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>double</code> type.
  31  *
  32  * @author Joseph D. Darcy
  33  */
  34 
  35 public class DoubleConsts {
  36     /**
  37      * Don't let anyone instantiate this class.
  38      */
  39     private DoubleConsts() {}
  40 
  41     public static final double POSITIVE_INFINITY = java.lang.Double.POSITIVE_INFINITY;
  42     public static final double NEGATIVE_INFINITY = java.lang.Double.NEGATIVE_INFINITY;
  43     public static final double NaN = java.lang.Double.NaN;
  44     public static final double MAX_VALUE = java.lang.Double.MAX_VALUE;
  45     public static final double MIN_VALUE = java.lang.Double.MIN_VALUE;
  46 
  47     /**
  48      * A constant holding the smallest positive normal value of type
  49      * <code>double</code>, 2<sup>-1022</sup>.  It is equal to the
  50      * value returned by
  51      * <code>Double.longBitsToDouble(0x0010000000000000L)</code>.
  52      *
  53      * @since 1.5
  54      */
  55     public static final double  MIN_NORMAL      = 2.2250738585072014E-308;
  56 
  57 
  58     /**
  59      * The number of logical bits in the significand of a
  60      * <code>double</code> number, including the implicit bit.
  61      */
  62     public static final int SIGNIFICAND_WIDTH   = 53;
  63 
  64     /**
  65      * Maximum exponent a finite <code>double</code> number may have.
  66      * It is equal to the value returned by
  67      * <code>Math.ilogb(Double.MAX_VALUE)</code>.
  68      */
  69     public static final int     MAX_EXPONENT    = 1023;
  70 
  71     /**
  72      * Minimum exponent a normalized <code>double</code> number may
  73      * have.  It is equal to the value returned by
  74      * <code>Math.ilogb(Double.MIN_NORMAL)</code>.
  75      */
  76     public static final int     MIN_EXPONENT    = -1022;
  77 
  78     /**
  79      * The exponent the smallest positive <code>double</code>
  80      * subnormal value would have if it could be normalized..
  81      */
  82     public static final int     MIN_SUB_EXPONENT = MIN_EXPONENT -
  83                                                    (SIGNIFICAND_WIDTH - 1);
  84 
  85     /**
  86      * Bias used in representing a <code>double</code> exponent.
  87      */
  88     public static final int     EXP_BIAS        = 1023;
  89 
  90     /**
  91      * Bit mask to isolate the sign bit of a <code>double</code>.
  92      */
  93     public static final long    SIGN_BIT_MASK   = 0x8000000000000000L;
  94 
  95     /**
  96      * Bit mask to isolate the exponent field of a
  97      * <code>double</code>.
  98      */
  99     public static final long    EXP_BIT_MASK    = 0x7FF0000000000000L;
 100 
 101     /**
 102      * Bit mask to isolate the significand field of a
 103      * <code>double</code>.
 104      */
 105     public static final long    SIGNIF_BIT_MASK = 0x000FFFFFFFFFFFFFL;
 106 
 107     static {
 108         // verify bit masks cover all bit positions and that the bit
 109         // masks are non-overlapping
 110         assert(((SIGN_BIT_MASK | EXP_BIT_MASK | SIGNIF_BIT_MASK) == ~0L) &&
 111                (((SIGN_BIT_MASK & EXP_BIT_MASK) == 0L) &&
 112                 ((SIGN_BIT_MASK & SIGNIF_BIT_MASK) == 0L) &&
 113                 ((EXP_BIT_MASK & SIGNIF_BIT_MASK) == 0L)));
 114     }
 115 }