def add(self, byte):
"""Add a new byte to the CRC engine. 'byte'
should be a python character. E.g: c.add('x')
"""
# CRC-16 polynomial
poly_s = byte ^ (self.state >> 8)
poly_t = poly_s ^ (poly_s >> 4)
result = s16l(self.state, 8) ^ poly_t ^ s16l(poly_t, 5) ^ s16l(poly_t, 12)
self.state = result
def add(self, byte):
"""Add a new byte to the CRC engine. 'byte'
should be a python character. E.g: c.add('x')
"""
# CRC-16 polynomial
s = byte ^ (self.state >> 8)
t = s ^ (s >> 4)
r = s16l(self.state, 8) ^ t ^ s16l(t, 5) ^ s16l(t, 12)
self.state = r
def check_s16l(value, n, expected):
assert s16l(value, n) == expected
def test_s16l_ffff(self):
for num, expected in [(1, 0xfffe), (8, 0xff00), (15, 0x8000), (16, 0)]:
self.assertEqual(s16l(0xffff, num), expected)
def test_s16l_zero(self):
for num in range(16):
self.assertEqual(s16l(0, num), 0)