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 * ________________________________________________________________
 * National Laboratory for Applied Network Research
 * National Center for Supercomputing Applications
 * University of Illinois at Urbana-Champaign
 * http://www.ncsa.uiuc.edu
 * ________________________________________________________________
 *
 * Timestamp.hpp
 * by Mark Gates <mgates@nlanr.net>
 * -------------------------------------------------------------------
 * A generic interface to a timestamp.
 * This implementation uses the unix gettimeofday().
 * -------------------------------------------------------------------
 * headers
 * uses
 *   <sys/types.h>
 *   <sys/time.h>
 *   <unistd.h>
 * ------------------------------------------------------------------- */

#ifndef TIMESTAMP_H
#define TIMESTAMP_H

#include "headers.h"

/* ------------------------------------------------------------------- */
class Timestamp {
public:
    /* -------------------------------------------------------------------
     * Create a timestamp, with the current time in it.
     * ------------------------------------------------------------------- */
    Timestamp(void) {
        setnow();
    }

    /* -------------------------------------------------------------------
     * Copy construcutor
     * ------------------------------------------------------------------- */
    Timestamp(const Timestamp &t2) {
        mTime.tv_sec = t2.mTime.tv_sec;
        mTime.tv_usec = t2.mTime.tv_usec;
    }

    /* -------------------------------------------------------------------
     * Create a timestamp, with the given seconds/microseconds
     * ------------------------------------------------------------------- */
    Timestamp(time_t sec, long usec) {
        set(sec, usec);
    }

    /* -------------------------------------------------------------------
     * Create a timestamp, with the given seconds
     * ------------------------------------------------------------------- */
    Timestamp(double sec) {
        set(sec);
    }

    /* -------------------------------------------------------------------
     * Set timestamp to current time.
     * ------------------------------------------------------------------- */
    void inline setnow(void) {
#ifdef HAVE_CLOCK_GETTIME
	struct timespec t1;
	clock_gettime(CLOCK_REALTIME, &t1);
	mTime.tv_sec  = t1.tv_sec;
        mTime.tv_usec = t1.tv_nsec / 1000;
#else
	gettimeofday(&mTime, NULL);
#endif
    }

    /* -------------------------------------------------------------------
     * Set timestamp to the given seconds/microseconds
     * ------------------------------------------------------------------- */
    void set(time_t sec, long usec) {
        assert(sec  >= 0);
        assert(usec >= 0  &&  usec < kMillion);

        mTime.tv_sec  = sec;
        mTime.tv_usec = usec;
    }

    /* -------------------------------------------------------------------
     * Set timestamp to the given seconds
     * ------------------------------------------------------------------- */
    void set(double sec) {
        mTime.tv_sec  = (time_t) sec;
        mTime.tv_usec = (long) ((sec - mTime.tv_sec) * kMillion);
    }

    /* -------------------------------------------------------------------
     * return seconds portion of timestamp
     * ------------------------------------------------------------------- */
    time_t inline getSecs(void) {
        return mTime.tv_sec;
    }

    /* -------------------------------------------------------------------
     * return microseconds portion of timestamp
     * ------------------------------------------------------------------- */
    long inline getUsecs(void) {
        return mTime.tv_usec;
    }

    /* -------------------------------------------------------------------
     * return timestamp as a floating point seconds
     * ------------------------------------------------------------------- */
    double get(void) {
        return mTime.tv_sec + mTime.tv_usec / ((double) kMillion);
    }

    /* -------------------------------------------------------------------
     * subtract the right timestamp from my timestamp.
     * return the difference in microseconds.
     * ------------------------------------------------------------------- */
    long subUsec(Timestamp right) {
        return(mTime.tv_sec  - right.mTime.tv_sec) * kMillion +
        (mTime.tv_usec - right.mTime.tv_usec);
    }

    /* -------------------------------------------------------------------
     * subtract the right timestamp from my timestamp.
     * return the difference in microseconds.
     * ------------------------------------------------------------------- */
    long subUsec(timeval right) {
        return(mTime.tv_sec  - right.tv_sec) * kMillion +
        (mTime.tv_usec - right.tv_usec);
    }

