sysdeps/arm/bits/huge_val.h

   1 /* `HUGE_VAL' constant for IEEE 754 machines (where it is infinity).
   2    Used by <stdlib.h> and <math.h> functions for overflow.
   3    ARM version.
   4    Copyright (C) 1992, 95, 96, 97, 98, 99, 2000, 2004
   5    Free Software Foundation, Inc.
   6    This file is part of the GNU C Library.
   7
   8    The GNU C Library is free software; you can redistribute it and/or
   9    modify it under the terms of the GNU Lesser General Public
  10    License as published by the Free Software Foundation; either
  11    version 2.1 of the License, or (at your option) any later version.
  12
  13    The GNU C Library is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16    Lesser General Public License for more details.
  17
  18    You should have received a copy of the GNU Lesser General Public
  19    License along with the GNU C Library; if not, write to the Free
  20    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  21    02111-1307 USA.  */
  22
  23 #ifndef _MATH_H
  24 # error "Never use <bits/huge_val.h> directly; include <math.h> instead."
  25 #endif
  26
  27 /* IEEE positive infinity (-HUGE_VAL is negative infinity).  */
  28
  29 #if __GNUC_PREREQ(3,3)
  30 # define HUGE_VAL  (__builtin_huge_val())
  31 #elif __GNUC_PREREQ(2,96)
  32 # define HUGE_VAL (__extension__ 0x1.0p2047)
  33 #elif defined __GNUC__
  34
  35 # define HUGE_VAL \
  36   (__extension__                                                              \
  37    ((union { unsigned __l __attribute__((__mode__(__DI__))); double __d; })   \
  38     { __l: 0x000000007ff00000ULL }).__d)
  39
  40 #else /* not GCC */
  41
  42 # include <endian.h>
  43
  44 typedef union { unsigned char __c[8]; double __d; } __huge_val_t;
  45
  46 # if __BYTE_ORDER == __BIG_ENDIAN
  47 #  define __HUGE_VAL_bytes      { 0, 0, 0, 0, 0x7f, 0xf0, 0, 0 }
  48 # endif
  49 # if __BYTE_ORDER == __LITTLE_ENDIAN
  50 #  define __HUGE_VAL_bytes      { 0, 0, 0xf0, 0x7f, 0, 0, 0, 0 }
  51 # endif
  52
  53 static __huge_val_t __huge_val = { __HUGE_VAL_bytes };
  54 # define HUGE_VAL       (__huge_val.__d)
  55
  56 #endif  /* GCC.  */