Method readStartDelimitedFrames

app/src/IO/FrameReader.cpp:417–477

* @brief Extracts frames bounded by consecutive start delimiters. */

 * @brief Extracts frames bounded by consecutive start delimiters.
 */
void IO::FrameReader::readStartDelimitedFrames()
{
  Q_ASSERT(!m_startSequences.isEmpty());
  Q_ASSERT(!m_startSequenceLps.isEmpty());
  Q_ASSERT(m_circularBuffer.capacity() > 0);

  const auto& startSeq = m_startSequences[0];
  const auto& startLps = m_startSequenceLps[0];

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

    int startIndex = m_circularBuffer.findPatternKMP(startSeq, startLps);
    if (startIndex == -1)
      break;

    if (startIndex > 0)
      consumeBytes(startIndex);

    int nextStartIndex = m_circularBuffer.findPatternKMP(startSeq, startLps, startSeq.size());
    if (nextStartIndex == -1)
      break;

    qsizetype frameStart  = startSeq.size();
    qsizetype frameEndPos = nextStartIndex;
    qsizetype frameLength = frameEndPos - frameStart;

    if (frameLength <= 0) {
      consumeBytes(frameEndPos);
      continue;
    }

    const auto crcPosition = frameEndPos - m_checksumLength;
    if (crcPosition < frameStart) {
      consumeBytes(frameEndPos);
      continue;
    }

    CapturedDataPtr ptr;
    CapturedData* cd = claimCapturedSlot(ptr);
    m_circularBuffer.peekRangeInto(frameStart, frameLength - m_checksumLength, 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);
  }