Radeon_TheatreReadFIFO
old_last_fifo_entry = Radeon_TheatreReadFIFO(ai, last_fifo_addr);
old_mid_fifo_entry = Radeon_TheatreReadFIFO(ai, 0x18f);
uint32 Radeon_TheatreReadFIFO( accelerator_info *ai, uint16 addr );