pragma Task_Dispatching_Policy (FIFO_Within_Priorities);
pragma Locking_Policy (Ceiling_Locking);

with Ada.Real_Time;
use Ada.Real_Time;

procedure Ceiling_ex is

   task T1 is
      pragma Priority (16);
   end T1;

   task T2 is
      pragma Priority (17);
   end T2;

   task T3 is
      pragma Priority (18);
   end T3;
   protected Obj is
      procedure Write;
   end Obj;

   protected body Obj is
      procedure Write is
         Next : Time;
         Period : Time_Span := Microseconds (300);
      begin
         Next := Clock + Period;
         while Next > Clock
         loop
            null;
         end loop;
      end Write;
   end obj;

   task body T1 is
      Next : Time;
      Period : Time_Span := Microseconds (800);
   begin
      Next := Clock + Period;
      loop
         Obj.Write;
         delay until Next;
         Next := Next + Period;
      end loop;

   end T1;

   task body T2 is
      Next : Time;
      Period : Time_Span := Milliseconds (2);
      Next_While : Time;
      Period_While : Time_Span := Microseconds(500);
   begin
      Next := Clock + Period;
      loop
         Next_While := Clock + Period_While;
         While (Next_While > Clock)
         loop
            null;
         end loop;
         delay until Next;
         Next := Next + Period;
      end loop;
   end T2;

   task body T3 is
      Next : Time;
      Period : Time_Span := Microseconds (750);
      Next_While : Time;
      Period_While : Time_Span := Microseconds(200);
   begin
      Next := Clock + Period;
      loop
         Next_While := Clock + Period_While;
         While (Next_While > Clock)
         loop
            null;
         end loop;
         delay until Next;
         Next := Next + Period;
      end loop;

   end T3;

begin
   null;
end Ceiling_ex;