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TITLE	D8EINT	"FEK" service routine for ANF-to-Ethernet
SUBTTL	RDH	26-NOV-85

	SEARCH	F,S,NETPRM,ETHPRM,MACSYM

	$RELOC
	$HIGH



;THIS SOFTWARE IS FURNISHED UNDER A LICENSE AND MAY ONLY BE USED
;  OR COPIED IN ACCORDANCE WITH THE TERMS OF SUCH LICENSE.
;
.CPYRT<1985,1986>
;COPYRIGHT (C) 1985,1986
;BY DIGITAL EQUIPMEMT CORP., MAYNARD, MASS.
;ALL RIGHTS RESERVED.


XP	VD8EINT,010	;VERSION NUMBER


IFE FTENET,<
	PASS2
	PRINTX [FTENET is turned off in D8EINT, suppressing assembly]
	END
> ;IFE FTENET


ENTRY	D8EINT
D8EINT::

                           Comment \

OVERVIEW

D8EINT is the ANF/Ethernet interface module.

As with D8SINT, D8EINT is a software-only interface between the ANF
network and actual hardware service routine (ETHSER in this case).
Unlike most FEKs however, the "NI" FEK is a hardware-independent in-
terface, and in particular doesn't care which cpu runs the FEK service
routines, or, for that matter, what type of cpu runs them.

At this writing, ETHSER presents only a single "channel" to the user
(e.g., ANF) with no provision for more than one "NI" network.  While
D8EINT was written with multiple "channels" in mind, D8EINI in partic-
ular will need work to run in a multiple-channel environment (there
are a lot of unanswered questions about such an environment, like what
it looks like).

D8EINT uses two types of FEKs, so-called "master" and "slave" FEKs.
Each Ethernet channel (ETH-n) has one master FEK associated with it.
The ETH-0 master FEK is hardwired into COMMON along with all the other
"normal" FEKs, FEKs for other Ethernet channels (if such ever occurs)
are generated dynamically at SYSINI time and linked into the FEK chain.
All Ethernet input operations are done via a master FEK and never
via a slave FEK. All multicast NCL traffic (the periodic NODEID as
described below) goes out via a master FEK.

Each master FEK points to a (conceivably-0-length) chain of slave FEKs.
There is one slave FEK for each NCL node on the Ethernet (this is how
the nodes are faked out as "neighbors" of this host node). NCL messages
for a specific node are output via these slave FEKs (but be aware that
the output-done interrupt comes back via the slave's master FEK!!).


RESTRICTIONS

The first pass at NCL on the ethernet implements a restricted NCL
service by treating each other NCL node on the ethernet as an immediate
neighbor (indistinguishable from any other 'point-to-point' communications
link). This means that the number of NCL nodes supportable on a single
ethernet is drastically limited by NGHMAX - the maximum number of
neighbors any node in the net can support. This restriction allows NCL
to directly support the ethernet with only the most minor of protocol
changes (support of a 'broadcast' NODEID message). To properly support
NCL on an ethernet would require a significant, ah, enhancement of the
neighbors-based routing philosophy . . .

Since the KLNI can't deal with 7-bit byte pointers (boy, ever since
the DL-10 passed away it's been a steady down-hill trend!!!!!!!!!!)
NETSER must provide an 8-bit byte buffer. For the moment, it is assumed
that the buffer is contiguous and that there is only one byte count
and pointer for the entire PCB.


ETHERNET-SPECIFIC NCL PROTOCOL

The NODEID message format is extended to include a 'serial number'
(based on the ethernet 'uptime').

As with other FEKs (the NUL FEK excluded of course) a NODEID is the
first message transmitted through a FEK when the FEK comes 'online'.
This NODEID is always a 'broadcast' ethernet message. Periodically
thereafter another NODEID is 'broadcast', with an incremented serial
number (unlike other FEKs where a NODEID is NEVER sent again until
the FEK has gone offline and come back online).

