//C++ header - Open Scene Graph - Copyright (C) 1998-2001 Robert Osfield
//Distributed under the terms of the GNU Library General Public License (LGPL)
//as published by the Free Software Foundation.

#ifndef OSG_TIMER
#define OSG_TIMER 1

#include <osg/Export>


namespace osg {

#if defined(WIN32 ) && !defined(__CYGWIN__)
    typedef __int64 Timer_t;
#elif defined(__linux) || defined(__FreeBSD__) || defined(__CYGWIN__)
    typedef unsigned long long Timer_t;
#elif defined(__sgi)
    typedef unsigned long long Timer_t;
#elif defined(unix)
    typedef unsigned long long Timer_t;
#elif defined __APPLE__ || defined macintosh
	typedef double Timer_t;
#else
    #include <ctime>
    typedef std::clock_t Timer_t;
#endif

/** A high resolution, low latency time stamper.*/
class SG_EXPORT Timer {

    public:

        Timer();
        ~Timer() {}

	#if defined __DARWIN_OSX__  || defined macintosh
	// PJA MAC OSX - inline Tick() pollutes namespace so badly 
	// we cant compile, due to Carbon.h ...
        Timer_t tick() const;
	#else
		inline Timer_t tick() const;
	#endif
		
        inline double delta_s( Timer_t t1, Timer_t t2 ) const { return (double)(t2 - t1)*_secsPerClick; }
        inline double delta_m( Timer_t t1, Timer_t t2 ) const { return delta_s(t1,t2)*1e3; }
        inline double delta_u( Timer_t t1, Timer_t t2 ) const { return delta_s(t1,t2)*1e6; }
        inline double delta_n( Timer_t t1, Timer_t t2 ) const { return delta_s(t1,t2)*1e9; }

    private :

        double                  _secsPerClick;
        bool                    _useStandardClock;
       
        #ifdef __sgi
        unsigned long*          _clockAddress;
        int                     _cycleCntrSize;
        static unsigned long    _dummy;
        #endif
        
};

}

#if defined(_WIN32) && !(defined(__CYGWIN__) || defined(__MINGW32__))
    #include <time.h>
    #pragma optimize("",off)

namespace osg{

    inline Timer_t Timer::tick( void ) const
    {
        if (_useStandardClock) return clock();
        
        volatile Timer_t ts;
        volatile unsigned int HighPart;
        volatile unsigned int LowPart;
        _asm
        {
            xor eax, eax        //  Used when QueryPerformanceCounter()
            xor edx, edx        //  not supported or minimal overhead
            _emit 0x0f          //  desired
            _emit 0x31          //
            mov HighPart,edx
            mov LowPart,eax
        }
        //ts = LowPart | HighPart >> 32;
        *((unsigned int*)&ts) = LowPart;
        *((unsigned int*)&ts+1) = HighPart;
        return ts;
    }

}
    #pragma optimize("",on)
    
#elif defined(__linux) || defined(__FreeBSD__) || defined(__CYGWIN__) || defined(__MINGW32__)

    #include <sys/time.h>

    #define CLK(x)      __asm__ volatile (".byte 0x0f, 0x31" : "=A" (x))

namespace osg{

    inline Timer_t Timer::tick() const
    {
        if (_useStandardClock)
        {
            struct timeval tv;
            gettimeofday(&tv, NULL);
            return ((osg::Timer_t)tv.tv_sec)*1000000+(osg::Timer_t)tv.tv_usec;
        }
        else
        {
            Timer_t x;CLK(x);return x;
        }
    }

}
  
#elif defined(__sgi)

    #include <sys/time.h>

namespace osg{

    inline  Timer_t Timer::tick()  const
    {
        if (_useStandardClock)
        {
            struct timeval tv;
            gettimeofday(&tv, NULL);
            return ((osg::Timer_t)tv.tv_sec)*1000000+(osg::Timer_t)tv.tv_usec;
        }
        else
        {
            return *_clockAddress;
        }
    }
}
    
#elif defined(unix)

    #include <sys/time.h>

namespace osg{
    inline  Timer_t Timer::tick() const
    {
        struct timeval tv;
        gettimeofday(&tv, NULL);
        return ((osg::Timer_t)tv.tv_sec)*1000000+(osg::Timer_t)tv.tv_usec;
    }
}

#elif !defined (__DARWIN_OSX__) && !defined (macintosh)

    // no choice, always use std::clock()

namespace osg{

    inline  Timer_t Timer::tick( void ) const { return std::clock(); }
}

#endif

// note, MacOSX compiled in the Timer.cpp.

#endif