ENGINE_READ64
acthd = ENGINE_READ64(engine, RING_ACTHD, RING_ACTHD_UDW);
bbaddr = ENGINE_READ64(engine, RING_BBADDR, RING_BBADDR_UDW);
addr = ENGINE_READ64(engine, RING_DMA_FADD, RING_DMA_FADD_UDW);