Annotation of sys/arch/alpha/include/ieee.h, Revision 1.1.1.1
1.1 nbrk 1: /* $OpenBSD: ieee.h,v 1.4 2003/06/02 23:27:43 millert Exp $ */
2: /* $NetBSD: ieee.h,v 1.1 1995/02/13 23:07:40 cgd 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: * from: Header: ieee.h,v 1.7 92/11/26 02:04:37 torek Exp
44: */
45:
46: /*
47: * ieee.h defines the machine-dependent layout of the machine's IEEE
48: * floating point. It does *not* define (yet?) any of the rounding
49: * mode bits, exceptions, and so forth.
50: */
51:
52: /*
53: * Define the number of bits in each fraction and exponent.
54: *
55: * k k+1
56: * Note that 1.0 x 2 == 0.1 x 2 and that denorms are represented
57: *
58: * (-exp_bias+1)
59: * as fractions that look like 0.fffff x 2 . This means that
60: *
61: * -126
62: * the number 0.10000 x 2 , for instance, is the same as the normalized
63: *
64: * -127 -128
65: * float 1.0 x 2 . Thus, to represent 2 , we need one leading zero
66: *
67: * -129
68: * in the fraction; to represent 2 , we need two, and so on. This
69: *
70: * (-exp_bias-fracbits+1)
71: * implies that the smallest denormalized number is 2
72: *
73: * for whichever format we are talking about: for single precision, for
74: *
75: * -126 -149
76: * instance, we get .00000000000000000000001 x 2 , or 1.0 x 2 , and
77: *
78: * -149 == -127 - 23 + 1.
79: */
80: #define SNG_EXPBITS 8
81: #define SNG_FRACBITS 23
82:
83: #define DBL_EXPBITS 11
84: #define DBL_FRACBITS 52
85:
86: struct ieee_single {
87: u_int sng_frac:23;
88: u_int sng_exp:8;
89: u_int sng_sign:1;
90: };
91:
92: struct ieee_double {
93: u_int dbl_fracl;
94: u_int dbl_frach:20;
95: u_int dbl_exp:11;
96: u_int dbl_sign:1;
97: };
98:
99: /*
100: * Floats whose exponent is in [1..INFNAN) (of whatever type) are
101: * `normal'. Floats whose exponent is INFNAN are either Inf or NaN.
102: * Floats whose exponent is zero are either zero (iff all fraction
103: * bits are zero) or subnormal values.
104: *
105: * A NaN is a `signalling NaN' if its QUIETNAN bit is clear in its
106: * high fraction; if the bit is set, it is a `quiet NaN'.
107: */
108: #define SNG_EXP_INFNAN 255
109: #define DBL_EXP_INFNAN 2047
110:
111: #if 0
112: #define SNG_QUIETNAN (1 << 22)
113: #define DBL_QUIETNAN (1 << 19)
114: #endif
115:
116: /*
117: * Exponent biases.
118: */
119: #define SNG_EXP_BIAS 127
120: #define DBL_EXP_BIAS 1023
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