ieee.h revision 1.1 1 1.1 itojun /* $NetBSD: ieee.h,v 1.1 1999/09/13 10:31:18 itojun Exp $ */
2 1.1 itojun
3 1.1 itojun /*
4 1.1 itojun * Copyright (c) 1992, 1993
5 1.1 itojun * The Regents of the University of California. All rights reserved.
6 1.1 itojun *
7 1.1 itojun * This software was developed by the Computer Systems Engineering group
8 1.1 itojun * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
9 1.1 itojun * contributed to Berkeley.
10 1.1 itojun *
11 1.1 itojun * All advertising materials mentioning features or use of this software
12 1.1 itojun * must display the following acknowledgement:
13 1.1 itojun * This product includes software developed by the University of
14 1.1 itojun * California, Lawrence Berkeley Laboratory.
15 1.1 itojun *
16 1.1 itojun * Redistribution and use in source and binary forms, with or without
17 1.1 itojun * modification, are permitted provided that the following conditions
18 1.1 itojun * are met:
19 1.1 itojun * 1. Redistributions of source code must retain the above copyright
20 1.1 itojun * notice, this list of conditions and the following disclaimer.
21 1.1 itojun * 2. Redistributions in binary form must reproduce the above copyright
22 1.1 itojun * notice, this list of conditions and the following disclaimer in the
23 1.1 itojun * documentation and/or other materials provided with the distribution.
24 1.1 itojun * 3. All advertising materials mentioning features or use of this software
25 1.1 itojun * must display the following acknowledgement:
26 1.1 itojun * This product includes software developed by the University of
27 1.1 itojun * California, Berkeley and its contributors.
28 1.1 itojun * 4. Neither the name of the University nor the names of its contributors
29 1.1 itojun * may be used to endorse or promote products derived from this software
30 1.1 itojun * without specific prior written permission.
31 1.1 itojun *
32 1.1 itojun * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
33 1.1 itojun * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
34 1.1 itojun * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
35 1.1 itojun * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
36 1.1 itojun * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
37 1.1 itojun * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
38 1.1 itojun * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
39 1.1 itojun * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
40 1.1 itojun * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
41 1.1 itojun * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
42 1.1 itojun * SUCH DAMAGE.
43 1.1 itojun *
44 1.1 itojun * @(#)ieee.h 8.1 (Berkeley) 6/11/93
45 1.1 itojun */
46 1.1 itojun
47 1.1 itojun /*
48 1.1 itojun * ieee.h defines the machine-dependent layout of the machine's IEEE
49 1.1 itojun * floating point. It does *not* define (yet?) any of the rounding
50 1.1 itojun * mode bits, exceptions, and so forth.
51 1.1 itojun */
52 1.1 itojun
53 1.1 itojun /*
54 1.1 itojun * Define the number of bits in each fraction and exponent.
55 1.1 itojun *
56 1.1 itojun * k k+1
57 1.1 itojun * Note that 1.0 x 2 == 0.1 x 2 and that denorms are represented
58 1.1 itojun *
59 1.1 itojun * (-exp_bias+1)
60 1.1 itojun * as fractions that look like 0.fffff x 2 . This means that
61 1.1 itojun *
62 1.1 itojun * -126
63 1.1 itojun * the number 0.10000 x 2 , for instance, is the same as the normalized
64 1.1 itojun *
65 1.1 itojun * -127 -128
66 1.1 itojun * float 1.0 x 2 . Thus, to represent 2 , we need one leading zero
67 1.1 itojun *
68 1.1 itojun * -129
69 1.1 itojun * in the fraction; to represent 2 , we need two, and so on. This
70 1.1 itojun *
71 1.1 itojun * (-exp_bias-fracbits+1)
72 1.1 itojun * implies that the smallest denormalized number is 2
73 1.1 itojun *
74 1.1 itojun * for whichever format we are talking about: for single precision, for
75 1.1 itojun *
76 1.1 itojun * -126 -149
77 1.1 itojun * instance, we get .00000000000000000000001 x 2 , or 1.0 x 2 , and
78 1.1 itojun *
79 1.1 itojun * -149 == -127 - 23 + 1.
