Programming Real-Time Abstractions in Ada

2nd March 2010

These are lecture notes from my Computer Science course, not a general reference for "Programming Real-Time Abstractions in Ada"

Periodic tasks in Ada

We did this in the previous lecture (under ‘Previous Activity’)

Aperiodic and Sporadic Activities in Ada

Again, covered these definitions in the previous lecture. To clarify; sporadic has a minimum inter-arrival time, otherwise it’s aperiodic.

For Aperiodics in Ada you need a task and a protected object. The protected object holds the trigger event that will trigger the release of the task. Then, the task just:

loop
	Aperiodic_Controller.Wait_For_Next_Interrupt;
	--action
end loop

Where Aperiodic_Controller is a protected object with a boolean variable as the barrier for entry.

Tasks and Events

You can use Tasks, or Events, for doing this sort of thing.

Tasks are long lived with state, they repeat.
Events are one-off and have no state.

Interrupts are events.

Timing Events

NEW (apparently). Timing events happen when a defined clock reaches a specified value. This is supported by the Ada.Real_Time.Timing_Events package. Apparently this package is also a good example of how newer packages look in Ada (the style, that is).