RING_GET
#define RING_GET(ap) ((ap)->async_ring[(ap)->async_rget++ & RINGMASK])
#define RING_GET(ring, n) \
#define RING_GET(zap) ((zap)->za_ring[(zap)->za_rget++ & RINGMASK])
#define RING_GET(ap) ((ap)->async_ring[(ap)->async_rget++ & RINGMASK])
#define RING_GET(qsp) ((qsp)->qcn_ring[(qsp)->qcn_rget++ & RINGMASK])