semaphore.adb

task type Semaphore is
	entry Init (Initial_Capacity: in Int);
	entry Wait;
	entry Signal;
end
task body Semaphore is
	Remaining_Capacity: Int;
begin
	accept Init (Initial_Capacity: in Int) do
		Remaining_Capacity := Initial_Capacity;
	end
	loop
		select
			when Remaining_Capacity > 0 accept Wait;
			Remaining_Capacity := Remaining_Capacity - 1;
		or
			accept Signal;
			Remaining_Capacity := Remaining_Capacity + 1;
		end select
	end loop
end Semaphore;