public static void InitializeRleTable(FiniteStateEntropyTable table, byte value)
{
table.log2Size = 0;
table.symbol[0] = value;
table.newState[0] = 0;
table.numberOfBits[0] = 0;
}
public int ReadFseTable(FiniteStateEntropyTable table, BinaryReader inputReader, long inputAddress, long inputLimit, int maxSymbol, int maxTableLog)
{
// read table headers
long input = inputAddress;
Util.Verify(inputLimit - inputAddress >= 4, input, "Not enough input bytes");
int threshold;
int symbolNumber = 0;
bool previousIsZero = false;
inputReader.BaseStream.Seek(input, SeekOrigin.Begin);
int bitStream = inputReader.ReadInt32();
int tableLog = (bitStream & 0xF) + FiniteStateEntropy.MIN_TABLE_LOG;
int numberOfBits = tableLog + 1;
bitStream = Util.UnsignedRightShift(bitStream, 4);
int bitCount = 4;
Util.Verify(tableLog <= maxTableLog, input, "FSE table size exceeds maximum allowed size");
int remaining = (1 << tableLog) + 1;
threshold = 1 << tableLog;
while (remaining > 1 && symbolNumber <= maxSymbol)
{
if (previousIsZero)
{
int n0 = symbolNumber;
while ((bitStream & 0xFFFF) == 0xFFFF)
{
n0 += 24;
if (input < inputLimit - 5)
{
input += 2;
inputReader.BaseStream.Seek(input, SeekOrigin.Begin);
bitStream = Util.UnsignedRightShift(inputReader.ReadInt32(), bitCount);
}
else
{
// end of bit stream
bitStream = Util.UnsignedRightShift(bitStream, 16);
bitCount += 16;
}
}
while ((bitStream & 3) == 3)
{
n0 += 3;
bitStream = Util.UnsignedRightShift(bitStream, 2);
bitCount += 2;
}
n0 += bitStream & 3;
bitCount += 2;
Util.Verify(n0 <= maxSymbol, input, "Symbol larger than max value");
while (symbolNumber < n0)
{
normalizedCounters[symbolNumber++] = 0;
}
if ((input <= inputLimit - 7) || (input + Util.UnsignedRightShift(bitCount, 3) <= inputLimit - 4))
{
input += Util.UnsignedRightShift(bitCount, 3);
bitCount &= 7;
inputReader.BaseStream.Seek(input, SeekOrigin.Begin);
bitStream = Util.UnsignedRightShift(inputReader.ReadInt32(), bitCount);
}
else
{
bitStream = Util.UnsignedRightShift(bitStream, 2);
}
}
short max = (short)((2 * threshold - 1) - remaining);
short count;
if ((bitStream & (threshold - 1)) < max)
{
count = (short)(bitStream & (threshold - 1));
bitCount += numberOfBits - 1;
}
else
{
count = (short)(bitStream & (2 * threshold - 1));
if (count >= threshold)
{
count -= max;
}
bitCount += numberOfBits;
}
count--; // extra accuracy
remaining -= Math.Abs(count);
normalizedCounters[symbolNumber++] = count;
previousIsZero = count == 0;
while (remaining < threshold)
{
numberOfBits--;
threshold = Util.UnsignedRightShift(threshold, 1);
}
if ((input <= inputLimit - 7) || (input + (bitCount >> 3) <= inputLimit - 4))
{
input += Util.UnsignedRightShift(bitCount, 3);
bitCount &= 7;
}
else
{
bitCount -= (int)(8 * (inputLimit - 4 - input));
input = inputLimit - 4;
}
inputReader.BaseStream.Seek(input, SeekOrigin.Begin);
bitStream = Util.UnsignedRightShift(inputReader.ReadInt32(), (bitCount & 31));
}
Util.Verify(remaining == 1 && bitCount <= 32, input, "Input is corrupted");
maxSymbol = symbolNumber - 1;
Util.Verify(maxSymbol <= FiniteStateEntropy.MAX_SYMBOL, input, "Max symbol value too large (too many symbols for FSE)");
input += (bitCount + 7) >> 3;
// populate decoding table
int symbolCount = maxSymbol + 1;
int tableSize = 1 << tableLog;
int highThreshold = tableSize - 1;
table.log2Size = tableLog;
for (byte symbol = 0; symbol < symbolCount; symbol++)
{
if (normalizedCounters[symbol] == -1)
{
table.symbol[highThreshold--] = symbol;
nextSymbol[symbol] = 1;
}
else
{
nextSymbol[symbol] = normalizedCounters[symbol];
}
}
int position = FseCompressionTable.SpreadSymbols(normalizedCounters, maxSymbol, tableSize, highThreshold, table.symbol);
// position must reach all cells once, otherwise normalizedCounter is incorrect
Util.Verify(position == 0, input, "Input is corrupted");
for (int i = 0; i < tableSize; i++)
{
byte symbol = table.symbol[i];
short nextState = nextSymbol[symbol]++;
table.numberOfBits[i] = (byte)(tableLog - Util.HighestBit(nextState));
table.newState[i] = (short)((nextState << table.numberOfBits[i]) - tableSize);
}
return((int)(input - inputAddress));
}
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));
}