Collate Bytes by Nibble

collate_nibbles.py

from collections.abc import Generator


def collate_nibbles(upper: bytes, lower: bytes) -> Generator[int]:
    def to_nibbles(data: bytes) -> bytes:
        """Convert bytes to nibbles"""
        return (
            nibble for byte in data for nibble in ((byte & 0xF0), (byte & 0x0F) << 4)
        )

    return (
        ((upper_nibble) | (lower_nibble >> 4))
        for upper_nibble, lower_nibble in zip(to_nibbles(upper), to_nibbles(lower))
    )


if __name__ == "__main__":
    upper = b"\xab\xab\xab\xab"
    lower = b"\xcd\xcd\xcd\xcd"

    # Alternate values (not as presentable)
    # upper = b"\x01\x23\x45"
    # lower = b"\xfe\xdc\xba\x98"

    combined = bytes(collate_nibbles(upper, lower))

    # Combining upper (b'\xab\xab\xab\xab') and lower (b'\xcd\xcd\xcd\xcd') one
    # nibble at a time results in combined (b'\xac\xbd\xac\xbd\xac\xbd\xac\xbd').
    print(
        f"Combining upper ({upper}) and lower ({lower}) one "
        f"nibble at a time results in combined ({combined})."
    )