code: public final void update(byte input) throws IllegalStateException {
          chooseFirstProvider();
          if (initialized == false) {
              throw new IllegalStateException("MAC not initialized");
          }
          spi.engineUpdate(input);
      }
docs: Processes the given byte.
  
  @param input the input byte to be processed.
  
  @exception IllegalStateException if this <code>Mac</code> has not been
  initialized.