\begin{verbatim}
__code SceneGraph((void *)rbuf,(void *)wbuf) 
{
    .........
    goto Schedular((void *)wbuf,PPU_Memory1);
}

__code PPU_Memory1((void *)polygon) {
    ..........
    goto Schedular((void *)wbuf,Create_SPAN);
}

__code Create_SPAN((void*)rbuf,(void*)wbuf) 
{
    .........
    goto Schedular((void *)wbuf,PPU_Memory2);
}

__code PPU_Memory2((void *)span) {
    ............
    goto Schedular((void *)wbuf,DRAW);
}

__code DRAW((void*)rbuf,(void*)wbuf) 
{
	..............
    goto Schedular((void*)0,SceneGraph);
}

__code Schedular((void*)rbuf,__code *next) {
	if(....)
         goto *next(rbuf);
	if(....)
         goto *next(rubf,wbuf);
}
\end{verbatim}