/// <summary>
/// Renormalizes the working state by appending a bit from
/// the ANS bitstream. If there still excists bits in the
/// ANS bitstream.
/// </summary>
/// <param name="input">Input ANS bitstream.</param>
/// <param name="state">Working state.</param>
private void RenormalizeDecode(BitStreamIO.Reader input, ref int state)
{
while (state < Config.TotalFrequencyCounts)
{
state <<= 1;
if (input.HasBits())
{
state ^= input.GetBit();
}
}
}
/// <summary>
/// Decodes metadata and bitstream into a list of bytes.
/// </summary>
/// <param name="input">Input ANS bitstream and metadata</param>
public List <byte> DecodeANSBitStream(BitStreamIO.Reader input)
{
SymbolStreamIO.Writer output = new SymbolStreamIO.Writer();
int state = input.BitStream.EndState;
for (int i = 0; i < (input.BitStream.UncompressedLength * 8); i++)
{
output.PutSymbol(DecodeSymbol(ref state));
RenormalizeDecode(input, ref state);
}
if (state != Config.TotalFrequencyCounts)
{
throw new ApplicationException("Decoding data corruption. Expected state " +
Config.TotalFrequencyCounts.ToString() + ", Received " + state.ToString() + ".");
}
output.Reverse();
return(output.SymbolStream.Data);
}
public void StreamDecodeFile(string inputFile, string outputFile)
{
StaticProbabilityANS.Decoder Decoder = new StaticProbabilityANS.Decoder(Alphabet, FrequencyCounts);
BinaryReader InputFile = new BinaryReader(File.Open(inputFile, FileMode.Open));
int endState = InputFile.ReadInt32();
int EndBitOffset = InputFile.ReadInt32();
long UncompressedLength = InputFile.ReadInt64();
List <byte> input = new List <byte>();
for (int i = 16; i < InputFile.BaseStream.Length; i++)
{
input.Add(InputFile.ReadByte());
}
BitStreamIO.Reader encodedChunk = new BitStreamIO.Reader(endState, EndBitOffset, input, UncompressedLength);
List <byte> output = Decoder.DecodeANSBitStream(encodedChunk);
BinaryWriter OutputFile = new BinaryWriter(File.Open(outputFile, FileMode.Create));
for (int i = 0; i < output.Count; i++)
{
OutputFile.Write(output[i]);
}
InputFile.Close();
OutputFile.Close();
}