public static void DecompressInPlace(byte[] buffer, int headerEnd)
{
BackwardsReader reader = new BackwardsReader(buffer, headerEnd);
int additionalDecLength = reader.ReadInt32();
int startOffset = reader.ReadInt32();
int compressedLength = reader.ReadInt32();
reader.SeekCurrent(12 - startOffset);
int decBase = headerEnd - compressedLength;
int decPos = compressedLength + additionalDecLength;
byte mask = 0;
byte header = 0;
while (decPos > 0)
{
if ((mask >>= 1) == 0)
{
header = reader.ReadByte();
mask = 0x80;
}
if ((header & mask) == 0)
{
buffer[decBase + --decPos] = reader.ReadByte();
}
else
{
ushort pair = (ushort)reader.ReadInt16();
int length = (pair >> 12) + 3;
int position = (pair & 0xfff) + 3;
if (length > decPos)
{
length = decPos;
}
decPos -= length;
int dstPos = decBase + decPos;
if (length <= position)
{
int srcPos = dstPos + position;
Buffer.BlockCopy(buffer, srcPos, buffer, dstPos, length);
}
else
{
for (int offset = 0; offset < length; offset++)
{
buffer[dstPos + offset] = buffer[dstPos + position + offset];
}
}
}
}
}
public static byte[] Decompress(Stream input, int decompressedLength)
{
long end = input.Position;
BackwardsReader reader = new BackwardsReader(input);
int additionalDecLength = reader.ReadInt32();
int startOffset = reader.ReadInt32();
int compressedLength = reader.ReadInt32();
input.Seek(12 - startOffset, SeekOrigin.Current);
byte[] dec = new byte[decompressedLength];
int decompressedLengthUnpadded = compressedLength + additionalDecLength;
int decompressionStart = decompressedLength - decompressedLengthUnpadded;
int decPos = dec.Length;
byte mask = 0;
byte header = 0;
while (decPos > decompressionStart)
{
if ((mask >>= 1) == 0)
{
header = reader.ReadByte();
mask = 0x80;
}
if ((header & mask) == 0)
{
dec[--decPos] = reader.ReadByte();
}
else
{
ushort pair = (ushort)reader.ReadInt16();
int length = (pair >> 12) + 3;
int position = (pair & 0xfff) + 3;
decPos -= length;
if (length <= position)
{
int srcPos = decPos + position;
Buffer.BlockCopy(dec, srcPos, dec, decPos, length);
}
else
{
for (int offset = 0; offset < length; offset++)
{
dec[decPos + offset] = dec[decPos + position + offset];
}
}
}
}
return(dec);
}
public static byte[] Decompress(Stream Input, int DecompressedLength)
{
long End = Input.Position;
BackwardsReader Reader = new BackwardsReader(Input);
int AdditionalDecLength = Reader.ReadInt32();
int StartOffset = Reader.ReadInt32();
int CompressedLength = Reader.ReadInt32();
Input.Seek(12 - StartOffset, SeekOrigin.Current);
byte[] Dec = new byte[DecompressedLength];
int DecompressedLengthUnpadded = CompressedLength + AdditionalDecLength;
int DecompressionStart = DecompressedLength - DecompressedLengthUnpadded;
int DecPos = Dec.Length;
byte Mask = 0;
byte Header = 0;
while (DecPos > DecompressionStart)
{
if ((Mask >>= 1) == 0)
{
Header = Reader.ReadByte();
Mask = 0x80;
}
if ((Header & Mask) == 0)
{
Dec[--DecPos] = Reader.ReadByte();
}
else
{
ushort Pair = (ushort)Reader.ReadInt16();
int Length = (Pair >> 12) + 3;
int Position = (Pair & 0xfff) + 3;
DecPos -= Length;
if (Length <= Position)
{
int SrcPos = DecPos + Position;
Buffer.BlockCopy(Dec, SrcPos, Dec, DecPos, Length);
}
else
{
for (int Offset = 0; Offset < Length; Offset++)
{
Dec[DecPos + Offset] = Dec[DecPos + Position + Offset];
}
}
}
}
return(Dec);
}
