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 sun.misc;

    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 }