static void _tx_management(gnrc_netif_t *netif)
{
gnrc_lwmac_tx_state_t state_tx = netif->mac.tx.state;
switch (state_tx) {
case GNRC_LWMAC_TX_STATE_STOPPED: {
_tx_management_stopped(netif);
break;
}
case GNRC_LWMAC_TX_STATE_FAILED: {
/* If transmission failure, do not try burst transmissions and quit other
* transmission attempts in this cycle for collision avoidance */
gnrc_lwmac_set_tx_continue(netif, false);
gnrc_lwmac_set_quit_tx(netif, true);
/* falls through */
/* TX packet will therefore be dropped. No automatic resending here,
* we did our best.
*/
}
case GNRC_LWMAC_TX_STATE_SUCCESSFUL: {
_tx_management_success(netif);
break;
}
default:
gnrc_lwmac_tx_update(netif);
}
/* If state has changed, reschedule main state machine */
if (state_tx != netif->mac.tx.state) {
lwmac_schedule_update(netif);
}
}
static void _sleep_management(gnrc_netif_t *netif)
{
/* If a packet is scheduled, no other (possible earlier) packet can be
* sent before the first one is handled, even no broadcast
*/
if (!gnrc_lwmac_timeout_is_running(netif, GNRC_LWMAC_TIMEOUT_WAIT_DEST_WAKEUP)) {
gnrc_mac_tx_neighbor_t *neighbour;
/* Check if there is packet remaining for retransmission */
if (netif->mac.tx.current_neighbor != NULL) {
neighbour = netif->mac.tx.current_neighbor;
}
else {
/* Check if there are broadcasts to send and transmit immediately */
if (gnrc_priority_pktqueue_length(&(netif->mac.tx.neighbors[0].queue)) > 0) {
netif->mac.tx.current_neighbor = &(netif->mac.tx.neighbors[0]);
lwmac_set_state(netif, GNRC_LWMAC_TRANSMITTING);
return;
}
neighbour = _next_tx_neighbor(netif);
}
if (neighbour != NULL) {
/* if phase is unknown, send immediately. */
if (neighbour->phase > RTT_TICKS_TO_US(GNRC_LWMAC_WAKEUP_INTERVAL_US)) {
netif->mac.tx.current_neighbor = neighbour;
gnrc_lwmac_set_tx_continue(netif, false);
netif->mac.tx.tx_burst_count = 0;
lwmac_set_state(netif, GNRC_LWMAC_TRANSMITTING);
return;
}
/* Offset in microseconds when the earliest (phase) destination
* node wakes up that we have packets for. */
uint32_t time_until_tx = RTT_TICKS_TO_US(_gnrc_lwmac_ticks_until_phase(neighbour->phase));
/* If there's not enough time to prepare a WR to catch the phase
* postpone to next interval */
if (time_until_tx < GNRC_LWMAC_WR_PREPARATION_US) {
time_until_tx += GNRC_LWMAC_WAKEUP_INTERVAL_US;
}
time_until_tx -= GNRC_LWMAC_WR_PREPARATION_US;
/* add a random time before goto TX, for avoiding one node for
* always holding the medium (if the receiver's phase is recorded earlier in this
* particular node) */
uint32_t random_backoff;
random_backoff = random_uint32_range(0, GNRC_LWMAC_TIME_BETWEEN_WR_US);
time_until_tx = time_until_tx + random_backoff;
gnrc_lwmac_set_timeout(netif, GNRC_LWMAC_TIMEOUT_WAIT_DEST_WAKEUP, time_until_tx);
/* Register neighbour to be the next */
netif->mac.tx.current_neighbor = neighbour;
/* Stop dutycycling, we're preparing to send. This prevents the
* timeout arriving late, so that the destination phase would
* be missed. */
/* TODO: bad for power savings */
rtt_handler(GNRC_LWMAC_EVENT_RTT_PAUSE, netif);
}
}
else if (gnrc_lwmac_timeout_is_expired(netif, GNRC_LWMAC_TIMEOUT_WAIT_DEST_WAKEUP)) {
LOG_DEBUG("[LWMAC] Got timeout for dest wakeup, ticks: %" PRIu32 "\n", rtt_get_counter());
gnrc_lwmac_set_tx_continue(netif, false);
netif->mac.tx.tx_burst_count = 0;
lwmac_set_state(netif, GNRC_LWMAC_TRANSMITTING);
}
}
/* return false if send data failed, otherwise return true */
static bool _send_data(gnrc_netif_t *netif)
{
assert(netif != NULL);
gnrc_pktsnip_t *pkt = netif->mac.tx.packet;
gnrc_pktsnip_t *pkt_payload;
assert(pkt != NULL);
/* Enable Auto ACK again */
netopt_enable_t autoack = NETOPT_ENABLE;
netif->dev->driver->set(netif->dev, NETOPT_AUTOACK,
&autoack, sizeof(autoack));
/* It's okay to retry sending DATA. Timing doesn't matter anymore and
* destination is waiting for a certain amount of time. */
uint8_t csma_retries = GNRC_LWMAC_DATA_CSMA_RETRIES;
netif->dev->driver->set(netif->dev, NETOPT_CSMA_RETRIES,
&csma_retries, sizeof(csma_retries));
netif->mac.mac_info |= GNRC_NETIF_MAC_INFO_CSMA_ENABLED;
netopt_enable_t csma_enable = NETOPT_ENABLE;
netif->dev->driver->set(netif->dev, NETOPT_CSMA,
&csma_enable, sizeof(csma_enable));
pkt_payload = pkt->next;
/* Insert LWMAC header above NETIF header. The burst (consecutive) transmission
* scheme works here (sender side). If the sender finds it has pending packets
* for the receiver (and under burst limit), it sets the packet type to
* FRAMETYPE_DATA_PENDING, to notice the receiver for next incoming packet.
