public void Initialize()
{
Util.Verify(endAddress - startAddress >= 1, startAddress, "Bitstream is empty");
this.input.BaseStream.Seek(endAddress - 1, SeekOrigin.Begin);
int lastByte = this.input.ReadByte() & 0xFF;
Util.Verify(lastByte != 0, endAddress, "Bitstream end mark not present");
bitsConsumed = Constants.SIZE_OF_LONG - Util.HighestBit(lastByte);
int inputSize = (int)(endAddress - startAddress);
if (inputSize >= Constants.SIZE_OF_LONG)
{ /* normal case */
this.currentAddress = this.endAddress - Constants.SIZE_OF_LONG;
this.input.BaseStream.Seek(this.currentAddress, SeekOrigin.Begin);
this.bits = this.input.ReadInt64();
}
else
{
this.currentAddress = this.startAddress;
bits = BitInputStream.ReadTail(this.input, this.startAddress, inputSize);
bitsConsumed += (Constants.SIZE_OF_LONG - inputSize) * 8;
}
}
private void DecodeTail(BinaryReader inputReader, long startAddress, long currentAddress, int bitsConsumed, long bits, BinaryWriter outputWriter, long outputAddress, long outputLimit)
{
int tableLog = this.tableLog;
byte[] numbersOfBits = this.numbersOfBits;
byte[] symbols = this.symbols;
// closer to the end
while (outputAddress < outputLimit)
{
BitInputStreamLoader loader = new BitInputStreamLoader(inputReader, startAddress, currentAddress, bits, bitsConsumed);
bool done = loader.Load();
bitsConsumed = loader.GetBitsConsumed();
bits = loader.GetBits();
currentAddress = loader.GetCurrentAddress();
if (done)
{
break;
}
bitsConsumed = DecodeSymbol(outputWriter, outputAddress++, bits, bitsConsumed, tableLog, numbersOfBits, symbols);
}
// not more data in bit stream, so no need to reload
while (outputAddress < outputLimit)
{
bitsConsumed = DecodeSymbol(outputWriter, outputAddress++, bits, bitsConsumed, tableLog, numbersOfBits, symbols);
}
Util.Verify(BitInputStream.IsEndOfStream(startAddress, currentAddress, bitsConsumed), startAddress, "Bit stream is not fully consumed");
}
private static int DecodeSymbol(BinaryWriter outputWriter, long outputAddress, long bitContainer, int bitsConsumed, int tableLog, byte[] numbersOfBits, byte[] symbols)
{
int value = (int)BitInputStream.PeekBitsFast(bitsConsumed, bitContainer, tableLog);
outputWriter.BaseStream.Seek(outputAddress, SeekOrigin.Begin);
outputWriter.Write(symbols[value]);
return(bitsConsumed + numbersOfBits[value]);
}
public static int Decompress(FiniteStateEntropyTable table, BinaryReader inputReader, long inputAddress, long inputLimit, byte[] outputBuffer)
{
BinaryWriter outputWriter = new BinaryWriter(new MemoryStream(outputBuffer));
long outputAddress = 0;
long outputLimit = outputAddress + outputBuffer.Length;
long input = inputAddress;
long output = outputAddress;
// initialize bit stream
BitInputStreamInitializer initializer = new BitInputStreamInitializer(inputReader, input, inputLimit);
initializer.Initialize();
int bitsConsumed = initializer.GetBitsConsumed();
long currentAddress = initializer.GetCurrentAddress();
long bits = initializer.GetBits();
// initialize first FSE stream
int state1 = (int)BitInputStream.PeekBits(bitsConsumed, bits, table.log2Size);
bitsConsumed += table.log2Size;
BitInputStreamLoader loader = new BitInputStreamLoader(inputReader, input, currentAddress, bits, bitsConsumed);
loader.Load();
bits = loader.GetBits();
bitsConsumed = loader.GetBitsConsumed();
currentAddress = loader.GetCurrentAddress();
