static inline int prev_slot(struct b43_dmaring *ring, int slot)
{
	B43_WARN_ON(!(slot >= 0 && slot <= ring->nr_slots - 1));
	if (slot == 0)
		return ring->nr_slots - 1;
	return slot - 1;
}
static inline int prev_slot(struct b43_dmaring *ring, int slot)
{
	B43_WARN_ON(!(slot >= 0 && slot <= ring->nr_slots - 1));
	if (slot == 0)
		return ring->nr_slots - 1;
	return slot - 1;
}