pack/unpack data with zero padding

import math
import struct
from typing import List, Generator


def padding(bits: int, amount: int):
    """
    Return size of data and the required padding fot fit the alignment of bytes
    """
    size = bits * amount
    pad = 0
    if size % 8:
         pad = (2 ** math.ceil(math.log2(size))) - size
    return size, pad


def pack(values: int, bits: int) -> bytes:
    """
    Pack the values by required bits.
    If a value is out of range, a ValueError is raised
    """
    size, pad = padding(bits, len(values))
    result = 0

    for idx, value in enumerate(values):
        if not 0 <= value < 2 ** bits:
            raise ValueError("Value is not in allowed range")
        result |= value << (idx * bits)

    return result.to_bytes(size + pad, "little")



def unpack(data: bytes, bits: int) -> Generator[List[int], None, None]:
    """
    Unpack bytes to integers with given bits.
    """

    value = int.from_bytes(data, "little")

    while value:
        yield value & 0xFF
        value >>= bits


data = pack([1,2,3,4,5], 12)
print(list(unpack(data, 12)))