RevIndex(screen, amount) register TScreen	*screen; register int	amount;
RevIndex(register TScreen *screen, register int amount)
RevIndex(screen, amount)register TScreen	*screen;register int	amount;{	/*	 * reverse indexing when above scrolling region is cursor up.	 * if cursor low enough, no reverse indexing needed	 */	if (screen->cur_row < screen->top_marg	 || screen->cur_row-amount >= screen->top_marg) {		CursorUp(screen, amount);		return;	}	RevScroll(screen, amount - (screen->cur_row - screen->top_marg));	CursorUp(screen, screen->cur_row - screen->top_marg);}