modernc.org/cc@v1.0.1/v2/headers/linux_amd64/usr/include/bits/huge_vall.h (about)

     1  /* `HUGE_VALL' constant for ix86 (where it is infinity).
     2     Used by <stdlib.h> and <math.h> functions for overflow.
     3     Copyright (C) 1992-2015 Free Software Foundation, Inc.
     4     This file is part of the GNU C Library.
     5  
     6     The GNU C Library is free software; you can redistribute it and/or
     7     modify it under the terms of the GNU Lesser General Public
     8     License as published by the Free Software Foundation; either
     9     version 2.1 of the License, or (at your option) any later version.
    10  
    11     The GNU C Library is distributed in the hope that it will be useful,
    12     but WITHOUT ANY WARRANTY; without even the implied warranty of
    13     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    14     Lesser General Public License for more details.
    15  
    16     You should have received a copy of the GNU Lesser General Public
    17     License along with the GNU C Library; if not, see
    18     <http://www.gnu.org/licenses/>.  */
    19  
    20  #ifndef _MATH_H
    21  # error "Never use <bits/huge_vall.h> directly; include <math.h> instead."
    22  #endif
    23  
    24  #if __GNUC_PREREQ(3,3)
    25  # define HUGE_VALL	(__builtin_huge_vall())
    26  #elif __GNUC_PREREQ(2,96)
    27  # define HUGE_VALL	(__extension__ 0x1.0p32767L)
    28  #else
    29  
    30  # define __HUGE_VALL_bytes	{ 0, 0, 0, 0, 0, 0, 0, 0x80, 0xff, 0x7f, 0, 0 }
    31  
    32  # define __huge_vall_t	union { unsigned char __c[12]; long double __ld; }
    33  # ifdef __GNUC__
    34  #  define HUGE_VALL	(__extension__ \
    35  			 ((__huge_vall_t) { __c: __HUGE_VALL_bytes }).__ld)
    36  # else				/* Not GCC.  */
    37  static __huge_vall_t __huge_vall = { __HUGE_VALL_bytes };
    38  
    39  #  define HUGE_VALL	(__huge_vall.__ld)
    40  #  endif			/* GCC.  */
    41  
    42  #endif				/* GCC 2.95 */