/*

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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 */

package sun.jvm.hotspot.utilities;

import java.util.*;

import sun.jvm.hotspot.debugger.*;

import sun.jvm.hotspot.oops.Oop;

import sun.jvm.hotspot.oops.ObjectHeap;

import sun.jvm.hotspot.types.*;

import sun.jvm.hotspot.runtime.*;

public class BasicHashtableEntry extends VMObject {

  static {

    VM.registerVMInitializedObserver(new Observer() {

        public void update(Observable o, Object data) {

          initialize(VM.getVM().getTypeDataBase());

        }

      });

  }

  private static synchronized void initialize(TypeDataBase db) {

    Type type = db.lookupType("BasicHashtableEntry<mtInternal>");

    hashField      = type.getCIntegerField("_hash");

    nextField      = type.getAddressField("_next");

  }

  // Fields

  private static CIntegerField hashField;

  private static AddressField  nextField;

  // Accessors

  public long hash() {

    return hashField.getValue(addr) & 0xFFFFFFFFL;

  }

  private long nextAddressValue() {

    Debugger dbg = VM.getVM().getDebugger();

    Address nextValue = nextField.getValue(addr);

    return (nextValue != null) ? dbg.getAddressValue(nextValue) : 0L;

  }

  public boolean isShared() {

    return (nextAddressValue() & 1L) != 0;

  }

  public BasicHashtableEntry next() {

    Address nextValue = nextField.getValue(addr);

    Address next = (nextValue != null)? nextValue.andWithMask(-2L) : null;

    // using this.getClass so that return type will be as expected in

    // subclass context. But, because we can't use covariant return type

    // caller has to use this next and cast the result to correct type.

    return (BasicHashtableEntry) VMObjectFactory.newObject(this.getClass(), next);

  }

  public BasicHashtableEntry(Address addr) {

    super(addr);

  }

}