def test_guess_standard_parameters_and_datarange(self):
c = GenericCRC(polynomial="16_ccitt", start_value=False, final_xor=False,
reverse_polynomial=False, reverse_all=False, lsb_first=False, little_endian=False)
inpt = "101010101010101010000000111000000000000011100000001011010010110100000000111000000101001010000100000000000100111001111110010000000011011111111001001101100001100010100000000000111011110100010"
vrfy_crc = "0011101111010001"
result = c.guess_standard_parameters_and_datarange(c.str2arr(inpt), c.str2arr(vrfy_crc))
self.assertEqual(result, (2, 84, 172))
self.assertEqual(vrfy_crc, c.bit2str(c.crc(c.str2arr(inpt[result[1]:result[2]]))))
def test_bruteforce_parameters_and_data_range_improved(self):
c = GenericCRC(polynomial="16_ccitt",
start_value=False,
final_xor=False,
reverse_polynomial=False,
reverse_all=False,
lsb_first=False,
little_endian=False)
inpt = "101010101010101010000000111000000000000011100000001011010010110100000000111000000101001010000100000000000100111001111110010000000011011111111001001101100001100010100000000000111011110100010"
vrfy_crc = "0011101111010001"
t1 = 0
runs = 100
for i in range(0, runs):
t = time.time()
result = c.bruteforce_parameters_and_data_range(
c.str2arr(inpt),
len(inpt) - len(vrfy_crc) - 1)
t1 += time.time() - t
# print(result, c.bit2str(c.crc(c.str2arr(inpt[result[1]:result[2]]))))
self.assertEqual(result[0], 2) # Parameters = 2
self.assertEqual(result[1],
len(inpt) - 1 - 16 - 88) # start of datarange
self.assertEqual(result[2], len(inpt) - 1 - 16) # end of datarange
inpt = "0" + inpt if i % 2 == 0 else "1" + inpt
# print("Performance:", t1/runs)
self.assertLess(t1 / runs,
0.1) # Should be faster than 100ms in average
def test_adaptive_crc_calculation(self):
c = GenericCRC(polynomial="16_ccitt", start_value=False, final_xor=False,
reverse_polynomial=False, reverse_all=False, lsb_first=False, little_endian=False)
inpt1 = "10101010101010"
inpt2 = "1010101010101001"
crc1 = c.crc(c.str2arr(inpt1))
crc2 = c.crc(c.str2arr(inpt2))
# Compute crc2 from crc1 in a faster way
# Note: In general only forward direction
delta = "01"
c.start_value = crc1
crcx = c.crc(c.str2arr(delta))
self.assertEqual(crcx, crc2)