verilog编写的异步fifo源代码，asyn_fifo.v为顶层，调用其他四个文件-asynchronous fifo prepared Verilog source code, asyn_fifo.v for top-level, call the other four documents

利用Verilog实现了一个FIFO，包含几个模块文件，适合初学Verilog的朋友，含测试代码。-Verilog achieved using a FIFO, a document contains several modules, suitable for novice Verilog friends, including test code.