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glibc  2.9
huge_vall.h
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00001 /* `HUGE_VALL' constant for IEEE 754 machines (where it is infinity).
00002    Used by <stdlib.h> and <math.h> functions for overflow.
00003    Copyright (C) 1992, 1995, 1996, 1997, 1999, 2000, 2004
00004    Free Software Foundation, Inc.
00005    This file is part of the GNU C Library.
00006 
00007    The GNU C Library is free software; you can redistribute it and/or
00008    modify it under the terms of the GNU Lesser General Public
00009    License as published by the Free Software Foundation; either
00010    version 2.1 of the License, or (at your option) any later version.
00011 
00012    The GNU C Library is distributed in the hope that it will be useful,
00013    but WITHOUT ANY WARRANTY; without even the implied warranty of
00014    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00015    Lesser General Public License for more details.
00016 
00017    You should have received a copy of the GNU Lesser General Public
00018    License along with the GNU C Library; if not, write to the Free
00019    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
00020    02111-1307 USA.  */
00021 
00022 #ifndef _MATH_H
00023 # error "Never use <bits/huge_vall.h> directly; include <math.h> instead."
00024 #endif
00025 
00026 #if __GNUC_PREREQ(3,3)
00027 # define HUGE_VALL   (__builtin_huge_vall())
00028 #else
00029 # include <bits/wordsize.h>
00030 # if __WORDSIZE == 32
00031 #  define HUGE_VALL  ((long double) HUGE_VAL)
00032 # elif __GNUC_PREREQ(2,96)
00033 #   define HUGE_VALL (__extension__ 0x1.0p32767L)
00034 # elif defined __GNUC__
00035 
00036 #   define HUGE_VALL \
00037   (__extension__                                                \
00038    ((union { struct { unsigned long __h, __l; } __i; long double __d; }) \
00039     { __i: { __h: 0x7fff000000000000UL, __l: 0 } }).__d)
00040 
00041 # else /* not GCC */
00042 
00043 typedef union { unsigned char __c[16]; long double __d; } __huge_vall_t;
00044 #  define __HUGE_VALL_bytes { 0x7f, 0xff, 0,0,0,0,0,0,0,0,0,0,0,0,0,0 }
00045 static __huge_vall_t __huge_vall = { __HUGE_VALL_bytes };
00046 #  define HUGE_VALL  (__huge_vall.__d)
00047 
00048 # endif /* GCC.  */
00049 #endif /* GCC 3.3.  */