1 /* $OpenBSD: ieee.h,v 1.2 2003/06/02 23:27:47 millert Exp $ */
2 /* $NetBSD: ieee.h,v 1.1 1996/09/30 16:34:25 ws 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. Neither the name of the University nor the names of its contributors
26 * may be used to endorse or promote products derived from this software
27 * without specific prior written permission.
28 *
29 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
30 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
31 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
32 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
33 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
34 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
35 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
36 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
37 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
38 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
39 * SUCH DAMAGE.
40 *
41 * @(#)ieee.h 8.1 (Berkeley) 6/11/93
42 */
43
44 /*
45 * ieee.h defines the machine-dependent layout of the machine's IEEE
46 * floating point. It does *not* define (yet?) any of the rounding
47 * mode bits, exceptions, and so forth.
48 */
49
50 /*
51 * Define the number of bits in each fraction and exponent.
52 *
53 * k k+1
54 * Note that 1.0 x 2 == 0.1 x 2 and that denorms are represented
55 *
56 * (-exp_bias+1)
57 * as fractions that look like 0.fffff x 2 . This means that
58 *
59 * -126
60 * the number 0.10000 x 2 , for instance, is the same as the normalized
61 *
62 * -127 -128
63 * float 1.0 x 2 . Thus, to represent 2 , we need one leading zero
64 *
65 * -129
66 * in the fraction; to represent 2 , we need two, and so on. This
67 *
68 * (-exp_bias-fracbits+1)
69 * implies that the smallest denormalized number is 2
70 *
71 * for whichever format we are talking about: for single precision, for
72 *
73 * -126 -149
74 * instance, we get .00000000000000000000001 x 2 , or 1.0 x 2 , and
75 *
76 * -149 == -127 - 23 + 1.
77 */
78 #define SNG_EXPBITS 8
79 #define SNG_FRACBITS 23
80
81 #define DBL_EXPBITS 11
82 #define DBL_FRACBITS 52
83
84 #define EXT_EXPBITS 15
85 #define EXT_FRACBITS 112
86
87 struct ieee_single {
88 u_int sng_frac:23;
89 u_int sng_exp:8;
90 u_int sng_sign:1;
91 };
92
93 struct ieee_double {
94 u_int dbl_fracl;
95 u_int dbl_frach:20;
96 u_int dbl_exp:11;
97 u_int dbl_sign:1;
98 };
99
100 struct ieee_ext {
101 u_int ext_fracl;
102 u_int ext_fraclm;
103 u_int ext_frachm;
104 u_int ext_frach:16;
105 u_int ext_exp:15;
106 u_int ext_sign:1;
107 };
108
109 /*
110 * Floats whose exponent is in [1..INFNAN) (of whatever type) are
111 * `normal'. Floats whose exponent is INFNAN are either Inf or NaN.
112 * Floats whose exponent is zero are either zero (iff all fraction
113 * bits are zero) or subnormal values.
114 *
115 * A NaN is a `signalling NaN' if its QUIETNAN bit is clear in its
116 * high fraction; if the bit is set, it is a `quiet NaN'.
117 */
118 #define SNG_EXP_INFNAN 255
119 #define DBL_EXP_INFNAN 2047
120 #define EXT_EXP_INFNAN 32767
121
122 #if 0
123 #define SNG_QUIETNAN (1 << 22)
124 #define DBL_QUIETNAN (1 << 19)
125 #define EXT_QUIETNAN (1 << 15)
126 #endif
127
128 /*
129 * Exponent biases.
130 */
131 #define SNG_EXP_BIAS 127
132 #define DBL_EXP_BIAS 1023
133 #define EXT_EXP_BIAS 16383