internal int Process(InflateBlocks blocks, int r)
        {
            int j;      // temporary storage
            int tindex; // temporary pointer
            int e;      // extra bits or operation
            int b = 0;  // bit buffer
            int k = 0;  // bits in bit buffer
            int p = 0;  // input data pointer
            int n;      // bytes available there
            int q;      // output window write pointer
            int m;      // bytes to end of window or read pointer
            int f;      // pointer to copy strings from

            ZlibCodec z = blocks._codec;

            // copy input/output information to locals (UPDATE macro restores)
            p = z.NextIn;
            n = z.AvailableBytesIn;
            b = blocks.bitb;
            k = blocks.bitk;
            q = blocks.writeAt; m = q < blocks.readAt ? blocks.readAt - q - 1 : blocks.end - q;

            // process input and output based on current state
            while (true)
            {
                switch (mode)
                {
                    // waiting for "i:"=input, "o:"=output, "x:"=nothing
                    case START:  // x: set up for LEN
                        if (m >= 258 && n >= 10)
                        {
                            blocks.bitb = b; blocks.bitk = k;
                            z.AvailableBytesIn = n;
                            z.TotalBytesIn += p - z.NextIn;
                            z.NextIn = p;
                            blocks.writeAt = q;
                            r = InflateFast(lbits, dbits, ltree, ltree_index, dtree, dtree_index, blocks, z);

                            p = z.NextIn;
                            n = z.AvailableBytesIn;
                            b = blocks.bitb;
                            k = blocks.bitk;
                            q = blocks.writeAt; m = q < blocks.readAt ? blocks.readAt - q - 1 : blocks.end - q;

                            if (r != ZlibConstants.Z_OK)
                            {
                                mode = (r == ZlibConstants.Z_STREAM_END) ? WASH : BADCODE;
                                break;
                            }
                        }
                        need = lbits;
                        tree = ltree;
                        tree_index = ltree_index;

                        mode = LEN;
                        goto case LEN;

                    case LEN:  // i: get length/literal/eob next
                        j = need;

                        while (k < j)
                        {
                            if (n != 0)
                                r = ZlibConstants.Z_OK;
                            else
                            {
                                blocks.bitb = b; blocks.bitk = k;
                                z.AvailableBytesIn = n;
                                z.TotalBytesIn += p - z.NextIn;
                                z.NextIn = p;
                                blocks.writeAt = q;
                                return blocks.Flush(r);
                            }
                            n--;
                            b |= (z.InputBuffer[p++] & 0xff) << k;
                            k += 8;
                        }

                        tindex = (tree_index + (b & InternalInflateConstants.InflateMask[j])) * 3;

                        b >>= (tree[tindex + 1]);
                        k -= (tree[tindex + 1]);

                        e = tree[tindex];

                        if (e == 0)
                        {
                            // literal
                            lit = tree[tindex + 2];
                            mode = LIT;
                            break;
                        }
                        if ((e & 16) != 0)
                        {
                            // length
                            bitsToGet = e & 15;
                            len = tree[tindex + 2];
                            mode = LENEXT;
                            break;
                        }
                        if ((e & 64) == 0)
                        {
                            // next table
                            need = e;
                            tree_index = tindex / 3 + tree[tindex + 2];
                            break;
                        }
                        if ((e & 32) != 0)
                        {
                            // end of block
                            mode = WASH;
                            break;
                        }
                        mode = BADCODE; // invalid code
                        z.Message = "invalid literal/length code";
                        r = ZlibConstants.Z_DATA_ERROR;

                        blocks.bitb = b; blocks.bitk = k;
                        z.AvailableBytesIn = n;
                        z.TotalBytesIn += p - z.NextIn;
                        z.NextIn = p;
                        blocks.writeAt = q;
                        return blocks.Flush(r);


                    case LENEXT:  // i: getting length extra (have base)
                        j = bitsToGet;