80 1.1 itojun */
81 1.1 itojun #define SNG_EXPBITS 8
82 1.1 itojun #define SNG_FRACBITS 23
83 1.1 itojun
84 1.1 itojun #define DBL_EXPBITS 11
85 1.1 itojun #define DBL_FRACBITS 52
86 1.1 itojun
87 1.1 itojun #define EXT_EXPBITS 15
88 1.1 itojun #define EXT_FRACBITS 112
89 1.1 itojun
90 1.1 itojun #ifndef BYTE_ORDER
91 1.1 itojun #error Define BYTE_ORDER!
92 1.1 itojun #endif
93 1.1 itojun
94 1.1 itojun #if BYTE_ORDER == BIG_ENDIAN
95 1.1 itojun struct ieee_single {
96 1.1 itojun u_int sng_sign:1;
97 1.1 itojun u_int sng_exp:8;
98 1.1 itojun u_int sng_frac:23;
99 1.1 itojun };
100 1.1 itojun
101 1.1 itojun struct ieee_double {
102 1.1 itojun u_int dbl_sign:1;
103 1.1 itojun u_int dbl_exp:11;
104 1.1 itojun u_int dbl_frach:20;
105 1.1 itojun u_int dbl_fracl;
106 1.1 itojun };
107 1.1 itojun
108 1.1 itojun struct ieee_ext {
109 1.1 itojun u_int ext_sign:1;
110 1.1 itojun u_int ext_exp:15;
111 1.1 itojun u_int ext_frach:16;
112 1.1 itojun u_int ext_frachm;
113 1.1 itojun u_int ext_fraclm;
114 1.1 itojun u_int ext_fracl;
115 1.1 itojun };
116 1.1 itojun #endif
117 1.1 itojun #if BYTE_ORDER == LITTLE_ENDIAN
118 1.1 itojun struct ieee_single {
119 1.1 itojun u_int sng_frac:23;
120 1.1 itojun u_int sng_exp:8;
121 1.1 itojun u_int sng_sign:1;
122 1.1 itojun };
123 1.1 itojun
124 1.1 itojun struct ieee_double {
125 1.1 itojun u_int dbl_fracl;
126 1.1 itojun u_int dbl_frach:20;
127 1.1 itojun u_int dbl_exp:11;
128 1.1 itojun u_int dbl_sign:1;
129 1.1 itojun };
130 1.1 itojun
131 1.1 itojun struct ieee_ext {
132 1.1 itojun u_int ext_fracl;
133 1.1 itojun u_int ext_fraclm;
134 1.1 itojun u_int ext_frachm;
135 1.1 itojun u_int ext_frach:16;
136 1.1 itojun u_int ext_exp:15;
137 1.1 itojun u_int ext_sign:1;
138 1.1 itojun };
139 1.1 itojun #endif
140 1.1 itojun /*
141 1.1 itojun * Floats whose exponent is in [1..INFNAN) (of whatever type) are
142 1.1 itojun * `normal'. Floats whose exponent is INFNAN are either Inf or NaN.
143 1.1 itojun * Floats whose exponent is zero are either zero (iff all fraction
144 1.1 itojun * bits are zero) or subnormal values.
145 1.1 itojun *
146 1.1 itojun * A NaN is a `signalling NaN' if its QUIETNAN bit is clear in its
147 1.1 itojun * high fraction; if the bit is set, it is a `quiet NaN'.
148 1.1 itojun */
149 1.1 itojun #define SNG_EXP_INFNAN 255
150 1.1 itojun #define DBL_EXP_INFNAN 2047
151 1.1 itojun #define EXT_EXP_INFNAN 32767
152 1.1 itojun
153 1.1 itojun #if 0
154 1.1 itojun #define SNG_QUIETNAN (1 << 22)
155 1.1 itojun #define DBL_QUIETNAN (1 << 19)
156 1.1 itojun #define EXT_QUIETNAN (1 << 15)
157 1.1 itojun #endif
158 1.1 itojun
159 1.1 itojun /*
160 1.1 itojun * Exponent biases.
161 1.1 itojun */
162 1.1 itojun #define SNG_EXP_BIAS 127
163 1.1 itojun #define DBL_EXP_BIAS 1023
164 1.1 itojun #define EXT_EXP_BIAS 16383
165