1 /* 2 * Copyright (c) 2003, 2022, 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 import static java.lang.Double.MIN_EXPONENT; 29 import static java.lang.Double.PRECISION; 30 import static java.lang.Double.SIZE; 31 32 /** 33 * This class contains additional constants documenting limits of the 34 * {@code double} type. 35 * 36 * @author Joseph D. Darcy 37 */ 38 39 public class DoubleConsts { 40 /** 41 * Don't let anyone instantiate this class. 42 */ DoubleConsts()43 private DoubleConsts() {} 44 45 public static final double POSITIVE_INFINITY = java.lang.Double.POSITIVE_INFINITY; 46 public static final double NEGATIVE_INFINITY = java.lang.Double.NEGATIVE_INFINITY; 47 public static final double NaN = java.lang.Double.NaN; 48 public static final double MAX_VALUE = java.lang.Double.MAX_VALUE; 49 public static final double MIN_VALUE = java.lang.Double.MIN_VALUE; 50 51 /** 52 * A constant holding the smallest positive normal value of type 53 * <code>double</code>, 2<sup>-1022</sup>. It is equal to the 54 * value returned by 55 * <code>Double.longBitsToDouble(0x0010000000000000L)</code>. 56 * 57 * @since 1.5 58 */ 59 public static final double MIN_NORMAL = 2.2250738585072014E-308; 60 61 62 /** 63 * The number of logical bits in the significand of a 64 * {@code double} number, including the implicit bit. 65 */ 66 public static final int SIGNIFICAND_WIDTH = PRECISION; 67 68 /** 69 * Maximum exponent a finite <code>double</code> number may have. 70 * It is equal to the value returned by 71 * <code>Math.ilogb(Double.MAX_VALUE)</code>. 72 */ 73 public static final int MAX_EXPONENT = 1023; 74 75 /** 76 * Minimum exponent a normalized <code>double</code> number may 77 * have. It is equal to the value returned by 78 * <code>Math.ilogb(Double.MIN_NORMAL)</code>. 79 */ 80 public static final int MIN_EXPONENT = -1022; 81 82 /** 83 * The exponent the smallest positive {@code double} 84 * subnormal value would have if it could be normalized.. 85 */ 86 public static final int MIN_SUB_EXPONENT = 87 MIN_EXPONENT - (SIGNIFICAND_WIDTH - 1); // -1074 88 89 /** 90 * Bias used in representing a {@code double} exponent. 91 */ 92 public static final int EXP_BIAS = 93 (1 << (SIZE - SIGNIFICAND_WIDTH - 1)) - 1; // 1023 94 95 /** 96 * Bit mask to isolate the sign bit of a {@code double}. 97 */ 98 public static final long SIGN_BIT_MASK = 1L << (SIZE - 1); 99 100 /** 101 * Bit mask to isolate the exponent field of a {@code double}. 102 */ 103 public static final long EXP_BIT_MASK = 104 ((1L << (SIZE - SIGNIFICAND_WIDTH)) - 1) << (SIGNIFICAND_WIDTH - 1); 105 106 /** 107 * Bit mask to isolate the significand field of a {@code double}. 108 */ 109 public static final long SIGNIF_BIT_MASK = (1L << (SIGNIFICAND_WIDTH - 1)) - 1; 110 111 /** 112 * Bit mask to isolate the magnitude bits (combined exponent and 113 * significand fields) of a {@code double}. 114 */ 115 public static final long MAG_BIT_MASK = EXP_BIT_MASK | SIGNIF_BIT_MASK; 116 117 static { 118 // verify bit masks cover all bit positions and that the bit 119 // masks are non-overlapping 120 assert(((SIGN_BIT_MASK | EXP_BIT_MASK | SIGNIF_BIT_MASK) == ~0L) && 121 (((SIGN_BIT_MASK & EXP_BIT_MASK) == 0L) && 122 ((SIGN_BIT_MASK & SIGNIF_BIT_MASK) == 0L) && 123 ((EXP_BIT_MASK & SIGNIF_BIT_MASK) == 0L)) && 124 ((SIGN_BIT_MASK | MAG_BIT_MASK) == ~0L)); 125 } 126 } 127