zc_switch
if (bcanputnext(RD(zc_switch(qp)), mp->b_band)) {
putnext(RD(zc_switch(qp)), mp);
if (zc_switch(RD(qp)) != NULL) {
putnext(zc_switch(RD(qp)), mp);
} else if ((zc_switch(RD(qp)) != NULL) &&
putnext(zc_switch(RD(qp)), nmp);
if (zc_switch(RD(qp)) == NULL) {
ASSERT(zc_switch(RD(qp)) != NULL);
putnext(zc_switch(RD(qp)), mp);
if (qp->q_first == NULL && bcanputnext(RD(zc_switch(qp)), mp->b_band)) {
putnext(RD(zc_switch(qp)), mp);
if (zc_switch(qp) == NULL) {
qenable(WR(zc_switch(qp)));
if (zc_switch(RD(qp)) == NULL) {