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13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
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15  * accompanied this code).
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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      */
DoubleConsts()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.  It is
81      * equal to the value returned by
82      * <code>FpUtils.ilogb(Double.MIN_VALUE)</code>.
83      */
84     public static final int     MIN_SUB_EXPONENT = MIN_EXPONENT -
85                                                    (SIGNIFICAND_WIDTH - 1);
86 
87     /**
88      * Bias used in representing a <code>double</code> exponent.
89      */
90     public static final int     EXP_BIAS        = 1023;
91 
92     /**
93      * Bit mask to isolate the sign bit of a <code>double</code>.
94      */
95     public static final long    SIGN_BIT_MASK   = 0x8000000000000000L;
96 
97     /**
98      * Bit mask to isolate the exponent field of a
99      * <code>double</code>.
100      */
101     public static final long    EXP_BIT_MASK    = 0x7FF0000000000000L;
102 
103     /**
104      * Bit mask to isolate the significand field of a
105      * <code>double</code>.
106      */
107     public static final long    SIGNIF_BIT_MASK = 0x000FFFFFFFFFFFFFL;
108 
109     static {
110         // verify bit masks cover all bit positions and that the bit
111         // masks are non-overlapping
112         assert(((SIGN_BIT_MASK | EXP_BIT_MASK | SIGNIF_BIT_MASK) == ~0L) &&
113                (((SIGN_BIT_MASK & EXP_BIT_MASK) == 0L) &&
114                 ((SIGN_BIT_MASK & SIGNIF_BIT_MASK) == 0L) &&
115                 ((EXP_BIT_MASK & SIGNIF_BIT_MASK) == 0L)));
116     }
117 }
118