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 * $FreeBSD$
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 struct ieee_single {
97 #if _BYTE_ORDER == _BIG_ENDIAN
98 u_int sng_sign:1;
99 u_int sng_exp:8;
100 u_int sng_frac:23;
101 #else
102 u_int sng_frac:23;
103 u_int sng_exp:8;
104 u_int sng_sign:1;
105 #endif
106 };
107
108 struct ieee_double {
109 #if _BYTE_ORDER == _BIG_ENDIAN
110 u_int dbl_sign:1;
111 u_int dbl_exp:11;
112 u_int dbl_frach:20;
113 u_int dbl_fracl;
114 #else
115 u_int dbl_fracl;
116 u_int dbl_frach:20;
117 u_int dbl_exp:11;
118 u_int dbl_sign:1;
119 #endif
120 };
121
122 /*
123 * Floats whose exponent is in [1..INFNAN) (of whatever type) are
124 * `normal'. Floats whose exponent is INFNAN are either Inf or NaN.
125 * Floats whose exponent is zero are either zero (iff all fraction
126 * bits are zero) or subnormal values.
127 *
128 * A NaN is a `signalling NaN' if its QUIETNAN bit is clear in its
129 * high fraction; if the bit is set, it is a `quiet NaN'.
130 */
131 #define SNG_EXP_INFNAN 255
132 #define DBL_EXP_INFNAN 2047
133
134 #if 0
135 #define SNG_QUIETNAN (1 << 22)
136 #define DBL_QUIETNAN (1 << 19)
137 #endif
138
139 /*
140 * Exponent biases.
141 */
142 #define SNG_EXP_BIAS 127
143 #define DBL_EXP_BIAS 1023
144
145 /*
146 * Convenience data structures.
147 */
148 union ieee_single_u {
149 float sngu_f;
150 struct ieee_single sngu_sng;
151 };
152
153 union ieee_double_u {
154 double dblu_d;
155 struct ieee_double dblu_dbl;
156 };
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