/*
    Copyright 2005-2014 Intel Corporation.  All Rights Reserved.

    This file is part of Threading Building Blocks. Threading Building Blocks is free software;
    you can redistribute it and/or modify it under the terms of the GNU General Public License
    version 2  as  published  by  the  Free Software Foundation.  Threading Building Blocks is
    distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the
    implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
    See  the GNU General Public License for more details.   You should have received a copy of
    the  GNU General Public License along with Threading Building Blocks; if not, write to the
    Free Software Foundation, Inc.,  51 Franklin St,  Fifth Floor,  Boston,  MA 02110-1301 USA

    As a special exception,  you may use this file  as part of a free software library without
    restriction.  Specifically,  if other files instantiate templates  or use macros or inline
    functions from this file, or you compile this file and link it with other files to produce
    an executable,  this file does not by itself cause the resulting executable to be covered
    by the GNU General Public License. This exception does not however invalidate any other
    reasons why the executable file might be covered by the GNU General Public License.
*/

#ifndef __TBB_tick_count_H
#define __TBB_tick_count_H

#include "tbb_stddef.h"

#if _WIN32||_WIN64
#include "machine/windows_api.h"
#elif __linux__
#include <ctime>
#else /* generic Unix */
#include <sys/time.h>
#endif /* (choice of OS) */

namespace tbb {

//! Absolute timestamp
/** @ingroup timing */
class tick_count {
public:
    //! Relative time interval.
    class interval_t {
        long long value;
        explicit interval_t( long long value_ ) : value(value_) {}
    public:
        //! Construct a time interval representing zero time duration
        interval_t() : value(0) {};

        //! Construct a time interval representing sec seconds time  duration
        explicit interval_t( double sec );

        //! Return the length of a time interval in seconds
        double seconds() const;

        friend class tbb::tick_count;

        //! Extract the intervals from the tick_counts and subtract them.
        friend interval_t operator-( const tick_count& t1, const tick_count& t0 );

        //! Add two intervals.
        friend interval_t operator+( const interval_t& i, const interval_t& j ) {
            return interval_t(i.value+j.value);
        }

        //! Subtract two intervals.
        friend interval_t operator-( const interval_t& i, const interval_t& j ) {
            return interval_t(i.value-j.value);
        }

        //! Accumulation operator
        interval_t& operator+=( const interval_t& i ) {value += i.value; return *this;}

        //! Subtraction operator
        interval_t& operator-=( const interval_t& i ) {value -= i.value; return *this;}
    private:
        static long long ticks_per_second(){
#if _WIN32||_WIN64
            LARGE_INTEGER qpfreq;
            int rval = QueryPerformanceFrequency(&qpfreq);
            __TBB_ASSERT_EX(rval, "QueryPerformanceFrequency returned zero");
            return static_cast<long long>(qpfreq.QuadPart);
#elif __linux__
            return static_cast<long long>(1E9);
#else /* generic Unix */
            return static_cast<long long>(1E6);
#endif /* (choice of OS) */
        }
    };
    
    //! Construct an absolute timestamp initialized to zero.
    tick_count() : my_count(0) {};

    //! Return current time.
    static tick_count now();
    
    //! Subtract two timestamps to get the time interval between
    friend interval_t operator-( const tick_count& t1, const tick_count& t0 );

    //! Return the resolution of the clock in seconds per tick.
    static double resolution() { return 1.0 / interval_t::ticks_per_second(); }

private:
    long long my_count;
};

inline tick_count tick_count::now() {
    tick_count result;
#if _WIN32||_WIN64
    LARGE_INTEGER qpcnt;
    int rval = QueryPerformanceCounter(&qpcnt);
    __TBB_ASSERT_EX(rval, "QueryPerformanceCounter failed");
    result.my_count = qpcnt.QuadPart;
#elif __linux__
    struct timespec ts;
    int status = clock_gettime( CLOCK_REALTIME, &ts );
    __TBB_ASSERT_EX( status==0, "CLOCK_REALTIME not supported" );
    result.my_count = static_cast<long long>(1000000000UL)*static_cast<long long>(ts.tv_sec) + static_cast<long long>(ts.tv_nsec);
#else /* generic Unix */
    struct timeval tv;
    int status = gettimeofday(&tv, NULL);
    __TBB_ASSERT_EX( status==0, "gettimeofday failed" );
    result.my_count = static_cast<long long>(1000000)*static_cast<long long>(tv.tv_sec) + static_cast<long long>(tv.tv_usec);
#endif /*(choice of OS) */
    return result;
}

inline tick_count::interval_t::interval_t( double sec ) {
    value = static_cast<long long>(sec*interval_t::ticks_per_second());
}

inline tick_count::interval_t operator-( const tick_count& t1, const tick_count& t0 ) {
    return tick_count::interval_t( t1.my_count-t0.my_count );
}

inline double tick_count::interval_t::seconds() const {
    return value*tick_count::resolution();
}

} // namespace tbb

#endif /* __TBB_tick_count_H */
