1*53ee8cc1Swenshuai.xi /* `NAN' constant for IEEE 754 machines. 2*53ee8cc1Swenshuai.xi Copyright (C) 1992, 1996, 1997, 1999, 2002, 2004 3*53ee8cc1Swenshuai.xi Free Software Foundation, Inc. 4*53ee8cc1Swenshuai.xi This file is part of the GNU C Library. 5*53ee8cc1Swenshuai.xi 6*53ee8cc1Swenshuai.xi The GNU C Library is free software; you can redistribute it and/or 7*53ee8cc1Swenshuai.xi modify it under the terms of the GNU Lesser General Public 8*53ee8cc1Swenshuai.xi License as published by the Free Software Foundation; either 9*53ee8cc1Swenshuai.xi version 2.1 of the License, or (at your option) any later version. 10*53ee8cc1Swenshuai.xi 11*53ee8cc1Swenshuai.xi The GNU C Library is distributed in the hope that it will be useful, 12*53ee8cc1Swenshuai.xi but WITHOUT ANY WARRANTY; without even the implied warranty of 13*53ee8cc1Swenshuai.xi MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 14*53ee8cc1Swenshuai.xi Lesser General Public License for more details. 15*53ee8cc1Swenshuai.xi 16*53ee8cc1Swenshuai.xi You should have received a copy of the GNU Lesser General Public 17*53ee8cc1Swenshuai.xi License along with the GNU C Library; if not, write to the Free 18*53ee8cc1Swenshuai.xi Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 19*53ee8cc1Swenshuai.xi 02111-1307 USA. */ 20*53ee8cc1Swenshuai.xi 21*53ee8cc1Swenshuai.xi #ifndef _MATH_H 22*53ee8cc1Swenshuai.xi # error "Never use <bits/nan.h> directly; include <math.h> instead." 23*53ee8cc1Swenshuai.xi #endif 24*53ee8cc1Swenshuai.xi 25*53ee8cc1Swenshuai.xi 26*53ee8cc1Swenshuai.xi /* IEEE Not A Number (QNaN). Note that MIPS has the QNaN and SNaN patterns 27*53ee8cc1Swenshuai.xi reversed compared to most other architectures. The IEEE spec left 28*53ee8cc1Swenshuai.xi the definition of this open to implementations, and for MIPS the top 29*53ee8cc1Swenshuai.xi bit of the mantissa must be SET to indicate a SNaN. */ 30*53ee8cc1Swenshuai.xi 31*53ee8cc1Swenshuai.xi #if __GNUC_PREREQ(3,3) 32*53ee8cc1Swenshuai.xi 33*53ee8cc1Swenshuai.xi # define NAN (__builtin_nanf("")) 34*53ee8cc1Swenshuai.xi 35*53ee8cc1Swenshuai.xi #elif defined __GNUC__ 36*53ee8cc1Swenshuai.xi 37*53ee8cc1Swenshuai.xi # define NAN \ 38*53ee8cc1Swenshuai.xi (__extension__ \ 39*53ee8cc1Swenshuai.xi ((union { unsigned __l __attribute__((__mode__(__SI__))); float __d; }) \ 40*53ee8cc1Swenshuai.xi { __l: 0x7fbfffffUL }).__d) 41*53ee8cc1Swenshuai.xi 42*53ee8cc1Swenshuai.xi #else 43*53ee8cc1Swenshuai.xi 44*53ee8cc1Swenshuai.xi # include <endian.h> 45*53ee8cc1Swenshuai.xi 46*53ee8cc1Swenshuai.xi # if __BYTE_ORDER == __BIG_ENDIAN 47*53ee8cc1Swenshuai.xi # define __nan_bytes { 0x7f, 0xbf, 0xff, 0xff } 48*53ee8cc1Swenshuai.xi # endif 49*53ee8cc1Swenshuai.xi # if __BYTE_ORDER == __LITTLE_ENDIAN 50*53ee8cc1Swenshuai.xi # define __nan_bytes { 0xff, 0xff, 0xbf, 0x7f } 51*53ee8cc1Swenshuai.xi # endif 52*53ee8cc1Swenshuai.xi 53*53ee8cc1Swenshuai.xi static union { unsigned char __c[4]; float __d; } __nan_union = { __nan_bytes }; 54*53ee8cc1Swenshuai.xi # define NAN (__nan_union.__d) 55*53ee8cc1Swenshuai.xi 56*53ee8cc1Swenshuai.xi #endif /* GCC. */ 57