public int hashCode(){
  int retval=0;
  int len=available();
  int p=pos;
  for (int i=0; i < len; i++)   retval+=buf[p + i] * i;
  return retval;
}

public int hashCode ( ) { int retval = 0 ; int len = available ( ) ; int p = pos ; for ( int i = 0 ; i < len ; i ++ ) retval += buf [ p + i ] * i ; return retval ; }
returns a hashcode for this derinputbuffer .
