samer@0: function Timer=msched(e0)
samer@0: % msched - Schedule events where each event returns the next event.
samer@0: %
samer@0: % msched ::
samer@0: %    cell {
samer@0: %       double ~'time of event',
samer@0: %       event  ~'first event action'
samer@0: %    }
samer@0: % -> action timer ~'timer being used'.
samer@0: %
samer@0: % event ::= 
samer@0: %    (  double ~'scheduled time',
samer@0: %       double ~'actual time'
samer@0: %    -> action (
samer@0: %          event  ~'the next event action', 
samer@0: %          double ~'time for next action',
samer@0: %          double ~'execution time of current event'
samer@0: %       )
samer@0: %    ).
samer@0: 
samer@0: % this is most like a Routine or Task in Supercollider, except
samer@0: % that instead of coroutining via yield, each action explicitly
samer@0: % returns the continuation action.
samer@0: 
samer@0: 	persistent ERROR
samer@0: 
samer@0: 	ERROR=[];
samer@0: 	warning('off','MATLAB:TIMER:STARTDELAYPRECISION');
samer@0: 
samer@0: 	[t0,a0]=cdeal(e0);
samer@0: 
samer@0: 	Timer=timer;
samer@0: 	set(Timer,'TimerFcn',@(o,e)timercb(o,e,t0,a0),'StopFcn',@chain);
samer@0: 	set(Timer,'StartDelay',max(0,t0-nows)); % there will be some small error here..
samer@0: 	start(Timer);
samer@0: 
samer@0: 	function timercb(o,e,t,a)
samer@0: 		[a1,t1,tt]=a(t,e.Data.time);
samer@0: 		set(o,'UserData',{a1,t1});
samer@0: 		ERROR=vertcat(ERROR,tt-t);
samer@0: 	end
samer@0: 
samer@0: 	function chain(o,e)
samer@0: 		[a1,t1]=cdeal(get(o,'UserData'));
samer@0: 		correction=mean(ERROR);
samer@0: 		while ~isempty(t1)
samer@0: 			tnow=nows;
samer@0: 			delay=t1-correction-tnow;
samer@0: 			if delay>=0, 
samer@0: 				set(o,'TimerFcn',@(oo,ee)timercb(oo,ee,t1,a1));
samer@0: 				set(o,'StartDelay',delay); 
samer@0: 				start(o);
samer@0: 				return; 
samer@0: 			end
samer@0: 			[a1,t1,tt]=a1(t1,tnow);
samer@0: 		end
samer@0: 			
samer@0: 		fprintf('\n| stopping\n');
samer@0: 		set(o,'UserData',ERROR);
samer@0: 		timer_release(o);
samer@0: 	end
samer@0: end