Method readStartEndDelimitedFrames

app/src/IO/FrameReader.cpp:482–539

* @brief Extracts frames bounded by matching start and end delimiters. */

 * @brief Extracts frames bounded by matching start and end delimiters.
 */
void IO::FrameReader::readStartEndDelimitedFrames()
{
  Q_ASSERT(!m_startSequences.isEmpty());
  Q_ASSERT(!m_startSequenceLps.isEmpty());
  Q_ASSERT(!m_finishSequences.isEmpty());
  Q_ASSERT(!m_finishSequenceLps.isEmpty());

  const auto& startSeq  = m_startSequences[0];
  const auto& startLps  = m_startSequenceLps[0];
  const auto& finishSeq = m_finishSequences[0];
  const auto& finishLps = m_finishSequenceLps[0];

  constexpr int kMaxFramesPerCall = 32768;
  int iterations                  = 0;
  while (iterations < kMaxFramesPerCall) {
    ++iterations;

    int finishIndex = m_circularBuffer.findPatternKMP(finishSeq, finishLps);
    if (finishIndex == -1)
      break;

    int startIndex = m_circularBuffer.findPatternKMP(startSeq, startLps);
    if (startIndex == -1 || startIndex >= finishIndex) {
      consumeBytes(finishIndex + finishSeq.size());
      continue;
    }

    qsizetype frameStart  = startIndex + startSeq.size();
    qsizetype frameLength = finishIndex - frameStart;
    if (frameLength <= 0) {
      consumeBytes(finishIndex + finishSeq.size());
      continue;
    }

    const auto crcPosition = finishIndex + finishSeq.size();
    const auto frameEndPos = crcPosition + m_checksumLength;

    CapturedDataPtr ptr;
    CapturedData* cd = claimCapturedSlot(ptr);
    m_circularBuffer.peekRangeInto(frameStart, frameLength, cd->data);
    if (cd->data.isEmpty()) {
      consumeBytes(frameEndPos);
      continue;
    }

    const auto result = checksum(cd->data, crcPosition);
    if (result == ValidationStatus::ChecksumIncomplete)
      break;

    if (result == ValidationStatus::FrameOk)
      enqueueCaptured(std::move(ptr), cd, frameEndPos);
    else
      consumeBytes(frameEndPos);
  }

  if (iterations >= kMaxFramesPerCall) [[unlikely]]
    qWarning() << "[FrameReader] Loop iteration limit reached in readStartEndDelimitedFrames";
}