ICSharpCode.SharpZipLib.Zip.Compression.InflaterDynHeader.BuildDistTree C# (CSharp) Method

        public InflaterHuffmanTree BuildDistTree()
        {
            byte[] distLens = new byte[dnum];
            Array.Copy(litdistLens, lnum, distLens, 0, dnum);
            return new InflaterHuffmanTree(distLens);
        }

        /// <summary>
        /// Decodes the deflated stream.
        /// </summary>
        /// <returns>
        /// false if more input is needed, or if finished.
        /// </returns>
        /// <exception cref="SharpZipBaseException">
        /// if deflated stream is invalid.
        /// </exception>
        private bool Decode()
        {
            switch (mode)
            {
            case DECODE_HEADER:
                return(DecodeHeader());

            case DECODE_DICT:
                return(DecodeDict());

            case DECODE_CHKSUM:
                return(DecodeChksum());

            case DECODE_BLOCKS:
                if (isLastBlock)
                {
                    if (noHeader)
                    {
                        mode = FINISHED;
                        return(false);
                    }
                    else
                    {
                        input.SkipToByteBoundary();
                        neededBits = 32;
                        mode       = DECODE_CHKSUM;
                        return(true);
                    }
                }

                int type = input.PeekBits(3);
                if (type < 0)
                {
                    return(false);
                }
                input.DropBits(3);

                if ((type & 1) != 0)
                {
                    isLastBlock = true;
                }
                switch (type >> 1)
                {
                case DeflaterConstants.STORED_BLOCK:
                    input.SkipToByteBoundary();
                    mode = DECODE_STORED_LEN1;
                    break;

                case DeflaterConstants.STATIC_TREES:
                    litlenTree = InflaterHuffmanTree.defLitLenTree;
                    distTree   = InflaterHuffmanTree.defDistTree;
                    mode       = DECODE_HUFFMAN;
                    break;

                case DeflaterConstants.DYN_TREES:
                    dynHeader = new InflaterDynHeader();
                    mode      = DECODE_DYN_HEADER;
                    break;

                default:
                    throw new SharpZipBaseException("Unknown block type " + type);
                }
                return(true);

            case DECODE_STORED_LEN1:
            {
                if ((uncomprLen = input.PeekBits(16)) < 0)
                {
                    return(false);
                }
                input.DropBits(16);
                mode = DECODE_STORED_LEN2;
            }
                goto case DECODE_STORED_LEN2;                         /* fall through */

            case DECODE_STORED_LEN2:
            {
                int nlen = input.PeekBits(16);
                if (nlen < 0)
                {
                    return(false);
                }
                input.DropBits(16);
                if (nlen != (uncomprLen ^ 0xffff))
                {
                    throw new SharpZipBaseException("broken uncompressed block");
                }
                mode = DECODE_STORED;
            }
                goto case DECODE_STORED;                        /* fall through */

            case DECODE_STORED:
            {
                int more = outputWindow.CopyStored(input, uncomprLen);
                uncomprLen -= more;
                if (uncomprLen == 0)
                {
                    mode = DECODE_BLOCKS;
                    return(true);
                }
                return(!input.IsNeedingInput);
            }

            case DECODE_DYN_HEADER:
                if (!dynHeader.Decode(input))
                {
                    return(false);
                }

                litlenTree = dynHeader.BuildLitLenTree();
                distTree   = dynHeader.BuildDistTree();
                mode       = DECODE_HUFFMAN;
                goto case DECODE_HUFFMAN;                         /* fall through */

            case DECODE_HUFFMAN:
            case DECODE_HUFFMAN_LENBITS:
            case DECODE_HUFFMAN_DIST:
            case DECODE_HUFFMAN_DISTBITS:
                return(DecodeHuffman());

            case FINISHED:
                return(false);

            default:
                throw new SharpZipBaseException("Inflater.Decode unknown mode");
            }
        }