/*=============================================================================
    Copyright (c) 2005-2007 Hartmut Kaiser
                  2007, 2009 Tim Blechmann

    Distributed under the Boost Software License, Version 1.0.
    (See accompanying file LICENSE_1_0.txt or copy at
    http://www.boost.org/LICENSE_1_0.txt)
=============================================================================*/
#if !defined( BOOST_HIGH_RESOLUTION_TIMER_HPP )
#    define BOOST_HIGH_RESOLUTION_TIMER_HPP

#    include <boost/config.hpp>
#    include <boost/throw_exception.hpp>

#    if _POSIX_C_SOURCE >= 199309L

#        include "time.h"

#        include <limits>
#        include <stdexcept>

namespace boost {

class high_resolution_timer
{
public:
    high_resolution_timer()
    {
        restart();
    }

    void restart()
    {
        int status = clock_gettime( CLOCK_REALTIME, &start_time );

        if ( status == -1 )
            boost::throw_exception( std::runtime_error( "Couldn't initialize start_time" ) );
    }

    double elapsed() const // return elapsed time in seconds
    {
        struct timespec now;

        int status = clock_gettime( CLOCK_REALTIME, &now );

        if ( status == -1 )
            boost::throw_exception( std::runtime_error( "Couldn't get current time" ) );

        struct timespec diff;

        double ret_sec  = double( now.tv_sec - start_time.tv_sec );
        double ret_nsec = double( now.tv_nsec - start_time.tv_nsec );

        while ( ret_nsec < 0 ) {
            ret_sec -= 1.0;
            ret_nsec += 1e9;
        }

        double ret = ret_sec + ret_nsec / 1e9;

        return ret;
    }

    double elapsed_max() const // return estimated maximum value for elapsed()
    {
        return double( ( std::numeric_limits< double >::max )() );
    }

    double elapsed_min() const // return minimum value for elapsed()
    {
        return 0.0;
    }

private:
    struct timespec start_time;
};

} // namespace boost

#    elif defined( __APPLE__ )

#        import <mach/mach_time.h>


namespace boost {

class high_resolution_timer
{
public:
    high_resolution_timer( void )
    {
        mach_timebase_info_data_t info;

        kern_return_t err = mach_timebase_info( &info );
        if ( err )
            throw std::runtime_error( "cannot create mach timebase info" );

        conversion_factor = (double)info.numer / (double)info.denom;
        restart();
    }

    void restart()
    {
        start = mach_absolute_time();
    }

    double elapsed() const // return elapsed time in seconds
    {
        uint64_t now      = mach_absolute_time();
        double   duration = double( now - start ) * conversion_factor;

        return duration
    }

    double elapsed_max() const // return estimated maximum value for elapsed()
    {
        return double( ( std::numeric_limits< double >::max )() );
    }

    double elapsed_min() const // return minimum value for elapsed()
    {
        return 0.0;
    }

private:
    uint64_t start;
    double   conversion_factor;
};

} // namespace boost

#    elif defined( BOOST_WINDOWS )

#        include <limits>
#        include <stdexcept>
#        include <windows.h>

namespace boost {

///////////////////////////////////////////////////////////////////////////////
//
//  high_resolution_timer
//      A timer object measures elapsed time.
//      CAUTION: Windows only!
//
///////////////////////////////////////////////////////////////////////////////
class high_resolution_timer
{
public:
    high_resolution_timer()
    {
        start_time.QuadPart = 0;
        frequency.QuadPart  = 0;

        if ( !QueryPerformanceFrequency( &frequency ) )
            boost::throw_exception( std::runtime_error( "Couldn't acquire frequency" ) );

        restart();
    }

    void restart()
    {
        if ( !QueryPerformanceCounter( &start_time ) )
            boost::throw_exception( std::runtime_error( "Couldn't initialize start_time" ) );
    }

    double elapsed() const // return elapsed time in seconds
    {
        LARGE_INTEGER now;
        if ( !QueryPerformanceCounter( &now ) )
            boost::throw_exception( std::runtime_error( "Couldn't get current time" ) );

        return double( now.QuadPart - start_time.QuadPart ) / frequency.QuadPart;
    }

    double elapsed_max() const // return estimated maximum value for elapsed()
    {
        return ( double( ( std::numeric_limits< LONGLONG >::max )() ) - double( start_time.QuadPart ) )
               / double( frequency.QuadPart );
    }

    double elapsed_min() const // return minimum value for elapsed()
    {
        return 1.0 / frequency.QuadPart;
    }

private:
    LARGE_INTEGER start_time;
    LARGE_INTEGER frequency;
};

} // namespace boost

#    else

//  For other platforms, simply fall back to boost::timer
#        include <boost/throw_exception.hpp>
#        include <boost/timer.hpp>

namespace boost {
typedef boost::timer high_resolution_timer;
} // namespace boost

#    endif

#endif // !defined(BOOST_HIGH_RESOLUTION_TIMER_HPP)