/*
    Copyright 2005-2013 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;}
    };
    
    //! 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 );

private:
    long long my_count;
};

inline tick_count tick_count::now() {
    tick_count result;
#if _WIN32||_WIN64
    LARGE_INTEGER qpcnt;
    QueryPerformanceCounter(&qpcnt);
    result.my_count = qpcnt.QuadPart;
#elif __linux__
    struct timespec ts;
#if TBB_USE_ASSERT
    int status = 
#endif /* TBB_USE_ASSERT */
        clock_gettime( CLOCK_REALTIME, &ts );
    __TBB_ASSERT( 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;
#if TBB_USE_ASSERT
    int status = 
#endif /* TBB_USE_ASSERT */
        gettimeofday(&tv, NULL);
    __TBB_ASSERT( 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 )
{
#if _WIN32||_WIN64
    LARGE_INTEGER qpfreq;
    QueryPerformanceFrequency(&qpfreq);
    value = static_cast<long long>(sec*qpfreq.QuadPart);
#elif __linux__
    value = static_cast<long long>(sec*1E9);
#else /* generic Unix */
    value = static_cast<long long>(sec*1E6);
#endif /* (choice of OS) */
}

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 {
#if _WIN32||_WIN64
    LARGE_INTEGER qpfreq;
    QueryPerformanceFrequency(&qpfreq);
    return value/(double)qpfreq.QuadPart;
#elif __linux__
    return value*1E-9;
#else /* generic Unix */
    return value*1E-6;
#endif /* (choice of OS) */
}

} // namespace tbb

#endif /* __TBB_tick_count_H */