with SYSTEM;                        use SYSTEM;
with UATL_DATA_TYPES;               use UATL_DATA_TYPES;
with INTERFACE_DATA_TYPES_488;      use INTERFACE_DATA_TYPES_488;

package COMMON_TO_BOTH_488 is

  RECEIVE_QUEUE  : MESSAGE_LINK;
  SEND_QUEUE     : MESSAGE_LINK;
  POLL_QUEUE     : array (ID_TYPE) of MESSAGE_POINTER;

  ACTIVE_DEVICES : DEVICE_LIST_ACCESS;

  RECEIVED_MESSAGE_PTR  : MESSAGE_POINTER; -- For direct deposit of returned
                                    -- messages.

  CONTROL     : BOOLEAN; -- True if this is the controller of the bus.
  DEVICE_ID   : ID_TYPE; -- The id of this unit.
  PORT_NUMBER : INTEGER := 0;
  
  -- This is where we receive information from the 488 bus.

  task IO_488 is
   --
   --\ Purpose:	This task hides details of the interface to the IEEE488
   --\		hardware and drivers, or to simulators, when these are
   --\		used with a test driver.
   --\

   pragma PRIORITY (PRIORITY'last-2);

      entry RECEIVE(BUFFER  : out GENERAL_488_MESSAGE);
      --\ Invoked when:  On demand.
      --\ Purpose:	Receive one inbound message from IEEE488 interface.
      --\       The interface copies the message into the callers buffer, so 
      --\	that the interface buffer is free at the end of the rendezvous.
      --\	The caller is expected to use only its own Function_id.
      --\ Maximum processing delay:  The caller is suspended waiting for a
      --\	rendezvous until an inbound message arrives.  To avoid being 
      --\	suspended, the caller may use a conditional or timed entry 
      --\	call.

      entry UNLOCK;
      --\ Invoked when:  A new message has arrived.
      --\ Purpose:	 To freeze up the caller and not release him until
      --\       a message has come in.
      --\ Maximum processing delay:  Howver long it takes a message to arrive.

    end IO_488;

  function QUEUE_COUNT (QUEUE_NAME : in MESSAGE_LINK) return INTEGER;

  task QUEUE_TASK is
    pragma PRIORITY(PRIORITY'last);
    entry   QUEUE(QUEUE_NAME  : in out MESSAGE_LINK;  LINK  : MESSAGE_POINTER);
    entry DEQUEUE(QUEUE_NAME  : in out MESSAGE_LINK);
  end QUEUE_TASK;

end COMMON_TO_BOTH_488;