/*

 * Copyright (c) 2000, 2005, Oracle and/or its affiliates. All rights reserved.

 * 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

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 *

 */

package sun.jvm.hotspot.runtime;

import java.util.*;

import sun.jvm.hotspot.debugger.*;

import sun.jvm.hotspot.types.*;

/** <P> A JavaCallWrapper is constructed before each JavaCall and

    destroyed after the call.  Its purpose is to allocate/deallocate a

    new handle block and to save/restore the last Java fp/sp. A

    pointer to the JavaCallWrapper is stored on the stack. </P>

    <P> NOTE: this port is very minimal and is only designed to get

    frame traversal working. FIXME: we will have to add platform-

    specific stuff later and therefore a factory for these

    objects. </P> */

public class JavaCallWrapper extends VMObject {

  protected static AddressField  anchorField;

  private static AddressField  lastJavaSPField;

  private static AddressField  lastJavaPCField;

  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("JavaCallWrapper");

    Type anchorType = db.lookupType("JavaFrameAnchor");

    anchorField      = type.getAddressField("_anchor");

    lastJavaSPField  = anchorType.getAddressField("_last_Java_sp");

    lastJavaPCField  = anchorType.getAddressField("_last_Java_pc");

  }

  public JavaCallWrapper(Address addr) {

    super(addr);

  }

  public Address getLastJavaSP() {

    return lastJavaSPField.getValue(addr.addOffsetTo(anchorField.getOffset()));

  }

  public Address getLastJavaPC() {

    return lastJavaPCField.getValue(addr.addOffsetTo(anchorField.getOffset()));

  }

}