[Cyan]<CedarChest6.0>PlotPackage>TimerImpl.mesa!1

TimerImpl.mesa

Last Modified On December 16, 1983 1:30 pm By Paul Rovner

DIRECTORY

BasicTime USING[Pulses, GetClockPulses, PulsesToSeconds],

Timer USING[Seconds];

TimerImpl: MONITOR

LOCKS self USING self: Handle

IMPORTS BasicTime

EXPORTS Timer

= {

TYPEs

Handle: TYPE = REF Object;

Object: PUBLIC TYPE = MONITORED RECORD[

bigBangTime, previousMark: BasicTime.Pulses,

secondsSinceFirstBigBang: Seconds ← 0.0

];

Seconds: TYPE = Timer.Seconds; -- REAL--

PROCEDUREs

Create: PUBLIC PROC RETURNS[Handle] = {

startMark: BasicTime.Pulses = BasicTime.GetClockPulses[];

RETURN[NEW[Object ← [LOCK:, bigBangTime: startMark, previousMark: startMark]]];

};

Read: PUBLIC ENTRY PROC[self: Handle]

RETURNS[time, deltaTime: Seconds] = {

nextMark: BasicTime.Pulses ← BasicTime.GetClockPulses[];

IF BasicTime.PulsesToSeconds[nextMark] - BasicTime.PulsesToSeconds[self.bigBangTime] > 15.0*60.0 -- 15 mins

THEN {self.secondsSinceFirstBigBang ← self.secondsSinceFirstBigBang + (BasicTime.PulsesToSeconds[self.previousMark]-BasicTime.PulsesToSeconds[self.bigBangTime]);

self.bigBangTime ← self.previousMark};

deltaTime ← (BasicTime.PulsesToSeconds[nextMark] - BasicTime.PulsesToSeconds[self.previousMark]);

time ← (BasicTime.PulsesToSeconds[nextMark]-BasicTime.PulsesToSeconds[self.bigBangTime]) + self.secondsSinceFirstBigBang;

self.previousMark ← nextMark;

};

Reset: PUBLIC ENTRY PROC[self: Handle] = {

startMark: BasicTime.Pulses = BasicTime.GetClockPulses[];

self.bigBangTime ← self.previousMark ← startMark;

self.secondsSinceFirstBigBang ← 0.0;

};