const int ChunkSize = 128 * 1024; // 128Kb throttling
public EncodingToken CreateEncodingToken(IEncodingInputStream inputStream, CancellationToken cancellationToken)
{
Guard.IsNotNull(inputStream, nameof(inputStream));
WeightsTable weightsTable = BuildWeightsTable(inputStream, cancellationToken);
HuffmanTreeBase huffmanTree = BuildHuffmanTree(weightsTable);
CodingTable codingTable = BuildCodingTable(huffmanTree);
return(new EncodingToken(weightsTable, huffmanTree, codingTable));
}
public WeightsTable BuildWeightsTable(IEncodingInputStream inputStream, CancellationToken cancellationToken)
{
Guard.IsNotNull(inputStream, nameof(inputStream));
WeightsTable weightsTable = new WeightsTable();
int currentChunkSz = 0;
while (inputStream.ReadSymbol(out byte symbol))
{
weightsTable.TrackSymbol(symbol);
if (++currentChunkSz == ChunkSize)
{
cancellationToken.ThrowIfCancellationRequested();
currentChunkSz = 0;
}
}
return(weightsTable);
}
public long Encode(IEncodingInputStream inputStream, IEncodingOutputStream outputStream, EncodingToken encodingToken, CancellationToken cancellationToken, IProgressHandler progress)
{
Guard.IsNotNull(inputStream, nameof(inputStream));
Guard.IsNotNull(outputStream, nameof(outputStream));
Guard.IsNotNull(encodingToken, nameof(encodingToken));
CodingTable codingTable = encodingToken.CodingTable;
inputStream.Reset();
long sequenceLength = 0;
long progressValue = progress?.State.CastTo <CodingProgressState>()?.Value ?? 0;
while (inputStream.ReadSymbol(out byte symbol))
{
BitSequence codingSequence = codingTable[symbol];
for (int n = 0; n < codingSequence.Size; n++)
{
Bit bit = codingSequence[n];
sequenceLength++;
outputStream.WriteBit(bit);
}
// Throttling
if (++progressValue == ChunkSize)
{
cancellationToken.ThrowIfCancellationRequested();
progress?.Report(ChunkSize, inputStream.Path);
progressValue = 0;
}
}
if (progress != null)
{
CodingProgressState progressState = (CodingProgressState)progress.State ?? new CodingProgressState();
progress.State = progressState.WithValue(progressValue);
}
return(sequenceLength);
}
