bt-lc.cc

NS2网络仿真软件是目前最为流行的网络仿真模拟软件

to send. Here data could even be LMP or L2CAP signaling
*/ 
int
LinkController::pktSize()
{
	Packet* pkt = curr_reg_;
	if (firsttime_) {
		LMP* linkq = (LMP*)uptarget_;
		linkq->callback();
		pkt = curr_reg_;
		firsttime_ = 0;
	}
	if (pkt) {
		hdr_bt* bt = HDR_BT(pkt);
		return (Payload[bt->type]);
	}
	else
		return 0;
}

Packet*  
LinkController::send()
{
	if (firsttime_) {
		LMP* linkq = (LMP*)uptarget_;
		linkq->callback();
		firsttime_ = 0;
	}
	//Copy the packet and send the copy
	if (curr_reg_) {
		/* if the current register has a packet, copy it
		and send it off if transmission count is less than
		a threshold */
		Packet* p = curr_reg_->copy();
		hdr_cmn* ch = HDR_CMN(p);
		hdr_bt* bt = HDR_BT(p);	
		tx_cnt_++;
		if ((tx_cnt_ > 1) && (ch->ptype() == PT_EXP)) {
			//printf("Should not happen without ErrModel!\n");
			//printf("Packet type %d and L_CH %d for am_addr %d retransmitted\n", bt->type, bt->ph.l_ch, bt->am_addr);
			tx_cnt_ = tx_thresh_+1;
		}
		if (tx_cnt_ <= tx_thresh_) {
			compose_pkt(p);
			return p;
		}
		/* if transmission count is exceeded, discard the 
		packet. Yet to take care of discarding following 
		segments of the same L2CAP packet, has to be implemented
		in the function 'flush_payload()' */
		else {
			//flush_payload();       
			Packet::free(p);
			tx_cnt_ = 0;
			if (curr_reg_) {
				Packet::free(curr_reg_);
				curr_reg_ = 0;
				switch_reg();
			}
			LMP* linkq = (LMP*)uptarget_;
			linkq->callback();	
			return 0;
		}
	}

	/* if there is no packet to send but a packet to 
	acknowledge, send a NULL packet */
	else if (ack_) {
		
		Packet* p = Packet::alloc();
		hdr_cmn* ch = HDR_CMN(p);
		hdr_bt*  bt = HDR_BT(p);
		bt->type = BT_NULL;	
		ch->size() = NullSize;
		compose_pkt(p);
		return p;
	}
	return 0;
}


/* set ARQ related fields of the packet and am_addr_ */
void LinkController::compose_pkt(Packet* p)
{
	hdr_bt*  bt = HDR_BT(p);
  	bt->seqn= seq_;
	bt->arqn= ack_;
	bt->am_addr = am_addr_;
	ack_ = 0;
}

void LinkController::sendUp(Packet* p, Handler* h)
{
	Scheduler& s = Scheduler::instance();
	hdr_cmn* ch = HDR_CMN(p);
	hdr_bt*  bt = HDR_BT(p);

	if (bt->type == BT_NULL) {
		//receive ack from a NULL packet
		if (bt->arqn) 
			recvACK();
		Packet::free(p);
		return; 
	}
	else {

		//Discard duplicate packet ...
		if (bt->seqn == seq_old_) {
			ack_=1;
			// ... but see if it carries a new ACK
			if (bt->arqn) 
				recvACK();
			Packet::free(p);
		}
		
		else 
		{	
			//Handle corrupt packet
			if (ch->error()) {
				Packet::free(p);    
				ack_=0;
			}

			//Handle valid data packet
			else {
				// set ack bit to acknowledge the packet
				ack_=1;
				// update sequence number
				seq_old_ = bt->seqn;
				// receive ACK
				if (bt->arqn) 
					recvACK();
				/* following block to make the slave 
				side aware of its AM_ADDR through the
				connection request LMP PDU */
				if (bt->ph.l_ch == 0x03) {
					uchar* data = p->accessdata();
					if (data[0] == 51)
						am_addr_ = bt->am_addr;
				}
				// send to upper layer
				uptarget_->recv(p,h);
			}
		}
	}
}

/* Switch between current and next register, 
see Bluetooth baseband Specifications */

void LinkController::switch_reg()
{
	Packet* temp; 
	temp = curr_reg_;
	curr_reg_ = next_reg_;
	next_reg_ = temp;
}

void LinkController::flush_payload()
{}

//initialize ARQ related variables for the new connection
void 
LinkController::initialize()
{
	seq_ = ack_ = tx_cnt_ = 0;
	seq_old_ = 1;
	curr_reg_ = 0;
	next_reg_ = 0;
}

// receive acknowledgement
void
LinkController::recvACK() 
{	
	//update next sequence number to be sent
	seq_ = 1-seq_;
	tx_cnt_ = 0;
	if (curr_reg_)
		Packet::free(curr_reg_);
	curr_reg_ = 0;
	switch_reg();
	LMP* linkq = (LMP*)uptarget_;
	linkq->callback();	// cause LinkQueues (L2CAP or LMP) to send a packet as soon as it has one
}