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