void* renderLines(void* pArg){
while(true){
	//Synchronize
	pthread_mutex_lock(&frame_mutex);
	pthread_cond_wait(&frame_cond, &frame_mutex);
	pthread_mutex_unlock(&frame_mutex);

	renderLinesArgs* arg = (renderLinesArgs*)pArg;
	for(int y = arg->y1; y < arg->y2; y++){
		for(int x = 0; x < arg->width; x++){
			Color C = arg->scene->renderPixel(x, y);
			putPixel(arg->screen, x, y, C);
		}
	}

	sem_post(&frame_rendered);
    }
}

//Signal a new frame
pthread_mutex_lock(&frame_mutex);
pthread_cond_broadcast(&frame_cond);
pthread_mutex_unlock(&frame_mutex);

//Wait for workers to be done
sem_wait(&frame_rendered);
sem_wait(&frame_rendered);

//Unlock SDL surface and flip it...

$uname -a
Linux jopsen-laptop 2.6.27-14-generic #1 SMP Fri Mar 13 18:00:20 UTC 2009 i686 GNU/Linux

pthread_mutex_lock(&frame_mutex);
pthread_cond_wait(&frame_cond, &frame_mutex);
pthread_mutex_unlock(&frame_mutex);

pthread_mutex_lock(&mutex);
new_frame = 1;
pthread_cond_signal(&cond);
pthread_mutex_unlock(&mutex);

pthread_mutex_lock(&mutex);
while(new_frame == 0)
  pthread_cond_wait(&cond, &mutex);
/* Here new_frame != 0, do things with the frame*/
pthread_mutex_unlock(&mutex);

pthread_mutex_lock(&frame_mutex);
pthread_cond_wait(&frame_cond, &frame_mutex);
pthread_mutex_unlock(&frame_mutex);