SRAM的读写代码，对SRAM进行了乒乓操作，用VHDL语言进行设计，很有参考价值，甚至可以直接复制代码来进行自己的设计-SRAM read and write code, ping-pong operation carried out on the SRAM, using VHDL language design, of great reference value, or even directly copy the code to carry out their own designs