/*
    Copyright (c) 2005-2019 Intel Corporation

    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
    You may obtain a copy of the License at

        http://www.apache.org/licenses/LICENSE-2.0

    Unless required by applicable law or agreed to in writing, software
    distributed under the License is distributed on an "AS IS" BASIS,
    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    See the License for the specific language governing permissions and
    limitations under the 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 */
