Annotation of sys/arch/powerpc/include/ieee.h, Revision 1.1.1.1
1.1 nbrk 1: /* $OpenBSD: ieee.h,v 1.4 2003/06/02 23:27:53 millert 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:
43: /*
44: * ieee.h defines the machine-dependent layout of the machine's IEEE
45: * floating point. It does *not* define (yet?) any of the rounding
46: * mode bits, exceptions, and so forth.
47: */
48:
49: /*
50: * Define the number of bits in each fraction and exponent.
51: *
52: * k k+1
53: * Note that 1.0 x 2 == 0.1 x 2 and that denorms are represented
54: *
55: * (-exp_bias+1)
56: * as fractions that look like 0.fffff x 2 . This means that
57: *
58: * -126
59: * the number 0.10000 x 2 , for instance, is the same as the normalized
60: *
61: * -127 -128
62: * float 1.0 x 2 . Thus, to represent 2 , we need one leading zero
63: *
64: * -129
65: * in the fraction; to represent 2 , we need two, and so on. This
66: *
67: * (-exp_bias-fracbits+1)
68: * implies that the smallest denormalized number is 2
69: *
70: * for whichever format we are talking about: for single precision, for
71: *
72: * -126 -149
73: * instance, we get .00000000000000000000001 x 2 , or 1.0 x 2 , and
74: *
75: * -149 == -127 - 23 + 1.
76: */
77: #define SNG_EXPBITS 8
78: #define SNG_FRACBITS 23
79:
80: #define DBL_EXPBITS 11
81: #define DBL_FRACBITS 52
82:
83: #define EXT_EXPBITS 15
84: #define EXT_FRACBITS 112
85:
86: struct ieee_single {
87: u_int sng_sign:1;
88: u_int sng_exp:8;
89: u_int sng_frac:23;
90: };
91:
92: struct ieee_double {
93: u_int dbl_sign:1;
94: u_int dbl_exp:11;
95: u_int dbl_frach:20;
96: u_int dbl_fracl;
97: };
98:
99: struct ieee_ext {
100: u_int ext_sign:1;
101: u_int ext_exp:15;
102: u_int ext_frach:16;
103: u_int ext_frachm;
104: u_int ext_fraclm;
105: u_int ext_fracl;
106: };
107:
108: /*
109: * Floats whose exponent is in [1..INFNAN) (of whatever type) are
110: * `normal'. Floats whose exponent is INFNAN are either Inf or NaN.
111: * Floats whose exponent is zero are either zero (iff all fraction
112: * bits are zero) or subnormal values.
113: *
114: * A NaN is a `signalling NaN' if its QUIETNAN bit is clear in its
115: * high fraction; if the bit is set, it is a `quiet NaN'.
116: */
117: #define SNG_EXP_INFNAN 255
118: #define DBL_EXP_INFNAN 2047
119: #define EXT_EXP_INFNAN 32767
120:
121: #if 0
122: #define SNG_QUIETNAN (1 << 22)
123: #define DBL_QUIETNAN (1 << 19)
124: #define EXT_QUIETNAN (1 << 15)
125: #endif
126:
127: /*
128: * Exponent biases.
129: */
130: #define SNG_EXP_BIAS 127
131: #define DBL_EXP_BIAS 1023
132: #define EXT_EXP_BIAS 16383
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