// stats.h //	Data structures for gathering statistics about Nachos performance.//// DO NOT CHANGE -- these stats are maintained by 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 STATS_H#define STATS_H#include "copyright.h"// The following class defines the statistics that are to be kept// about Nachos behavior -- how much time (ticks) elapsed, how// many user instructions executed, etc.//// The fields in this class are public to make it easier to update.class Statistics {  public:    int totalTicks;      	// Total time running Nachos    int idleTicks;       	// Time spent idle (no threads to run)    int systemTicks;	 	// Time spent executing system code    int userTicks;       	// Time spent executing user code				// (this is also equal to # of				// user instructions executed)    int numDiskReads;		// number of disk read requests    int numDiskWrites;		// number of disk write requests    int numConsoleCharsRead;	// number of characters read from the keyboard    int numConsoleCharsWritten; // number of characters written to the display    int numPageFaults;		// number of virtual memory page faults    int numPacketsSent;		// number of packets sent over the network    int numPacketsRecvd;	// number of packets received over the network    Statistics(); 		// initialize everything to zero    void Print();		// print collected statistics};// Constants used to reflect the relative time an operation would// take in a real system.  A "tick" is a just a unit of time -- if you // like, a microsecond.//// Since Nachos kernel code is directly executed, and the time spent// in the kernel measured by the number of calls to enable interrupts,// these time constants are none too exact.#define UserTick 	1	// advance for each user-level instruction #define SystemTick 	10 	// advance each time interrupts are enabled#define RotationTime 	500 	// time disk takes to rotate one sector#define SeekTime 	500    	// time disk takes to seek past one track#define ConsoleTime 	100	// time to read or write one character#define NetworkTime 	100   	// time to send or receive one packet#define TimerTicks 	100    	// (average) time between timer interrupts#endif // STATS_H