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      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