An RDS group, when transmitted, is a 104 bit item consisting of 4 blocks
(A, B, C, D). Each block consists of 26 bits: a 16 data information word
followed by a 10 bit checkword. The receiver strips the 10 bit checkword,
and evaluates it to determine if the the block should be passed along for
decoding.
Convert an array of bytes from the code table to a string. If the destination
string is too small then characters will be silently dropped. If desired
call rds_to_utf8_required_bytes() to determine the number of bytes that
the output string needs to be to contain all characters specified in bytes.
Returns the exact number of UTF-8 bytes needed to represent the RDS-decoded string,
not including a trailing null terminator (unless you explicitly want one).