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ieee.h revision 1.2 
      1 /*	$NetBSD: ieee.h,v 1.2 2003/08/07 16:27:52 agc Exp $	*/
      2 
      3 /*	$OpenBSD: ieee.h,v 1.1 1999/04/20 19:44:04 mickey Exp $	*/
      4 
      5 /*
      6  * Copyright (c) 1992, 1993
      7  *	The Regents of the University of California.  All rights reserved.
      8  *
      9  * This software was developed by the Computer Systems Engineering group
     10  * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
     11  * contributed to Berkeley.
     12  *
     13  * All advertising materials mentioning features or use of this software
     14  * must display the following acknowledgement:
     15  *	This product includes software developed by the University of
     16  *	California, Lawrence Berkeley Laboratory.
     17  *
     18  * Redistribution and use in source and binary forms, with or without
     19  * modification, are permitted provided that the following conditions
     20  * are met:
     21  * 1. Redistributions of source code must retain the above copyright
     22  *    notice, this list of conditions and the following disclaimer.
     23  * 2. Redistributions in binary form must reproduce the above copyright
     24  *    notice, this list of conditions and the following disclaimer in the
     25  *    documentation and/or other materials provided with the distribution.
     26  * 3. Neither the name of the University nor the names of its contributors
     27  *    may be used to endorse or promote products derived from this software
     28  *    without specific prior written permission.
     29  *
     30  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     31  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     32  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     33  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     34  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     35  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     36  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     37  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     38  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     39  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     40  * SUCH DAMAGE.
     41  *
     42  *	@(#)ieee.h	8.1 (Berkeley) 6/11/93
     43  */
     44 
     45 /*
     46  * ieee.h defines the machine-dependent layout of the machine's IEEE
     47  * floating point.  It does *not* define (yet?) any of the rounding
     48  * mode bits, exceptions, and so forth.
     49  */
     50 
     51 /*
     52  * Define the number of bits in each fraction and exponent.
     53  *
     54  *		     k	         k+1
     55  * Note that  1.0 x 2  == 0.1 x 2      and that denorms are represented
     56  *
     57  *					  (-exp_bias+1)
     58  * as fractions that look like 0.fffff x 2             .  This means that
     59  *
     60  *			 -126
     61  * the number 0.10000 x 2    , for instance, is the same as the normalized
     62  *
     63  *		-127			   -128
     64  * float 1.0 x 2    .  Thus, to represent 2    , we need one leading zero
     65  *
     66  *				  -129
     67  * in the fraction; to represent 2    , we need two, and so on.  This
     68  *
     69  *						     (-exp_bias-fracbits+1)
     70  * implies that the smallest denormalized number is 2
     71  *
     72  * for whichever format we are talking about: for single precision, for
     73  *
     74  *						-126		-149
     75  * instance, we get .00000000000000000000001 x 2    , or 1.0 x 2    , and
     76  *
     77  * -149 == -127 - 23 + 1.
     78  */
     79 #define	SNG_EXPBITS	8
     80 #define	SNG_FRACBITS	23
     81 
     82 #define	DBL_EXPBITS	11
     83 #define	DBL_FRACBITS	52
     84 
     85 #ifdef notyet
     86 #define	E80_EXPBITS	15
     87 #define	E80_FRACBITS	64
     88 #endif
     89 
     90 #define	EXT_EXPBITS	15
     91 #define	EXT_FRACBITS	112
     92 
     93 struct ieee_single {
     94 	u_int	sng_sign:1;
     95 	u_int	sng_exp:8;
     96 	u_int	sng_frac:23;
     97 };
     98 
     99 struct ieee_double {
    100 	u_int	dbl_sign:1;
    101 	u_int	dbl_exp:11;
    102 	u_int	dbl_frach:20;
    103 	u_int	dbl_fracl;
    104 };
    105 
    106 struct ieee_ext {
    107 	u_int	ext_sign:1;
    108 	u_int	ext_exp:15;
    109 	u_int	ext_frach:16;
    110 	u_int	ext_frachm;
    111 	u_int	ext_fraclm;
    112 	u_int	ext_fracl;
    113 };
    114 
    115 /*
    116  * Floats whose exponent is in [1..INFNAN) (of whatever type) are
    117  * `normal'.  Floats whose exponent is INFNAN are either Inf or NaN.
    118  * Floats whose exponent is zero are either zero (iff all fraction
    119  * bits are zero) or subnormal values.
    120  *
    121  * A NaN is a `signalling NaN' if its QUIETNAN bit is clear in its
    122  * high fraction; if the bit is set, it is a `quiet NaN'.
    123  */
    124 #define	SNG_EXP_INFNAN	255
    125 #define	DBL_EXP_INFNAN	2047
    126 #define	EXT_EXP_INFNAN	32767
    127 
    128 #if 0
    129 #define	SNG_QUIETNAN	(1 << 22)
    130 #define	DBL_QUIETNAN	(1 << 19)
    131 #define	EXT_QUIETNAN	(1 << 15)
    132 #endif
    133 
    134 /*
    135  * Exponent biases.
    136  */
    137 #define	SNG_EXP_BIAS	127
    138 #define	DBL_EXP_BIAS	1023
    139 #define	EXT_EXP_BIAS	16383
    140