p802_15_4csmaca.cc

Low Rate Wireless Personal Area Networks (LR-WPANs)in C

		tmpf += t_transacTime;
		if (tmpf > t_fCAP)
			ok = false;
		else
			ok= true;
	}
	else
	{
		//in this case, we need to handle individual CAP 
		ok = true;
		t_fCAP = mac->getCAPbyType(1);

		/* Linux floating number compatibility
		if (CURRENT_TIME + wtime + t_transacTime > t_fCAP)
		*/
		double tmpf;
		tmpf = CURRENT_TIME + wtime;
		tmpf += t_transacTime;
		if (tmpf > t_fCAP)
			ok = false;
		if (ok)
		{
			t_fCAP = mac->getCAPbyType(2);
			t_transacTime += max_pDelay;						//one-way trip propagation delay (802.15.4 ignores this, but it should be there even though it is very small)
			t_transacTime += 12/phy->getRate('s');					//transceiver turn-around time (receiver may need to do this to transmit next beacon)
			t_transacTime += t_IFS;							//IFS time -- not only ensure that the sender can finish the transaction, but also the receiver

			/* Linux floating number compatibility
			if (CURRENT_TIME + wtime + t_transacTime > t_fCAP)
			*/
			double tmpf;
			tmpf = CURRENT_TIME + wtime;
			tmpf += t_transacTime;
			if (tmpf > t_fCAP)
				ok = false;
		}
		if (ok)
		{
			t_fCAP = mac->getCAPbyType(3);
			t_transacTime -= t_IFS;							//the third node does not need to handle the transaction

			/* Linux floating number compatibility
			if (CURRENT_TIME + wtime + t_transacTime > t_fCAP)
			*/
			double tmpf;
			tmpf = CURRENT_TIME + wtime;
			tmpf += t_transacTime;
			if (tmpf > t_fCAP)
				ok = false;
		}
	}

	//check if have enough CAP to finish the transaction
	if (!ok)
	{
		bPeriodsLeft = 0;
		if ((mac->mpib.macBeaconOrder == 15)
		&&  (mac->macBeaconOrder2 == 15)
		&&  (mac->macBeaconOrder3 != 15))
		{
			/* Linux floating number compatibility
			bcnOtherTime = (mac->macBcnOtherRxTime + mac->sfSpec3.BI) / phy->getRate('s');
			*/
			{
			double tmpf;
			tmpf = (mac->macBcnOtherRxTime + mac->sfSpec3.BI);
			bcnOtherTime = tmpf / phy->getRate('s');
			}

			while (bcnOtherTime < CURRENT_TIME)
				bcnOtherTime += (mac->sfSpec3.BI / phy->getRate('s'));
			bcnOtherT->start(bcnOtherTime - CURRENT_TIME);
		}
#ifdef DEBUG802_15_4
	fprintf(stdout,"[%s::%s][%f](node %d) cannot proceed: orders = %d/%d/%d, type = %s, src = %d, dst = %d, uid = %d, mac_uid = %ld, size = %d\n",__FILE__,__FUNCTION__,CURRENT_TIME,mac->index_,mac->mpib.macBeaconOrder,mac->macBeaconOrder2,mac->macBeaconOrder3,wpan_pName(txPkt),p802_15_4macSA(txPkt),p802_15_4macDA(txPkt),ch->uid(),HDR_LRWPAN(txPkt)->uid,ch->size());
#endif
		if (mac->macBeaconOrder2 != 15)
		if (!mac->bcnRxT->busy())
			mac->bcnRxT->start();
		waitNextBeacon = true;
		return false;
	}
	else
	{
		bPeriodsLeft = -1;
		return true;
	}
}

void CsmaCA802_15_4::newBeacon(char trx)
{
	//this function will be called by MAC each time a new beacon received or sent within the current PAN
	double rate,wtime;

	if (!mac->txAck)
		mac->plme_set_trx_state_request(p_RX_ON);	

	if (bcnOtherT->busy())
		bcnOtherT->stop();

	//update values
	beaconEnabled = ((mac->mpib.macBeaconOrder != 15)||(mac->macBeaconOrder2 != 15));
	beaconOther = (mac->macBeaconOrder3 != 15);
	reset();	
	rate = phy->getRate('s');
	bcnTxTime = mac->macBcnTxTime / rate;
	bcnRxTime = mac->macBcnRxTime / rate;
	bPeriod = aUnitBackoffPeriod / rate;

	if (waitNextBeacon)
	if ((txPkt)
        && (!backoffT->busy()))
	{
		assert(bPeriodsLeft >= 0);
		if (bPeriodsLeft == 0)
		{
			wtime = adjustTime(0.0);
			if (canProceed(wtime));
				backoffHandler();	//no need to resume backoff
		}
		else
		{
			wtime = adjustTime(0.0);
			wtime += bPeriodsLeft * bPeriod;
			if (canProceed(wtime));
				backoffT->start(wtime);
		}
	}
	waitNextBeacon = false;
}