Whenever an ethernet broadcast NODEID is received from an unknown NCL
node (or even a known NCL node not on the ethernet) that node is marked
as a "neighbor" (*) on the ethernet and the serial number is stashed away.
Any subsequent broadcast NODEID is ignored as long as the serial number
monotonically increases. If a broadcast NODEID is received with a serial
number which is smaller, then the NCL logical link is reinitialized.

Other than the serial-numbered NODEID message, the NCL protocol treats
the ethernet just like any other communications line.

(*) = The NCL "neighbor" is given its very own "slave" FEK, linked back
to the master FEK for that Ethernet channel. As far as NETSER is concerned
it looks just like any other "real" FEK.


FEK USAGE

The Ethernet FEKs have several (quite a few, actually) specific entries.
They are:

FEKNIA	For a master FEK, FEKNIA contains the ANF protocol "broadcast"
	address (same as %NTNIM). For a slave FEK, FEKNIA contains the
	remote Ethernet destination address for the ANF node associated
	with this FEK. With this setup, and output to a specific node is
	queued via that node's FEK, while any output to be "broadcast"
	is queued via the master FEK.

FEKNIC	For a master FEK, FEKNIC is the Ethernet "channel" ID. Not used
	by slave FEKs.

FEKNID	For a master FEK, FEKNID is the Ethernet "portal" ID. Not used
	by slave FEKs.

FEKNIF	FEKNIF contains the address of the FEK's associated master FEK
	(a master FEK points to itself).

FEKNIQ	For a master FEK, FEKNIQ is the count of PCBs (buffers) queued to
	to the Ethernet service layer. Not used by slave FEKs.

FEKNIS	For a master FEK, FEKNIS is the current NODEID "serial number",
	incremented for each broadcast NODEID. For a slave FEK, FEKNIS
	is the last received NODEID serial number from the remote ANF
	node.

FEKNIT	For a master FEK, FEKNIT contains XWD <int>,<tim> where <int> is
	the current (sliding) interval between consecutive broadcast NODEID
	messages, and <tim> is the current timer until the next broadcast
	NODEID message. For a slave FEK, FEKNIT is the time since the last
	received NODEID from the FEK's associated remote node. All values
	are in seconds.


USING D8EINT

To utilize ANF on the Ethernet, the user must explicitly define the two
symbols ANFNIP and ANFNIM via MONGEN. If the symbol ANFNIP is not defined,
then D8EINT will not be loaded with the monitor (COMMON FEK definitions).

If ANFNIP is defined, it is the Ethernet protocol type to be used by ANF.
If ANFNIP is 0, then ANF will not use the Ethernet (even though D8EINT is
loaded). This allows the adventurous user to have D8EINT loaded with the
monitor for playtime experiments (by patching the protocol type value
into location %NTNIP in NETSER) without having to rebuild the monitor,
yet still bring the monitor up sans ANF Ethernet. If ANFNIP is non-zero,
it will be used as the Ethernet protocol type for ANF NCL communications.
The protocol type is 16 bits in size. Protocol 60-06 (60006 octal) is
reserved for customer usage, as are multicast addresses AB-00-04-00-xx-xx.

The symbol ANFNIM defines the "xx-xx" part of the multicast address, and
is also 16 bits wide - but **MUST** be defined as a left-justified integer
value (bits 00-15), as opposed to ANFNIP which is a right-justified integer
value (bits 20-35). If ANFNIM is not explicitly defined, it will default
to the ANFNIP value (shifted to left-most 16 bits).

For example, in the MONGEN dialog for "OCTAL SYMBOL,VALUE", include:

    ANFNIP,<60006B35>	;ANF Ethernet protocol 60-06
    ANFNIM,<60006B15>	;ANF Ethernet broadcast address AB-00-04-00-60-06
\

	SUBTTL	D8EINT parameters varied and sundry

ND	RSBLEN,10		;LENGTH OF RANDOM SCRATCH BLOCK

;D8EINI  --  ONCE-only D8EINT initialization
;
;This routine is called by SYSINI to dynamically build a master FEK for
;each of the Ethernet "channels". The individual "channels" (or FEKs)
;will be set online later (FF.ONC FEK dispatch from SYSINI/FEKINI).

