init: init nachos hw01, should pass jenkins os_group_20_hw job but fail on os_group_20_ta job

code/machine/timer.h

@@ -0,0 +1,53 @@
+// 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) 1992-1996 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"
+#include "callback.h"
+
+// The following class defines a hardware timer. 
+class Timer : public CallBackObj {
+  public:
+    Timer(bool doRandom, CallBackObj *toCall);
+				// Initialize the timer, and callback to "toCall"
+				// every time slice.
+    virtual ~Timer() {}
+    
+    void Disable() { disable = TRUE; }
+    				// Turn timer device off, so it doesn't
+				// generate any more interrupts.
+
+  private:
+    bool randomize;		// set if we need to use a random timeout delay
+    CallBackObj *callPeriodically; // call this every TimerTicks time units 
+    bool disable;		// turn off the timer device after next
+    				// interrupt.
+    
+    void CallBack();		// called internally when the hardware
+				// timer generates an interrupt
+
+    void SetInterrupt();  	// cause an interrupt to occur in the
+    				// the future after a fixed or random
+				// delay
+};
+
+#endif // TIMER_H