void CsmaCA802_15_4::start(bool firsttime,Packet *pkt,bool ackreq)
{
	bool backoff;
	double rate,wtime,BI2;


	if (mac->txAck)
	{
		mac->backoffStatus = 0;
		txPkt = 0;
		return;
	}

	assert(backoffT->busy() == 0);
	if (firsttime)
	{
		beaconEnabled = ((mac->mpib.macBeaconOrder != 15)||(mac->macBeaconOrder2 != 15));
		beaconOther = (mac->macBeaconOrder3 != 15);
		reset();	
		assert(txPkt == 0);
		txPkt = pkt;
		ackReq = ackreq;
		rate = phy->getRate('s');
		bPeriod = aUnitBackoffPeriod / rate;
		if (beaconEnabled)
		{
			bcnTxTime = mac->macBcnTxTime / rate;
			bcnRxTime = mac->macBcnRxTime / rate;
			//it's possible we missed some beacons
			BI2 = (mac->sfSpec2.BI / phy->getRate('s'));
			if (mac->macBeaconOrder2 != 15)
			while (bcnRxTime + BI2 < CURRENT_TIME)
				bcnRxTime += BI2;
		}
	}

	wtime = (Random::random() % (1<<BE)) * bPeriod;
	wtime = adjustTime(wtime);
	backoff = true;
	if (beaconEnabled||beaconOther)
	{
		if (beaconEnabled)
		if (firsttime)
			wtime = mac->locateBoundary(mac->toParent(txPkt),wtime);
		if (!canProceed(wtime))		
			backoff = false;
	}
	if (backoff)
		backoffT->start(wtime);
}

void CsmaCA802_15_4::cancel(void)
{
	if (bcnOtherT->busy())
		bcnOtherT->stop();
	else if (backoffT->busy())
		backoffT->stop();
	else if (deferCCAT->busy())
		deferCCAT->stop();
	else
		mac->taskP.taskStatus(TP_CCA_csmaca) = false;
	txPkt = 0;
}

void CsmaCA802_15_4::backoffHandler(void)
{
	mac->taskP.taskStatus(TP_RX_ON_csmaca) = true;
	mac->plme_set_trx_state_request(p_RX_ON);
}

void CsmaCA802_15_4::RX_ON_confirm(PHYenum status)
{
	double now,wtime;

	if (status != p_RX_ON)
	{
		if (status == p_BUSY_TX)
			mac->taskP.taskStatus(TP_RX_ON_csmaca) = true;
		else
			backoffHandler();
		return;
	}

	//locate backoff boundary if needed
	now = CURRENT_TIME;
	if (beaconEnabled)
		wtime = mac->locateBoundary(mac->toParent(txPkt),0.0);
	else
		wtime = 0.0;

	if (wtime == 0.0)
	{
		mac->taskP.taskStatus(TP_CCA_csmaca) = true;
		phy->PLME_CCA_request();
	}
	else
		deferCCAT->start(wtime);
}

void CsmaCA802_15_4::bcnOtherHandler(void)
{
	newBeacon('R');
}

void CsmaCA802_15_4::deferCCAHandler(void)
{
	mac->taskP.taskStatus(TP_CCA_csmaca) = true;
	phy->PLME_CCA_request();
}

void CsmaCA802_15_4::CCA_confirm(PHYenum status)
{
	//This function should be called when mac receiving CCA_confirm.
	bool idle;

	idle = (status == p_IDLE)?1:0;	
	if (idle)
	{
		if ((!beaconEnabled)&&(!beaconOther))
		{
			txPkt = 0;
			mac->csmacaCallBack(p_IDLE);
		}
		else
		{
			if (beaconEnabled)
				CW--;
			else
				CW = 0;
			if (CW == 0)
			{
				//timing condition may not still hold -- check again
				if (canProceed(0.0, true))
				{
					txPkt = 0;
					mac->csmacaCallBack(p_IDLE);
				}
				else	//postpone until next beacon sent or received
				{
					if (beaconEnabled) CW = 2;
					bPeriodsLeft = 0;
				}
			}
			else	//perform CCA again
				backoffHandler();
		}
	}
	else	//busy
	{
		if (beaconEnabled) CW = 2;
		NB++;
		if (NB > mac->mpib.macMaxCSMABackoffs)
		{
			txPkt = 0;
			mac->csmacaCallBack(p_BUSY);
		}
		else	//backoff again
		{
			BE++;
			if (BE > aMaxBE)
				BE = aMaxBE;
			start(false);
		}
	}
}

// End of file: p802_15_4csmaca.cc