ieee754.h

glibc 2.9,最新版的C语言库函数

/* Copyright (C) 1992, 1995, 1996, 1999, 2004, 2006
   Free Software Foundation, Inc.
   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 _IEEE754_H

#define _IEEE754_H 1
#include <features.h>

#include <endian.h>

__BEGIN_DECLS

union ieee754_float
  {
    float f;

    /* This is the IEEE 754 single-precision format.  */
    struct
      {
#if	__BYTE_ORDER == __BIG_ENDIAN
	unsigned int negative:1;
	unsigned int exponent:8;
	unsigned int mantissa:23;
#endif				/* Big endian.  */
#if	__BYTE_ORDER == __LITTLE_ENDIAN
	unsigned int mantissa:23;
	unsigned int exponent:8;
	unsigned int negative:1;
#endif				/* Little endian.  */
      } ieee;

    /* This format makes it easier to see if a NaN is a signalling NaN.  */
    struct
      {
#if	__BYTE_ORDER == __BIG_ENDIAN
	unsigned int negative:1;
	unsigned int exponent:8;
	unsigned int quiet_nan:1;
	unsigned int mantissa:22;
#endif				/* Big endian.  */
#if	__BYTE_ORDER == __LITTLE_ENDIAN
	unsigned int mantissa:22;
	unsigned int quiet_nan:1;
	unsigned int exponent:8;
	unsigned int negative:1;
#endif				/* Little endian.  */
      } ieee_nan;
  };

#define IEEE754_FLOAT_BIAS	0x7f /* Added to exponent.  */


union ieee754_double
  {
    double d;

    /* This is the IEEE 754 double-precision format.  */
    struct
      {
#if	__BYTE_ORDER == __BIG_ENDIAN
	unsigned int negative:1;
	unsigned int exponent:11;
	/* Together these comprise the mantissa.  */
	unsigned int mantissa0:20;
	unsigned int mantissa1:32;
#endif				/* Big endian.  */
#if	__BYTE_ORDER == __LITTLE_ENDIAN
	/* Together these comprise the mantissa.  */
	unsigned int mantissa1:32;
	unsigned int mantissa0:20;
	unsigned int exponent:11;
	unsigned int negative:1;
#endif				/* Little endian.  */
      } ieee;

    /* This format makes it easier to see if a NaN is a signalling NaN.  */
    struct
      {
#if	__BYTE_ORDER == __BIG_ENDIAN
	unsigned int negative:1;
	unsigned int exponent:11;
	unsigned int quiet_nan:1;
	/* Together these comprise the mantissa.  */
	unsigned int mantissa0:19;
	unsigned int mantissa1:32;
#else
	/* Together these comprise the mantissa.  */
	unsigned int mantissa1:32;
	unsigned int mantissa0:19;
	unsigned int quiet_nan:1;
	unsigned int exponent:11;
	unsigned int negative:1;
#endif
      } ieee_nan;
  };

#define IEEE754_DOUBLE_BIAS	0x3ff /* Added to exponent.  */


union ieee854_long_double
  {
    long double d;

    /* This is the IEEE 854 quad-precision format.  */
    struct
      {
#if	__BYTE_ORDER == __BIG_ENDIAN
	unsigned int negative:1;
	unsigned int exponent:15;
	/* Together these comprise the mantissa.  */
	unsigned int mantissa0:16;
	unsigned int mantissa1:32;
	unsigned int mantissa2:32;
	unsigned int mantissa3:32;
#endif				/* Big endian.  */
#if	__BYTE_ORDER == __LITTLE_ENDIAN
	/* Together these comprise the mantissa.  */
	unsigned int mantissa3:32;
	unsigned int mantissa2:32;
	unsigned int mantissa1:32;
	unsigned int mantissa0:16;
	unsigned int exponent:15;
	unsigned int negative:1;
#endif				/* Little endian.  */
      } ieee;

    /* This format makes it easier to see if a NaN is a signalling NaN.  */
    struct
      {
#if	__BYTE_ORDER == __BIG_ENDIAN
	unsigned int negative:1;
	unsigned int exponent:15;
	unsigned int quiet_nan:1;
	/* Together these comprise the mantissa.  */
	unsigned int mantissa0:15;
	unsigned int mantissa1:32;
	unsigned int mantissa2:32;
	unsigned int mantissa3:32;
#else
	/* Together these comprise the mantissa.  */
	unsigned int mantissa3:32;
	unsigned int mantissa2:32;
	unsigned int mantissa1:32;
	unsigned int mantissa0:15;
	unsigned int quiet_nan:1;
	unsigned int exponent:15;
	unsigned int negative:1;
#endif
      } ieee_nan;
  };

#define IEEE854_LONG_DOUBLE_BIAS 0x3fff /* Added to exponent.  */


/* IBM extended format for long double.

   Each long double is made up of two IEEE doubles.  The value of the
   long double is the sum of the values of the two parts.  The most
   significant part is required to be the value of the long double
   rounded to the nearest double, as specified by IEEE.  For Inf
   values, the least significant part is required to be one of +0.0 or
   -0.0.  No other requirements are made; so, for example, 1.0 may be
   represented as (1.0, +0.0) or (1.0, -0.0), and the low part of a
   NaN is don't-care.  */

union ibm_extended_long_double
  {
    long double d;
    double dd[2];

    /* This is the IBM extended format long double.  */
    struct
      { /* Big endian.  There is no other.  */

	unsigned int negative:1;
	unsigned int exponent:11;
	/* Together Mantissa0-3 comprise the mantissa.  */
	unsigned int mantissa0:20;
	unsigned int mantissa1:32;

	unsigned int negative2:1;
	unsigned int exponent2:11;
	/* There is an implied 1 here?  */
	/* Together these comprise the mantissa.  */
	unsigned int mantissa2:20;
	unsigned int mantissa3:32;
      } ieee;
   };

#define IBM_EXTENDED_LONG_DOUBLE_BIAS 0x3ff /* Added to exponent.  */

__END_DECLS

#endif /* ieee754.h */