def string_to_bytes_fixed_size(src: str, size: int, encoding='utf-8') -> bytes:
    assert type(src) is str, "src must be a string"
    src_bin = src.encode(encoding)
    while len(src_bin) > size:
        src = src[:-1]
        src_bin = src.encode(encoding)
    return src_bin + b'\x00' * (size - len(src_bin))


def bytes_to_string(src: bytes, encoding='utf-8') -> str:
    assert type(src) is bytes, "src must be bytes"
    return src.decode(encoding).rstrip('\x00')