public final int _hashToIndex(int rawHash){
  rawHash+=(rawHash >>> 15);
  return (rawHash & _indexMask);
}

public final int _hashToIndex ( int rawHash ) { rawHash += ( rawHash > > > 15 ) ; return ( rawHash & _indexMask ) ; }
helper method that takes in a " raw " hash value , shuffles it as necessary , and truncates to be used as the index .