// initialize second FSE stream
int state2 = (int)BitInputStream.PeekBits(bitsConsumed, bits, table.log2Size);
bitsConsumed += table.log2Size;
loader = new BitInputStreamLoader(inputReader, input, currentAddress, bits, bitsConsumed);
loader.Load();
bits = loader.GetBits();
bitsConsumed = loader.GetBitsConsumed();
currentAddress = loader.GetCurrentAddress();
byte[] symbols = table.symbol;
byte[] numbersOfBits = table.numberOfBits;
int[] newStates = table.newState;
// decode 4 symbols per loop
while (output <= outputLimit - 4)
{
int numberOfBits;
outputWriter.BaseStream.Seek(output, SeekOrigin.Begin);
outputWriter.Write(symbols[state1]);
numberOfBits = numbersOfBits[state1];
state1 = (int)(newStates[state1] + BitInputStream.PeekBits(bitsConsumed, bits, numberOfBits));
bitsConsumed += numberOfBits;
outputWriter.BaseStream.Seek(output + 1, SeekOrigin.Begin);
outputWriter.Write(symbols[state2]);
numberOfBits = numbersOfBits[state2];
state2 = (int)(newStates[state2] + BitInputStream.PeekBits(bitsConsumed, bits, numberOfBits));
bitsConsumed += numberOfBits;
outputWriter.BaseStream.Seek(output + 2, SeekOrigin.Begin);
outputWriter.Write(symbols[state1]);
numberOfBits = numbersOfBits[state1];
state1 = (int)(newStates[state1] + BitInputStream.PeekBits(bitsConsumed, bits, numberOfBits));
bitsConsumed += numberOfBits;
outputWriter.BaseStream.Seek(output + 3, SeekOrigin.Begin);
outputWriter.Write(symbols[state2]);
numberOfBits = numbersOfBits[state2];
state2 = (int)(newStates[state2] + BitInputStream.PeekBits(bitsConsumed, bits, numberOfBits));
bitsConsumed += numberOfBits;
output += Constants.SIZE_OF_INT;
loader = new BitInputStreamLoader(inputReader, input, currentAddress, bits, bitsConsumed);
bool done = loader.Load();
bitsConsumed = loader.GetBitsConsumed();
bits = loader.GetBits();
currentAddress = loader.GetCurrentAddress();
if (done)
{
break;
}
}
while (true)
{
Util.Verify(output <= outputLimit - 2, input, "Output buffer is too small");
outputWriter.BaseStream.Seek(output++, SeekOrigin.Begin);
outputWriter.Write(symbols[state1]);
int numberOfBits = numbersOfBits[state1];
state1 = (int)(newStates[state1] + BitInputStream.PeekBits(bitsConsumed, bits, numberOfBits));
bitsConsumed += numberOfBits;
loader = new BitInputStreamLoader(inputReader, input, currentAddress, bits, bitsConsumed);
loader.Load();
bitsConsumed = loader.GetBitsConsumed();
bits = loader.GetBits();
currentAddress = loader.GetCurrentAddress();
if (loader.IsOverflow())
{
outputWriter.BaseStream.Seek(output++, SeekOrigin.Begin);
outputWriter.Write(symbols[state2]);
break;
}
Util.Verify(output <= outputLimit - 2, input, "Output buffer is too small");
outputWriter.BaseStream.Seek(output++, SeekOrigin.Begin);
outputWriter.Write(symbols[state2]);
int numberOfBits1 = numbersOfBits[state2];
state2 = (int)(newStates[state2] + BitInputStream.PeekBits(bitsConsumed, bits, numberOfBits1));
bitsConsumed += numberOfBits1;
loader = new BitInputStreamLoader(inputReader, input, currentAddress, bits, bitsConsumed);
loader.Load();
bitsConsumed = loader.GetBitsConsumed();
bits = loader.GetBits();
currentAddress = loader.GetCurrentAddress();
if (loader.IsOverflow())
{
outputWriter.BaseStream.Seek(output++, SeekOrigin.Begin);
outputWriter.Write(symbols[state1]);
break;
}
}
return((int)(output - outputAddress));
}
