Ejemplo n.º 1
0
        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];
                        }
                    }
                }
            }
        }
Ejemplo n.º 2
0
        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);
        }
Ejemplo n.º 3
0
        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);
        }