public bool IsValid(Span <byte> data, int checksumTagStartIndex)
{
if (checksumTagStartIndex < 0 || (checksumTagStartIndex + ChecksumLength) != data.Length)
{
return(false);
}
int sum = 0;
for (int i = 0; i < checksumTagStartIndex; i++)
{
sum += data[i];
}
int expectedChecksum = sum % Modulus;
Span <byte> expectedDigits = stackalloc byte[ChecksumValueLength];
_converter.Convert(number: expectedChecksum, into: expectedDigits, count: ChecksumValueLength);
var receivedChecksum = data.Slice(checksumTagStartIndex + 3, ChecksumValueLength);
return(receivedChecksum.SequenceEqual(expectedDigits));
}
public bool IsValid(ReadOnlySpan <byte> data, FixMessageContext msgContext)
{
var endingTagPos = msgContext.ChecksumTagStartIndex;
if (endingTagPos < 0 || (endingTagPos + KnownFixTags.Checksum.Length + ChecksumLength + 1) != data.Length)
{
return(false);
}
Span <byte> expectedDigits = stackalloc byte[ChecksumLength];
_converter.Convert(number: msgContext.ChecksumValue, into: expectedDigits, count: ChecksumLength);
var receivedChecksum = data.Slice(endingTagPos + KnownFixTags.Checksum.Length, ChecksumLength);
return(receivedChecksum.SequenceEqual(expectedDigits));
}
public bool IsValid(ReadOnlySpan <byte> data, FixMessageContext msgContext)
{
var endingTagPos = msgContext.ChecksumTagStartIndex;
int startingTagPos = msgContext.MessageTypeTagStartIndex;
int expectedLength = endingTagPos - startingTagPos;
if (expectedLength <= 0)
{
return(false);
}
int digitsCount = (int)(Math.Log10(expectedLength) + 1);
Span <byte> expectedDigits = stackalloc byte[digitsCount + 1];
_converter.Convert(number: expectedLength, into: expectedDigits, count: digitsCount);
expectedDigits[digitsCount] = Constants.SOHByte;
int lengthTagPos = msgContext.LengthTagStartIndex;
var fromLengthStart = data.Slice(lengthTagPos + KnownFixTags.Length.Length);
return(fromLengthStart.StartsWith(expectedDigits));
}