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ieee.h revision 1.1
      1  1.1  itojun /*	$NetBSD: ieee.h,v 1.1 1999/09/13 10:31:18 itojun Exp $ */
      2  1.1  itojun 
      3  1.1  itojun /*
      4  1.1  itojun  * Copyright (c) 1992, 1993
      5  1.1  itojun  *	The Regents of the University of California.  All rights reserved.
      6  1.1  itojun  *
      7  1.1  itojun  * This software was developed by the Computer Systems Engineering group
      8  1.1  itojun  * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
      9  1.1  itojun  * contributed to Berkeley.
     10  1.1  itojun  *
     11  1.1  itojun  * All advertising materials mentioning features or use of this software
     12  1.1  itojun  * must display the following acknowledgement:
     13  1.1  itojun  *	This product includes software developed by the University of
     14  1.1  itojun  *	California, Lawrence Berkeley Laboratory.
     15  1.1  itojun  *
     16  1.1  itojun  * Redistribution and use in source and binary forms, with or without
     17  1.1  itojun  * modification, are permitted provided that the following conditions
     18  1.1  itojun  * are met:
     19  1.1  itojun  * 1. Redistributions of source code must retain the above copyright
     20  1.1  itojun  *    notice, this list of conditions and the following disclaimer.
     21  1.1  itojun  * 2. Redistributions in binary form must reproduce the above copyright
     22  1.1  itojun  *    notice, this list of conditions and the following disclaimer in the
     23  1.1  itojun  *    documentation and/or other materials provided with the distribution.
     24  1.1  itojun  * 3. All advertising materials mentioning features or use of this software
     25  1.1  itojun  *    must display the following acknowledgement:
     26  1.1  itojun  *	This product includes software developed by the University of
     27  1.1  itojun  *	California, Berkeley and its contributors.
     28  1.1  itojun  * 4. Neither the name of the University nor the names of its contributors
     29  1.1  itojun  *    may be used to endorse or promote products derived from this software
     30  1.1  itojun  *    without specific prior written permission.
     31  1.1  itojun  *
     32  1.1  itojun  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     33  1.1  itojun  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     34  1.1  itojun  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     35  1.1  itojun  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     36  1.1  itojun  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     37  1.1  itojun  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     38  1.1  itojun  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     39  1.1  itojun  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     40  1.1  itojun  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     41  1.1  itojun  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     42  1.1  itojun  * SUCH DAMAGE.
     43  1.1  itojun  *
     44  1.1  itojun  *	@(#)ieee.h	8.1 (Berkeley) 6/11/93
     45  1.1  itojun  */
     46  1.1  itojun 
     47  1.1  itojun /*
     48  1.1  itojun  * ieee.h defines the machine-dependent layout of the machine's IEEE
     49  1.1  itojun  * floating point.  It does *not* define (yet?) any of the rounding
     50  1.1  itojun  * mode bits, exceptions, and so forth.
     51  1.1  itojun  */
     52  1.1  itojun 
     53  1.1  itojun /*
     54  1.1  itojun  * Define the number of bits in each fraction and exponent.
     55  1.1  itojun  *
     56  1.1  itojun  *		     k	         k+1
     57  1.1  itojun  * Note that  1.0 x 2  == 0.1 x 2      and that denorms are represented
     58  1.1  itojun  *
     59  1.1  itojun  *					  (-exp_bias+1)
     60  1.1  itojun  * as fractions that look like 0.fffff x 2             .  This means that
     61  1.1  itojun  *
     62  1.1  itojun  *			 -126
     63  1.1  itojun  * the number 0.10000 x 2    , for instance, is the same as the normalized
     64  1.1  itojun  *
     65  1.1  itojun  *		-127			   -128
     66  1.1  itojun  * float 1.0 x 2    .  Thus, to represent 2    , we need one leading zero
     67  1.1  itojun  *
     68  1.1  itojun  *				  -129
     69  1.1  itojun  * in the fraction; to represent 2    , we need two, and so on.  This
     70  1.1  itojun  *
     71  1.1  itojun  *						     (-exp_bias-fracbits+1)
     72  1.1  itojun  * implies that the smallest denormalized number is 2
     73  1.1  itojun  *
     74  1.1  itojun  * for whichever format we are talking about: for single precision, for
     75  1.1  itojun  *
     76  1.1  itojun  *						-126		-149
     77  1.1  itojun  * instance, we get .00000000000000000000001 x 2    , or 1.0 x 2    , and
     78  1.1  itojun  *
     79  1.1  itojun  * -149 == -127 - 23 + 1.
