Пример #1
0
        /// <summary>
        /// Decodes the deflated stream.
        /// </summary>
        /// <returns>
        /// false if more input is needed, or if finished.
        /// </returns>
        /// <exception cref="System.FormatException">
        /// DataFormatException, 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 (nowrap) {
                            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 FormatException("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 FormatException("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 FormatException();
            }
        }
Пример #2
0
 /// <summary>
 /// Resets the inflater so that a new stream can be decompressed.  All
 /// pending input and output will be discarded.
 /// </summary>
 public void Reset()
 {
     mode = nowrap ? DECODE_BLOCKS : DECODE_HEADER;
     totalIn = totalOut = 0;
     input.Reset();
     outputWindow.Reset();
     dynHeader = null;
     litlenTree = null;
     distTree = null;
     isLastBlock = false;
     adler.Reset();
 }