BitMiracle.LibJpeg.Classic.Internal.jpeg_marker_reader.save_marker C# (CSharp) Method

        private static bool save_marker(jpeg_decompress_struct cinfo)
        {
            jpeg_marker_struct cur_marker = cinfo.m_marker.m_cur_marker;

            byte[] data = null;
            int length = 0;
            int bytes_read;
            int data_length;
            int dataOffset = 0;

            if (cur_marker == null)
            {
                /* begin reading a marker */
                if (!cinfo.m_src.GetTwoBytes(out length))
                    return false;

                length -= 2;
                if (length >= 0)
                {
                    /* watch out for bogus length word */
                    /* figure out how much we want to save */
                    int limit;
                    if (cinfo.m_unread_marker == (int)JPEG_MARKER.COM)
                        limit = cinfo.m_marker.m_length_limit_COM;
                    else
                        limit = cinfo.m_marker.m_length_limit_APPn[cinfo.m_unread_marker - (int)JPEG_MARKER.APP0];

                    if (length < limit)
                        limit = length;

                    /* allocate and initialize the marker item */
                    cur_marker = new jpeg_marker_struct((byte)cinfo.m_unread_marker, length, limit);

                    /* data area is just beyond the jpeg_marker_struct */
                    data = cur_marker.Data;
                    cinfo.m_marker.m_cur_marker = cur_marker;
                    cinfo.m_marker.m_bytes_read = 0;
                    bytes_read = 0;
                    data_length = limit;
                }
                else
                {
                    /* deal with bogus length word */
                    bytes_read = data_length = 0;
                    data = null;
                }
            }
            else
            {
                /* resume reading a marker */
                bytes_read = cinfo.m_marker.m_bytes_read;
                data_length = cur_marker.Data.Length;
                data = cur_marker.Data;
                dataOffset = bytes_read;
            }

            byte[] tempData = null;
            if (data_length != 0)
                tempData = new byte[data.Length];

            while (bytes_read < data_length)
            {
                /* move the restart point to here */
                cinfo.m_marker.m_bytes_read = bytes_read;

                /* If there's not at least one byte in buffer, suspend */
                if (!cinfo.m_src.MakeByteAvailable())
                    return false;

                /* Copy bytes with reasonable rapidity */
                int read = cinfo.m_src.GetBytes(tempData, data_length - bytes_read);
                Buffer.BlockCopy(tempData, 0, data, dataOffset, read);
                bytes_read += read;
                dataOffset += read;
            }

            /* Done reading what we want to read */
            if (cur_marker != null)
            {
                /* will be null if bogus length word */
                /* Add new marker to end of list */
                cinfo.m_marker_list.Add(cur_marker);

                /* Reset pointer & calc remaining data length */
                data = cur_marker.Data;
                dataOffset = 0;
                length = cur_marker.OriginalLength - data_length;
            }

            /* Reset to initial state for next marker */
            cinfo.m_marker.m_cur_marker = null;

            JPEG_MARKER currentMarker = (JPEG_MARKER)cinfo.m_unread_marker;
            if (data_length != 0 && (currentMarker == JPEG_MARKER.APP0 || currentMarker == JPEG_MARKER.APP14))
            {
                tempData = new byte[data.Length];
                Buffer.BlockCopy(data, dataOffset, tempData, 0, data.Length - dataOffset);
            }

            /* Process the marker if interesting; else just make a generic trace msg */
            switch ((JPEG_MARKER)cinfo.m_unread_marker)
            {
                case JPEG_MARKER.APP0:
                    examine_app0(cinfo, tempData, data_length, length);
                    break;
                case JPEG_MARKER.APP14:
                    examine_app14(cinfo, tempData, data_length, length);
                    break;
                default:
                    cinfo.TRACEMS(1, J_MESSAGE_CODE.JTRC_MISC_MARKER, cinfo.m_unread_marker, data_length + length);
                    break;
            }

            /* skip any remaining data -- could be lots */
            if (length > 0)
                cinfo.m_src.skip_input_data(length);

            return true;
        }