MissionPlanner.MAVLinkInterface.readlogPacketMavlink C# (CSharp) Method

        MAVLinkMessage readlogPacketMavlink()
        {
            byte[] datearray = new byte[8];

            bool missingtimestamp = false;

            if (logplaybackfile.BaseStream is FileStream)
            {
                if (((FileStream) _logplaybackfile.BaseStream).Name.ToLower().EndsWith(".rlog"))
                    missingtimestamp = true;
            }

            if (!missingtimestamp)
            {
                int tem = logplaybackfile.BaseStream.Read(datearray, 0, datearray.Length);

                Array.Reverse(datearray);

                DateTime date1 = new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc);

                UInt64 dateint = BitConverter.ToUInt64(datearray, 0);

                try
                {
                    // array is reversed above
                    if (datearray[7] == 254 || datearray[7] == 253)
                    {
                        //rewind 8bytes
                        logplaybackfile.BaseStream.Seek(-8, SeekOrigin.Current);
                    }
                    else
                    {
                        if ((dateint/1000/1000/60/60) < 9999999)
                        {
                            date1 = date1.AddMilliseconds(dateint/1000);

                            lastlogread = date1.ToLocalTime();
                        }
                    }
                }
                catch
                {
                }
            }

            byte[] temp = new byte[0];

            byte byte0 = 0;
            byte byte1 = 0;
            byte byte2 = 0;

            var filelength = logplaybackfile.BaseStream.Length;
            var filepos = logplaybackfile.BaseStream.Position;

            if(filelength == filepos)
                return MAVLinkMessage.Invalid;

            int length = 5;
            int a = 0;
            while (a < length)
            {
                if (filelength == filepos)
                    return MAVLinkMessage.Invalid;

                var tempb = (byte) logplaybackfile.ReadByte();
                filepos++;

                switch (a)
                {
                    case 0:
                        byte0 = tempb;
                        if (byte0 != 'U' && byte0 != 254 && byte0 != 253)
                        {
                            log.DebugFormat("logread - lost sync byte {0} pos {1}", byte0,
                                logplaybackfile.BaseStream.Position);
                            // seek to next valid
                            do
                            {
                                byte0 = logplaybackfile.ReadByte();
                            }
                            while (byte0 != 'U' && byte0 != 254 && byte0 != 253);
                            a = 1;
                            continue;
                        }
                        break;
                    case 1:
                        byte1 = tempb;
                        // handle length
                        {
                            int headerlength = byte0 == MAVLINK_STX ? 9 : 5;
                            int headerlengthstx = headerlength + 1;

                            length = byte1 + headerlengthstx + 2; // header + 2 checksum
                        }
                        break;
                    case 2:
                        byte2 = tempb;
                        // handle signing and mavlink2
                        if (byte0 == MAVLINK_STX)
                        {
                            if ((byte2 & MAVLINK_IFLAG_SIGNED) > 0)
                                length += MAVLINK_SIGNATURE_BLOCK_LEN;
                        }
                        // handle rest
                        {
                            temp = new byte[length];
                            temp[0] = byte0;
                            temp[1] = byte1;
                            temp[2] = byte2;

                            var readto = a + 1;
                            var readlength = length - (a + 1);
                            logplaybackfile.Read(temp, readto, readlength);
                            a = length;
                        }
                        break;
                }

                a++;
            }

            MAVLinkMessage tmp = new MAVLinkMessage(temp);

            MAVlist[tmp.sysid, tmp.compid].cs.datetime = lastlogread;

            return tmp;
        }