public static TelloDatagram DeserializeNew(byte[] buffer, int offset, int count, out TelloErrorCode errorCode)
{
if (buffer == null)
{
throw new ArgumentNullException(nameof(buffer));
}
if (count <= 0)
{
throw new ArgumentOutOfRangeException(nameof(count), count, $"Argument {nameof(count)} must be positive.");
}
if (buffer.Length < offset + count)
{
throw new ArgumentException(
$"The length of '{nameof(buffer)}' can't be " +
$"less than the sum of '{nameof(offset)}' and '{nameof(count)}'.");
}
var magic = buffer[offset];
switch (magic)
{
case TelloCommand.Magic:
return(TelloCommand.DeserializeNew(buffer, offset, count, out errorCode));
default:
var datagram = TelloAsciiDatagram.DeserializeNew(buffer, offset, count, out errorCode);
if (errorCode == TelloErrorCode.NoError)
{
return(datagram);
}
if (errorCode == TelloErrorCode.InvalidAsciiCharacter)
{
errorCode = TelloErrorCode.UnsupportedMagic;
}
return(null);
}
}
public static new TelloAsciiDatagram DeserializeNew(byte[] buffer, int offset, int count, out TelloErrorCode errorCode)
{
if (buffer == null)
{
throw new ArgumentNullException(nameof(buffer));
}
if (count <= 0)
{
throw new ArgumentOutOfRangeException(nameof(count), count, $"Argument {nameof(count)} must be positive.");
}
if (buffer.Length < offset + count)
{
throw new ArgumentException(
$"The length of '{nameof(buffer)}' can't be " +
$"less than the sum of '{nameof(offset)}' and '{nameof(count)}'.");
}
// find the colon character in the buffer:
int asciiLength;
bool found = false;
for (asciiLength = 0; asciiLength < count; ++asciiLength)
{
var b = buffer[offset + asciiLength];
found = b == (byte)':';
if (found)
{
break;
}
else if (!IsPrintableAscii(b))
{
errorCode = TelloErrorCode.InvalidAsciiCharacter;
return(null);
}
}
if (!found)
{
errorCode = TelloErrorCode.UnexpectedAsciiSequence;
return(null);
}
var text = Encoding.ASCII.GetString(buffer, offset, asciiLength);
var datagram = Create(text);
errorCode = datagram.DeserializeBody(buffer, asciiLength + 1, count - asciiLength - 1);
return(datagram);
}
public static TelloDatagram DeserializeNew(byte[] buffer, out TelloErrorCode errorCode)
{
return(DeserializeNew(buffer, 0, buffer.Length, out errorCode));
}
public static new TelloCommand DeserializeNew(byte[] buffer, int offset, int count, out TelloErrorCode errorCode)
{
if (buffer == null)
{
throw new ArgumentNullException(nameof(buffer));
}
if (buffer.Length < offset + count)
{
throw new ArgumentException(
$"The length of '{nameof(buffer)}' can't be " +
$"less than the sum of '{nameof(offset)}' and '{nameof(count)}'.");
}
if (count < HeaderSize)
{
errorCode = TelloErrorCode.PacketTooShort;
return(null);
}
using (var reader = new BinaryReader(new MemoryStream(buffer, offset, count)))
{
var magic = reader.ReadByte();
if (magic != Magic)
{
errorCode = TelloErrorCode.UnsupportedMagic;
return(null);
}
var size = reader.ReadUInt16() >> 3;
var givenCrc8 = reader.ReadByte();
var computedCrc8 = ComputeCrc8(buffer, offset, 3);
if (givenCrc8 != computedCrc8)
{
errorCode = TelloErrorCode.BadCrc8;
return(null);
}
var packetType = (TelloPacketType)reader.ReadByte();
var commandId = (TelloCommandId)reader.ReadUInt16();
var command = Create(packetType, commandId);
command.SequenceNumber = reader.ReadUInt16();
var data = reader.ReadBytes(count - HeaderSize);
var givenCrc16 = reader.ReadUInt16();
var computedCrc16 = ComputeCrc16(buffer, offset, count - sizeof(UInt16));
if (givenCrc16 != computedCrc16)
{
errorCode = TelloErrorCode.BadCrc16;
return(null);
}
errorCode = command.DeserializeBody(data, 0, data.Length);
return(command);
}
}