* In case the sender has no more packet for the receiver, it simply sets the
* data type to FRAMETYPE_DATA. */
gnrc_lwmac_hdr_t hdr;
if ((gnrc_priority_pktqueue_length(&netif->mac.tx.current_neighbor->queue) > 0) &&
(netif->mac.tx.tx_burst_count < GNRC_LWMAC_MAX_TX_BURST_PKT_NUM)) {
hdr.type = GNRC_LWMAC_FRAMETYPE_DATA_PENDING;
gnrc_lwmac_set_tx_continue(netif, true);
netif->mac.tx.tx_burst_count++;
}
else {
hdr.type = GNRC_LWMAC_FRAMETYPE_DATA;
gnrc_lwmac_set_tx_continue(netif, false);
}
pkt->next = gnrc_pktbuf_add(pkt->next, &hdr, sizeof(hdr), GNRC_NETTYPE_LWMAC);
if (pkt->next == NULL) {
LOG_ERROR("ERROR: [LWMAC-tx] Cannot allocate pktbuf of type GNRC_NETTYPE_LWMAC\n");
LOG_ERROR("ERROR: [LWMAC-tx] Memory maybe full, drop the data packet\n");
netif->mac.tx.packet->next = pkt_payload;
gnrc_pktbuf_release(netif->mac.tx.packet);
/* clear packet point to avoid TX retry */
netif->mac.tx.packet = NULL;
return false;
}
/* if found ongoing transmission, quit this cycle for collision avoidance.
* Data packet will be re-queued and try to send in the next cycle. */
if (_gnrc_lwmac_get_netdev_state(netif) == NETOPT_STATE_RX) {
/* save pointer to netif header */
gnrc_pktsnip_t *netif_snip = pkt->next->next;
/* remove LWMAC header */
pkt->next->next = NULL;
gnrc_pktbuf_release(pkt->next);
/* make append netif header after payload again */
pkt->next = netif_snip;
if (!gnrc_mac_queue_tx_packet(&netif->mac.tx, 0, netif->mac.tx.packet)) {
gnrc_pktbuf_release(netif->mac.tx.packet);
LOG_WARNING("WARNING: [LWMAC-tx] TX queue full, drop packet\n");
}
/* drop pointer so it wont be free'd */
netif->mac.tx.packet = NULL;
return false;
}
/* Send data */
int res = _gnrc_lwmac_transmit(netif, pkt);
if (res < 0) {
LOG_ERROR("ERROR: [LWMAC-tx] Send data failed.");
gnrc_pktbuf_release(pkt);
/* clear packet point to avoid TX retry */
netif->mac.tx.packet = NULL;
return false;
}
/* Packet has been released by netdev, so drop pointer */
netif->mac.tx.packet = NULL;
DEBUG("[LWMAC-tx]: spent %lu WR in TX\n",
(unsigned long)netif->mac.tx.wr_sent);
#if (LWMAC_ENABLE_DUTYCYLE_RECORD == 1)
netif->mac.prot.lwmac.pkt_start_sending_time_ticks =
rtt_get_counter() - netif->mac.prot.lwmac.pkt_start_sending_time_ticks;
DEBUG("[LWMAC-tx]: pkt sending delay in TX: %lu us\n",
RTT_TICKS_TO_US(netif->mac.prot.lwmac.pkt_start_sending_time_ticks));
#endif
return true;
}
