private long readPrevChunkAddress(long chunkAddress, @NotNull DataInputStream in) throws IOException {
    if (myOptions.myHasNoChunks) return 0;
    final long prevOffsetDiff = DataInputOutputUtil.readLONG(in);
    if (prevOffsetDiff >= chunkAddress) {
      throw new IOException("readPrevChunkAddress:" + chunkAddress + "," + prevOffsetDiff + "," + mySize + "," + myPath);
    }
    return prevOffsetDiff != 0 ? chunkAddress - prevOffsetDiff : 0;
  }
private long readPrevChunkAddress(long chunkAddress, @NotNull DataInputStream in)