Names of Both MIDN:____________________

global variables
  astate =0 // can be 0-3, corresponds to state diagram for a/sender (3.15)
  astored_pkt // saved in case we need to retransmit - for a/sender
  bstate = 0 // can be 0-1,state diagram for b (3.14)
  bOnceThru = 0 // A flag to track if this is the first time through the receiver
  bstored_pkt // saved in case we need to retransmit - for b/sender

aOutput

	if astate==0 
		calculate checksum
		seqno=0
		create astored_pkt
		sendpkt(astored_pkt)		
		Print "A: sending packet #" 
		start_timer
		astate=1
		
	else if astate==2
		calculate checksum
		seqno=1
		create astored_pkt

		sendpkt(____________________)		
		Print "A: sending packet #" 
		
		start_ ____________________
		astate=3
	else
		refuse packet, warn  //timers need to be longer	
	
aInput

	if astate==0
		do nothing
	if astate==1 
		if 	pkt is corrupt
			do nothing
			Print "A: ACK corrupt"
		if acknum==1

			do ____________________
			
			Print "A: got ACK1, we're waiting for ACK ________________"	
		if acknum==0 
			stop_timer
			astate=2
			Print "A: got ACK #"
	
	if astate==____________________
		
		do nothing		
	if astate==3 
		if pkt is corrupt
			do nothing
			Print "A: ACK corrupt"
		
		if acknum==____________________
			do nothing
			Print "A: got ACK0, we're waiting for ACK 1"	
		if acknum==1
			stop_timer
			astate=0
			Print "A: got ACK #"
		else
			do nothing	
		
		
aTimerInterrupt
	Print "A: Timer interrupt, resending packet"
	
	sendpkt(____________________)
	
	start_timer
		
bInput
	if pkt is corrupt
		if bOnceThru==1
			send bstored_pkt
		else
			do nothing
	else
		if (seqno==0 && bstate==0) || (seqno==1 && bstate==1)
			deliver data to layer 5
			Print "B: got packet #"
			create bstored_pkt
			sendpkt(bstored_pkt)
			Print "B: sending ACK #"
			incr bstate mod 2
			bOnceThru=1
		else
			if bstate==1 || bOnceThru==1
				send bstored_pkt
				Print "B: sending ACK #"