show_board.py

import numpy as np


def show_board(black_board, white_board):
    black_bytes = black_board.to_bytes(8, byteorder='big')
    black_array = np.unpackbits(np.frombuffer(black_bytes, dtype=np.uint8))
    white_bytes = white_board.to_bytes(8, byteorder='big')
    white_array = np.unpackbits(np.frombuffer(white_bytes, dtype=np.uint8))

    chars = (black_array * (ord(b'b') - ord(b'-')) +
             white_array * (ord(b'w') - ord(b'-')) +
             ord(b'-'))
    chars = np.pad(chars.reshape((8, 8)), ((0, 0), (0, 1)), 'constant',
                   constant_values=ord(b'\n'))
    return bytes(chars).decode()


print(show_board(0x0000001008000000, 0x0000000810000000))