/**
    *
    */
   package javax.jmdns.impl.constants;
   
   /**
    * DNS label.
    * 
    * @author Arthur van Hoff, Jeff Sonstein, Werner Randelshofer, Pierre Frisch, Rick Blair
   */
  public enum DNSLabel {
      /**
       * This is unallocated.
       */
      Unknown("", 0x80),
      /**
       * Standard label [RFC 1035]
       */
      Standard("standard label", 0x00),
      /**
       * Compressed label [RFC 1035]
       */
      Compressed("compressed label", 0xC0),
      /**
       * Extended label [RFC 2671]
       */
      Extended("extended label", 0x40);
  
      /**
       * DNS label types are encoded on the first 2 bits
       */
      static final int     LABEL_MASK     = 0xC0;
      static final int     LABEL_NOT_MASK = 0x3F;
  
      private final String _externalName;
  
      private final int    _index;
  
      DNSLabel(String name, int index) {
          _externalName = name;
          _index = index;
      }
  
      /**
       * Return the string representation of this type
       * 
       * @return String
       */
      public String externalName() {
          return _externalName;
      }
  
      /**
       * Return the numeric value of this type
       * 
       * @return String
       */
      public int indexValue() {
          return _index;
      }
  
      /**
       * @param index
       * @return label
       */
      public static DNSLabel labelForByte(int index) {
          int maskedIndex = index & LABEL_MASK;
          for (DNSLabel aLabel : DNSLabel.values()) {
              if (aLabel._index == maskedIndex) return aLabel;
          }
          return Unknown;
      }
  
      /**
       * @param index
       * @return masked value
       */
      public static int labelValue(int index) {
          return index & LABEL_NOT_MASK;
      }
  
      @Override
      public String toString() {
          return this.name() + " index " + this.indexValue();
      }
  
  }