编码/解码。本例实现将3个8位转换成4个8位。同时将4个8位转换成3个8位。这种转换经常用在通信中。-Encoding/decoding. Example implementation of this will be three 8-bit conversion into four 8-bit. At the same time will be four 8-bit converted into 3 8. Such conversion often used in communications.