system.h

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// system.h
//      All global variables used in Nachos are defined here.
//
// 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 SYSTEM_H
#define SYSTEM_H

#include "copyright.h"
#include "utility.h"
#include "thread.h"
#include "scheduler.h"
#include "interrupt.h"
#include "stats.h"
#include "timer.h"

#define NSECS_PER_SEC 1000000000 
#define PREEMPTION    1
#define TICKS_PER_SEC 15
extern long timerCount;
extern long secCount;

// Initialization and cleanup routines
extern void Initialize(int argc, char **argv);  // Initialization,
                                                // called before anything else
extern void Cleanup();                          // Cleanup, called when
                                                // Nachos is done.

extern Thread     *currentThread;                       // the thread holding the CPU
extern Thread     *threadToBeDestroyed;                 // the thread that just finished
extern Scheduler  *scheduler;                   // the ready list
extern Interrupt  *interrupt;                   // interrupt status
extern Statistics *stats;                       // performance metrics
extern Timer      *timer;                               // the hardware alarm clock

#ifdef USER_PROGRAM
#include "machine.h"
extern Machine* machine;        // user program memory and registers
#endif

#ifdef FILESYS_NEEDED           // FILESYS or FILESYS_STUB 
#include "filesys.h"
extern FileSystem  *fileSystem;
#endif

#ifdef FILESYS
#include "synchdisk.h"
extern SynchDisk   *synchDisk;
#endif

#ifdef NETWORK
#include "post.h"
extern PostOffice* postOffice;
#endif

#endif // SYSTEM_H

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