1/*	$NetBSD: ieee754.h,v 1.6 2005/12/03 17:10:46 christos 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#ifndef _SYS_IEEE754_H_
43#define _SYS_IEEE754_H_
44
45/*
46 * NOTICE: This is not a standalone file.  To use it, #include it in
47 * your port's ieee.h header.
48 */
49
50#include <machine/endian.h>
51
52/*
53 * <sys/ieee754.h> defines the layout of IEEE 754 floating point types.
54 * Only single-precision and double-precision types are defined here;
55 * extended types, if available, are defined in the machine-dependent
56 * header.
57 */
58
59/*
60 * Define the number of bits in each fraction and exponent.
61 *
62 *		     k	         k+1
63 * Note that  1.0 x 2  == 0.1 x 2      and that denorms are represented
64 *
65 *					  (-exp_bias+1)
66 * as fractions that look like 0.fffff x 2             .  This means that
67 *
68 *			 -126
69 * the number 0.10000 x 2    , for instance, is the same as the normalized
70 *
71 *		-127			   -128
72 * float 1.0 x 2    .  Thus, to represent 2    , we need one leading zero
73 *
74 *				  -129
75 * in the fraction; to represent 2    , we need two, and so on.  This
76 *
77 *						     (-exp_bias-fracbits+1)
78 * implies that the smallest denormalized number is 2
79 *
80 * for whichever format we are talking about: for single precision, for
81 *
82 *						-126		-149
83 * instance, we get .00000000000000000000001 x 2    , or 1.0 x 2    , and
84 *
85 * -149 == -127 - 23 + 1.
86 */
87#define	SNG_EXPBITS	8
88#define	SNG_FRACBITS	23
89
90struct ieee_single {
91#if _BYTE_ORDER == _BIG_ENDIAN
92	u_int	sng_sign:1;
93	u_int	sng_exp:SNG_EXPBITS;
94	u_int	sng_frac:SNG_FRACBITS;
95#else
96	u_int	sng_frac:SNG_FRACBITS;
97	u_int	sng_exp:SNG_EXPBITS;
98	u_int	sng_sign:1;
99#endif
100};
101
102#define	DBL_EXPBITS	11
103#define	DBL_FRACHBITS	20
104#define	DBL_FRACLBITS	32
105#define	DBL_FRACBITS	(DBL_FRACHBITS + DBL_FRACLBITS)
106
107struct ieee_double {
108#if _BYTE_ORDER == _BIG_ENDIAN
109	u_int	dbl_sign:1;
110	u_int	dbl_exp:DBL_EXPBITS;
111	u_int	dbl_frach:DBL_FRACHBITS;
112	u_int	dbl_fracl:DBL_FRACLBITS;
113#else
114	u_int	dbl_fracl:DBL_FRACLBITS;
115	u_int	dbl_frach:DBL_FRACHBITS;
116	u_int	dbl_exp:DBL_EXPBITS;
117	u_int	dbl_sign:1;
118#endif
119};
120
121/*
122 * Floats whose exponent is in [1..INFNAN) (of whatever type) are
123 * `normal'.  Floats whose exponent is INFNAN are either Inf or NaN.
124 * Floats whose exponent is zero are either zero (iff all fraction
125 * bits are zero) or subnormal values.
126 *
127 * At least one `signalling NaN' and one `quiet NaN' value must be
128 * implemented.  It is left to the architecture to specify how to
129 * distinguish between these.
130 */
131#define	SNG_EXP_INFNAN	255
132#define	DBL_EXP_INFNAN	2047
133
134/*
135 * Exponent biases.
136 */
137#define	SNG_EXP_BIAS	127
138#define	DBL_EXP_BIAS	1023
139
140/*
141 * Convenience data structures.
142 */
143union ieee_single_u {
144	float			sngu_f;
145	struct ieee_single	sngu_sng;
146};
147
148union ieee_double_u {
149	double			dblu_d;
150	struct ieee_double	dblu_dbl;
151};
152#endif /* _SYS_IEEE754_H_ */
153