                        while (k < j)
                        {
                            if (n != 0)
                                r = ZlibConstants.Z_OK;
                            else
                            {
                                blocks.bitb = b; blocks.bitk = k;
                                z.AvailableBytesIn = n; z.TotalBytesIn += p - z.NextIn; z.NextIn = p;
                                blocks.writeAt = q;
                                return blocks.Flush(r);
                            }
                            n--; b |= (z.InputBuffer[p++] & 0xff) << k;
                            k += 8;
                        }

                        len += (b & InternalInflateConstants.InflateMask[j]);

                        b >>= j;
                        k -= j;

                        need = dbits;
                        tree = dtree;
                        tree_index = dtree_index;
                        mode = DIST;
                        goto case DIST;

                    case DIST:  // i: get distance next
                        j = need;

                        while (k < j)
                        {
                            if (n != 0)
                                r = ZlibConstants.Z_OK;
                            else
                            {
                                blocks.bitb = b; blocks.bitk = k;
                                z.AvailableBytesIn = n; z.TotalBytesIn += p - z.NextIn; z.NextIn = p;
                                blocks.writeAt = q;
                                return blocks.Flush(r);
                            }
                            n--; b |= (z.InputBuffer[p++] & 0xff) << k;
                            k += 8;
                        }

                        tindex = (tree_index + (b & InternalInflateConstants.InflateMask[j])) * 3;

                        b >>= tree[tindex + 1];
                        k -= tree[tindex + 1];

                        e = (tree[tindex]);
                        if ((e & 0x10) != 0)
                        {
                            // distance
                            bitsToGet = e & 15;
                            dist = tree[tindex + 2];
                            mode = DISTEXT;
                            break;
                        }
                        if ((e & 64) == 0)
                        {
                            // next table
                            need = e;
                            tree_index = tindex / 3 + tree[tindex + 2];
                            break;
                        }
                        mode = BADCODE; // invalid code
                        z.Message = "invalid distance code";
                        r = ZlibConstants.Z_DATA_ERROR;

                        blocks.bitb = b; blocks.bitk = k;
                        z.AvailableBytesIn = n; z.TotalBytesIn += p - z.NextIn; z.NextIn = p;
                        blocks.writeAt = q;
                        return blocks.Flush(r);


                    case DISTEXT:  // i: getting distance extra
                        j = bitsToGet;

                        while (k < j)
                        {
                            if (n != 0)
                                r = ZlibConstants.Z_OK;
                            else
                            {
                                blocks.bitb = b; blocks.bitk = k;
                                z.AvailableBytesIn = n; z.TotalBytesIn += p - z.NextIn; z.NextIn = p;
                                blocks.writeAt = q;
                                return blocks.Flush(r);
                            }
                            n--; b |= (z.InputBuffer[p++] & 0xff) << k;
                            k += 8;
                        }

                        dist += (b & InternalInflateConstants.InflateMask[j]);

                        b >>= j;
                        k -= j;

                        mode = COPY;
                        goto case COPY;

                    case COPY:  // o: copying bytes in window, waiting for space
                        f = q - dist;
                        while (f < 0)
                        {
                            // modulo window size-"while" instead
                            f += blocks.end; // of "if" handles invalid distances
                        }
                        while (len != 0)
                        {
                            if (m == 0)
                            {
                                if (q == blocks.end && blocks.readAt != 0)
                                {
                                    q = 0; m = q < blocks.readAt ? blocks.readAt - q - 1 : blocks.end - q;
                                }
                                if (m == 0)
                                {
                                    blocks.writeAt = q; r = blocks.Flush(r);
                                    q = blocks.writeAt; m = q < blocks.readAt ? blocks.readAt - q - 1 : blocks.end - q;

                                    if (q == blocks.end && blocks.readAt != 0)
                                    {
                                        q = 0; m = q < blocks.readAt ? blocks.readAt - q - 1 : blocks.end - q;
                                    }

                                    if (m == 0)
                                    {
                                        blocks.bitb = b; blocks.bitk = k;
                                        z.AvailableBytesIn = n;
                                        z.TotalBytesIn += p - z.NextIn;
                                        z.NextIn = p;
                                        blocks.writeAt = q;
                                        return blocks.Flush(r);
                                    }
                                }
                            }

