anchor.diff:      B.
   
   id(I) -> I.
  -    
  
positive.code:     <<Op:32>> = list_to_binary(R).
  
  echo_to_busy(Config) when is_list(Config) ->
      ?line Dog = test_server:timetrap(test_server:seconds(10)),
      ?line load_control_drv(Config),
      ?line P = open_port({spawn, control_drv}, []),
      ?line erlang:port_control(P, $b, [1]),	% Set to busy.
      Self = self(),
      ?line Echoer = spawn(fun() -> echoer(P, Self) end),
      ?line receive after 500 -> ok end,
      ?line erlang:port_control(P, $b, [0]),	% Set to not busy.
      ?line receive 
  	      {Echoer, done} ->
  		  ok;
  	      {Echoer, Other} ->
  		  test_server:fail(Other);
  	      Other ->
  		  test_server:fail({unexpected_message, Other})
  	  end,
      ?line test_server:timetrap_cancel(Dog),
      ok.
  
  echoer(P, ReplyTo) ->
  
negative.code:     test_server:timetrap_cancel(Dog).
  
  command(Config) when is_list(Config) ->
      load_control_drv(Config),
  
      P = open_port({spawn, control_drv}, []),
      do_command(P, "hello"),
      do_command(P, <<"hello">>),
      do_command(P, sub_bin(<<"1234kalle">>)),
      do_command(P, unaligned_sub_bin(<<"blurf">>)),
      do_command(P, ["bl"|unaligned_sub_bin(<<"urf">>)]),
      true = erlang:port_close(P),
      ok.
  
  do_command(P, Data) ->
  