Annotation of sys/arch/m88k/include/ieee.h, Revision 1.1.1.1
1.1 nbrk 1: /* $OpenBSD: ieee.h,v 1.2 2006/05/04 19:28:43 miod Exp $ */
2: /*
3: * Copyright (c) 1992, 1993
4: * The Regents of the University of California. All rights reserved.
5: *
6: * This software was developed by the Computer Systems Engineering group
7: * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
8: * contributed to Berkeley.
9: *
10: * All advertising materials mentioning features or use of this software
11: * must display the following acknowledgement:
12: * This product includes software developed by the University of
13: * California, Lawrence Berkeley Laboratory.
14: *
15: * Redistribution and use in source and binary forms, with or without
16: * modification, are permitted provided that the following conditions
17: * are met:
18: * 1. Redistributions of source code must retain the above copyright
19: * notice, this list of conditions and the following disclaimer.
20: * 2. Redistributions in binary form must reproduce the above copyright
21: * notice, this list of conditions and the following disclaimer in the
22: * documentation and/or other materials provided with the distribution.
23: * 3. Neither the name of the University nor the names of its contributors
24: * may be used to endorse or promote products derived from this software
25: * without specific prior written permission.
26: *
27: * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
28: * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
29: * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
30: * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
31: * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
32: * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
33: * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
34: * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
35: * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
36: * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
37: * SUCH DAMAGE.
38: *
39: * @(#)ieee.h 8.1 (Berkeley) 6/11/93
40: */
41:
42: /*
43: * ieee.h defines the machine-dependent layout of the machine's IEEE
44: * floating point. It does *not* define (yet?) any of the rounding
45: * mode bits, exceptions, and so forth.
46: */
47:
48: /*
49: * Define the number of bits in each fraction and exponent.
50: *
51: * k k+1
52: * Note that 1.0 x 2 == 0.1 x 2 and that denorms are represented
53: *
54: * (-exp_bias+1)
55: * as fractions that look like 0.fffff x 2 . This means that
56: *
57: * -126
58: * the number 0.10000 x 2 , for instance, is the same as the normalized
59: *
60: * -127 -128
61: * float 1.0 x 2 . Thus, to represent 2 , we need one leading zero
62: *
63: * -129
64: * in the fraction; to represent 2 , we need two, and so on. This
65: *
66: * (-exp_bias-fracbits+1)
67: * implies that the smallest denormalized number is 2
68: *
69: * for whichever format we are talking about: for single precision, for
70: *
71: * -126 -149
72: * instance, we get .00000000000000000000001 x 2 , or 1.0 x 2 , and
73: *
74: * -149 == -127 - 23 + 1.
75: */
76: #define SNG_EXPBITS 8
77: #define SNG_FRACBITS 23
78:
79: #define DBL_EXPBITS 11
80: #define DBL_FRACBITS 52
81:
82: #define EXT_EXPBITS 15
83: #define EXT_FRACBITS 64
84:
85: struct ieee_single {
86: u_int sng_sign:1;
87: u_int sng_exp:8;
88: u_int sng_frac:23;
89: };
90:
91: struct ieee_double {
92: u_int dbl_sign:1;
93: u_int dbl_exp:11;
94: u_int dbl_frach:20;
95: u_int dbl_fracl;
96: };
97:
98: struct ieee_ext {
99: u_int ext_sign:1;
100: u_int ext_exp:15;
101: u_int ext_lead:1;
102: u_int ext_frach:31;
103: u_int ext_fracl;
104: };
105:
106: /*
107: * Floats whose exponent is in [1..INFNAN) (of whatever type) are
108: * `normal'. Floats whose exponent is INFNAN are either Inf or NaN.
109: * Floats whose exponent is zero are either zero (iff all fraction
110: * bits are zero) or subnormal values.
111: *
112: * A NaN is a `signalling NaN' if its QUIETNAN bit is clear in its
113: * high fraction; if the bit is set, it is a `quiet NaN'.
114: */
115: #define SNG_EXP_INFNAN 255
116: #define DBL_EXP_INFNAN 2047
117: #define EXT_EXP_INFNAN 32767
118:
119: #if 0
120: #define SNG_QUIETNAN (1 << 22)
121: #define DBL_QUIETNAN (1 << 19)
122: #define EXT_QUIETNAN (1 << 30)
123: #endif
124:
125: /*
126: * Exponent biases.
127: */
128: #define SNG_EXP_BIAS 127
129: #define DBL_EXP_BIAS 1023
130: #define EXT_EXP_BIAS 16383
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