工作中写的一个含串口访问功能的小测试程序含多线程CRC校验-work written by a serial access function with a small test program with multithreading CRC

实时监测打印机状态的程序，演示如何使用多线程和WINDOWS打印API的开发例子-Real time monitoring of the printer status program, demonstrates how to use the multithreading and WINDOWS print API development examples