1 /*
2 * Copyright (c) 2003, 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. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package jdk.internal.math;
27
28 /**
29 * This class contains additional constants documenting limits of the
30 * <code>float</code> type.
31 *
32 * @author Joseph D. Darcy
33 */
34
35 public class FloatConsts {
36 /**
37 * Don't let anyone instantiate this class.
38 */
39 private FloatConsts() {}
40
41 public static final float POSITIVE_INFINITY = java.lang.Float.POSITIVE_INFINITY;
42 public static final float NEGATIVE_INFINITY = java.lang.Float.NEGATIVE_INFINITY;
43 public static final float NaN = java.lang.Float.NaN;
44 public static final float MAX_VALUE = java.lang.Float.MAX_VALUE;
45 public static final float MIN_VALUE = java.lang.Float.MIN_VALUE;
46
47 /**
48 * A constant holding the smallest positive normal value of type
49 * <code>float</code>, 2<sup>-126</sup>. It is equal to the value
50 * returned by <code>Float.intBitsToFloat(0x00800000)</code>.
51 */
52 public static final float MIN_NORMAL = 1.17549435E-38f;
53
54 /**
55 * The number of logical bits in the significand of a
56 * <code>float</code> number, including the implicit bit.
57 */
58 public static final int SIGNIFICAND_WIDTH = 24;
59
60 /**
61 * Maximum exponent a finite <code>float</code> number may have.
62 * It is equal to the value returned by
63 * <code>Math.ilogb(Float.MAX_VALUE)</code>.
64 */
65 public static final int MAX_EXPONENT = 127;
66
67 /**
68 * Minimum exponent a normalized <code>float</code> number may
69 * have. It is equal to the value returned by
70 * <code>Math.ilogb(Float.MIN_NORMAL)</code>.
71 */
72 public static final int MIN_EXPONENT = -126;
73
74 /**
75 * The exponent the smallest positive <code>float</code> subnormal
76 * value would have if it could be normalized.
77 */
78 public static final int MIN_SUB_EXPONENT = MIN_EXPONENT -
79 (SIGNIFICAND_WIDTH - 1);
80
81 /**
82 * Bias used in representing a <code>float</code> exponent.
83 */
84 public static final int EXP_BIAS = 127;
85
86 /**
87 * Bit mask to isolate the sign bit of a <code>float</code>.
88 */
89 public static final int SIGN_BIT_MASK = 0x80000000;
90
91 /**
92 * Bit mask to isolate the exponent field of a
93 * <code>float</code>.
94 */
95 public static final int EXP_BIT_MASK = 0x7F800000;
96
97 /**
98 * Bit mask to isolate the significand field of a
99 * <code>float</code>.
100 */
101 public static final int SIGNIF_BIT_MASK = 0x007FFFFF;
102
103 static {
104 // verify bit masks cover all bit positions and that the bit
105 // masks are non-overlapping
106 assert(((SIGN_BIT_MASK | EXP_BIT_MASK | SIGNIF_BIT_MASK) == ~0) &&
107 (((SIGN_BIT_MASK & EXP_BIT_MASK) == 0) &&
108 ((SIGN_BIT_MASK & SIGNIF_BIT_MASK) == 0) &&
109 ((EXP_BIT_MASK & SIGNIF_BIT_MASK) == 0)));
110 }
111 }