D8EINI::SKIPG	%NTNIP##	;GOT AN ANF PROTOCOL TYPE?
	POPJ	P,		;NOPE, CAN DO NOTHING HERE
	SE1ENT			;GET INTO SECTION 1 FOR ETHSER
	PUSHJ	P,D8EGUN	;GET A UN BLOCK (RETURN IN P4)
	 POPJ	P,		;NO UN? CAN DO NOTHING HERE
	MOVEI	T1,RSBLEN	;LENGTH OF A RANDOM SCRATCH BLOCK
	STOR	T1,UNBSZ,(P4)	;SET THAT AS SIZE OF "BUFFER"
	XMOVEI	T1,D8EBLK	;ADDRESS OF A RANDOM SCRATCH BLOCK
	STOR	T1,UNBFA,(P4)	;SET AS ADDRESS OF "BUFFER"
	MOVX	T1,NU.RCL	;FUNCTION: "RETURN CHANNEL LIST"
	XMOVEI	T2,(P4)		;ADDRESS OF "UN" BLOCK
	PUSHJ	P,ETHSER##	;ASK ETHSER FOR KNOWN CHANNELS
	 POPJ	P,		;NO? THEN NO ETHERNET SERVICE HERE!
	LOAD	T1,UNBSZ,(P4)	;GET RETURNED COUNT (OF CHANNELS)
	JUMPE	T1,CPOPJ##	;IF NO CHANNELS THEN QUIT NOW
	CAIE	T1,1		;*** ONLY ALLOW FOR ONE ETHERNET CHANNEL FOR NOW
	STOPCD	CPOPJ,DEBUG,D8ETME  ;++ TOO MANY ETHERNETS

;Loop buildng a "master" FEK for each Ethernet channel (ETH-0, etc.)

	PUSHJ	P,SAVE4##	;WILL NEED SOME ACS HERE
	MOVN	P1,T1		;NEGATIVE COUNT OF ETH CHANNELS
	HRLZ	P1,P1		;AOBJN COUNT
D8EIN2:	XMOVEI	T1,ET0FEK##	;PROTOTYPE (AND HARDWIRED ETH-0) FEK
;RDH	TRNN	P1,-1		;IS THIS CHANNEL "0"?
;RDH	JRST	D8EIN3		;YES, USE PRE-EXISTING FEK THEN
;RDH	MOVEI	J,ET0FEK##	;USE ET0FEK AS A PROTOTYPE
;RDH	PUSHJ	P,D8EFGN	;ALLOCATE AN ETHERNET FEK
;RDH	 POPJ	P,		;CAN'T GO ANY FURTHER HERE
D8EIN3:	MOVEM	T1,FEKNIF(T1)	;POINT FEK TO ITSELF AS MASTER FEK
	MOVSI	T2,FK.ETH!FK.ETM;THE "ETHERNET-MASTER-FEK" FLAG(S)
	IORM	T2,FEKBLK(T1)	;MARK THIS FEK AS AN ETHERNET MASTER
	MOVE	T2,D8EBLK(P1)	;GET THE ETHSER "CHANNEL" ID
	MOVEM	T2,FEKNIC(T1)	;AND SAVE IT
	DMOVE	T2,%NTNIM##	;ANF MULTICAST ADDRESS
	DMOVEM	T2,FEKNIA(T1)	;SET THAT ADDRESS IN MASTER FEK
	MOVSI	T2,4		;INITIAL BROADCAST TIMER INTERVAL
	MOVEM	T2,FEKNIT(T1)	;SET IT UP
	SETZM	FEKNIS(T1)	;INITIALIZE NODEID SERIAL NUMBER
;RDH	TRNN	P1,-1		;IS THIS THE PROTOTYPE ETH-0 FEK?
;RDH	JRST	D8EIN5		;YES, IT'S ALREADY PROPERLY LINKED
;RDH	HRRZ	T2,ET0FEK##+FEKBLK  ;SPLICE THIS NEWLY-CREATED
;RDH	HRRM	T1,ET0FEK##+FEKBLK  ;  ETHERNET MASTER FEK INTO THE
;RDH	HRRM	T2,FEKBLK(T1)	    ;  SYSTEM FEK CHAIN
D8EIN5:	AOBJN	P1,D8EIN2	;LOOP FOR ALL ETHERNET "CHANNELS"
	POPJ	P,		;ALL FEKS BUILT

