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class DumbCRC32(object):
def __init__(self):
self._remainder = 0xffffffff
self._reversed_polynomial = 0xedb88320
self._final_xor = 0xffffffff
def update(self, data):
bit_count = len(data) * 8
for bit_n in range(bit_count):
bit_in = data[bit_n >> 3] & (1 << (bit_n & 7))
self._remainder ^= 1 if bit_in != 0 else 0
bit_out = (self._remainder & 1)
self._remainder >>= 1;
if bit_out != 0:
self._remainder ^= self._reversed_polynomial;
def digest(self):
return self._remainder ^ self._final_xor
def hexdigest(self):
return '%08x' % self.digest()
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