public void Build(BitReader br, int valueBitCount)
{
_root = new Node();
ReadNode(br, _root, valueBitCount);
}
public static byte[] Decompress(byte[] data, byte[] prev = null)
{
var output = new List <byte>();
var outputPosition = 0;
if (prev != null)
{
output = new List <byte>(prev);
outputPosition = prev.Length;
}
using (var br = new BitReader(new MemoryStream(data), BitOrder.LSBFirst, 1, ByteOrder.LittleEndian))
{
var initialByte = br.ReadBits <int>(8);
// 3 init holders
var rawValueMapping = new Tree();
rawValueMapping.Build(br, 8);
var indexValueMapping = new Tree();
indexValueMapping.Build(br, 6);
var displacementIndexMapping = new Tree();
displacementIndexMapping.Build(br, 5);
while (true)
{
var index = indexValueMapping.ReadValue(br);
if (index == 0)
{
// Finish decompression
if (initialByte < 3)
{
break;
}
var outputLength = output.Count - outputPosition;
var iVar4 = initialByte - 2;
if (outputLength <= iVar4)
{
break;
}
var length = outputLength - iVar4;
var position = 0;
do
{
length--;
var byte1 = output[outputPosition + position];
var byte2 = output[outputPosition + iVar4 + position];
output[outputPosition + iVar4 + position] = (byte)(byte1 + byte2);
position++;
} while (length != 0);
break;
}
if (index < 0x20)
{
// Match reading
// Max displacement 0x8000; Min displacement 1
// Max length 0x102; Min length 1
var counter = Counters[index];
if (CounterBitReads[index] != 0)
{
counter += br.ReadBits <int>(CounterBitReads[index]);
}
var displacementIndex = displacementIndexMapping.ReadValue(br);
var displacement = DisplacementRanges[displacementIndex];
if (DisplacementBitReads[displacementIndex] != 0)
{
displacement += br.ReadBits <int>(DisplacementBitReads[displacementIndex]);
}
if (counter == 0)
{
continue;
}
var bufferIndex = _windowBufferPosition + WindowBuffer.Length - displacement;
for (int i = 0; i < counter; i++)
{
var next = WindowBuffer[bufferIndex++ % WindowBuffer.Length];
output.Add(next);
WindowBuffer[_windowBufferPosition] = next;
_windowBufferPosition = (_windowBufferPosition + 1) % WindowBuffer.Length;
}
}
else
{
// Raw data reading
index -= 0x20;
var counter = Counters[index];
if (CounterBitReads[index] != 0)
{
counter += br.ReadBits <int>(CounterBitReads[index]);
}
if (counter == 0)
{
continue;
}
for (int i = 0; i < counter; i++)
{
var rawValue = (byte)rawValueMapping.ReadValue(br);
output.Add(rawValue);
WindowBuffer[_windowBufferPosition] = rawValue;
_windowBufferPosition = (_windowBufferPosition + 1) % WindowBuffer.Length;
}
}
}
}
return(output.ToArray());
}
