process method

List<int> process(List<int?> dataWords)

Implementation

List<int> process(List<int?> dataWords) {
  var blockSize = 2;

  if (forEncryption == true) {
    pkcs7Pad(dataWords, blockSize);
  }

  var doFlush = false;
  var dataSigBytes = dataWords.length;
  var blockSizeBytes = blockSize * 4;
  var minBufferSize = 0;

  // Count blocks ready
  var nBlocksReady = dataSigBytes ~/ blockSizeBytes;
  if (doFlush) {
    // Round up to include partial blocks
    nBlocksReady = nBlocksReady.ceil();
  } else {
    // Round down to include only full blocks,
    // less the number of blocks that must remain in the buffer
    nBlocksReady = max((nBlocksReady | 0) - minBufferSize, 0);
  }

  // Count words ready
  var nWordsReady = nBlocksReady * blockSize;

  // Count bytes ready
  var nBytesReady = min(nWordsReady * 4, dataSigBytes);

  // Process blocks
  List<int?>? processedWords;
  if (nWordsReady != 0) {
    for (var offset = 0; offset < nWordsReady; offset += blockSize) {
      // Perform concrete-algorithm logic
      processBlock(dataWords, offset);
    }

    // Remove processed words
    processedWords = dataWords.getRange(0, nWordsReady).toList();
    dataWords.removeRange(0, nWordsReady);
  }

  var result = new List<int>.generate(nBytesReady, (i) {
    if (i < processedWords!.length) {
      return processedWords[i]!;
    }
    return 0;
  });

  if (forEncryption == false) {
    pkcs7Unpad(result, blockSize);
  }

  return result;
}