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ieee.h revision 1.1 
      1 /*	$NetBSD: ieee.h,v 1.1 2001/01/10 19:02:06 bjh21 Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 1992, 1993
      5  *	The Regents of the University of California.  All rights reserved.
      6  *
      7  * This software was developed by the Computer Systems Engineering group
      8  * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
      9  * contributed to Berkeley.
     10  *
     11  * All advertising materials mentioning features or use of this software
     12  * must display the following acknowledgement:
     13  *	This product includes software developed by the University of
     14  *	California, Lawrence Berkeley Laboratory.
     15  *
     16  * Redistribution and use in source and binary forms, with or without
     17  * modification, are permitted provided that the following conditions
     18  * are met:
     19  * 1. Redistributions of source code must retain the above copyright
     20  *    notice, this list of conditions and the following disclaimer.
     21  * 2. Redistributions in binary form must reproduce the above copyright
     22  *    notice, this list of conditions and the following disclaimer in the
     23  *    documentation and/or other materials provided with the distribution.
     24  * 3. All advertising materials mentioning features or use of this software
     25  *    must display the following acknowledgement:
     26  *	This product includes software developed by the University of
     27  *	California, Berkeley and its contributors.
     28  * 4. Neither the name of the University nor the names of its contributors
     29  *    may be used to endorse or promote products derived from this software
     30  *    without specific prior written permission.
     31  *
     32  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     33  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     34  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     35  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     36  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     37  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     38  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     39  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     40  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     41  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     42  * SUCH DAMAGE.
     43  *
     44  *	@(#)ieee.h	8.1 (Berkeley) 6/11/93
     45  */
     46 
     47 /*
     48  * ieee.h defines the machine-dependent layout of the machine's IEEE
     49  * floating point.
     50  */
     51 
     52 /*
     53  * Define the number of bits in each fraction and exponent.
     54  *
     55  *		     k	         k+1
     56  * Note that  1.0 x 2  == 0.1 x 2      and that denorms are represented
     57  *
     58  *					  (-exp_bias+1)
     59  * as fractions that look like 0.fffff x 2             .  This means that
     60  *
     61  *			 -126
     62  * the number 0.10000 x 2    , for instance, is the same as the normalized
     63  *
     64  *		-127			   -128
     65  * float 1.0 x 2    .  Thus, to represent 2    , we need one leading zero
     66  *
     67  *				  -129
     68  * in the fraction; to represent 2    , we need two, and so on.  This
     69  *
     70  *						     (-exp_bias-fracbits+1)
     71  * implies that the smallest denormalized number is 2
     72  *
     73  * for whichever format we are talking about: for single precision, for
     74  *
     75  *						-126		-149
     76  * instance, we get .00000000000000000000001 x 2    , or 1.0 x 2    , and
     77  *
     78  * -149 == -127 - 23 + 1.
     79  */
     80 #define	SNG_EXPBITS	8
     81 #define	SNG_FRACBITS	23
     82 
     83 #define	DBL_EXPBITS	11
     84 #define	DBL_FRACBITS	52
     85 
     86 #define	E80_EXPBITS	15
     87 #define	E80_FRACBITS	64
     88 
     89 #define	EXT_EXPBITS	15
     90 #define	EXT_FRACBITS	112
     91 
     92 struct ieee_single {
     93 	u_int	sng_frac:23;
     94 	u_int	sng_exponent:8;
     95 	u_int	sng_sign:1;
     96 };
     97 
     98 struct ieee_double {
     99 	u_int	dbl_frach:20;
    100 	u_int	dbl_exp:11;
    101 	u_int	dbl_sign:1;
    102 	u_int	dbl_fracl;
    103 };
    104 
    105 struct ieee_e80 {
    106 	u_int	e80_exp:15;
    107 	u_int	e80_zero:16;
    108 	u_int	e80_sign:1;
    109 	u_int	e80_frach:31;
    110 	u_int	e80_j:1;
    111 	u_int	e80_fracl;
    112 };
    113 
    114 struct ieee_ext {
    115 	u_int	ext_frach:16;
    116 	u_int	ext_exp:15;
    117 	u_int	ext_sign:1;
    118 	u_int	ext_frachm;
    119 	u_int	ext_fraclm;
    120 	u_int	ext_fracl;
    121 };
    122 
    123 /*
    124  * Floats whose exponent is in [1..INFNAN) (of whatever type) are
    125  * `normal'.  Floats whose exponent is INFNAN are either Inf or NaN.
    126  * Floats whose exponent is zero are either zero (iff all fraction
    127  * bits are zero) or subnormal values.
    128  *
    129  * A NaN is a `signalling NaN' if its QUIETNAN bit is clear in its
    130  * high fraction; if the bit is set, it is a `quiet NaN'.
    131  */
    132 #define	SNG_EXP_INFNAN	255
    133 #define	DBL_EXP_INFNAN	2047
    134 #define	E80_EXP_INFNAN	32767
    135 #define	EXT_EXP_INFNAN	32767
    136 
    137 #if 0
    138 #define	SNG_QUIETNAN	(1 << 22)
    139 #define	DBL_QUIETNAN	(1 << 19)
    140 #define	E80_QUIETNAN	(1 << 15)
    141 #define	EXT_QUIETNAN	(1 << 15)
    142 #endif
    143 
    144 /*
    145  * Exponent biases.
    146  */
    147 #define	SNG_EXP_BIAS	127
    148 #define	DBL_EXP_BIAS	1023
    149 #define	E80_EXP_BIAS	16383
    150 #define	EXT_EXP_BIAS	16383
    151