#ifndef _SYSTIMER_H
#define _SYSTIMER_H

// systimer.h
//
// July 3, 1996
// David Levine, Chris Nevison
//
// (modified format on 5/20/97, Owen Astrachan)
//
// This file specifies a timer class.  The purpose of this class is to 
// permit the programmer to measure the amount of system time which is 
// spent during particular phases of a program.  The general model for 
// this timer class was taken from _A Computer Science Tapestry_ by 
// Owen Astrachan, McGraw-Hill, ISBN 0-07-002036-1.
//
// The basic model of the class is that of a stop watch which has two 
// buttons.  One button is used to toggle the stop watch between the 
// "recording" and "idle" states and the other button is used to reset 
// the stop watch.
//
// Concerning units:  All times are given in units of seconds returned
// as a double.
//
// The class is based in the C library function clock(), which returns
// the number of ticks of the system clock since the program started, 
// where the system constant CLOCKS_PER_SEC specifies the number of 
// ticks per second.  This constant determines the smallest time 
// differential which can be measured, ranging from a few microseconds
// to more than a hundredth of a second.  This smallest time difference
// is returned by the function granularity.
//
// On some systems the constant CLK_TCK may be used 
// instead of CLOCKS_PER_SEC, in which case the line after the 
// includes should be uncommented.


//#include "bool.h"
#include <time.h> 
// const CLOCKS_PER_SEC CLK_TCK;


class SysTimer
{
  public:

    SysTimer();             // constructor

        // methods to modify the state of the stopwatch

    void start();           // begin timing
    void stop();            // stop timing
    void reset();           // reset timer to 0; stops watch if running

        // methods to query the stopwatch

    bool isRunning()        const;  // true iff stopwatch is running
    double lapTime()        const;  // number of microseconds since start
    double elapsedTime()    const;  // microseconds between start and stop
    double cumulativeTime() const;  // returns time since last reset
    double granularity()    const;  // returns smallest measurable time 

  private:

    bool amRunning;            // true iff stopwatch is currently running
    clock_t myStartTime;       // holds the last time the watch was started
    clock_t myElapsed;         // holds the time between the last start
                               // and the last stop
    clock_t myCumulative;      // holds the total amount of time that the
                               // stopwatch has been on since the last reset
                               // (except for the current "lap" time)
};

#endif