81 lines
1.9 KiB
Python
81 lines
1.9 KiB
Python
from binary import encode_bin, decode_bin
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class BitStreamReader(object):
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__slots__ = ["substream", "buffer", "total_size"]
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def __init__(self, substream):
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self.substream = substream
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self.total_size = 0
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self.buffer = ""
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def close(self):
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if self.total_size % 8 != 0:
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raise ValueError("total size of read data must be a multiple of 8",
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self.total_size)
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def tell(self):
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return self.substream.tell()
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def seek(self, pos, whence = 0):
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self.buffer = ""
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self.total_size = 0
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self.substream.seek(pos, whence)
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def read(self, count):
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assert count >= 0
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l = len(self.buffer)
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if count == 0:
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data = ""
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elif count <= l:
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data = self.buffer[:count]
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self.buffer = self.buffer[count:]
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else:
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data = self.buffer
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count -= l
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bytes = count // 8
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if count & 7:
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bytes += 1
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buf = encode_bin(self.substream.read(bytes))
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data += buf[:count]
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self.buffer = buf[count:]
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self.total_size += len(data)
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return data
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class BitStreamWriter(object):
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__slots__ = ["substream", "buffer", "pos"]
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def __init__(self, substream):
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self.substream = substream
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self.buffer = []
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self.pos = 0
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def close(self):
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self.flush()
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def flush(self):
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bytes = decode_bin("".join(self.buffer))
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self.substream.write(bytes)
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self.buffer = []
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self.pos = 0
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def tell(self):
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return self.substream.tell() + self.pos // 8
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def seek(self, pos, whence = 0):
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self.flush()
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self.substream.seek(pos, whence)
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def write(self, data):
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if not data:
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return
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if type(data) is not str:
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raise TypeError("data must be a string, not %r" % (type(data),))
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self.buffer.append(data)
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