Ejemplo n.º 1
0
 public int GetSymbol(StreamManipulator input)
 {
     int lookahead, symbol;
     if ((lookahead = input.PeekBits(9)) >= 0)
     {
         if ((symbol = tree[lookahead]) >= 0)
         {
             input.DropBits(symbol & 15);
             return symbol >> 4;
         }
         int subtree = -(symbol >> 4);
         int bitlen = symbol & 15;
         if ((lookahead = input.PeekBits(bitlen)) >= 0)
         {
             symbol = tree[subtree | (lookahead >> 9)];
             input.DropBits(symbol & 15);
             return symbol >> 4;
         }
         else
         {
             int bits = input.AvailableBits;
             lookahead = input.PeekBits(bits);
             symbol = tree[subtree | (lookahead >> 9)];
             if ((symbol & 15) <= bits)
             {
                 input.DropBits(symbol & 15);
                 return symbol >> 4;
             }
             else
             {
                 return -1;
             }
         }
     }
     else
     {
         int bits = input.AvailableBits;
         lookahead = input.PeekBits(bits);
         symbol = tree[lookahead];
         if (symbol >= 0 && (symbol & 15) <= bits)
         {
             input.DropBits(symbol & 15);
             return symbol >> 4;
         }
         else
         {
             return -1;
         }
     }
 }
Ejemplo n.º 2
0
        /// <summary>
        /// Copy from input manipulator to internal window
        /// </summary>
        /// <param name="input">source of data</param>
        /// <param name="length">length of data to copy</param>
        /// <returns>the number of bytes copied</returns>
        public int CopyStored(StreamManipulator input, int length)
        {
            length = Math.Min(Math.Min(length, WindowSize - windowFilled), input.AvailableBytes);
            int copied;

            int tailLen = WindowSize - windowEnd;
            if (length > tailLen)
            {
                copied = input.CopyBytes(window, windowEnd, tailLen);
                if (copied == tailLen)
                {
                    copied += input.CopyBytes(window, 0, length - tailLen);
                }
            }
            else
            {
                copied = input.CopyBytes(window, windowEnd, length);
            }

            windowEnd = (windowEnd + copied) & WindowMask;
            windowFilled += copied;
            return copied;
        }
Ejemplo n.º 3
0
 /// <summary>
 /// Creates a new inflater.
 /// </summary>
 /// <param name="noHeader">
 /// True if no RFC1950/Zlib header and footer fields are expected in the input data
 /// 
 /// This is used for GZIPed/Zipped input.
 /// 
 /// For compatibility with
 /// Sun JDK you should provide one byte of input more than needed in
 /// this case.
 /// </param>
 public Inflater(bool noHeader)
 {
     this.noHeader = noHeader;
     //this.adler = new Adler32();
     input = new StreamManipulator();
     outputWindow = new OutputWindow();
     mode = noHeader ? DECODE_BLOCKS : DECODE_HEADER;
 }
Ejemplo n.º 4
0
        public bool Decode(StreamManipulator input)
        {
        decode_loop:
            for (; ; )
            {
                switch (mode)
                {
                    case LNUM:
                        lnum = input.PeekBits(5);
                        if (lnum < 0)
                        {
                            return false;
                        }
                        lnum += 257;
                        input.DropBits(5);
                        mode = DNUM;
                        goto case DNUM;
                    case DNUM:
                        dnum = input.PeekBits(5);
                        if (dnum < 0)
                        {
                            return false;
                        }
                        dnum++;
                        input.DropBits(5);
                        num = lnum + dnum;
                        litdistLens = new byte[num];
                        mode = BLNUM;
                        goto case BLNUM;
                    case BLNUM:
                        blnum = input.PeekBits(4);
                        if (blnum < 0)
                        {
                            return false;
                        }
                        blnum += 4;
                        input.DropBits(4);
                        blLens = new byte[19];
                        ptr = 0;
                        mode = BLLENS;
                        goto case BLLENS;
                    case BLLENS:
                        while (ptr < blnum)
                        {
                            int len = input.PeekBits(3);
                            if (len < 0)
                            {
                                return false;
                            }
                            input.DropBits(3);
                            blLens[BL_ORDER[ptr]] = (byte)len;
                            ptr++;
                        }
                        blTree = new InflaterHuffmanTree(blLens);
                        blLens = null;
                        ptr = 0;
                        mode = LENS;
                        goto case LENS;
                    case LENS:
                        {
                            int symbol;
                            while (((symbol = blTree.GetSymbol(input)) & ~15) == 0)
                            {
                                litdistLens[ptr++] = lastLen = (byte)symbol;

                                if (ptr == num)
                                {
                                    return true;
                                }
                            }

                            if (symbol < 0)
                            {
                                return false;
                            }

                            if (symbol >= 17)
                            {
                                lastLen = 0;
                            }
                            else
                            {
                                if (ptr == 0)
                                {
                                    throw new Exception();
                                }
                            }
                            repSymbol = symbol - 16;
                        }
                        mode = REPS;
                        goto case REPS;
                    case REPS:
                        {
                            int bits = repBits[repSymbol];
                            int count = input.PeekBits(bits);
                            if (count < 0)
                            {
                                return false;
                            }
                            input.DropBits(bits);
                            count += repMin[repSymbol];

                            if (ptr + count > num)
                            {
                                throw new Exception();
                            }
                            while (count-- > 0)
                            {
                                litdistLens[ptr++] = lastLen;
                            }

                            if (ptr == num)
                            {
                                return true;
                            }
                        }
                        mode = LENS;
                        goto decode_loop;
                }
            }
        }