(FILECREATED "16-Apr-85 15:36:13" {ERIS}<LISPNEW>INTERMEZZO>PATCHES>SPPPATCH.;1
 4945   

      changes to:  (VARS SPPPATCHCOMS))


(* Copyright (c) 1985 by Xerox Corporation. All rights reserved.)

(PRETTYCOMPRINT SPPPATCHCOMS)

(RPAQQ SPPPATCHCOMS
 ((FNS \GETSPP \SPP.SENDPKT)))
(DEFINEQ

(\GETSPP

  [LAMBDA (CON TIMEOUT PEEKFLG)                              (* bvm: "16-Apr-85 13:10")


          (* Obtains the next packet on this SPP connection. If TIMEOUT is specified and expires before a packet arrives, 

	  returns NIL. Also returns NIL if the connection is terminated. If PEEKFLG is true, returns the next packet without 

	  removing it from queue.)



    (WITH.MONITOR (fetch
 SPPLOCK of
 CON)
		  (bind
 (EPKT ← NIL)
			(TIMER ←(
AND
 TIMEOUT (
SETUPTIMER
 TIMEOUT)))
		     do
 (
COND

			  ((
AND
 (
SETQ
 EPKT (\QUEUEHEAD (fetch
 SPPINPUTQ of
 CON)))
				(
ILESSP
 (fetch
 (SPPXIP SEQNO) of
 EPKT)
					(fetch
 SPPACKNO of
 CON)))
                                                             (* This is the packet we've been waiting for.

							     The ACKNO field has already been incremented in 

							     \SPP.HANDLE.DATA)

			    [
COND

			      ((
NOT
 PEEKFLG)
				(UNINTERRUPTABLY
                                    (
\DEQUEUE
 (fetch
 SPPINPUTQ of
 CON))
				    (add
 (fetch
 SPPACCEPTNO of
 CON)
					 1))
				(
COND

				  ((
AND
 (fetch
 SPPINPUTBLOCKED of
 CON)
					(
GREATERP
 (fetch
 SPPACCEPTNO of
 CON)
						  (fetch
 SPPACKNO of
 CON)))

          (* Partner was waiting to be able to transmit again, so allow it now. Don't send this gratuitous ack the moment we 

	  open up; wait for the window to at least get a couple of packets wide)



				    (\SPP.SENDPKT
 CON (
\SPP.SYSPKT
 CON]
			    (
RETURN
 EPKT))
			  ((
OR
 (
AND
 TIMEOUT (
TIMEREXPIRED?
 TIMER))
			       (fetch
 SPPTERMINATEDP of
 CON))
			    (
RETURN
 NIL))
			  (T (
MONITOR.AWAIT.EVENT
 (fetch
 SPPLOCK of
 CON)
						  (fetch
 SPPINPUTEVENT of
 CON)
						  TIMER T])

(\SPP.SENDPKT

  [LAMBDA (CON EPKT RETRANSMITP)                             (* bvm: "16-Apr-85 13:03")


          (* This function makes sure the variable connection information in the packet is current, and actually sends the 

	  packet. If the packet is to be retransmitted, the connection must be locked when this function is called.

	  Note that the sequence number is NOT updated; it was allocated once and for all by \SENDSPP)



    (
PROG
 ((ACK# (fetch
 SPPACKNO of
 CON))
	   (ALLOC# (fetch
 SPPACCEPTNO of
 CON))
	   (BASE (fetch
 XIPCONTENTS of
 EPKT))
	   SEQNO)
          (
AND
 RETRANSMITP (
HELP
 "RETRANSMITP on"))
          (replace
 (SPPHEAD ACKNO) of
 BASE with
 ACK#)
          (replace
 (SPPHEAD ALLOCNO) of
 BASE with
 ALLOC#)
          (replace
 SPPINPUTBLOCKED of
 CON with
 (
IGREATERP
 ACK# ALLOC#))
                                                             (* If ACK# > ALLOC# then partner cannot send more data 

							     until we eat some of what we have)

          [
COND

	    ((fetch
 (SPPHEAD SENDACK) of
 BASE)

          (* We start a timer when we send an Ack request, and turn it off when the next packet arrives 

	  (in \SPPINPUTWORK.) If the timer expires, we assume that the connection is wedged. Otherwise, the elapsed time will 

	  be used to update our estimate of the round trip delay. The timer will go off after the user-level timeout, or twice

	  the round trip delay, whichever is longer.)



	      (
SETQ
 SEQNO (fetch
 (SPPHEAD SEQNO) of
 BASE))
	      (
COND

		((
OR
 (
NOT
 (fetch
 SPPACKREQUESTED of
 CON))
		     (
IGREATERP
 SEQNO (fetch
 SPPACKREQUESTED of
 CON)))
		  (replace
 SPPACKREQUESTED of
 CON with
 SEQNO)
		  (replace
 SPPACKREQTIMEOUT of
 CON with
 (
SETUPTIMER
 (
MAX
 SPP.USER.TIMEOUT
									 (UNFOLD (fetch
 
										 SPPROUNDTRIPTIME
										    of
 CON)
										 4))
								    (fetch
 SPPACKREQTIMEOUT
								       of
 CON)))
		  (replace
 SPPACKREQTIME of
 CON with
 (
SETUPTIMER
 0 (fetch
 SPPACKREQTIME of
 CON]
          (replace
 SPPACKPENDING of
 CON with
 NIL)            (* If partner asked for an ack, this will satisfy it)

          (
SENDXIP
 (fetch
 SPPMYNSOCKET of
 CON)
		   EPKT)
          (replace
 SPPRETRANSMITTIMER of
 CON with
 (
SETUPTIMER
 (
COND

								((fetch
 SPPRETRANSMITTING
								    of
 CON)
								  SPP.MIN.TIMEOUT)
								(T (UNFOLD (fetch
 SPPROUNDTRIPTIME
									      of
 CON)
									   2)))
							      (fetch
 SPPRETRANSMITTIMER of
 CON])
)
(PUTPROPS SPPPATCH COPYRIGHT ("Xerox Corporation" 1985))
(DECLARE: DONTCOPY
  (FILEMAP (NIL (289 4866 (\GETSPP 299 . 2149) (\SPP.SENDPKT 2151 . 4864)))))
STOP