verilog实现的FPGA三态以太网链路层通信代码，里面有状态机，并按各个模块的功能分了文件夹，还有说明文档，自定义帧的产生和接收，开发环境为Xilinx ISE，测试无误。-verilog realization FPGA Tri-Mode Ethernet link layer communication code, which the state machine, according to the function of each module sub folder, as well a