RBUF_SIZE
rcvbuf[n].rb_pop = &rcvbuf[n].rb_buf[RBUF_SIZE]; \
uint8_t rb_buf[RBUF_SIZE + 4];
rcvbuf[n].rb_pop = rcvbuf[n].rb_push = &rcvbuf[n].rb_buf[RBUF_SIZE]; \
rcvbuf[n].rb_push = &rcvbuf[n].rb_buf[RBUF_SIZE]; \