	SUBTTL	FEK 'Kontroller' service

;D8EDSP - Kontroller dispatch service from NETSER
;Call is:
;
;	MOVEI	T1,<FNC>
;	MOVE	J, <FEK>
;	PUSHJ	P,D8EDSP
;	 return always
;
;where <FEK> is the address of the FEK block; and <FNC> is the FEK-level
;function (FF.???) to be performed.   See the individual functions for
;the passing of function-specific data.
;
;Return is CPOPJ always.

D8EDSP::SE1ENT			;NEED TO BE IN EXTENDED ADDRESSING
	CAIL	T1,FF.ONC	;RANGE CHECK THE FUNCTION
	CAILE	T1,FF.DFK	;  CODE AND STOP IF BAD
	PUSHJ	P,NTDSTP##	;++ ERROR: BAD FUNCTION CODE TO FEK
	JRST	@D8EDST(T1)	;DISPATCH TO APPROPRIATE ROUTINE


;FEK function dispatch table

D8EDST:	IFIW	D8EONC		;FF.ONC - 00 - ONCE-ONLY INITIALIZATION
	IFIW	D8ESEC		;FF.SEC - 01 - ONCE-A-SECOND CODE
	IFIW	D8ERDD		;FF.RDD - 02 - POST A RECEIVE BUFFER
	IFIW	D8EWRT		;FF.WRT - 03 - POST A TRANSMIT BUFFER
	IFIW	D8ECRS		;FF.CRS - 04 - CRASH THE 'FE'
	IFIW	D8EDWN		;FF.DWN - 05 - ENTRY WHEN 'FE' CRASHES
	IFIW	D8EUPP		;FF.UP  - 06 - ENTRY WHEN 'FE' COMES UP
	IFIW	D8ESTC		;FF.STC - 07 - STATION CONTROL
	IFIW	D8ECPS		;FF.CPS - 10 - CPU IS GOING TO SLEEP
	IFIW	D8ECPW		;FF.CPW - 11 - CPU IS WAKING UP
	IFIW	D8ECFK		;FF.CFK - 12 - CREATE NEW SLAVE FEK
	IFIW	D8EDFK		;FF.DFK - 13 - DESTROY OLD SLAVE FEK

;D8EONC  --  ONCE-only FEK initialization
;
;D8EINI has already been called and has built the various master FEK
;blocks for each Ethernet "channel". This code is a per-FEK call to
;turn on each individual FEK.

