public void Communication_CRC8_CRCTest()
{
byte[] testdata1 = new byte[] { 0x01, 0x02, 0x04, 0x05 };
byte[] testdata2 = new byte[] { 0x01, 0x02, 0x04, 0x06 };
byte crcValue1 = CRC8CCITT.Calculate(testdata1);
byte crcValue2 = CRC8CCITT.Calculate(testdata2);
Assert.AreNotEqual(crcValue2, crcValue1);
}
private void CreateChecksum()
{
byte checksum = 0;
for (int n = 1; n < CALIBRATION_RECORD_SIZE; ++n)
{
checksum = CRC8CCITT.Update(checksum, request.GetByte(n));
}
request.InsertByte(CALIBRATION_RECORD_SIZE, checksum);
}
public byte[] ToArray()
{
byte[] retValue;
if (Extended)
{
int offset = GetDataOffset();
retValue = new byte[GetPacketSize()];
retValue[0] = Code;
EncodeFormat(retValue);
EncodeLength(retValue);
if (AddressEnabled)
{
retValue[2 + GetLengthSize()] = Address;
}
for (int i = 0; i < _length; ++i)
{
retValue[i + offset] = data[i];
}
switch (ChecksumAlgorithm)
{
case ChecksumAlgorithmType.Additive:
_checksum = AdditiveChecksum.Calculate(retValue, retValue.Length - 1);
retValue[retValue.Length - 1] = _checksum;
break;
case ChecksumAlgorithmType.CRC8CCIT:
_checksum = CRC8CCITT.Calculate(retValue, retValue.Length - 1);
retValue[retValue.Length - 1] = _checksum;
break;
default:
break;
}
}
else
{
int offset = 2;
retValue = new byte[_length + offset];
retValue[0] = Code;
retValue[1] = (byte)_length;
for (int i = 0; i < _length; ++i)
{
retValue[i + offset] = data[i];
}
}
return(retValue);
}
public Packet(byte[] frame)
{
if (!(frame is object))
{
throw new ArgumentException(Resources.FRAME_IS_NULL);
}
if (frame.Length < 2)
{
throw new PacketFormatException(Resources.INVALID_FRAME_TOO_SHORT);
}
// Parsing the code byte
_code = frame[0];
// Parsing the format byte
if (frame[1] < 128)
{
_length = frame[1];
_lengthEncoding = LengthEncodingType.UInt8Encoding;
Address = 0;
_checksumType = ChecksumAlgorithmType.None;
}
else
{
// Parse the length encoding
switch ((LengthEncodingType)(0x03 & frame[1]))
{
case LengthEncodingType.UInt8Encoding:
_lengthEncoding = LengthEncodingType.UInt8Encoding;
break;
case LengthEncodingType.UInt16Encoding:
_lengthEncoding = LengthEncodingType.UInt16Encoding;
break;
case LengthEncodingType.UInt32Encoding:
_lengthEncoding = LengthEncodingType.UInt32Encoding;
break;
default:
throw new InvalidOperationException($"Invalid length encoding [ {0x03 & frame[1]} ]");
}
// Parse the checksum field
switch ((ChecksumAlgorithmType)(0x0C & frame[1]))
{
case ChecksumAlgorithmType.None:
_checksumType = ChecksumAlgorithmType.None;
break;
case ChecksumAlgorithmType.Additive:
_checksumType = ChecksumAlgorithmType.Additive;
break;
case ChecksumAlgorithmType.CRC8CCIT:
_checksumType = ChecksumAlgorithmType.CRC8CCIT;
break;
default:
throw new InvalidOperationException($"Invalid checksum type [ {0x0C & frame[1]} ]");
}
// Parse the address bit.
if ((0x10 & frame[1]) != 0)
{
Address = frame[2 + GetLengthSize()];
}
}
if (Extended)
{
int offset = GetDataOffset();
_length = DecodeLength(frame);
data = new byte[_length];
for (int i = 0; i < _length; ++i)
{
data[i] = frame[i + offset];
}
// Validate checksum
switch (ChecksumAlgorithm)
{
case ChecksumAlgorithmType.Additive:
{
_checksum = frame[GetChecksumOffset()];
byte actualChecksum = AdditiveChecksum.Calculate(frame, frame.Length - 1);
if (_checksum != actualChecksum)
{
throw new InvalidOperationException($"Checksum incorrect (expected: {_checksum}, actual: {actualChecksum})");
}
}
break;
case ChecksumAlgorithmType.CRC8CCIT:
{
_checksum = frame[GetChecksumOffset()];
byte actualChecksum = CRC8CCITT.Calculate(frame, frame.Length - 1);
if (_checksum != actualChecksum)
{
throw new InvalidOperationException($"Checksum incorrect (expected: {_checksum}, actual: {actualChecksum})");
}
}
break;
default:
break;
}
}
else // Standard frame
{
data = new byte[_length];
int offset = 2;
for (int i = 0; i < _length; ++i)
{
data[i] = frame[i + offset];
}
}
}
