leon3系统中ddr2控制器的相关代码（还包包括存储器的仿真模型），该控制器可以与amba2.0的ahb总线相连，机构比较复杂，代码量很大-ddr2 controller code (package includes the memory of the simulation model) leon3 system, the controller can with amba2.0 the ahb bus connected to more complex institutions, the am