/*
  File: SynchronizedByte.java

  Originally written by Doug Lea and released into the public domain.
  This may be used for any purposes whatsoever without acknowledgment.
  Thanks for the assistance and support of Sun Microsystems Labs,
  and everyone contributing, testing, and using this code.

  History:
  Date       Who                What
  19Jun1998  dl               Create public version
  15Apr2003  dl               Removed redundant "synchronized" for multiply()
*/

package EDU.oswego.cs.dl.util.concurrent;

/**
 * A class useful for offloading synch for byte instance variables.
 *
 * <p>[<a href="http://gee.cs.oswego.edu/dl/classes/EDU/oswego/cs/dl/util/concurrent/intro.html"> Introduction to this package. </a>]
 **/

public class SynchronizedByte extends SynchronizedVariable implements Comparable, Cloneable {

  protected byte value_;

  /** 
   * Make a new SynchronizedByte with the given initial value,
   * and using its own internal lock.
   **/
  public SynchronizedByte(byte initialValue) { 
    super(); 
    value_ = initialValue; 
  }

  /** 
   * Make a new SynchronizedByte with the given initial value,
   * and using the supplied lock.
   **/
  public SynchronizedByte(byte initialValue, Object lock) { 
    super(lock); 
    value_ = initialValue; 
  }

  /** 
   * Return the current value 
   **/
  public final byte get() { synchronized(lock_) { return value_; } }

  /** 
   * Set to newValue.
   * @return the old value 
   **/

  public byte set(byte newValue) { 
    synchronized (lock_) {
      byte old = value_;
      value_ = newValue; 
      return old;
    }
  }

  /**
   * Set value to newValue only if it is currently assumedValue.
   * @return true if successful
   **/
  public boolean commit(byte assumedValue, byte newValue) {
    synchronized(lock_) {
      boolean success = (assumedValue == value_);
      if (success) value_ = newValue;
      return success;
    }
  }


  /** 
   * Atomically swap values with another SynchronizedByte.
   * Uses identityHashCode to avoid deadlock when
   * two SynchronizedBytes attempt to simultaneously swap with each other.
   * (Note: Ordering via identyHashCode is not strictly guaranteed
   * by the language specification to return unique, orderable
   * values, but in practice JVMs rely on them being unique.)
   * @return the new value 
   **/

  public byte swap(SynchronizedByte other) {
    if (other == this) return get();
    SynchronizedByte fst = this;
    SynchronizedByte snd = other;
    if (System.identityHashCode(fst) > System.identityHashCode(snd)) {
      fst = other;
      snd = this;
    }
    synchronized(fst.lock_) {
      synchronized(snd.lock_) {
        fst.set(snd.set(fst.get()));
        return get();
      }
    }
  }

  /** 
   * Increment the value.
   * @return the new value 
   **/
  public byte increment() { 
    synchronized (lock_) {
      return ++value_; 
    }
  }

  /** 
   * Decrement the value.
   * @return the new value 
   **/
  public byte decrement() { 
    synchronized (lock_) {
      return --value_; 
    }
  }

  /** 
   * Add amount to value (i.e., set value += amount)
   * @return the new value 
   **/
  public byte add(byte amount) { 
    synchronized (lock_) {
      return value_ += amount; 
    }
  }

  /** 
   * Subtract amount from value (i.e., set value -= amount)
   * @return the new value 
   **/
  public byte subtract(byte amount) { 
    synchronized (lock_) {
      return value_ -= amount; 
    }
  }

  /** 
   * Multiply value by factor (i.e., set value *= factor)
   * @return the new value 
   **/
  public byte multiply(byte factor) { 
    synchronized (lock_) {
      return value_ *= factor; 
    }
  }

  /** 
   * Divide value by factor (i.e., set value /= factor)
   * @return the new value 
   **/
  public byte divide(byte factor) { 
    synchronized (lock_) {
      return value_ /= factor; 
    }
  }

  /** 
   * Set the value to the negative of its old value
   * @return the new value 
   **/
  public  byte negate() { 
    synchronized (lock_) {
      value_ = (byte)(-value_);
      return value_;
    }
  }

  /** 
   * Set the value to its complement
   * @return the new value 
   **/
  public  byte complement() { 
    synchronized (lock_) {
      value_ = (byte)~value_;
      return value_;
    }
  }

  /** 
   * Set value to value &amp; b.
   * @return the new value 
   **/
  public  byte and(byte b) { 
    synchronized (lock_) {
      value_ = (byte)(value_ & b);
      return value_;
    }
  }

  /** 
   * Set value to value | b.
   * @return the new value 
   **/
  public  byte or(byte b) { 
    synchronized (lock_) {
      value_ = (byte)(value_ | b);
      return value_;
    }
  }


  /** 
   * Set value to value ^ b.
   * @return the new value 
   **/
  public  byte xor(byte b) { 
    synchronized (lock_) {
      value_ = (byte)(value_ ^ b);
      return value_;
    }
  }

  public int compareTo(byte other) {
    byte val = get();
    return (val < other)? -1 : (val == other)? 0 : 1;
  }

  public int compareTo(SynchronizedByte other) {
    return compareTo(other.get());
  }

  public int compareTo(Object other) {
    return compareTo((SynchronizedByte)other);
  }

  public boolean equals(Object other) {
    if (other != null &&
        other instanceof SynchronizedByte)
      return get() == ((SynchronizedByte)other).get();
    else
      return false;
  }

  public int hashCode() {
    return (int)(get());
  }

  public String toString() { return Byte.toString(get()); }

}

