time.cc

void Timer::init(uint32_t targetRate)
{
	if(targetRate <= 0) this->frameTime = 0;
	else this->frameTime = MILLI / targetRate;
	this->prevTime = SDL_GetTicks();
	this->curTime = SDL_GetTicks();
}

void Timer::mark()
{
	this->prevTime = this->curTime;
	this->curTime = SDL_GetTicks();
	this->deltaTime = this->curTime - this->prevTime;
}

bool Timer::sleep()
{
	if(this->frameTime <= 0) return true;
	uint32_t sleepTime = SDL_GetTicks() - this->curTime;
	if(sleepTime < this->frameTime)
	{
		SDL_Delay(this->frameTime - sleepTime);
		return true;
	}
	else return false;
}

time.hh

struct Timer
{
	void init(uint32_t targetRate);
	void mark();
	bool sleep();
	inline void setFrameTime(uint32_t targetRate){this->frameTime = MILLI / targetRate;}
	
	float deltaTime = 0.0f;
	
	private:
	uint32_t prevTime = 0, curTime = 0, frameTime = 0;
};