1/*	$NetBSD: ieee754.h,v 1.4 2003/10/27 02:30:26 simonb 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. Neither the name of the University nor the names of its contributors
25 *    may be used to endorse or promote products derived from this software
26 *    without specific prior written permission.
27 *
28 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
29 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
30 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
31 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
32 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
33 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
34 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
35 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
37 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
38 * SUCH DAMAGE.
39 *
40 *	@(#)ieee.h	8.1 (Berkeley) 6/11/93
41 *
42 * $FreeBSD$
43 *
44 */
45
46/*
47 * NOTICE: This is not a standalone file.  To use it, #include it in
48 * your port's ieee.h header.
49 */
50
51#include <machine/endian.h>
52
53/*
54 * <sys/ieee754.h> defines the layout of IEEE 754 floating point types.
55 * Only single-precision and double-precision types are defined here;
56 * extended types, if available, are defined in the machine-dependent
57 * header.
58 */
59
60/*
61 * Define the number of bits in each fraction and exponent.
62 *
63 *		     k	         k+1
64 * Note that  1.0 x 2  == 0.1 x 2      and that denorms are represented
65 *
66 *					  (-exp_bias+1)
67 * as fractions that look like 0.fffff x 2             .  This means that
68 *
69 *			 -126
70 * the number 0.10000 x 2    , for instance, is the same as the normalized
71 *
72 *		-127			   -128
73 * float 1.0 x 2    .  Thus, to represent 2    , we need one leading zero
74 *
75 *				  -129
76 * in the fraction; to represent 2    , we need two, and so on.  This
77 *
78 *						     (-exp_bias-fracbits+1)
79 * implies that the smallest denormalized number is 2
80 *
81 * for whichever format we are talking about: for single precision, for
82 *
83 *						-126		-149
84 * instance, we get .00000000000000000000001 x 2    , or 1.0 x 2    , and
85 *
86 * -149 == -127 - 23 + 1.
87 */
88#define	SNG_EXPBITS	8
89#define	SNG_FRACBITS	23
90
91#define	DBL_EXPBITS	11
92#define	DBL_FRACBITS	52
93
94struct ieee_single {
95#if _BYTE_ORDER == _BIG_ENDIAN
96	u_int	sng_sign:1;
97	u_int	sng_exp:8;
98	u_int	sng_frac:23;
99#else
100	u_int	sng_frac:23;
101	u_int	sng_exp:8;
102	u_int	sng_sign:1;
103#endif
104};
105
106struct ieee_double {
107#if _BYTE_ORDER == _BIG_ENDIAN
108	u_int	dbl_sign:1;
109	u_int	dbl_exp:11;
110	u_int	dbl_frach:20;
111	u_int	dbl_fracl;
112#else
113	u_int	dbl_fracl;
114	u_int	dbl_frach:20;
115	u_int	dbl_exp:11;
116	u_int	dbl_sign:1;
117#endif
118};
119
120/*
121 * Floats whose exponent is in [1..INFNAN) (of whatever type) are
122 * `normal'.  Floats whose exponent is INFNAN are either Inf or NaN.
123 * Floats whose exponent is zero are either zero (iff all fraction
124 * bits are zero) or subnormal values.
125 *
126 * A NaN is a `signalling NaN' if its QUIETNAN bit is clear in its
127 * high fraction; if the bit is set, it is a `quiet NaN'.
128 */
129#define	SNG_EXP_INFNAN	255
130#define	DBL_EXP_INFNAN	2047
131
132#if 0
133#define	SNG_QUIETNAN	(1 << 22)
134#define	DBL_QUIETNAN	(1 << 19)
135#endif
136
137/*
138 * Exponent biases.
139 */
140#define	SNG_EXP_BIAS	127
141#define	DBL_EXP_BIAS	1023
142
143/*
144 * Convenience data structures.
145 */
146union ieee_single_u {
147	float			sngu_f;
148	struct ieee_single	sngu_sng;
149};
150
151union ieee_double_u {
152	double			dblu_d;
153	struct ieee_double	dblu_dbl;
154};
155