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, write to the Free 17 Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 18 02111-1307 USA. */ 19 20 #ifndef _MATH_H 21 # error "Never use <bits/nan.h> directly; include <math.h> instead." 22 #endif 23 24 25 /* IEEE Not A Number. */ 26 27 #if __GNUC_PREREQ(3,3) 28 29 # define NAN (__builtin_nanf ("")) 30 31 #elif defined __GNUC__ 32 33 # define NAN \ 34 (__extension__ \ 35 ((union { unsigned __l __attribute__ ((__mode__ (__SI__))); float __d; }) \ 36 { __l: 0x7fc00000UL }).__d) 37 38 #else 39 40 # include <endian.h> 41 42 # if __BYTE_ORDER == __BIG_ENDIAN 43 # define __nan_bytes { 0x7f, 0xc0, 0, 0 } 44 # endif 45 # if __BYTE_ORDER == __LITTLE_ENDIAN 46 # define __nan_bytes { 0, 0, 0xc0, 0x7f } 47 # endif 48 49 static union { unsigned char __c[4]; float __d; } __nan_union 50 __attribute_used__ = { __nan_bytes }; 51 # define NAN (__nan_union.__d) 52 53 #endif /* GCC. */ 54
