Method GetAligned

cpp/src/arrow/util/bit_stream_utils_internal.h:298–326

template <typename T>
inline bool BitReader::GetAligned(int num_bytes, T* v) {
  if (ARROW_PREDICT_FALSE(num_bytes > static_cast<int>(sizeof(T)))) {
    return false;
  }

  int bytes_read = static_cast<int>(bit_util::BytesForBits(bit_offset_));
  if (ARROW_PREDICT_FALSE(byte_offset_ + bytes_read + num_bytes > max_bytes_)) {
    return false;
  }

  // Advance byte_offset to next unread byte and read num_bytes
  byte_offset_ += bytes_read;
  if constexpr (std::is_same_v<T, bool>) {
    // ARROW-18031: if we're trying to get an aligned bool, just check
    // the LSB of the next byte and move on. If we memcpy + FromLittleEndian
    // as usual, we have potential undefined behavior for bools if the value
    // isn't 0 or 1
    *v = *(buffer_ + byte_offset_) & 1;
  } else {
    memcpy(v, buffer_ + byte_offset_, num_bytes);
    *v = arrow::bit_util::FromLittleEndian(*v);
  }
  byte_offset_ += num_bytes;

  bit_offset_ = 0;
  buffered_values_ =
      detail::ReadLittleEndianWord(buffer_ + byte_offset_, max_bytes_ - byte_offset_);
  return true;
}

inline bool BitReader::Advance(int64_t num_bits) {
  int64_t bits_required = bit_offset_ + num_bits;