shmif_buswrite
shmif_buswrite(busmem, busmem->shm_last, &sp, sizeof(sp), &wrap);
dataoff = shmif_buswrite(busmem, dataoff, mtod(m, void *),
uint32_t shmif_buswrite(struct shmif_mem *, uint32_t,
dataoff = shmif_buswrite(bmem, bmem->shm_last, &sp,
dataoff = shmif_buswrite(bmem, dataoff, buf, pcaphdr.len, &wrap);