     80  1.1  itojun  */
     81  1.1  itojun #define	SNG_EXPBITS	8
     82  1.1  itojun #define	SNG_FRACBITS	23
     83  1.1  itojun 
     84  1.1  itojun #define	DBL_EXPBITS	11
     85  1.1  itojun #define	DBL_FRACBITS	52
     86  1.1  itojun 
     87  1.1  itojun #define	EXT_EXPBITS	15
     88  1.1  itojun #define	EXT_FRACBITS	112
     89  1.1  itojun 
     90  1.1  itojun #ifndef BYTE_ORDER
     91  1.1  itojun #error Define BYTE_ORDER!
     92  1.1  itojun #endif
     93  1.1  itojun 
     94  1.1  itojun #if BYTE_ORDER == BIG_ENDIAN
     95  1.1  itojun struct ieee_single {
     96  1.1  itojun 	u_int	sng_sign:1;
     97  1.1  itojun 	u_int	sng_exp:8;
     98  1.1  itojun 	u_int	sng_frac:23;
     99  1.1  itojun };
    100  1.1  itojun 
    101  1.1  itojun struct ieee_double {
    102  1.1  itojun 	u_int	dbl_sign:1;
    103  1.1  itojun 	u_int	dbl_exp:11;
    104  1.1  itojun 	u_int	dbl_frach:20;
    105  1.1  itojun 	u_int	dbl_fracl;
    106  1.1  itojun };
    107  1.1  itojun 
    108  1.1  itojun struct ieee_ext {
    109  1.1  itojun 	u_int	ext_sign:1;
    110  1.1  itojun 	u_int	ext_exp:15;
    111  1.1  itojun 	u_int	ext_frach:16;
    112  1.1  itojun 	u_int	ext_frachm;
    113  1.1  itojun 	u_int	ext_fraclm;
    114  1.1  itojun 	u_int	ext_fracl;
    115  1.1  itojun };
    116  1.1  itojun #endif
    117  1.1  itojun #if BYTE_ORDER == LITTLE_ENDIAN
    118  1.1  itojun struct ieee_single {
    119  1.1  itojun 	u_int	sng_frac:23;
    120  1.1  itojun 	u_int	sng_exp:8;
    121  1.1  itojun 	u_int	sng_sign:1;
    122  1.1  itojun };
    123  1.1  itojun 
    124  1.1  itojun struct ieee_double {
    125  1.1  itojun 	u_int	dbl_fracl;
    126  1.1  itojun 	u_int	dbl_frach:20;
    127  1.1  itojun 	u_int	dbl_exp:11;
    128  1.1  itojun 	u_int	dbl_sign:1;
    129  1.1  itojun };
    130  1.1  itojun 
    131  1.1  itojun struct ieee_ext {
    132  1.1  itojun 	u_int	ext_fracl;
    133  1.1  itojun 	u_int	ext_fraclm;
    134  1.1  itojun 	u_int	ext_frachm;
    135  1.1  itojun 	u_int	ext_frach:16;
    136  1.1  itojun 	u_int	ext_exp:15;
    137  1.1  itojun 	u_int	ext_sign:1;
    138  1.1  itojun };
    139  1.1  itojun #endif
    140  1.1  itojun /*
    141  1.1  itojun  * Floats whose exponent is in [1..INFNAN) (of whatever type) are
    142  1.1  itojun  * `normal'.  Floats whose exponent is INFNAN are either Inf or NaN.
    143  1.1  itojun  * Floats whose exponent is zero are either zero (iff all fraction
    144  1.1  itojun  * bits are zero) or subnormal values.
    145  1.1  itojun  *
    146  1.1  itojun  * A NaN is a `signalling NaN' if its QUIETNAN bit is clear in its
    147  1.1  itojun  * high fraction; if the bit is set, it is a `quiet NaN'.
    148  1.1  itojun  */
    149  1.1  itojun #define	SNG_EXP_INFNAN	255
    150  1.1  itojun #define	DBL_EXP_INFNAN	2047
    151  1.1  itojun #define	EXT_EXP_INFNAN	32767
    152  1.1  itojun 
    153  1.1  itojun #if 0
    154  1.1  itojun #define	SNG_QUIETNAN	(1 << 22)
    155  1.1  itojun #define	DBL_QUIETNAN	(1 << 19)
    156  1.1  itojun #define	EXT_QUIETNAN	(1 << 15)
    157  1.1  itojun #endif
    158  1.1  itojun 
    159  1.1  itojun /*
    160  1.1  itojun  * Exponent biases.
    161  1.1  itojun  */
    162  1.1  itojun #define	SNG_EXP_BIAS	127
    163  1.1  itojun #define	DBL_EXP_BIAS	1023
    164  1.1  itojun #define	EXT_EXP_BIAS	16383
    165