sysdeps/ieee754/bits/huge_val.h

   1 /* `HUGE_VAL' constants 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 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, write to the Free
  18    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19    02111-1307 USA.  */
  20
  21 #ifndef _MATH_H
  22 # error "Never use <bits/huge_val.h> directly; include <math.h> instead."
  23 #endif
  24
  25 #include <features.h>
  26
  27 /* IEEE positive infinity (-HUGE_VAL is negative infinity).  */
  28
  29 #ifdef  __GNUC__
  30
  31 # if __GNUC_PREREQ(2,96)
  32
  33 #  define HUGE_VAL (__extension__ 0x1.0p2047)
  34
  35 # else
  36
  37 #  define HUGE_VAL \
  38   (__extension__                                                              \
  39    ((union { unsigned __l __attribute__((__mode__(__DI__))); double __d; })   \
  40     { __l: 0x7ff0000000000000ULL }).__d)
  41
  42 # endif
  43
  44 #else /* not GCC */
  45
  46 # include <endian.h>
  47
  48 typedef union { unsigned char __c[8]; double __d; } __huge_val_t;
  49
  50 # if __BYTE_ORDER == __BIG_ENDIAN
  51 #  define __HUGE_VAL_bytes      { 0x7f, 0xf0, 0, 0, 0, 0, 0, 0 }
  52 # endif
  53 # if __BYTE_ORDER == __LITTLE_ENDIAN
  54 #  define __HUGE_VAL_bytes      { 0, 0, 0, 0, 0, 0, 0xf0, 0x7f }
  55 # endif
  56
  57 static __huge_val_t __huge_val = { __HUGE_VAL_bytes };
  58 # define HUGE_VAL       (__huge_val.__d)
  59
  60 #endif  /* GCC.  */
  61
  62
  63 /* ISO C99 extensions: (float) HUGE_VALF and (long double) HUGE_VALL.  */
  64
  65 #ifdef __USE_ISOC99
  66
  67 # ifdef __GNUC__
  68
  69 #  if __GNUC_PREREQ(2,96)
  70
  71 #   define HUGE_VALF (__extension__ 0x1.0p255f)
  72
  73 #  else
  74
  75 #   define HUGE_VALF \
  76   (__extension__                                                              \
  77    ((union { unsigned __l __attribute__((__mode__(__SI__))); float __d; })    \
  78     { __l: 0x7f800000UL }).__d)
  79
  80 #  endif
  81
  82 # else /* not GCC */
  83
  84 typedef union { unsigned char __c[4]; float __f; } __huge_valf_t;
  85
  86 #  if __BYTE_ORDER == __BIG_ENDIAN
  87 #   define __HUGE_VALF_bytes    { 0x7f, 0x80, 0, 0 }
  88 #  endif
  89 #  if __BYTE_ORDER == __LITTLE_ENDIAN
  90 #   define __HUGE_VALF_bytes    { 0, 0, 0x80, 0x7f }
  91 #  endif
  92
  93 static __huge_valf_t __huge_valf = { __HUGE_VALF_bytes };
  94 #  define HUGE_VALF     (__huge_valf.__f)
  95
  96 # endif /* GCC.  */
  97
  98
  99 /* Generally there is no separate `long double' format and it is the
 100    same as `double'.  */
 101 # define HUGE_VALL HUGE_VAL
 102
 103 #endif /* __USE_ISOC99.  */