huge_val.h

来自「Glibc 2.3.2源代码(解压后有100多M)」· C头文件 代码 · 共 70 行

/* `HUGE_VAL' constants for S/390 (where it is infinity).
   Used by <stdlib.h> and <math.h> functions for overflow.
   Copyright (C) 2000, 2001 Free Software Foundation, Inc.
   Contributed by Martin Schwidefsky ([e-mail]).
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, write to the Free
   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   02111-1307 USA.  */

#ifndef _MATH_H
# error "Never use <bits/huge_val.h> directly; include <math.h> instead."
#endif

#include <features.h>

/* IEEE positive infinity (-HUGE_VAL is negative infinity).  */

#if __GNUC_PREREQ(2,96)
# define HUGE_VAL	(__extension__ 0x1.0p2047)
#else
# define __HUGE_VAL_bytes	{ 0x7f, 0xf0, 0, 0, 0, 0, 0, 0 }

# define __huge_val_t	union { unsigned char __c[8]; double __d; }
# ifdef __GNUC__
#  define HUGE_VAL	(__extension__ \
			 ((__huge_val_t) { __c: __HUGE_VAL_bytes }).__d)
# else	/* Not GCC.  */
static __huge_val_t __huge_val = { __HUGE_VAL_bytes };
#  define HUGE_VAL	(__huge_val.__d)
# endif	/* GCC.  */
#endif  /* GCC 2.95 */


/* ISO C 99 extensions: (float) HUGE_VALF and (long double) HUGE_VALL.  */

#ifdef __USE_ISOC99

# if __GNUC_PREREQ(2,96)
#  define HUGE_VALF	(__extension__ 0x1.0p255f)
#  define HUGE_VALL	(__extension__ 0x1.0p255f)
# else
#  define __HUGE_VALF_bytes	{ 0x7f, 0x80, 0, 0 }
#  define __huge_valf_t	union { unsigned char __c[4]; float __f; }
#  ifdef	__GNUC__
#   define HUGE_VALF	(__extension__ \
			 ((__huge_valf_t) { __c: __HUGE_VALF_bytes }).__f)
#  else	/* Not GCC.  */
static __huge_valf_t __huge_valf = { __HUGE_VALF_bytes };
#   define HUGE_VALF	(__huge_valf.__f)
#  endif  /* GCC.  */

/* On 390 there is no 'long double' format. Make it the same as 'double' */
# define HUGE_VALL HUGE_VAL

# endif /* GCC 2.95 */

#endif	/* __USE_ISOC99.  */