love/src/modules/timer/sdl/Timer.cpp

/**
* Copyright (c) 2006-2012 LOVE Development Team
*
* This software is provided 'as-is', without any express or implied
* warranty.  In no event will the authors be held liable for any damages
* arising from the use of this software.
*
* Permission is granted to anyone to use this software for any purpose,
* including commercial applications, and to alter it and redistribute it
* freely, subject to the following restrictions:
*
* 1. The origin of this software must not be misrepresented; you must not
*    claim that you wrote the original software. If you use this software
*    in a product, an acknowledgment in the product documentation would be
*    appreciated but is not required.
* 2. Altered source versions must be plainly marked as such, and must not be
*    misrepresented as being the original software.
* 3. This notice may not be removed or altered from any source distribution.
**/

#include <common/config.h>
#include <common/delay.h>

#ifdef LOVE_WINDOWS
#	include <windows.h>
#	include <time.h>
#else
#	include <sys/time.h>
#endif

#include "Timer.h"

namespace love
{
namespace timer
{
namespace sdl
{
	Timer::Timer()
		: currTime(0), prevFpsUpdate(0), fps(0), fpsUpdateFrequency(1),
		frames(0), dt(0)
	{
		// Init the SDL timer system.
		if (SDL_InitSubSystem(SDL_INIT_TIMER) < 0)
			throw Exception(SDL_GetError());
	}

	Timer::~Timer()
	{
		// Quit SDL timer.
		SDL_QuitSubSystem(SDL_INIT_TIMER);
	}

	const char * Timer::getName() const
	{
		return "love.timer.sdl";
	}

	void Timer::step()
	{
		// Frames rendered
		frames++;

		// "Current" time is previous time by now.
		prevTime = currTime;

		// Get ticks from SDL
		currTime = SDL_GetTicks();

		// Convert to number of seconds
		dt = (currTime - prevTime)/1000.0;

		double timeSinceLast = (currTime - prevFpsUpdate)/1000.0;
		// Update FPS?
		if (timeSinceLast > fpsUpdateFrequency)
		{
			fps = int((frames/timeSinceLast) + 0.5);
			prevFpsUpdate = currTime;
			frames = 0;
		}
	}

	void Timer::sleep(double seconds)
	{
		if (seconds > 0)
			delay((int) (seconds*1000));
	}

	double Timer::getDelta() const
	{
		return dt;
	}

	int Timer::getFPS() const
	{
		return fps;
	}

	double Timer::getTime() const
	{
		return SDL_GetTicks()/1000.0;
	}

	double Timer::getMicroTime() const
	{
#ifdef LOVE_WINDOWS
		static __int64 freq = 0;

		if (!freq)
		{
			LARGE_INTEGER temp;
			QueryPerformanceFrequency(&temp);

			freq = (__int64) temp.QuadPart;
		}

		LARGE_INTEGER microTime;
		QueryPerformanceCounter(&microTime);

		// The 64 to 32 bit integer conversion, assuming the fraction part down
		// to microseconds takes 20 bits, should not be a problem unless the
		// system has an uptime of a few decades.
		return (double) microTime.QuadPart / (double) freq;
#else
		timeval t;
		gettimeofday(&t, NULL);
		return t.tv_sec + t.tv_usec/1000000.0;
#endif
	}

} // sdl
} // timer
} // love