code: private static long addDigest(long digest, long v)
    {
      digest = Crc64.generate(digest, (byte) (v >> 24));
      digest = Crc64.generate(digest, (byte) (v >> 16));
      digest = Crc64.generate(digest, (byte) (v >> 8));
      digest = Crc64.generate(digest, (byte) v);
  
      return digest;
    }
docs: Adds the int to the digest.