Alexandria.Engines.Sciagi.Resource.Open C# (CSharp) Метод

        public override System.IO.Stream Open()
        {
            var reader = Map.OpenPage(Id.Page);
            reader.BaseStream.Position = Id.Offset;

            ResourceType type;
            int id, compressedSize, uncompressedSize;
            CompressionMethod compressionMethod;
            int compressionCode;

            switch (Id.Version) {
                case ResourceMapVersion.Sci0:
                    id = reader.ReadUInt16();
                    compressedSize = reader.ReadUInt16() - 4;
                    uncompressedSize = reader.ReadUInt16();
                    compressionCode = reader.ReadUInt16();

                    if (id != CombinedIndex)
                        throw new Exception("Non-matching index.");

                    switch (compressionCode) {
                        case 0: compressionMethod = CompressionMethod.None; break;
                        case 1: compressionMethod = CompressionMethod.Lzw; break;
                        case 2: compressionMethod = CompressionMethod.Huffman; break;
                        default: throw new NotSupportedException("Compression mode " + compressionCode + " for engine " + Map.EngineVersion + " is not supported.");

                    }
                    break;

                case ResourceMapVersion.Sci1:
                    type = (ResourceType)reader.ReadByte();
                    id = reader.ReadUInt16();
                    compressedSize = reader.ReadUInt16();
                    uncompressedSize = reader.ReadUInt16();
                    compressionCode = reader.ReadUInt16();

                    if(id != CombinedIndex)
                        throw new Exception("Non-matching index.");
                    if (type != (Id.Type | ResourceType.Sci1Mask))
                        throw new InvalidDataException("Incorrect type.");

                    switch (compressionCode) {
                        case 0: compressionMethod = CompressionMethod.None; break;
                        case 1: compressionMethod = CompressionMethod.Lzw; break;
                        case 2: compressionMethod = CompressionMethod.Comp3; break;
                        case 18:
                        case 19:
                        case 20:
                            compressionMethod = CompressionMethod.DclImplode;
                            break;
                        default: throw new NotSupportedException("Compression code " + compressionCode + " for engine " + Id.Version + " is not supported.");
                    }
                    break;

                case ResourceMapVersion.Sci2:
                    type = (ResourceType)reader.ReadByte();
                    id = reader.ReadUInt16();
                    compressedSize = reader.ReadInt32();
                    uncompressedSize = reader.ReadInt32();
                    compressionCode = reader.ReadUInt16();

                    if (id != CombinedIndex)
                        throw new InvalidDataException("Non-matching index.");
                    if (type != Id.FullType)
                        throw new InvalidDataException(string.Format("Incorrect type found in the resource data; {0} was expected but {1} was found.", Id.FullType, type));

                    switch (compressionCode) {
                        case 32: compressionMethod = CompressionMethod.Lzs; break;
                        default: throw new NotSupportedException(string.Format("Compression code " + compressionCode + " for engine " + Id.Version + " is not supported (Page file=\"{0}\", Offset={1:X}h).", Map.GetPagePath(Id.Page), reader.BaseStream.Position));
                    }
                    break;

                default:
                    throw new NotImplementedException("Operation not implemented for version " + Id.Version);
            }

            byte[] data = ResourceDecompressor.Decompress(reader.BaseStream, compressedSize, uncompressedSize, compressionMethod);
            return new MemoryStream(data, false);
        }