                            blocks.window[q++] = blocks.window[f++]; m--;

                            if (f == blocks.end)
                                f = 0;
                            len--;
                        }
                        mode = START;
                        break;

                    case LIT:  // o: got literal, waiting for output space
                        if (m == 0)
                        {
                            if (q == blocks.end && blocks.readAt != 0)
                            {
                                q = 0; m = q < blocks.readAt ? blocks.readAt - q - 1 : blocks.end - q;
                            }
                            if (m == 0)
                            {
                                blocks.writeAt = q; r = blocks.Flush(r);
                                q = blocks.writeAt; m = q < blocks.readAt ? blocks.readAt - q - 1 : blocks.end - q;

                                if (q == blocks.end && blocks.readAt != 0)
                                {
                                    q = 0; m = q < blocks.readAt ? blocks.readAt - q - 1 : blocks.end - q;
                                }
                                if (m == 0)
                                {
                                    blocks.bitb = b; blocks.bitk = k;
                                    z.AvailableBytesIn = n; z.TotalBytesIn += p - z.NextIn; z.NextIn = p;
                                    blocks.writeAt = q;
                                    return blocks.Flush(r);
                                }
                            }
                        }
                        r = ZlibConstants.Z_OK;

                        blocks.window[q++] = (byte)lit; m--;

                        mode = START;
                        break;

                    case WASH:  // o: got eob, possibly more output
                        if (k > 7)
                        {
                            // return unused byte, if any
                            k -= 8;
                            n++;
                            p--; // can always return one
                        }

                        blocks.writeAt = q; r = blocks.Flush(r);
                        q = blocks.writeAt; m = q < blocks.readAt ? blocks.readAt - q - 1 : blocks.end - q;

                        if (blocks.readAt != blocks.writeAt)
                        {
                            blocks.bitb = b; blocks.bitk = k;
                            z.AvailableBytesIn = n; z.TotalBytesIn += p - z.NextIn; z.NextIn = p;
                            blocks.writeAt = q;
                            return blocks.Flush(r);
                        }
                        mode = END;
                        goto case END;

                    case END:
                        r = ZlibConstants.Z_STREAM_END;
                        blocks.bitb = b; blocks.bitk = k;
                        z.AvailableBytesIn = n; z.TotalBytesIn += p - z.NextIn; z.NextIn = p;
                        blocks.writeAt = q;
                        return blocks.Flush(r);

                    case BADCODE:  // x: got error

                        r = ZlibConstants.Z_DATA_ERROR;

                        blocks.bitb = b; blocks.bitk = k;
                        z.AvailableBytesIn = n; z.TotalBytesIn += p - z.NextIn; z.NextIn = p;
                        blocks.writeAt = q;
                        return blocks.Flush(r);

                    default:
                        r = ZlibConstants.Z_STREAM_ERROR;

                        blocks.bitb = b; blocks.bitk = k;
                        z.AvailableBytesIn = n; z.TotalBytesIn += p - z.NextIn; z.NextIn = p;
                        blocks.writeAt = q;
                        return blocks.Flush(r);
                }
            }
        }
 internal int End()
 {
     if (blocks != null)
         blocks.Free();
     blocks = null;
     return ZlibConstants.Z_OK;
 }
        internal int Initialize(ZlibCodec codec, int w)
        {
            _codec = codec;
            _codec.Message = null;
            blocks = null;

            // handle undocumented nowrap option (no zlib header or check)
            //nowrap = 0;
            //if (w < 0)
            //{
            //    w = - w;
            //    nowrap = 1;
            //}

            // set window size
            if (w < 8 || w > 15)
            {
                End();
                throw new ZlibException("Bad window size.");

                //return ZlibConstants.Z_STREAM_ERROR;
            }
            wbits = w;

            blocks = new InflateBlocks(codec,
                HandleRfc1950HeaderBytes ? this : null,
                1 << w);

