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