Initial version

code/machine/timer.h

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+// timer.h 
+//	Data structures to emulate a hardware timer.
+//
+//	A hardware timer generates a CPU interrupt every X milliseconds.
+//	This means it can be used for implementing time-slicing, or for
+//	having a thread go to sleep for a specific period of time. 
+//
+//	We emulate a hardware timer by scheduling an interrupt to occur
+//	every time stats->totalTicks has increased by TimerTicks.
+//
+//	In order to introduce some randomness into time-slicing, if "doRandom"
+//	is set, then the interrupt comes after a random number of ticks.
+//
+//  DO NOT CHANGE -- part of the machine emulation
+//
+// Copyright (c) 1992-1993 The Regents of the University of California.
+// All rights reserved.  See copyright.h for copyright notice and limitation 
+// of liability and disclaimer of warranty provisions.
+
+#ifndef TIMER_H
+#define TIMER_H
+
+#include "copyright.h"
+#include "utility.h"
+
+// The following class defines a hardware timer. 
+class Timer {
+  public:
+    Timer(VoidFunctionPtr timerHandler, void *callArg, bool doRandom);
+				// Initialize the timer, to call the interrupt
+				// handler "timerHandler" every time slice.
+    ~Timer() {}
+
+// Internal routines to the timer emulation -- DO NOT call these
+
+    void TimerExpired();	// called internally when the hardware
+				// timer generates an interrupt
+
+    int TimeOfNextInterrupt();  // figure out when the timer will generate
+				// its next interrupt 
+
+  private:
+    bool randomize;		// set if we need to use a random timeout delay
+    VoidFunctionPtr handler;	// timer interrupt handler 
+    void *arg;			// argument to pass to interrupt handler
+
+};
+
+#endif // TIMER_H