npf_tcpstate_t
npf_tcpstate_t nst_tcpst[2];
const npf_tcpstate_t *fst = &nst->nst_tcpst[0];
const npf_tcpstate_t *tst = &nst->nst_tcpst[1];
npf_tcpstate_t *fstate, *tstate;
npf_tcpstate_t *fstate = &cstream_state.nst_tcpst[di];
npf_tcpstate_t *tstate = &cstream_state.nst_tcpst[!di];