private static void WriteBackrefLength(CrilaylaBitstream output, long len)
{
len -= 3;
if (len < 3)
{
output.PushBits2((uint)len);
return;
}
output.PushBits2(3);
len -= 3;
if (len < 7)
{
output.PushBits3((uint)len);
return;
}
output.PushBits3(7);
len -= 7;
if (len < 31)
{
output.PushBits5((uint)len);
return;
}
output.PushBits5(31);
len -= 31;
while (true)
{
if (len < 255)
{
output.PushBits8((uint)len);
return;
}
output.PushBits8(255);
len -= 255;
}
}
public static long compress(Stream infile, long offset, long length, Stream outfile)
{
if (length <= 0x100)
{
throw new Exception("data too short, can't compress this");
}
// read bytes to be compressed into buffers
long dataLength = length - 0x100;
byte[] uncompressedData = new byte[0x100];
byte[] input = new byte[dataLength];
Util.get_bytes_seek(offset, infile, uncompressedData, 0x100);
Util.get_bytes(infile, input, dataLength);
long currentPosition = input.LongLength - 1;
// compress
CrilaylaBitstream output = new CrilaylaBitstream();
BackrefFinderCache cache = new BackrefFinderCache(input.LongLength);
while (currentPosition >= 0)
{
ushort backrefPos;
long backrefLen;
cache.GetBackref(input, currentPosition, out backrefPos, out backrefLen);
if (backrefLen >= 3)
{
output.PushBit(1);
output.PushBits13(backrefPos);
WriteBackrefLength(output, backrefLen);
currentPosition -= backrefLen;
}
else
{
output.PushBit(0);
output.PushBits8(input[currentPosition]);
--currentPosition;
}
}
MemoryStream ms = output.Finalize();
long compressedLength = ms.Length;
// write header
outfile.WriteByte((byte)((CpkUncompress.CRILAYLA_sig >> 56) & 0xff));
outfile.WriteByte((byte)((CpkUncompress.CRILAYLA_sig >> 48) & 0xff));
outfile.WriteByte((byte)((CpkUncompress.CRILAYLA_sig >> 40) & 0xff));
outfile.WriteByte((byte)((CpkUncompress.CRILAYLA_sig >> 32) & 0xff));
outfile.WriteByte((byte)((CpkUncompress.CRILAYLA_sig >> 24) & 0xff));
outfile.WriteByte((byte)((CpkUncompress.CRILAYLA_sig >> 16) & 0xff));
outfile.WriteByte((byte)((CpkUncompress.CRILAYLA_sig >> 8) & 0xff));
outfile.WriteByte((byte)((CpkUncompress.CRILAYLA_sig) & 0xff));
outfile.WriteByte((byte)((dataLength) & 0xff));
outfile.WriteByte((byte)((dataLength >> 8) & 0xff));
outfile.WriteByte((byte)((dataLength >> 16) & 0xff));
outfile.WriteByte((byte)((dataLength >> 24) & 0xff));
outfile.WriteByte((byte)((compressedLength) & 0xff));
outfile.WriteByte((byte)((compressedLength >> 8) & 0xff));
outfile.WriteByte((byte)((compressedLength >> 16) & 0xff));
outfile.WriteByte((byte)((compressedLength >> 24) & 0xff));
// write compressed data
byte[] buffer = ms.GetBuffer();
long bufferpos = compressedLength - 1;
while (bufferpos >= 0)
{
outfile.WriteByte(buffer[bufferpos]);
--bufferpos;
}
// write uncompressed data
outfile.Write(uncompressedData, 0, 0x100);
// and we're done!
return(compressedLength + 0x110);
}