D8EONC:	SKIPG	%NTNIP##	;ANF PROTOCOL DEFINED?
	POPJ	P,		;NO, THEN NO ETHERNET SERVICE
	PUSHJ	P,D8EGUN	;GET A UN BLOCK
	 POPJ	P,		;NONE AVAILABLE?
	MOVE	T1,FEKNIC(J)	;GET ETHERNET "CHANNEL" ID
	STOR	T1,UNCHN,(P4)	;STORE IN "UN" BLOCK
	STOR	J,UNUID,(P4)	;STORE FEK ADDRESS ("USER ID") IN "UN" BLOCK
	XMOVEI	T1,D8EISR	;GET OUR "CALLBACK" (OR ISR) DISPATCH ADDRESS
	STOR	T1,UNCBA,(P4)	;STORE IN "UN" BLOCK
	MOVE	T1,%NTNIP##	;GET ANF ETHERNET PROTOCOL TYPE
	STOR	T1,UNPRO,(P4)	;STORE IN "UN" BLOCK
	SETONE	UNPAD,(P4)	;ENABLE "PADDING" OF MESSAGES
	MOVEI	T1,NU.OPN	;FUNCTION: OPEN PORTAL
	XMOVEI	T2,(P4)		;ADDRESS OF "UN" BLOCK
	PUSHJ	P,ETHSER##	;ASK ETHSER TO OPEN A PORTAL FOR US
	 POPJ	P,		;NO???
	LOAD	T1,UNPID,(P4)	;GET PORTAL ID
	MOVEM	T1,FEKNID(J)	;SAVE FOR FUTURE CALLS TO ETHSER
	PUSHJ	P,D8EOOF	;SET FEK ON- OR OFF-LINE
	 JFCL			;CAN'T FAIL
	DMOVE	T1,%NTNIM##	;GET ANF ETHERNET MULTICAST ADDRESS
	DMOVEM	T1,UN.DAD(P4)	;STOR IN "UN" BLOCK
	MOVEI	T1,NU.EMA	;FUNCTION: ENABLE MULTICAST ADDRESS
	XMOVEI	T2,(P4)		;ADDRESS OF "UN" BLOCK
	PUSHJ	P,ETHSER##	;TURN ON MULTICAST ADDRESS RECEPTION
	 JFCL			;CAN'T FAIL!
	POPJ	P,		;RETURN WITH FEK ENABLED

;D8ESEC  --  Once-a-second FEK service
;
;Here once-per-second for each of the Ethernet FEKs. Perform the broad-
;cast NODEID timing for "master" FEKs.

D8ESEC:	SKIPL	T1,FEKBLK(J)	;GET THE FEK FLAGS
		.CREF	FK.ONL	;CREF REFERENCE TO FEK-ONLINE FLAG
	POPJ	P,		;FEK IS OFFLINE, FORGET IT
	TLNN	T1,FK.ETM	;THIS IS A MASTER FEK, ISN'T IT?
	JRST	D8ESE6		;NO, A SLAVE, CHECK FOR COMMUNICATIONS TIMEOUT
D8ESE1:	HRRE	T1,FEKNIT(J)	;GET COUNTDOWN TIMER
	SOJLE	T1,D8ESE3	;REQUEST NODEID BROADCAST IF EXPIRED
	HRRM	T1,FEKNIT(J)	;SET NEW TIMER VALUE
	PJRST	NTFSEC##	;AND DO NORMAL NETSER ONCE/SECOND STUFF

D8ESE3:	MOVSI	T2,FK.NID	;THE "NODEID SENT" FLAG
	TDNN	T2,FEKBLK(J)	;HAVE WE SENT A NODEID?
	PJRST	NTFSEC##	;NOT YET, LEAVE TIMER(S) ALONE
	ANDCAM	T2,FEKBLK(J)	;YES, REQUEST ANOTHER NODEID BE SENT
	HLRZ	T1,FEKNIT(J)	;GET INCREMENTAL TIMER VALUE
	LSH	T1,1		;SCALE IT UP A BIT,
	CAMLE	T1,%NTNII##	; BUT PEG IT
	MOVE	T1,%NTNII##	;  AT [NOMINALLY] A ONE-MINUTE INTERVAL
	HRLZM	T1,FEKNIT(J)	;STORE NEW INTERVAL
	PJRST	NTFSEC##	;AND DO NORMAL NETSER ONCE/SECOND STUFF


;Here for a slave FEK, make sure we are in "constant" contact with the remote
;  node. This must be done on a per-FEK (and associated NODEID) basis since
;  we can't rely on normal NCL traffic (in case multiple Ethernet channels
;  to the same node ever arise).

