#include "FPS.h"

FPS::FPS(unsigned short frames /* = 2 */) :
	m_iter(frames), m_frames(frames)
{
	if (frames < 2)
		throw "Frames is too small";
	m_clocks = new clock_t[m_frames];
}


FPS::~FPS()
{
	if (m_clocks)
		delete[] m_clocks;
}

const clock_t& FPS::get_clock() const
{
	return m_clocks[m_iter];
}

float FPS::get_spf() const
{
	clock_t diff = (m_clocks[m_iter] - m_clocks[(m_iter + 1) % m_frames]) / (m_frames - 1);
	return ((float)diff) / CLOCKS_PER_SEC;
}

float FPS::get_fps() const
{
	clock_t diff = (m_clocks[m_iter] - m_clocks[(m_iter + 1) % m_frames]) / (m_frames - 1);
	return ((float)CLOCKS_PER_SEC) / diff;
}

void FPS::prepare()
{
	clock_t c = clock();
	for (unsigned short i = 0; i < m_frames; ++i)
		m_clocks[i] = c;
}

float FPS::mark()
{
	(++m_iter) %= m_frames;
	m_clocks[m_iter] = clock();
	clock_t diff = (m_clocks[m_iter] - m_clocks[(m_iter > 0 ? m_iter - 1 : m_frames - 1)]);
	return ((float)diff) / CLOCKS_PER_SEC;
}