Method NextTrailingByte

cpp/src/arrow/util/bitmap_reader.h:199–231

  }

  uint8_t NextTrailingByte(int& valid_bits) {
    uint8_t byte;
    assert(trailing_bits_ > 0);

    if (trailing_bits_ <= 8) {
      // last byte
      valid_bits = trailing_bits_;
      trailing_bits_ = 0;
      byte = 0;
      internal::BitmapReader reader(bitmap_, offset_, valid_bits);
      for (int i = 0; i < valid_bits; ++i) {
        byte >>= 1;
        if (reader.IsSet()) {
          byte |= 0x80;
        }
        reader.Next();
      }
      byte >>= (8 - valid_bits);
    } else {
      ++bitmap_;
      const uint8_t next_byte = load<uint8_t>(bitmap_);
      byte = current_data.epi.byte_;
      if (may_have_byte_offset && offset_) {
        byte >>= offset_;
        byte |= next_byte << (8 - offset_);
      }
      current_data.epi.byte_ = next_byte;
      trailing_bits_ -= 8;
      trailing_bytes_--;
      valid_bits = 8;
    }
    return byte;
  }

  int64_t words() const { return nwords_; }
  int trailing_bytes() const { return trailing_bytes_; }