D8ESE6:	SOSL	FEKNIT(J)	;DECREMENT TIMER
	POPJ	P,		;STILL ALIVE, AFTER ALL THESE . . .
	PJRST	D8EDFK		;TIMED OUT, KILL OFF THE FEK

;D8ERDD  --  Read request (post a receive buffer)
;
;FEKIAD contains a PCB address to be filled with receive data.
;
;This function merely gives the buffer to the "FE" service routine to
;be filled, no actual data is returned by this call.
;
; Note:	Unlike other ANF FEKs, this routine actually decouples the input
;	PCB and gives it to ETHSER to queue, using FEKNIQ as a count of
;	buffers hiding inside ETHSER. See NETSER's NETRDD routine. This
;	skulduggery is necessary to keep multiple buffers available such
;	that the KLNI [probably] won't run out of buffers and lose input
;	messages . . .

D8ERDD:	AOSE	FEKBSI(J)	;GET THE INPUT INTERLOCK (WE GET HERE FROM
				;  BOTH UUO AND INTERRUPT LEVEL)
	POPJ	P,		;IF ALREADY DOING INPUT, EXIT
	PUSHJ	P,D8EGUN	;GET A UN BLOCK
	 JRST	D8ERD7		;NONE AVAILABLE, TRY AGAIN LATER
	SKIPN	T1,FEKIAD(J)	;GOT AN INPUT BUFFER?
	JRST	D8ERD9		;NO
	MOVE	T2,FEKBLK(J)	;GET THE FEK FLAGS
	TLNN	T2,FK.ETM	;ONLY THE MASTER FEK GETS TO DO INPUT
	STOPCD	D8ERD9,DEBUG,D8ESFI  ;++ SLAVE FEK HAS INPUT BUFFER
	MOVE	T2,FEKNID(J)	;ETHSER'S PORTAL ID
	STOR	T2,UNPID,(P4)	;STORE IN "UN" BLOCK
	STOR	T1,UNRID,(P4)	;STORE PCB ADDRESS IN "UN" BLOCK RID FIELD
;RDH	SETZRO	UNBSZ,(P4)	;NO BYTE COUNT MEANS MSD-STYLE CALL
;RDH	XMOVEI	T2,PCBMS1(T1)	;ADDRESS OF MSD PORTION OF PCB
;RDH	STOR	T2,UNBFA,(P4)	;STORE IN "UN" BLOCK
;RDH	SETZM	PCBNXX(T1)	;NO SECOND MSD HERE (STUPID KLNI!!!)
	MOVE	T2,PCBCTR(T1)	;COUNT OF DATA BYTES IN BUFFER
	ADDI	T2,4		;ALLOW FOR STUPID CRC BYTES (*!!$!*#!!)
				; BUT *NOT* THE OTHER TWO COUNT BYTES
				; YEAH, THIS LOOKS REALLY ODD, BUT NETSER
				; CAREFULLY ALLOCATES A BUFFER THAT IS
				; SECRETLY 6 BYTES LARGER THAN MSGMAX . . .
	STOR	T2,UNBSZ,(P4)	;STORE IN "UN" BLOCK
	HLLZ	T2,PCBPTR(T1)	;NOW MUST CONCOCT A TWO-WORD GLOBAL
	HRRZ	T3,PCBPTR(T1)	; BYTE POINTER FOR ETHSER
	TLO	T2,(1B12)	; OTHERWISE IT GOES DING DING DING
	DMOVEM	T2,UN.BFA(P4)	;STORE IN "UN" BLOCK
	MOVX	T2,UNA.EV	;THE DATA BUFFER IS IN EXEC VIRTUAL MEMORY
	STOR	T2,UNADS,(P4)	;STORE THAT IN "UN" BLOCK
	MOVEI	T1,NU.RCV	;FUNCTION: POST RECEIVE BUFFER
	XMOVEI	T2,(P4)		;ADDRESS OF "UN" BLOCK
	PUSHJ	P,ETHSER##	;QUEUE UP RECEIVE BUFFER
	 JRST	D8ERD4		;ERROR? GO CHECK IT OUT
	HRRZ	T1,FEKIAD(J)	;RETRIEVE ADDRESS OF PCB
	HRRZ	T2,PCBBLK(T1)	;ADDRESS OF NEXT PCB (MUST BE 0)
	CAIE	T2,0		;JUST TO MAKE SURE IS REALLY TRULY 0
	PUSHJ	P,NTDSTP##	;THIS IS A NO-NO
	MOVEM	T2,FEKIAD(J)	;INDICATE PCB GIVEN TO ETHSER
	AOS	FEKNIQ(J)	;COUNT UP BUFFERS QUEUED TO ETHSER
	JRST	D8ERD9		;ALL DONE HERE

