Category : Miscellaneous Language Source Code
Archive   : ADATUT12.ZIP
Filename : TASKING.ANS

-- Our solution to Outside Assignment 6:
with text_io, calendar; use text_io, calendar;
procedure tasking is
interval : constant duration := 5.0;
total_intervals : constant positive := 9;
start_time : constant time := clock;
quitting_time : constant time := start_time +
total_intervals*interval;
next_time : time := start_time;
task type tick is
ENTRY IDENTIFY(TASK_NUMBER : IN NATURAL);
entry shutdown;
end tick;
T : ARRAY(1 .. 3) OF TICK;
PERIOD : CONSTANT ARRAY(T'RANGE) OF POSITIVE := (2, 3, 4);
TIMER : ARRAY(T'RANGE) OF NATURAL := (OTHERS => 0);
task body tick is
quit : boolean := false;
begin
while not quit loop
select
ACCEPT IDENTIFY(TASK_NUMBER : IN NATURAL) DO
PUT_LINE("Task number" & INTEGER'IMAGE(TASK_NUMBER) &
" is starting.");
END IDENTIFY;
or
accept shutdown;
quit := true;
end select;
end loop;
end tick;
begin
while next_time < quitting_time loop
FOR I IN T'RANGE LOOP
IF TIMER(I) = 0 THEN
T(I).IDENTIFY(I);
TIMER(I) := PERIOD(I);
END IF;
TIMER(I) := TIMER(I) - 1;
END LOOP;
next_time := next_time + interval;
delay next_time - clock; new_line;
end loop;
FOR I IN T'RANGE LOOP
T(I).SHUTDOWN;
END LOOP;
end tasking;