turns a long-int into a normalized byte string (adapted from Crypto.Util.number)

def deflate_long(n, add_sign_padding=True):
    """turns a long-int into a normalized byte string (adapted from Crypto.Util.number)"""
    # after much testing, this algorithm was deemed to be the fastest
    s = bytes()
    n = long(n)
    while (n != 0) and (n != -1):
        s = struct.pack('>I', n & xffffffff) + s
        n >>= 32
    # strip off leading zeros, FFs
    for i in enumerate(s):
        if (n == 0) and (i[1] != deflate_zero):
            break
        if (n == -1) and (i[1] != deflate_ff):
            break
    else:
        # degenerate case, n was either 0 or -1
        i = (0,)
        if n == 0:
            s = zero_byte
        else:
            s = max_byte
    s = s[i[0]:]
    if add_sign_padding:
        if (n == 0) and (byte_ord(s[0]) >= 0x80):
            s = zero_byte + s
        if (n == -1) and (byte_ord(s[0]) < 0x80):
            s = max_byte + s
    return s