#ifndef UNIX_TIME_PORT_H
#define UNIX_TIME_PORT_H

#include <time.h>
#include <sys/time.h>
#include <unistd.h>

/**
 * This class wraps some simple timing functons of Unix(Linux) System.
 * In general, UnixTime class provide a wall clock of the program and it can be paused and resumed.
 * The timing used in UNIX/Linux system is not accurate.
 * we wrap basic timing operations in this class, for example we are going to map
 * a timeval structure to a double absolute time value.
 */

class UnixTime{
 public:
   UnixTime(int externalcaliber = -1 );
   void setOrigin();
   /**Function to get the original time indication in system clock.
    */
   inline double getOrigin(){return origin_;}
   double getAbsoluteTime();
   inline void setAbsoluteOrigin(int hours){if (hours>0)abs_origin_ = hours*3600.0;  };
   double getCurrentTime(); 
   bool  pauseClock();
   bool  resumeClock();
   /**
    * Function to shift the orginal time.
    */
   inline void shiftOrigin(double shifttime){ origin_ += shifttime;}
   void waitAt(double timestamp);
          	        
 private:
   double  origin_;  ///< original time. timing are in the unit of seconds of system clock
   double  abs_origin_; ///< starting time offset to calculate absolute time
   double  pauseinstant_;  ///< The clock time (relative time) when the clock is paused
   bool    paused_;    ///< A flag to indicate if the clock is paused now
};

#endif