long long UnserializeUInt(IMkvReader* pReader, long long pos, long long size) {
  if (!pReader || pos < 0 || (size <= 0) || (size > 8))
    return E_FILE_FORMAT_INVALID;

  long long result = 0;

  for (long long i = 0; i < size; ++i) {
    unsigned char b;

    const long status = pReader->Read(pos, 1, &b);

    if (status < 0)
      return status;

    result <<= 8;
    result |= b;

    ++pos;
  }

  return result;
}
Unknown