1/*	$OpenBSD: ieee.h,v 1.2 2003/06/02 23:27:47 millert Exp $ */
2/*	$NetBSD: ieee.h,v 1.1 1996/09/30 16:34:25 ws Exp $ */
3
4/*
5 * Copyright (c) 1992, 1993
6 *	The Regents of the University of California.  All rights reserved.
7 *
8 * This software was developed by the Computer Systems Engineering group
9 * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
10 * contributed to Berkeley.
11 *
12 * All advertising materials mentioning features or use of this software
13 * must display the following acknowledgement:
14 *	This product includes software developed by the University of
15 *	California, Lawrence Berkeley Laboratory.
16 *
17 * Redistribution and use in source and binary forms, with or without
18 * modification, are permitted provided that the following conditions
19 * are met:
20 * 1. Redistributions of source code must retain the above copyright
21 *    notice, this list of conditions and the following disclaimer.
22 * 2. Redistributions in binary form must reproduce the above copyright
23 *    notice, this list of conditions and the following disclaimer in the
24 *    documentation and/or other materials provided with the distribution.
25 * 3. Neither the name of the University nor the names of its contributors
26 *    may be used to endorse or promote products derived from this software
27 *    without specific prior written permission.
28 *
29 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
30 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
31 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
32 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
33 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
34 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
35 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
36 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
37 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
38 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
39 * SUCH DAMAGE.
40 *
41 *	@(#)ieee.h	8.1 (Berkeley) 6/11/93
42 */
43
44/*
45 * ieee.h defines the machine-dependent layout of the machine's IEEE
46 * floating point.  It does *not* define (yet?) any of the rounding
47 * mode bits, exceptions, and so forth.
48 */
49
50/*
51 * Define the number of bits in each fraction and exponent.
52 *
53 *		     k	         k+1
54 * Note that  1.0 x 2  == 0.1 x 2      and that denorms are represented
55 *
56 *					  (-exp_bias+1)
57 * as fractions that look like 0.fffff x 2             .  This means that
58 *
59 *			 -126
60 * the number 0.10000 x 2    , for instance, is the same as the normalized
61 *
62 *		-127			   -128
63 * float 1.0 x 2    .  Thus, to represent 2    , we need one leading zero
64 *
65 *				  -129
66 * in the fraction; to represent 2    , we need two, and so on.  This
67 *
68 *						     (-exp_bias-fracbits+1)
69 * implies that the smallest denormalized number is 2
70 *
71 * for whichever format we are talking about: for single precision, for
72 *
73 *						-126		-149
74 * instance, we get .00000000000000000000001 x 2    , or 1.0 x 2    , and
75 *
76 * -149 == -127 - 23 + 1.
77 */
78#define	SNG_EXPBITS	8
79#define	SNG_FRACBITS	23
80
81#define	DBL_EXPBITS	11
82#define	DBL_FRACBITS	52
83
84#define	EXT_EXPBITS	15
85#define	EXT_FRACBITS	112
86
87struct ieee_single {
88	u_int	sng_frac:23;
89	u_int	sng_exp:8;
90	u_int	sng_sign:1;
91};
92
93struct ieee_double {
94	u_int	dbl_fracl;
95	u_int	dbl_frach:20;
96	u_int	dbl_exp:11;
97	u_int	dbl_sign:1;
98};
99
100struct ieee_ext {
101	u_int	ext_fracl;
102	u_int	ext_fraclm;
103	u_int	ext_frachm;
104	u_int	ext_frach:16;
105	u_int	ext_exp:15;
106	u_int	ext_sign:1;
107};
108
109/*
110 * Floats whose exponent is in [1..INFNAN) (of whatever type) are
111 * `normal'.  Floats whose exponent is INFNAN are either Inf or NaN.
112 * Floats whose exponent is zero are either zero (iff all fraction
113 * bits are zero) or subnormal values.
114 *
115 * A NaN is a `signalling NaN' if its QUIETNAN bit is clear in its
116 * high fraction; if the bit is set, it is a `quiet NaN'.
117 */
118#define	SNG_EXP_INFNAN	255
119#define	DBL_EXP_INFNAN	2047
120#define	EXT_EXP_INFNAN	32767
121
122#if 0
123#define	SNG_QUIETNAN	(1 << 22)
124#define	DBL_QUIETNAN	(1 << 19)
125#define	EXT_QUIETNAN	(1 << 15)
126#endif
127
128/*
129 * Exponent biases.
130 */
131#define	SNG_EXP_BIAS	127
132#define	DBL_EXP_BIAS	1023
133#define	EXT_EXP_BIAS	16383
134