ieee.h revision 66458 
1/* $FreeBSD: head/sys/ia64/include/ieee.h 66458 2000-09-29 13:46:07Z dfr $ */
2/* From: NetBSD: ieee.h,v 1.2 1997/04/06 08:47:27 cgd 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. All advertising materials mentioning features or use of this software
26 *    must display the following acknowledgement:
27 *	This product includes software developed by the University of
28 *	California, Berkeley and its contributors.
29 * 4. Neither the name of the University nor the names of its contributors
30 *    may be used to endorse or promote products derived from this software
31 *    without specific prior written permission.
32 *
33 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
34 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
35 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
36 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
37 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
38 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
39 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
40 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
41 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
42 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
43 * SUCH DAMAGE.
44 *
45 *	@(#)ieee.h	8.1 (Berkeley) 6/11/93
46 *
47 * from: Header: ieee.h,v 1.7 92/11/26 02:04:37 torek Exp
48 */
49
50/*
51 * ieee.h defines the machine-dependent layout of the machine's IEEE
52 * floating point.  It does *not* define (yet?) any of the rounding
53 * mode bits, exceptions, and so forth.
54 */
55
56/*
57 * Define the number of bits in each fraction and exponent.
58 *
59 *		     k	         k+1
60 * Note that  1.0 x 2  == 0.1 x 2      and that denorms are represented
61 *
62 *					  (-exp_bias+1)
63 * as fractions that look like 0.fffff x 2             .  This means that
64 *
65 *			 -126
66 * the number 0.10000 x 2    , for instance, is the same as the normalized
67 *
68 *		-127			   -128
69 * float 1.0 x 2    .  Thus, to represent 2    , we need one leading zero
70 *
71 *				  -129
72 * in the fraction; to represent 2    , we need two, and so on.  This
73 *
74 *						     (-exp_bias-fracbits+1)
75 * implies that the smallest denormalized number is 2
76 *
77 * for whichever format we are talking about: for single precision, for
78 *
79 *						-126		-149
80 * instance, we get .00000000000000000000001 x 2    , or 1.0 x 2    , and
81 *
82 * -149 == -127 - 23 + 1.
83 */
84#define	SNG_EXPBITS	8
85#define	SNG_FRACBITS	23
86
87#define	DBL_EXPBITS	11
88#define	DBL_FRACBITS	52
89
90struct ieee_single {
91	u_int	sng_frac:23;
92	u_int	sng_exp:8;
93	u_int	sng_sign:1;
94};
95
96struct ieee_double {
97	u_int	dbl_fracl;
98	u_int	dbl_frach:20;
99	u_int	dbl_exp:11;
100	u_int	dbl_sign:1;
101};
102
103/*
104 * Floats whose exponent is in [1..INFNAN) (of whatever type) are
105 * `normal'.  Floats whose exponent is INFNAN are either Inf or NaN.
106 * Floats whose exponent is zero are either zero (iff all fraction
107 * bits are zero) or subnormal values.
108 *
109 * A NaN is a `signalling NaN' if its QUIETNAN bit is clear in its
110 * high fraction; if the bit is set, it is a `quiet NaN'.
111 */
112#define	SNG_EXP_INFNAN	255
113#define	DBL_EXP_INFNAN	2047
114
115#if 0
116#define	SNG_QUIETNAN	(1 << 22)
117#define	DBL_QUIETNAN	(1 << 19)
118#endif
119
120/*
121 * Exponent biases.
122 */
123#define	SNG_EXP_BIAS	127
124#define	DBL_EXP_BIAS	1023
125