可实现不定长度的二进制流转换为Base64格式，末尾补‘=’。可实现符合规则的Base64字符串转换为二进制流。已手动对原代码进行修改，可适应无=，一个= 两个= 的字符串。亲测可用。适合单片机使用-It can realize the binary indefinite length of the stream is converted into Base64 format, at the end of fill　= . Can conform to the rules of the Base64 string is converted to binary stream. The original code has been manually modified, can adapt to a string of = =, = two. Pro test available. Suitable for single chip microcomputer use