Method CopySubset

src/io/dense_nbits_bin.hpp:345–360

  }

  void CopySubset(const Bin* full_bin, const data_size_t* used_indices, data_size_t num_used_indices) override {
    auto other_bin = dynamic_cast<const Dense4bitsBin*>(full_bin);
    const data_size_t rest = num_used_indices & 1;
    for (int i = 0; i < num_used_indices - rest; i += 2) {
      data_size_t idx = used_indices[i];
      const auto bin1 = static_cast<uint8_t>((other_bin->data_[idx >> 1] >> ((idx & 1) << 2)) & 0xf);
      idx = used_indices[i + 1];
      const auto bin2 = static_cast<uint8_t>((other_bin->data_[idx >> 1] >> ((idx & 1) << 2)) & 0xf);
      const int i1 = i >> 1;
      data_[i1] = (bin1 | (bin2 << 4));
    }
    if (rest) {
      data_size_t idx = used_indices[num_used_indices - 1];
      data_[num_used_indices >> 1] = (other_bin->data_[idx >> 1] >> ((idx & 1) << 2)) & 0xf;
    }
  }

  void SaveBinaryToFile(const VirtualFileWriter* writer) const override {
    writer->Write(data_.data(), sizeof(uint8_t) * data_.size());