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.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 package sun.jvm.hotspot.utilities;
  26 
  27 import java.util.*;
  28 import sun.jvm.hotspot.debugger.*;
  29 import sun.jvm.hotspot.types.*;
  30 import sun.jvm.hotspot.runtime.*;
  31 
  32 public class Hashtable extends BasicHashtable {
  33   static {
  34     VM.registerVMInitializedObserver(new Observer() {
  35         public void update(Observable o, Object data) {
  36           initialize(VM.getVM().getTypeDataBase());
  37         }
  38       });
  39   }
  40 
  41   private static synchronized void initialize(TypeDataBase db) {
  42     // just to confirm that type exists
  43     Type type = db.lookupType("IntptrHashtable");
  44   }
  45 
  46   // derived class may return Class<? extends HashtableEntry>
  47   protected Class getHashtableEntryClass() {
  48     return HashtableEntry.class;
  49   }
  50 
  51   public int hashToIndex(long fullHash) {
  52     return (int) (fullHash % tableSize());
  53   }
  54 
  55   public Hashtable(Address addr) {
  56     super(addr);
  57   }
  58 
  59   // VM's Hashtable::hash_symbol
  60   protected static long hashSymbol(byte[] buf) {
  61     long h = 0;
  62     int s = 0;
  63     int len = buf.length;
  64     while (len-- > 0) {
  65       h = 31*h + (0xFFL & buf[s]);
  66       s++;
  67     }
  68     return h & 0xFFFFFFFFL;
  69   }
  70 }