packint.py

def pack(int32):
    mask = (2**8)-1
    parts = []
    ret = ""

    for i in range(4):
        parts.append((int32 & mask) >> i*8)
        mask <<= 8

    parts.reverse()

    for part in parts:
        ret += chr(part)

    return ret


def unpack(str4):
    parts = []
    ret   = 0

    for char in str4[::-1]:
        parts.append(ord(char))

    for i, part in enumerate(parts):
        ret += (part << (i * 8))

    return ret