    /* -------------------------------------------------------------------
     * Return the number of microseconds from now to last time of setting.
     * ------------------------------------------------------------------- */
    long delta_usec(void) {
        struct timeval previous = mTime;
        setnow();
        return subUsec(previous);
    }

    /* -------------------------------------------------------------------
     * subtract the right timestamp from my timestamp.
     * return the difference in seconds as a floating point.
     * ------------------------------------------------------------------- */
    double subSec(Timestamp right) {
        return(mTime.tv_sec  - right.mTime.tv_sec) +
        (mTime.tv_usec - right.mTime.tv_usec) / ((double) kMillion);
    }

    /* -------------------------------------------------------------------
     * add the right timestamp to my timestamp.
     * ------------------------------------------------------------------- */
    void add(Timestamp right) {
        mTime.tv_sec  += right.mTime.tv_sec;
        mTime.tv_usec += right.mTime.tv_usec;

        // watch for under- and overflow
        if (mTime.tv_usec < 0) {
            mTime.tv_usec += kMillion;
            mTime.tv_sec--;
        }
        if (mTime.tv_usec >= kMillion) {
            mTime.tv_usec -= kMillion;
            mTime.tv_sec++;
        }

        assert(mTime.tv_usec >= 0  &&
                mTime.tv_usec <  kMillion);
    }

    /* -------------------------------------------------------------------
     * add the right timestamp to my timestamp.
     * ------------------------------------------------------------------- */
    void add (struct timeval *right) {
        mTime.tv_sec  += right->tv_sec;
        mTime.tv_usec += right->tv_usec;

        // watch for under- and overflow
        if (mTime.tv_usec < 0) {
            mTime.tv_usec += kMillion;
            mTime.tv_sec--;
        }
        if (mTime.tv_usec >= kMillion) {
            mTime.tv_usec -= kMillion;
            mTime.tv_sec++;
        }

        assert(mTime.tv_usec >= 0  &&
                mTime.tv_usec <  kMillion);
    }

    /* -------------------------------------------------------------------
     * add the seconds to my timestamp.
     * TODO optimize?
     * ------------------------------------------------------------------- */
    void add(double sec) {
        mTime.tv_sec  += (time_t) sec;
        mTime.tv_usec += (long) ((sec - ((time_t) sec)) * kMillion);

        // watch for overflow
        if (mTime.tv_usec >= kMillion) {
            mTime.tv_usec -= kMillion;
            mTime.tv_sec++;
        }

        assert(mTime.tv_usec >= 0  &&
                mTime.tv_usec <  kMillion);
    }

    /* -------------------------------------------------------------------
     * add micro seconds to my timestamp.
     * ------------------------------------------------------------------- */
    void add(unsigned int usec) {
        mTime.tv_usec += usec;
	mTime.tv_sec += mTime.tv_usec / kMillion;
	mTime.tv_usec = mTime.tv_usec % kMillion;
	// assert((mTime.tv_usec >= 0) && (mTime.tv_usec < kMillion));
    }

    /* -------------------------------------------------------------------
     * return true if my timestamp is before the right timestamp.
     * ------------------------------------------------------------------- */
    bool before(timeval right) {
        return mTime.tv_sec < right.tv_sec  ||
        (mTime.tv_sec == right.tv_sec &&
         mTime.tv_usec < right.tv_usec);
    }
    bool before(Timestamp right) { return before(right.mTime); }

    /* -------------------------------------------------------------------
     * return true if my timestamp is after the right timestamp.
     * ------------------------------------------------------------------- */
    bool after(timeval right) {
        return mTime.tv_sec > right.tv_sec  ||
        (mTime.tv_sec == right.tv_sec &&
         mTime.tv_usec > right.tv_usec);
    }
    bool after(Timestamp right) { return after(right.mTime); }

    /**
     * This function returns the fraction of time elapsed after the beginning
     * till the end
     */
    double fraction(Timestamp currentTime, Timestamp endTime) {
        if ((currentTime.after(*this)) && (endTime.after(currentTime))) {
            return(((double)currentTime.subUsec(*this)) /
                   ((double)endTime.subUsec(*this)));
        } else {
            return -1.0;
        }
    }

protected:
    enum {
        kMillion = 1000000
    };

    struct timeval mTime;

}; // end class Timestamp

#endif // TIMESTAMP_H
