ieee.h revision 330897 
1/*	$NetBSD: ieee754.h,v 1.4 2003/10/27 02:30:26 simonb Exp $	*/
2
3/*-
4 * SPDX-License-Identifier: BSD-3-Clause
5 *
6 * Copyright (c) 1992, 1993
7 *	The Regents of the University of California.  All rights reserved.
8 *
9 * This software was developed by the Computer Systems Engineering group
10 * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
11 * contributed to Berkeley.
12 *
13 * All advertising materials mentioning features or use of this software
14 * must display the following acknowledgement:
15 *	This product includes software developed by the University of
16 *	California, Lawrence Berkeley Laboratory.
17 *
18 * Redistribution and use in source and binary forms, with or without
19 * modification, are permitted provided that the following conditions
20 * are met:
21 * 1. Redistributions of source code must retain the above copyright
22 *    notice, this list of conditions and the following disclaimer.
23 * 2. Redistributions in binary form must reproduce the above copyright
24 *    notice, this list of conditions and the following disclaimer in the
25 *    documentation and/or other materials provided with the distribution.
26 * 3. Neither the name of the University nor the names of its contributors
27 *    may be used to endorse or promote products derived from this software
28 *    without specific prior written permission.
29 *
30 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
31 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
32 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
33 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
34 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
35 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
36 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
37 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
38 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
39 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
40 * SUCH DAMAGE.
41 *
42 *	@(#)ieee.h	8.1 (Berkeley) 6/11/93
43 *
44 * $FreeBSD: stable/11/sys/arm/include/ieee.h 330897 2018-03-14 03:19:51Z eadler $
45 *
46 */
47
48/*
49 * NOTICE: This is not a standalone file.  To use it, #include it in
50 * your port's ieee.h header.
51 */
52
53#include <machine/endian.h>
54
55/*
56 * <sys/ieee754.h> defines the layout of IEEE 754 floating point types.
57 * Only single-precision and double-precision types are defined here;
58 * extended types, if available, are defined in the machine-dependent
59 * header.
60 */
61
62/*
63 * Define the number of bits in each fraction and exponent.
64 *
65 *		     k	         k+1
66 * Note that  1.0 x 2  == 0.1 x 2      and that denorms are represented
67 *
68 *					  (-exp_bias+1)
69 * as fractions that look like 0.fffff x 2             .  This means that
70 *
71 *			 -126
72 * the number 0.10000 x 2    , for instance, is the same as the normalized
73 *
74 *		-127			   -128
75 * float 1.0 x 2    .  Thus, to represent 2    , we need one leading zero
76 *
77 *				  -129
78 * in the fraction; to represent 2    , we need two, and so on.  This
79 *
80 *						     (-exp_bias-fracbits+1)
81 * implies that the smallest denormalized number is 2
82 *
83 * for whichever format we are talking about: for single precision, for
84 *
85 *						-126		-149
86 * instance, we get .00000000000000000000001 x 2    , or 1.0 x 2    , and
87 *
88 * -149 == -127 - 23 + 1.
89 */
90#define	SNG_EXPBITS	8
91#define	SNG_FRACBITS	23
92
93#define	DBL_EXPBITS	11
94#define	DBL_FRACBITS	52
95
96#if defined(__VFP_FP__) || defined(__ARM_EABI__)
97#define	_IEEE_WORD_ORDER	_BYTE_ORDER
98#else
99#define	_IEEE_WORD_ORDER	_BIG_ENDIAN
100#endif
101
102struct ieee_single {
103#if _BYTE_ORDER == _BIG_ENDIAN
104	u_int	sng_sign:1;
105	u_int	sng_exp:8;
106	u_int	sng_frac:23;
107#else
108	u_int	sng_frac:23;
109	u_int	sng_exp:8;
110	u_int	sng_sign:1;
111#endif
112};
113
114struct ieee_double {
115#if _BYTE_ORDER == _BIG_ENDIAN
116	u_int	dbl_sign:1;
117	u_int	dbl_exp:11;
118	u_int	dbl_frach:20;
119	u_int	dbl_fracl;
120#else
121#if _IEEE_WORD_ORDER == _LITTLE_ENDIAN
122	u_int	dbl_fracl;
123#endif
124	u_int	dbl_frach:20;
125	u_int	dbl_exp:11;
126	u_int	dbl_sign:1;
127#if _IEEE_WORD_ORDER == _BIG_ENDIAN
128	u_int   dbl_fracl;
129#endif
130#endif
131};
132
133/*
134 * Floats whose exponent is in [1..INFNAN) (of whatever type) are
135 * `normal'.  Floats whose exponent is INFNAN are either Inf or NaN.
136 * Floats whose exponent is zero are either zero (iff all fraction
137 * bits are zero) or subnormal values.
138 *
139 * A NaN is a `signalling NaN' if its QUIETNAN bit is clear in its
140 * high fraction; if the bit is set, it is a `quiet NaN'.
141 */
142#define	SNG_EXP_INFNAN	255
143#define	DBL_EXP_INFNAN	2047
144
145#if 0
146#define	SNG_QUIETNAN	(1 << 22)
147#define	DBL_QUIETNAN	(1 << 19)
148#endif
149
150/*
151 * Exponent biases.
152 */
153#define	SNG_EXP_BIAS	127
154#define	DBL_EXP_BIAS	1023
155
156/*
157 * Convenience data structures.
158 */
159union ieee_single_u {
160	float			sngu_f;
161	struct ieee_single	sngu_sng;
162};
163
164union ieee_double_u {
165	double			dblu_d;
166	struct ieee_double	dblu_dbl;
167};
168