DB_CKSUMEND
DB_CKSUMEND(mp1) = DB_CKSUMEND(mp);
DB_CKSUMEND(mp) = pktlen;
DB_CKSUMEND(mp) = pktlen;
if (((len) = (DB_CKSUMEND(mp) - len)) > 0) { \
DB_CKSUMEND(fin->fin_m) += (short)err;
*end = (uint32_t)DB_CKSUMEND(mp);
DB_CKSUMEND(mp) = (intptr_t)end;
DB_CKSUMEND(dst) = DB_CKSUMEND(src);
DB_CKSUMEND(nhdrmp) = oiphlen + otcphlen + seg_len;
(uint32_t)DB_CKSUMEND(mp);
DB_CKSUMEND(mp) = 0;