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package sun.jvm.hotspot.runtime.linux_x86;

import java.io.*;
import java.util.*;
import sun.jvm.hotspot.debugger.*;
import sun.jvm.hotspot.debugger.x86.*;
import sun.jvm.hotspot.runtime.*;
import sun.jvm.hotspot.runtime.x86.*;
import sun.jvm.hotspot.types.*;
import sun.jvm.hotspot.utilities.*;
import sun.jvm.hotspot.utilities.Observable;
import sun.jvm.hotspot.utilities.Observer;

public class LinuxX86JavaThreadPDAccess implements JavaThreadPDAccess {
  private static AddressField  lastJavaFPField;
  private static AddressField  osThreadField;

  // Field from OSThread
  private static CIntegerField osThreadThreadIDField;

  // This is currently unneeded but is being kept in case we change
  // the currentFrameGuess algorithm
  private static final long GUESS_SCAN_RANGE = 128 * 1024;

  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("JavaThread");
    osThreadField           = type.getAddressField("_osthread");

    Type anchorType = db.lookupType("JavaFrameAnchor");
    lastJavaFPField         = anchorType.getAddressField("_last_Java_fp");

    Type osThreadType = db.lookupType("OSThread");
    osThreadThreadIDField   = osThreadType.getCIntegerField("_thread_id");
  }

  public    Address getLastJavaFP(Address addr) {
    return lastJavaFPField.getValue(addr.addOffsetTo(sun.jvm.hotspot.runtime.JavaThread.getAnchorField().getOffset()));
  }

  public    Address getLastJavaPC(Address addr) {
    return null;
  }

  public    Address getBaseOfStackPointer(Address addr) {
    return null;
  }

  public    Frame getLastFramePD(JavaThread thread, Address addr) {
    Address fp = thread.getLastJavaFP();
    if (fp == null) {
      return null; // no information
    }
    return new X86Frame(thread.getLastJavaSP(), fp);
  }

  public    RegisterMap newRegisterMap(JavaThread thread, boolean updateMap) {
    return new X86RegisterMap(thread, updateMap);
  }

  public    Frame getCurrentFrameGuess(JavaThread thread, Address addr) {
    ThreadProxy t = getThreadProxy(addr);
    X86ThreadContext context = (X86ThreadContext) t.getContext();
    X86CurrentFrameGuess guesser = new X86CurrentFrameGuess(context, thread);
    if (!guesser.run(GUESS_SCAN_RANGE)) {
      return null;
    }
    if (guesser.getPC() == null) {
      return new X86Frame(guesser.getSP(), guesser.getFP());
    } else {
      return new X86Frame(guesser.getSP(), guesser.getFP(), guesser.getPC());
    }
  }

  public    void printThreadIDOn(Address addr, PrintStream tty) {
    tty.print(getThreadProxy(addr));
  }

  public    void printInfoOn(Address threadAddr, PrintStream tty) {
    tty.print("Thread id: ");
    printThreadIDOn(threadAddr, tty);
//    tty.println("\nPostJavaState: " + getPostJavaState(threadAddr));
  }

  public    Address getLastSP(Address addr) {
    ThreadProxy t = getThreadProxy(addr);
    X86ThreadContext context = (X86ThreadContext) t.getContext();
    return context.getRegisterAsAddress(X86ThreadContext.SP);
  }

  public    ThreadProxy getThreadProxy(Address addr) {
    // Addr is the address of the JavaThread.
    // Fetch the OSThread (for now and for simplicity, not making a
    // separate "OSThread" class in this package)
    Address osThreadAddr = osThreadField.getValue(addr);
    // Get the address of the _thread_id from the OSThread
    Address threadIdAddr = osThreadAddr.addOffsetTo(osThreadThreadIDField.getOffset());

    JVMDebugger debugger = VM.getVM().getDebugger();
    return debugger.getThreadForIdentifierAddress(threadIdAddr);
  }
}
