DDR

https://blog.csdn.net/sinat_15677011/article/details/113786705?utm_medium=distribute.pc_relevant_download.none-task-blog-baidujs-1.nonecase&depth_1-utm_source=distribute.pc_relevant_download.none-task-blog-baidujs-1.nonecase

 

 

https://zhuanlan.zhihu.com/p/382612204