Help in breaking bytes into bits through masking and shifting

[Gribouillis]

You can encode this by using ordinary integer operations

def encode(sign, x, y):
    assert 0 <= x <= 2
    assert 0 <= y <= 9
    assert sign in (0, 1)
    return 64 * sign + 16 * x + y

def decode(n):
    m, y = divmod(n, 16)
    sign, x = divmod(m, 4)
    return sign, x, y

if __name__ == '__main__':
    from itertools import product
    for s, x, y in product(range(2), range(3), range(10)):
        n = encode(s, x, y)
        print(s, x, y, bin(n), decode(n))

Output:
0 0 9 0b1001 (0, 0, 9)
0 1 0 0b10000 (0, 1, 0)
0 1 1 0b10001 (0, 1, 1)
0 1 2 0b10010 (0, 1, 2)
0 1 3 0b10011 (0, 1, 3)
0 1 4 0b10100 (0, 1, 4)
0 1 5 0b10101 (0, 1, 5)
0 1 6 0b10110 (0, 1, 6)
0 1 7 0b10111 (0, 1, 7)
0 1 8 0b11000 (0, 1, 8)
0 1 9 0b11001 (0, 1, 9)
0 2 0 0b100000 (0, 2, 0)
0 2 1 0b100001 (0, 2, 1)
0 2 2 0b100010 (0, 2, 2)
0 2 3 0b100011 (0, 2, 3)
0 2 4 0b100100 (0, 2, 4)
0 2 5 0b100101 (0, 2, 5)
0 2 6 0b100110 (0, 2, 6)
0 2 7 0b100111 (0, 2, 7)
0 2 8 0b101000 (0, 2, 8)
0 2 9 0b101001 (0, 2, 9)
1 0 0 0b1000000 (1, 0, 0)
1 0 1 0b1000001 (1, 0, 1)
1 0 2 0b1000010 (1, 0, 2)
1 0 3 0b1000011 (1, 0, 3)
1 0 4 0b1000100 (1, 0, 4)
1 0 5 0b1000101 (1, 0, 5)
1 0 6 0b1000110 (1, 0, 6)
1 0 7 0b1000111 (1, 0, 7)
1 0 8 0b1001000 (1, 0, 8)
1 0 9 0b1001001 (1, 0, 9)
1 1 0 0b1010000 (1, 1, 0)
1 1 1 0b1010001 (1, 1, 1)
1 1 2 0b1010010 (1, 1, 2)
1 1 3 0b1010011 (1, 1, 3)
1 1 4 0b1010100 (1, 1, 4)
1 1 5 0b1010101 (1, 1, 5)
1 1 6 0b1010110 (1, 1, 6)
1 1 7 0b1010111 (1, 1, 7)
1 1 8 0b1011000 (1, 1, 8)
1 1 9 0b1011001 (1, 1, 9)
1 2 0 0b1100000 (1, 2, 0)
1 2 1 0b1100001 (1, 2, 1)
1 2 2 0b1100010 (1, 2, 2)
1 2 3 0b1100011 (1, 2, 3)
1 2 4 0b1100100 (1, 2, 4)
1 2 5 0b1100101 (1, 2, 5)
1 2 6 0b1100110 (1, 2, 6)
1 2 7 0b1100111 (1, 2, 7)
1 2 8 0b1101000 (1, 2, 8)
1 2 9 0b1101001 (1, 2, 9)