说明：  1、写一个程序来模拟网桥功能。 2、编写一个计算机程序用来计算一个文件的16位效验和。最快速的方法是用一个32位的整数来存放这个和。记住要处理进位（例如，超过16位的那些位），把它们加到效验和中。
(1, write a program to simulate the bridge function. 2, the preparation of a computer program used to calculate a 16-bit file checksum. The fastest way is to use a 32-bit integer to store this and. Remember to handle binary (for example, more than 16 of those bits), add them to the efficacy and medium.)