            // reset state
            Reset();
            return ZlibConstants.Z_OK;
        }
        // Called with number of bytes left to write in window at least 258
        // (the maximum string length) and number of input bytes available
        // at least ten.  The ten bytes are six bytes for the longest length/
        // distance pair plus four bytes for overloading the bit buffer.

        internal int InflateFast(int bl, int bd, int[] tl, int tl_index, int[] td, int td_index, InflateBlocks s, ZlibCodec z)
        {
            int t;        // temporary pointer
            int[] tp;     // temporary pointer
            int tp_index; // temporary pointer
            int e;        // extra bits or operation
            int b;        // bit buffer
            int k;        // bits in bit buffer
            int p;        // input data pointer
            int n;        // bytes available there
            int q;        // output window write pointer
            int m;        // bytes to end of window or read pointer
            int ml;       // mask for literal/length tree
            int md;       // mask for distance tree
            int c;        // bytes to copy
            int d;        // distance back to copy from
            int r;        // copy source pointer

            int tp_index_t_3; // (tp_index+t)*3

            // load input, output, bit values
            p = z.NextIn; n = z.AvailableBytesIn; b = s.bitb; k = s.bitk;
            q = s.writeAt; m = q < s.readAt ? s.readAt - q - 1 : s.end - q;

            // initialize masks
            ml = InternalInflateConstants.InflateMask[bl];
            md = InternalInflateConstants.InflateMask[bd];

            // do until not enough input or output space for fast loop
            do
            {
                // assume called with m >= 258 && n >= 10
                // get literal/length code
                while (k < (20))
                {
                    // max bits for literal/length code
                    n--;
                    b |= (z.InputBuffer[p++] & 0xff) << k; k += 8;
                }

                t = b & ml;
                tp = tl;
                tp_index = tl_index;
                tp_index_t_3 = (tp_index + t) * 3;
                if ((e = tp[tp_index_t_3]) == 0)
                {
                    b >>= (tp[tp_index_t_3 + 1]); k -= (tp[tp_index_t_3 + 1]);

                    s.window[q++] = (byte)tp[tp_index_t_3 + 2];
                    m--;
                    continue;
                }
                do
                {

                    b >>= (tp[tp_index_t_3 + 1]); k -= (tp[tp_index_t_3 + 1]);

                    if ((e & 16) != 0)
                    {
                        e &= 15;
                        c = tp[tp_index_t_3 + 2] + ((int)b & InternalInflateConstants.InflateMask[e]);

                        b >>= e; k -= e;

                        // decode distance base of block to copy
                        while (k < 15)
                        {
                            // max bits for distance code
                            n--;
                            b |= (z.InputBuffer[p++] & 0xff) << k; k += 8;
                        }

                        t = b & md;
                        tp = td;
                        tp_index = td_index;
                        tp_index_t_3 = (tp_index + t) * 3;
                        e = tp[tp_index_t_3];

                        do
                        {

                            b >>= (tp[tp_index_t_3 + 1]); k -= (tp[tp_index_t_3 + 1]);

                            if ((e & 16) != 0)
                            {
                                // get extra bits to add to distance base
                                e &= 15;
                                while (k < e)
                                {
                                    // get extra bits (up to 13)
                                    n--;
                                    b |= (z.InputBuffer[p++] & 0xff) << k; k += 8;
                                }

                                d = tp[tp_index_t_3 + 2] + (b & InternalInflateConstants.InflateMask[e]);

                                b >>= e; k -= e;

