DIFF_STAT
s1->rbytes = DIFF_STAT(s2->rbytes, s3->rbytes);
s1->ipackets = DIFF_STAT(s2->ipackets, s3->ipackets);
s1->ierrors = DIFF_STAT(s2->ierrors, s3->ierrors);
s1->obytes = DIFF_STAT(s2->obytes, s3->obytes);
s1->opackets = DIFF_STAT(s2->opackets, s3->opackets);
s1->oerrors = DIFF_STAT(s2->oerrors, s3->oerrors);
s1->snaptime = DIFF_STAT(s2->snaptime, s3->snaptime);
*diff_val = DIFF_STAT(*op1_val, *op2_val);