/* ---------------------------------------------------------------------------------------------------------------------------------- */
public static int DecompressChapter(WdtFile wdtFile, Chapter chapter, Stream outStream)
{
int decompressedSize;
var compressedBuffer = new byte[chapter.Size + 16]; // Additional safety bytes for LZSS
using (var wdtFileStream = new FileStream(wdtFile.Path, FileMode.Open, FileAccess.Read, FileShare.Read))
{
wdtFileStream.Seek(chapter.StartPosition, SeekOrigin.Begin);
wdtFileStream.Read(compressedBuffer, 0, chapter.Size);
}
// TODO: Cleanup gotos; decompose the method
var compressedPartStream = new MemoryStream(compressedBuffer);
var compressedReader = new BinaryReader(compressedPartStream);
var decompressedWriter = new BinaryWriter(outStream);
{
ushort shifter = 0;
uint processedValue = 0;
int bytesDecompressed = 0;
bool carryFlag = false;
long outStreamBasePosition = outStream.Position;
mainPart:
while (bytesDecompressed < chapter.Size - 1)
{
compressedPartStream.Seek(bytesDecompressed, SeekOrigin.Begin);
processedValue = BinaryUtils.SwapBytes(compressedReader.ReadUInt32());
processedValue = processedValue << (byte)shifter;
bool isShiftCarry = (processedValue & 0x80000000) > 0;
processedValue = processedValue << 1;
if (!isShiftCarry)
{
break;
}
if (shifter == 57351)
{
shifter += 0x2001;
carryFlag = true;
}
else
{
shifter += 0x2001;
carryFlag = false;
}
bytesDecompressed += carryFlag ? 2 : 1;
shifter = (ushort)(shifter & 0xFF07);
processedValue = BinaryUtils.SwapBytes(processedValue);
decompressedWriter.Write((byte)processedValue);
if ((outStream.Position - outStreamBasePosition) >= wdtFile.PageSize)
{
goto endOfFile;
}
}
if (shifter == 57351)
{
shifter += 0x2001;
carryFlag = true;
}
else
{
shifter += 0x2001;
carryFlag = false;
}
BinaryUtils.AddWithCarry(ref bytesDecompressed, 2, carryFlag);
shifter = (ushort)(shifter & 0xFF07);
uint helper = (processedValue >> 0x14);
{
bool shrCarryFlag = false;
if ((helper & 0x80000) > 0)
{
shrCarryFlag = true;
}
if (shrCarryFlag)
{
processedValue &= 0xF0000;
processedValue = processedValue >> 0x10;
decompressedWriter.Seek((int)(outStreamBasePosition + processedValue) + 2, SeekOrigin.Current);
if (bytesDecompressed < chapter.Size - 1)
{
goto endOfFile;
}
else
{
goto mainPart;
}
}
}
{
processedValue &= 0xF0000;
bool shrCarryFlag = false;
if ((processedValue & 0x10000) > 0)
{
shrCarryFlag = true;
}
processedValue = processedValue >> 0x11;
if (shrCarryFlag)
{
long outStreamPosition = outStream.Position;
outStream.Seek(outStreamPosition + helper - 0x1000, SeekOrigin.Begin);
byte someByte = (byte)outStream.ReadByte();
outStream.Seek(outStreamPosition, SeekOrigin.Begin);
decompressedWriter.Write(someByte);
}
}
processedValue++;
while (processedValue > 0)
{
long outStreamPosition = outStream.Position;
outStream.Seek(outStreamPosition + helper - 0x1000, SeekOrigin.Begin);
byte copiedByte = (byte)outStream.ReadByte();
outStream.Seek(outStreamPosition, SeekOrigin.Begin);
decompressedWriter.Write(copiedByte);
outStreamPosition = outStream.Position;
outStream.Seek(outStreamPosition + helper - 0x1000, SeekOrigin.Begin);
copiedByte = (byte)outStream.ReadByte();
outStream.Seek(outStreamPosition, SeekOrigin.Begin);
decompressedWriter.Write(copiedByte);
processedValue--;
}
if (bytesDecompressed < chapter.Size - 1)
{
goto mainPart;
}
endOfFile:
decompressedSize = (int)(outStream.Position - outStreamBasePosition);
}
compressedPartStream.Dispose();
return(decompressedSize);
}
