nbpf_chan_read
status = nbpf_chan_read(chan, NBPF_CHAN_STAT);
nbpf_chan_read(chan, NBPF_CHAN_NXLA), nbpf_chan_read(chan, NBPF_CHAN_CRLA));
return nbpf_chan_read(chan, NBPF_CHAN_CUR_TR_BYTE);