说明：  状态机是逻辑设计的重要内容，状态机的设计水平直接反应工程师的逻辑功底，所以许多公司的硬件和逻辑工程师面试中，状态机设计几乎是必选题目。本章在引入状态机设计思想的基础上，重点讨论如何写好状态机。
(The state machine is an important part of the logic design. The design level of the state machine directly reflects the logic foundation of the engineer. Therefore, in the interview of the hardware and logic engineers of many companies, the design of the state machine is almost a must. This chapter focuses on how to write a state machine based on the concept of state machine design.)