Index(screen, amount) register TScreen	*screen; register int	amount;
Index(register TScreen *screen, register int amount)
Index(screen, amount)register TScreen	*screen;register int	amount;{	register int j;	/* 	 * indexing when below scrolling region is cursor down.	 * if cursor high enough, no scrolling necessary.	 */	if (screen->cur_row > screen->bot_marg	 || screen->cur_row + amount <= screen->bot_marg) {		CursorDown(screen, amount);		return;	}	CursorDown(screen, j = screen->bot_marg - screen->cur_row);	Scroll(screen, amount - j);}