1/*
2 * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 */
23
24/**
25 * Common library for additional constants of the {@code double} type.
26 */
27public final class DoubleConsts {
28    /**
29     * Don't let anyone instantiate this class.
30     */
31    private DoubleConsts() {}
32
33    /**
34     * Bias used in representing a {@code double} exponent.
35     */
36    public static final int     EXP_BIAS        = 1023;
37
38    /**
39     * Bit mask to isolate the exponent field of a {@code double}.
40     */
41    public static final long    EXP_BIT_MASK    = 0x7FF0000000000000L;
42
43    /**
44     * Bit mask to isolate the sign bit of a {@code double}.
45     */
46    public static final long    SIGN_BIT_MASK   = 0x8000000000000000L;
47
48    /**
49     * Bit mask to isolate the significand field of a {@code double}.
50     */
51    public static final long    SIGNIF_BIT_MASK = 0x000FFFFFFFFFFFFFL;
52
53    /**
54     * The number of logical bits in the significand of a
55     * {@code double} number, including the implicit bit.
56     */
57    public static final int SIGNIFICAND_WIDTH   = 53;
58
59    /**
60     * The exponent the smallest positive {@code double}
61     * subnormal value would have if it could be normalized.
62     */
63    public static final int     MIN_SUB_EXPONENT = Double.MIN_EXPONENT -
64                                                   (SIGNIFICAND_WIDTH - 1);
65
66    static {
67        // verify bit masks cover all bit positions and that the bit
68        // masks are non-overlapping
69        assert(((SIGN_BIT_MASK | EXP_BIT_MASK | SIGNIF_BIT_MASK) == ~0L) &&
70               (((SIGN_BIT_MASK & EXP_BIT_MASK) == 0L) &&
71                ((SIGN_BIT_MASK & SIGNIF_BIT_MASK) == 0L) &&
72                ((EXP_BIT_MASK & SIGNIF_BIT_MASK) == 0L)));
73    }
74}
75