/
ieee754.h
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/
ieee754.h
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/* $NetBSD: ieee754.h,v 1.4.4.6 2005/12/11 10:29:36 christos Exp $ */
/*
* Copyright (c) 1992, 1993
* The Regents of the University of California. All rights reserved.
*
* This software was developed by the Computer Systems Engineering group
* at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
* contributed to Berkeley.
*
* All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Lawrence Berkeley Laboratory.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* @(#)ieee.h 8.1 (Berkeley) 6/11/93
*/
#ifndef _SYS_IEEE754_H_
#define _SYS_IEEE754_H_
/*
* NOTICE: This is not a standalone file. To use it, #include it in
* your port's ieee.h header.
*/
#include <machine/endian.h>
/*
* <sys/ieee754.h> defines the layout of IEEE 754 floating point types.
* Only single-precision and double-precision types are defined here;
* extended types, if available, are defined in the machine-dependent
* header.
*/
/*
* Define the number of bits in each fraction and exponent.
*
* k k+1
* Note that 1.0 x 2 == 0.1 x 2 and that denorms are represented
*
* (-exp_bias+1)
* as fractions that look like 0.fffff x 2 . This means that
*
* -126
* the number 0.10000 x 2 , for instance, is the same as the normalized
*
* -127 -128
* float 1.0 x 2 . Thus, to represent 2 , we need one leading zero
*
* -129
* in the fraction; to represent 2 , we need two, and so on. This
*
* (-exp_bias-fracbits+1)
* implies that the smallest denormalized number is 2
*
* for whichever format we are talking about: for single precision, for
*
* -126 -149
* instance, we get .00000000000000000000001 x 2 , or 1.0 x 2 , and
*
* -149 == -127 - 23 + 1.
*/
#define SNG_EXPBITS 8
#define SNG_FRACBITS 23
#define DBL_EXPBITS 11
#define DBL_FRACBITS 52
struct ieee_single {
#if _BYTE_ORDER == _BIG_ENDIAN
u_int sng_sign:1;
u_int sng_exp:8;
u_int sng_frac:23;
#else
u_int sng_frac:23;
u_int sng_exp:8;
u_int sng_sign:1;
#endif
};
struct ieee_double {
#if _BYTE_ORDER == _BIG_ENDIAN
u_int dbl_sign:1;
u_int dbl_exp:11;
u_int dbl_frach:20;
u_int dbl_fracl;
#else
u_int dbl_fracl;
u_int dbl_frach:20;
u_int dbl_exp:11;
u_int dbl_sign:1;
#endif
};
/*
* Floats whose exponent is in [1..INFNAN) (of whatever type) are
* `normal'. Floats whose exponent is INFNAN are either Inf or NaN.
* Floats whose exponent is zero are either zero (iff all fraction
* bits are zero) or subnormal values.
*
* At least one `signalling NaN' and one `quiet NaN' value must be
* implemented. It is left to the architecture to specify how to
* distinguish between these.
*/
#define SNG_EXP_INFNAN 255
#define DBL_EXP_INFNAN 2047
/*
* Exponent biases.
*/
#define SNG_EXP_BIAS 127
#define DBL_EXP_BIAS 1023
/*
* Convenience data structures.
*/
union ieee_single_u {
float sngu_f;
struct ieee_single sngu_sng;
};
union ieee_double_u {
double dblu_d;
struct ieee_double dblu_dbl;
};
#endif /* _SYS_IEEE754_H_ */