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BitArray.py
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BitArray.py
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# -*- coding: utf-8 -*-
class BitArray:
def __init__(self, data):
self._Data = data
self._DataBitsLeft = len(data) * 8
self._ByteIdx = 0
self._BitIdx = 0
def mask(self, bitcount):
return (1 << bitcount) - 1
def read(self, bitsleftcount):
result = 0
bitsdonecount = 0
while bitsleftcount:
curbitsleftcount = 8 - self._BitIdx
curdata = ord(self._Data[self._ByteIdx]) & self.mask(curbitsleftcount)
if curbitsleftcount >= bitsleftcount:
result <<= bitsleftcount
result |= curdata >> (curbitsleftcount - bitsleftcount)
self._BitIdx += bitsleftcount
bitsleftcount = 0
else:
result <<= curbitsleftcount
result |= curdata
bitsleftcount -= curbitsleftcount
self._BitIdx += curbitsleftcount
if self._BitIdx >= 8:
self._BitIdx = 0
self._ByteIdx += 1
return result