FIFO以及跨时钟域的同步问题。 FIFO有分离的地址总线和用以读写数据的数据通道，以及指示堆栈状态（满、将满等）的状态线。-FIFO as well as cross-clock domain synchronization. FIFO have separate address bus and read and write data to the data channel, as well as the instructions state stack (full, will be fu