说明：  FIFO（先进先出队列）通常用于数据的缓存和用于容纳异步信号的频率或相位的差异。本FIFO的实现是利用 双口RAM 和读写地址产生模块来实现的.FIFO的接口信号包括异步的写时钟（wr_clk）和读时钟（rd_clk）、 与写时钟同步的写有效（wren）和写数据（wr_data） 、与读时钟同步的读有效（rden）和读数据（rd_data） 为了实现正确的读写和避免FIFO的上溢或下溢，给出与读时钟和写时钟分别同步的FIFO的空标志（empty）和 满标志（full）以禁止读写操作。
(FIFO (FIFO queue) is usually used for data caching and asynchronous signal used to accommodate the frequency or phase differences. The realization of this FIFO is to use dual-port RAM and to read and write address generator module achieved. FIFO interface signals, including asynchronous write clock (wr_clk) and read clock (rd_clk), and write effectively write clock synchronization (wren) and write data (wr_data), clock synchronization and time effective reading (rden) and read data (rd_data) in order to realize the right to read and write and to avoid FIFO overflow or the underflow, is given with the time clock and write clock synchronization FIFO respectively empty signs (empty) and full logo (full) to prohibit the read and write operations.)