in signature/csharp/core/SM3Digest.cs [409:418]
internal override void ProcessLength(long bitLength)
{
if (xOff > 14)
{
ProcessBlock();
}
X[14] = (int)(SupportClass.URShift(bitLength, 32));
X[15] = (int)(bitLength & unchecked((int)0xffffffff));
}