{ Test / Demonstrate UMTimer.p macro commands. }

{StartElapsed(elapsed timer number);}
{ (there are two elapsed time timers)}
{This starts the specified elapsed time timer.}

{secs := MeasureElapsed(1 or 2);}
{This stops the specified elapsed time timer and reports}
{the elapsed time in seconds to high resolution.}

{StartDelay(delay timer number, time seconds);}
{ (there is only one delay timer so first argument is always 1)}
{Starts the delay timer.  Be sure to call KillDelay first unless }
{you mean for the delay to start at the previous expiration.}

{(Under system 6, the delay will probably start at the startDelay}
{call rather than at the previous expiration even if KillDelay is not}
{called, because a different version of the time manager is provided}
{by the system software).}

{KillDelay(1);}
{Stops the delay timer without waiting for it to expire.}
{Also, adjusts the timer so that the next delay will begin}
{when the next StartDelay call is made, rather than when}
{the previous delay expired.}

{WaitDelay(1);}
{Waits for the delay timer to expire, or command period.}
{NOTE:  delay starts at the pervious expiration, not at the}
{StartDelay call, unless KillDelay was called first.}

{Periodic timer calls have not been tested.}

{StartPeriodic(periodic timer number, period seconds);}
{(there is only one periodic timer so first argument is always 1)}
{Start the periodic timer with specified period.}
{Be careful, very small periods will hang the system.}

{It may be possible to achieve the desired results using StartDelay}
{and WaitDelay without KillDelay, and with no chance of hanging}
{the system.}

{KillPeriodic(1);}
{stop the periodic timer without waiting.}

{AdjustPeriodic(1,period,phase)}
{Adjust the period and phase of periodic timer.}
{if phase is negative next period will happen sooner}
{if phase is positive next period will happen later}
{period will change after next expiration.}
{Be careful, very small periods will hang the system.}

{p := WaitPeriodic(1,periodNumber);}
{Wait for specified period to occur, and report how many}
{periods have occurred.}

var 
  overhead: real;
  delayAdjust: real;

macro 'measure timer overhead';
begin
  RequiresUser('timer',1);
  StartElapsed(1);
  overhead := MeasureElapsed(1);
  ShowMessage('Overhead is ',overhead:1:6,' seconds');
end;

macro 'Delay 2.0 seconds';
var
  secs: Real;
begin
  RequiresUser('timer',1);
  if delayAdjust < -0.010 then
    delayAdjust := -0.010;
  if delayAdjust > 0.010 then
    delayAdjust := 0.010;
  KillDelay(1); {interval starts at StartDelay}
  StartElapsed(1);
  StartDelay(1,2.0 + delayAdjust);
  WaitDelay(1);
  secs := MeasureElapsed(1);
  delayAdjust := delayAdjust + 2.0 - secs;
  ShowMessage('Elapsed time is ',secs:1:6,' seconds',
    '\DelayAdjust is ',delayAdjust:1:6,' secs');
end;