OBSOLETE!
External Xtensa TIE interface for the output queue type. Two callbacks
should be registered in order to receive data from the object obj
that implements the interface, typically a processor. When the queue is
accessed the callbacks are called. user_object is the user object
to use in the full_callback and data_callback
callbacks.
The types of the full_callback and data_callback are defined in the
xtensa/tie/cstub-extif.h file in the Xtensa model build
directory. The full_callback should return 1 if the queue is full, otherwise
0. The data_callback is used for receiving the data.