Annotation of sys/arch/i386/include/ieee.h, Revision 1.1.1.1
1.1 nbrk 1: /* $OpenBSD: ieee.h,v 1.2 2003/06/02 23:27:47 millert Exp $ */
2: /* $NetBSD: ieee.h,v 1.1 1996/09/30 16:34:25 ws 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:
44: /*
45: * ieee.h defines the machine-dependent layout of the machine's IEEE
46: * floating point. It does *not* define (yet?) any of the rounding
47: * mode bits, exceptions, and so forth.
48: */
49:
50: /*
51: * Define the number of bits in each fraction and exponent.
52: *
53: * k k+1
54: * Note that 1.0 x 2 == 0.1 x 2 and that denorms are represented
55: *
56: * (-exp_bias+1)
57: * as fractions that look like 0.fffff x 2 . This means that
58: *
59: * -126
60: * the number 0.10000 x 2 , for instance, is the same as the normalized
61: *
62: * -127 -128
63: * float 1.0 x 2 . Thus, to represent 2 , we need one leading zero
64: *
65: * -129
66: * in the fraction; to represent 2 , we need two, and so on. This
67: *
68: * (-exp_bias-fracbits+1)
69: * implies that the smallest denormalized number is 2
70: *
71: * for whichever format we are talking about: for single precision, for
72: *
73: * -126 -149
74: * instance, we get .00000000000000000000001 x 2 , or 1.0 x 2 , and
75: *
76: * -149 == -127 - 23 + 1.
77: */
78: #define SNG_EXPBITS 8
79: #define SNG_FRACBITS 23
80:
81: #define DBL_EXPBITS 11
82: #define DBL_FRACBITS 52
83:
84: #define EXT_EXPBITS 15
85: #define EXT_FRACBITS 112
86:
87: struct ieee_single {
88: u_int sng_frac:23;
89: u_int sng_exp:8;
90: u_int sng_sign:1;
91: };
92:
93: struct ieee_double {
94: u_int dbl_fracl;
95: u_int dbl_frach:20;
96: u_int dbl_exp:11;
97: u_int dbl_sign:1;
98: };
99:
100: struct ieee_ext {
101: u_int ext_fracl;
102: u_int ext_fraclm;
103: u_int ext_frachm;
104: u_int ext_frach:16;
105: u_int ext_exp:15;
106: u_int ext_sign:1;
107: };
108:
109: /*
110: * Floats whose exponent is in [1..INFNAN) (of whatever type) are
111: * `normal'. Floats whose exponent is INFNAN are either Inf or NaN.
112: * Floats whose exponent is zero are either zero (iff all fraction
113: * bits are zero) or subnormal values.
114: *
115: * A NaN is a `signalling NaN' if its QUIETNAN bit is clear in its
116: * high fraction; if the bit is set, it is a `quiet NaN'.
117: */
118: #define SNG_EXP_INFNAN 255
119: #define DBL_EXP_INFNAN 2047
120: #define EXT_EXP_INFNAN 32767
121:
122: #if 0
123: #define SNG_QUIETNAN (1 << 22)
124: #define DBL_QUIETNAN (1 << 19)
125: #define EXT_QUIETNAN (1 << 15)
126: #endif
127:
128: /*
129: * Exponent biases.
130: */
131: #define SNG_EXP_BIAS 127
132: #define DBL_EXP_BIAS 1023
133: #define EXT_EXP_BIAS 16383
CVSweb