fifo_read
static char *fifo_read(struct cyapa_fifo *fifo, size_t n);
uint8_t *ptr = fifo_read(&sc->rfifo, 0);
error = uiomove(fifo_read(&sc->rfifo, 0), n, uio);
fifo_read(&sc->rfifo, n);
.vop_read = fifo_read,
static int fifo_read (struct vop_read_args *);