127 lines
4.5 KiB
Java
127 lines
4.5 KiB
Java
/*
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* Copyright (c) 2003, 2022, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation. Oracle designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Oracle in the LICENSE file that accompanied this code.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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package jdk.internal.math;
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import static java.lang.Double.MIN_EXPONENT;
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import static java.lang.Double.PRECISION;
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import static java.lang.Double.SIZE;
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/**
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* This class contains additional constants documenting limits of the
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* {@code double} type.
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*
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* @author Joseph D. Darcy
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*/
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public class DoubleConsts {
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/**
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* Don't let anyone instantiate this class.
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*/
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private DoubleConsts() {}
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public static final double POSITIVE_INFINITY = java.lang.Double.POSITIVE_INFINITY;
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public static final double NEGATIVE_INFINITY = java.lang.Double.NEGATIVE_INFINITY;
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public static final double NaN = java.lang.Double.NaN;
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public static final double MAX_VALUE = java.lang.Double.MAX_VALUE;
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public static final double MIN_VALUE = java.lang.Double.MIN_VALUE;
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/**
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* A constant holding the smallest positive normal value of type
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* <code>double</code>, 2<sup>-1022</sup>. It is equal to the
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* value returned by
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* <code>Double.longBitsToDouble(0x0010000000000000L)</code>.
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*
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* @since 1.5
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*/
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public static final double MIN_NORMAL = 2.2250738585072014E-308;
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/**
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* The number of logical bits in the significand of a
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* {@code double} number, including the implicit bit.
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*/
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public static final int SIGNIFICAND_WIDTH = PRECISION;
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/**
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* Maximum exponent a finite <code>double</code> number may have.
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* It is equal to the value returned by
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* <code>Math.ilogb(Double.MAX_VALUE)</code>.
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*/
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public static final int MAX_EXPONENT = 1023;
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/**
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* Minimum exponent a normalized <code>double</code> number may
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* have. It is equal to the value returned by
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* <code>Math.ilogb(Double.MIN_NORMAL)</code>.
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*/
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public static final int MIN_EXPONENT = -1022;
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/**
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* The exponent the smallest positive {@code double}
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* subnormal value would have if it could be normalized..
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*/
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public static final int MIN_SUB_EXPONENT =
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MIN_EXPONENT - (SIGNIFICAND_WIDTH - 1); // -1074
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/**
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* Bias used in representing a {@code double} exponent.
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*/
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public static final int EXP_BIAS =
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(1 << (SIZE - SIGNIFICAND_WIDTH - 1)) - 1; // 1023
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/**
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* Bit mask to isolate the sign bit of a {@code double}.
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*/
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public static final long SIGN_BIT_MASK = 1L << (SIZE - 1);
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/**
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* Bit mask to isolate the exponent field of a {@code double}.
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*/
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public static final long EXP_BIT_MASK =
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((1L << (SIZE - SIGNIFICAND_WIDTH)) - 1) << (SIGNIFICAND_WIDTH - 1);
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/**
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* Bit mask to isolate the significand field of a {@code double}.
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*/
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public static final long SIGNIF_BIT_MASK = (1L << (SIGNIFICAND_WIDTH - 1)) - 1;
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/**
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* Bit mask to isolate the magnitude bits (combined exponent and
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* significand fields) of a {@code double}.
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*/
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public static final long MAG_BIT_MASK = EXP_BIT_MASK | SIGNIF_BIT_MASK;
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static {
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// verify bit masks cover all bit positions and that the bit
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// masks are non-overlapping
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assert(((SIGN_BIT_MASK | EXP_BIT_MASK | SIGNIF_BIT_MASK) == ~0L) &&
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(((SIGN_BIT_MASK & EXP_BIT_MASK) == 0L) &&
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((SIGN_BIT_MASK & SIGNIF_BIT_MASK) == 0L) &&
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((EXP_BIT_MASK & SIGNIF_BIT_MASK) == 0L)) &&
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((SIGN_BIT_MASK | MAG_BIT_MASK) == ~0L));
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}
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}
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