2006 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. */ #if __GNUC_PREREQ(3,3) # define NAN (__builtin_nanf ("")) #elif defined __GNUC__ # define NAN \ (__extension__ \ ((union { unsigned __l __attribute__ ((__mode__ (__SI__))); float __d; }) \ { __l: 0x7fc00000UL }).__d) #else # include <endian.h> # if __BYTE_ORDER == __BIG_ENDIAN # define __nan_bytes { 0x7f, 0xc0, 0, 0 } # endif # if __BYTE_ORDER == __LITTLE_ENDIAN # define __nan_bytes { 0, 0, 0xc0, 0x7f } # endif static union { unsigned char __c[4]; float __d; } __nan_union __attribute_used__ = { __nan_bytes }; # define NAN (__nan_union.__d) #endif /* GCC. */