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

code/machine/timer.cc

@@ -0,0 +1,81 @@
+// timer.cc 
+//	Routines to emulate a hardware timer device.
+//
+//      A hardware timer generates a CPU interrupt every X milliseconds.
+//      This means it can be used for implementing time-slicing.
+//
+//      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 is comes after a random number of ticks.
+//
+//	Remember -- nothing in here is part of Nachos.  It is just
+//	an emulation for the hardware that Nachos is running on top of.
+//
+//  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.
+
+#include "copyright.h"
+#include "timer.h"
+#include "main.h"
+#include "sysdep.h"
+
+//----------------------------------------------------------------------
+// Timer::Timer
+//      Initialize a hardware timer device.  Save the place to call
+//	on each interrupt, and then arrange for the timer to start
+//	generating interrupts.
+//
+//      "doRandom" -- if true, arrange for the interrupts to occur
+//		at random, instead of fixed, intervals.
+//      "toCall" is the interrupt handler to call when the timer expires.
+//----------------------------------------------------------------------
+
+Timer::Timer(bool doRandom, CallBackObj *toCall)
+{
+    randomize = doRandom;
+    callPeriodically = toCall;
+    disable = FALSE;
+    SetInterrupt();
+}
+
+//----------------------------------------------------------------------
+// Timer::CallBack
+//      Routine called when interrupt is generated by the hardware 
+//	timer device.  Schedule the next interrupt, and invoke the
+//	interrupt handler.
+//----------------------------------------------------------------------
+void 
+Timer::CallBack() 
+{
+    // invoke the Nachos interrupt handler for this device
+    callPeriodically->CallBack();
+    
+    SetInterrupt();	// do last, to let software interrupt handler
+    			// decide if it wants to disable future interrupts
+}
+
+//----------------------------------------------------------------------
+// Timer::SetInterrupt
+//      Cause a timer interrupt to occur in the future, unless
+//	future interrupts have been disabled.  The delay is either
+//	fixed or random.
+//----------------------------------------------------------------------
+
+void
+Timer::SetInterrupt() 
+{
+    if (!disable) {
+       int delay = TimerTicks;
+    
+       if (randomize) {
+	     delay = 1 + (RandomNumber() % (TimerTicks * 2));
+        }
+       // schedule the next timer device interrupt
+       kernel->interrupt->Schedule(this, delay, TimerInt);
+    }
+}