                                // do the copy
                                m -= c;
                                if (q >= d)
                                {
                                    // offset before dest
                                    //  just copy
                                    r = q - d;
                                    if (q - r > 0 && 2 > (q - r))
                                    {
                                        s.window[q++] = s.window[r++]; // minimum count is three,
                                        s.window[q++] = s.window[r++]; // so unroll loop a little
                                        c -= 2;
                                    }
                                    else
                                    {
                                        Array.Copy(s.window, r, s.window, q, 2);
                                        q += 2; r += 2; c -= 2;
                                    }
                                }
                                else
                                {
                                    // else offset after destination
                                    r = q - d;
                                    do
                                    {
                                        r += s.end; // force pointer in window
                                    }
                                    while (r < 0); // covers invalid distances
                                    e = s.end - r;
                                    if (c > e)
                                    {
                                        // if source crosses,
                                        c -= e; // wrapped copy
                                        if (q - r > 0 && e > (q - r))
                                        {
                                            do
                                            {
                                                s.window[q++] = s.window[r++];
                                            }
                                            while (--e != 0);
                                        }
                                        else
                                        {
                                            Array.Copy(s.window, r, s.window, q, e);
                                            q += e; r += e; e = 0;
                                        }
                                        r = 0; // copy rest from start of window
                                    }
                                }

                                // copy all or what's left
                                if (q - r > 0 && c > (q - r))
                                {
                                    do
                                    {
                                        s.window[q++] = s.window[r++];
                                    }
                                    while (--c != 0);
                                }
                                else
                                {
                                    Array.Copy(s.window, r, s.window, q, c);
                                    q += c; r += c; c = 0;
                                }
                                break;
                            }
                            else if ((e & 64) == 0)
                            {
                                t += tp[tp_index_t_3 + 2];
                                t += (b & InternalInflateConstants.InflateMask[e]);
                                tp_index_t_3 = (tp_index + t) * 3;
                                e = tp[tp_index_t_3];
                            }
                            else
                            {
                                z.Message = "invalid distance code";

                                c = z.AvailableBytesIn - n; c = (k >> 3) < c ? k >> 3 : c; n += c; p -= c; k -= (c << 3);

                                s.bitb = b; s.bitk = k;
                                z.AvailableBytesIn = n; z.TotalBytesIn += p - z.NextIn; z.NextIn = p;
                                s.writeAt = q;

                                return ZlibConstants.Z_DATA_ERROR;
                            }
                        }
                        while (true);
                        break;
                    }

                    if ((e & 64) == 0)
                    {
                        t += tp[tp_index_t_3 + 2];
                        t += (b & InternalInflateConstants.InflateMask[e]);
                        tp_index_t_3 = (tp_index + t) * 3;
                        if ((e = tp[tp_index_t_3]) == 0)
                        {
                            b >>= (tp[tp_index_t_3 + 1]); k -= (tp[tp_index_t_3 + 1]);
                            s.window[q++] = (byte)tp[tp_index_t_3 + 2];
                            m--;
                            break;
                        }
                    }
                    else if ((e & 32) != 0)
                    {
                        c = z.AvailableBytesIn - n; c = (k >> 3) < c ? k >> 3 : c; n += c; p -= c; k -= (c << 3);

                        s.bitb = b; s.bitk = k;
                        z.AvailableBytesIn = n; z.TotalBytesIn += p - z.NextIn; z.NextIn = p;
                        s.writeAt = q;

                        return ZlibConstants.Z_STREAM_END;
                    }
                    else
                    {
                        z.Message = "invalid literal/length code";

                        c = z.AvailableBytesIn - n; c = (k >> 3) < c ? k >> 3 : c; n += c; p -= c; k -= (c << 3);

                        s.bitb = b; s.bitk = k;
                        z.AvailableBytesIn = n; z.TotalBytesIn += p - z.NextIn; z.NextIn = p;
                        s.writeAt = q;

                        return ZlibConstants.Z_DATA_ERROR;
                    }
                }
                while (true);
            }
            while (m >= 258 && n >= 10);

            // not enough input or output--restore pointers and return
            c = z.AvailableBytesIn - n; c = (k >> 3) < c ? k >> 3 : c; n += c; p -= c; k -= (c << 3);

            s.bitb = b; s.bitk = k;
            z.AvailableBytesIn = n; z.TotalBytesIn += p - z.NextIn; z.NextIn = p;
            s.writeAt = q;

            return ZlibConstants.Z_OK;
        }