DoubleConsts.java

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package jdk.internal.math;

/**
 * This class contains additional constants documenting limits of the
 * {@code double} type.
 *
 * @author Joseph D. Darcy
 */

public class DoubleConsts {
    /**
     * Don't let anyone instantiate this class.
     */
    private DoubleConsts() {}

    /**
     * The number of logical bits in the significand of a
     * {@code double} number, including the implicit bit.
     */
    public static final int SIGNIFICAND_WIDTH   = 53;

    /**
     * The exponent the smallest positive {@code double}
     * subnormal value would have if it could be normalized..
     */
    public static final int     MIN_SUB_EXPONENT = Double.MIN_EXPONENT -
                                                   (SIGNIFICAND_WIDTH - 1);

    /**
     * Bias used in representing a {@code double} exponent.
     */
    public static final int     EXP_BIAS        = 1023;

    /**
     * Bit mask to isolate the sign bit of a {@code double}.
     */
    public static final long    SIGN_BIT_MASK   = 0x8000000000000000L;

    /**
     * Bit mask to isolate the exponent field of a
     * {@code double}.
     */
    public static final long    EXP_BIT_MASK    = 0x7FF0000000000000L;

    /**
     * Bit mask to isolate the significand field of a
     * {@code double}.
     */
    public static final long    SIGNIF_BIT_MASK = 0x000FFFFFFFFFFFFFL;

    static {
        // verify bit masks cover all bit positions and that the bit
        // masks are non-overlapping
        assert(((SIGN_BIT_MASK | EXP_BIT_MASK | SIGNIF_BIT_MASK) == ~0L) &&
               (((SIGN_BIT_MASK & EXP_BIT_MASK) == 0L) &&
                ((SIGN_BIT_MASK & SIGNIF_BIT_MASK) == 0L) &&
                ((EXP_BIT_MASK & SIGNIF_BIT_MASK) == 0L)));
    }
}