ieee.h revision 331722 
1/*-
2 * Copyright (c) 1992, 1993
3 *	The Regents of the University of California.  All rights reserved.
4 *
5 * This software was developed by the Computer Systems Engineering group
6 * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
7 * contributed to Berkeley.
8 *
9 * All advertising materials mentioning features or use of this software
10 * must display the following acknowledgement:
11 *	This product includes software developed by the University of
12 *	California, Lawrence Berkeley Laboratory.
13 *
14 * Redistribution and use in source and binary forms, with or without
15 * modification, are permitted provided that the following conditions
16 * are met:
17 * 1. Redistributions of source code must retain the above copyright
18 *    notice, this list of conditions and the following disclaimer.
19 * 2. Redistributions in binary form must reproduce the above copyright
20 *    notice, this list of conditions and the following disclaimer in the
21 *    documentation and/or other materials provided with the distribution.
22 * 4. Neither the name of the University nor the names of its contributors
23 *    may be used to endorse or promote products derived from this software
24 *    without specific prior written permission.
25 *
26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
29 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36 * SUCH DAMAGE.
37 *
38 *	@(#)ieee.h	8.1 (Berkeley) 6/11/93
39 *	from: NetBSD: ieee.h,v 1.1.1.1 1998/06/20 04:58:51 eeh Exp
40 * $FreeBSD: stable/11/sys/powerpc/include/ieee.h 331722 2018-03-29 02:50:57Z eadler $
41 */
42
43#ifndef _MACHINE_IEEE_H_
44#define	_MACHINE_IEEE_H_
45
46/*
47 * ieee.h defines the machine-dependent layout of the machine's IEEE
48 * floating point.  It does *not* define (yet?) any of the rounding
49 * mode bits, exceptions, and so forth.
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#ifdef notyet
87#define	E80_EXPBITS	15
88#define	E80_FRACBITS	64
89#endif
90
91#define	EXT_EXPBITS	15
92#define	EXT_FRACBITS	112
93
94struct ieee_single {
95	u_int	sng_sign:1;
96	u_int	sng_exp:8;
97	u_int	sng_frac:23;
98};
99
100struct ieee_double {
101	u_int	dbl_sign:1;
102	u_int	dbl_exp:11;
103	u_int	dbl_frach:20;
104	u_int	dbl_fracl;
105};
106
107struct ieee_ext {
108	u_int	ext_sign:1;
109	u_int	ext_exp:15;
110	u_int	ext_frach:16;
111	u_int	ext_frachm;
112	u_int	ext_fraclm;
113	u_int	ext_fracl;
114};
115
116/*
117 * Floats whose exponent is in [1..INFNAN) (of whatever type) are
118 * `normal'.  Floats whose exponent is INFNAN are either Inf or NaN.
119 * Floats whose exponent is zero are either zero (iff all fraction
120 * bits are zero) or subnormal values.
121 *
122 * A NaN is a `signalling NaN' if its QUIETNAN bit is clear in its
123 * high fraction; if the bit is set, it is a `quiet NaN'.
124 */
125#define	SNG_EXP_INFNAN	255
126#define	DBL_EXP_INFNAN	2047
127#define	EXT_EXP_INFNAN	32767
128
129#if 0
130#define	SNG_QUIETNAN	(1 << 22)
131#define	DBL_QUIETNAN	(1 << 19)
132#define	EXT_QUIETNAN	(1 << 15)
133#endif
134
135/*
136 * Exponent biases.
137 */
138#define	SNG_EXP_BIAS	127
139#define	DBL_EXP_BIAS	1023
140#define	EXT_EXP_BIAS	16383
141
142#endif
143