FreeBSD/Linux Kernel Cross Reference
sys/arm/include/ieee.h
1 /* $NetBSD: ieee754.h,v 1.4 2003/10/27 02:30:26 simonb Exp $ */
2
3 /*-
4 * Copyright (c) 1992, 1993
5 * The Regents of the University of California. All rights reserved.
6 *
7 * This software was developed by the Computer Systems Engineering group
8 * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
9 * contributed to Berkeley.
10 *
11 * All advertising materials mentioning features or use of this software
12 * must display the following acknowledgement:
13 * This product includes software developed by the University of
14 * California, Lawrence Berkeley Laboratory.
15 *
16 * Redistribution and use in source and binary forms, with or without
17 * modification, are permitted provided that the following conditions
18 * are met:
19 * 1. Redistributions of source code must retain the above copyright
20 * notice, this list of conditions and the following disclaimer.
21 * 2. Redistributions in binary form must reproduce the above copyright
22 * notice, this list of conditions and the following disclaimer in the
23 * documentation and/or other materials provided with the distribution.
24 * 3. Neither the name of the University nor the names of its contributors
25 * may be used to endorse or promote products derived from this software
26 * without specific prior written permission.
27 *
28 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
29 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
30 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
31 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
32 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
33 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
34 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
35 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
37 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
38 * SUCH DAMAGE.
39 *
40 * @(#)ieee.h 8.1 (Berkeley) 6/11/93
41 *
42 * $FreeBSD: src/sys/arm/include/ieee.h,v 1.3 2008/12/23 22:20:59 marcel Exp $
43 *
44 */
45
46 /*
47 * NOTICE: This is not a standalone file. To use it, #include it in
48 * your port's ieee.h header.
49 */
50
51 #include <machine/endian.h>
52
53 /*
54 * <sys/ieee754.h> defines the layout of IEEE 754 floating point types.
55 * Only single-precision and double-precision types are defined here;
56 * extended types, if available, are defined in the machine-dependent
57 * header.
58 */
59
60 /*
61 * Define the number of bits in each fraction and exponent.
62 *
63 * k k+1
64 * Note that 1.0 x 2 == 0.1 x 2 and that denorms are represented
65 *
66 * (-exp_bias+1)
67 * as fractions that look like 0.fffff x 2 . This means that
68 *
69 * -126
70 * the number 0.10000 x 2 , for instance, is the same as the normalized
71 *
72 * -127 -128
73 * float 1.0 x 2 . Thus, to represent 2 , we need one leading zero
74 *
75 * -129
76 * in the fraction; to represent 2 , we need two, and so on. This
77 *
78 * (-exp_bias-fracbits+1)
79 * implies that the smallest denormalized number is 2
80 *
81 * for whichever format we are talking about: for single precision, for
82 *
83 * -126 -149
84 * instance, we get .00000000000000000000001 x 2 , or 1.0 x 2 , and
85 *
86 * -149 == -127 - 23 + 1.
87 */
88 #define SNG_EXPBITS 8
89 #define SNG_FRACBITS 23
90
91 #define DBL_EXPBITS 11
92 #define DBL_FRACBITS 52
93
94 #if defined(__VFP_FP__)
95 #define _IEEE_WORD_ORDER _BYTE_ORDER
96 #else
97 #define _IEEE_WORD_ORDER _BIG_ENDIAN
98 #endif
99
100 struct ieee_single {
101 #if _BYTE_ORDER == _BIG_ENDIAN
102 u_int sng_sign:1;
103 u_int sng_exp:8;
104 u_int sng_frac:23;
105 #else
106 u_int sng_frac:23;
107 u_int sng_exp:8;
108 u_int sng_sign:1;
109 #endif
110 };
111
112 struct ieee_double {
113 #if _BYTE_ORDER == _BIG_ENDIAN
114 u_int dbl_sign:1;
115 u_int dbl_exp:11;
116 u_int dbl_frach:20;
117 u_int dbl_fracl;
118 #else
119 #if _IEEE_WORD_ORDER == _LITTLE_ENDIAN
120 u_int dbl_fracl;
121 #endif
122 u_int dbl_frach:20;
123 u_int dbl_exp:11;
124 u_int dbl_sign:1;
125 #if _IEEE_WORD_ORDER == _BIG_ENDIAN
126 u_int dbl_fracl;
127 #endif
128 #endif
129 };
130
131 /*
132 * Floats whose exponent is in [1..INFNAN) (of whatever type) are
133 * `normal'. Floats whose exponent is INFNAN are either Inf or NaN.
134 * Floats whose exponent is zero are either zero (iff all fraction
135 * bits are zero) or subnormal values.
136 *
137 * A NaN is a `signalling NaN' if its QUIETNAN bit is clear in its
138 * high fraction; if the bit is set, it is a `quiet NaN'.
139 */
140 #define SNG_EXP_INFNAN 255
141 #define DBL_EXP_INFNAN 2047
142
143 #if 0
144 #define SNG_QUIETNAN (1 << 22)
145 #define DBL_QUIETNAN (1 << 19)
146 #endif
147
148 /*
149 * Exponent biases.
150 */
151 #define SNG_EXP_BIAS 127
152 #define DBL_EXP_BIAS 1023
153
154 /*
155 * Convenience data structures.
156 */
157 union ieee_single_u {
158 float sngu_f;
159 struct ieee_single sngu_sng;
160 };
161
162 union ieee_double_u {
163 double dblu_d;
164 struct ieee_double dblu_dbl;
165 };
166 Cache object: 1ccbd17418dafcfa137976222aa4cbf9
|