Example #1
0
        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);
                }
            }
        }