;Here when ETHSER rejects our attempt to queue up an input buffer

D8ERD4:	CAIN	T1,UNRES%	;NO RESOURCES TO DEAL WITH BUFFER?
	JRST	D8ERD7		;YEAH, FLAG TO TRY AGAIN LATER
	STOPCD	CPOPJ,DEBUG,D8ERFU  ;++ "RDD" REQUEST FOULED UP
				; NOTE WELL: THIS LEAVES FEKBSI SET!!!!
				; EFFECTIVELY "HANGING" THIS FEK . . .
				; BUT AT LEAST IT SHOULD CAUSE NO MORE TROUBLE


;No resources for input buffer, try again later

D8ERD7:	MOVSI	T1,FK.STI	;THE "KICK ME" FEK FLAG
	IORM	T1,FEKBLK(J)	;ASK FOR CLOCK-DRIVEN SERVICE LATER ON
D8ERD9:	SETOM	FEKBSI(J)	;INPUT NOW IDLE
	POPJ	P,		;RETURN

;D8EWRT  --  Write request (post a transmit buffer)
;
;FEKOAD contains a PCB address chain to be transmitted (in order of
;entry on the PCB chain); FEKOCT incremented by the caller.
;
;This function merely "queues" the PCB(s) from FEKOAD to the "FE"
;service routine.

D8EWRT:	AOSE	FEKBSO(J)	;GET THE "OUTPUT BUSY" INTERLOCK
	POPJ	P,		;  IF ALREADY DOING OUTPUT, EXIT NOW
	PUSHJ	P,D8EGUN	;GET A UN BLOCK
	 JRST	D8EWR7		;NONE AVAILABLE, TRY AGAIN LATER
D8EWR0:	NETOFF			;KEEP THE PCB CHAIN(S) CLEAN
	SKIPG	FEKOCT(J)	;CHECK IF ANYTHING TO DO
	JRST	D8EWR8		;IF NO OUTPUT MSGS, SET OUTPUT IDLE
	SOS	FEKOCT(J)	;COUNT DOWN PCB'S ON THE QUEUE
	HRRZ	T1,FEKOAD(J)	;FIRST OUTPUT PCB ON QUEUE
	HRRZ	T2,PCBBLK(T1)	;NEXT (IF ANY) PCB ON THE CHAIN
	HRRZM	T2,FEKOAD(J)	;BECOMES NEW FIRST PCB ON OUTPUT QUEUE
	NETON			;SAFE AGAIN
	HLLZS	PCBBLK(T1)	;DELINK THIS PCB FROM THE QUEUE
	HRLM	J,PCBFEK(T1)	;REMEMBER FROM WHICH FEK CAME THIS PCB
	MOVE	T4,FEKNIF(J)	;GET MASTER FEK ADDRESS
	MOVE	T2,FEKNID(T4)	;ETHSER'S PORTAL ID VALUE (FROM MASTER)
	STOR	T2,UNPID,(P4)	;STORE IN "UN" BLOCK
	DMOVE	T2,FEKNIA(J)	;REMOTE ETHERNET NODE ADDRESS
				; (OR MULTICAST ADDRESS IF MASTER FEK)
	DMOVEM	T2,UN.DAD(P4)	;STORE IN "UN" BLOCK
	STOR	T1,UNRID,(P4)	;STORE PCB ADDRESS IN "UN" BLOCK RID FIELD
;RDH	SETZRO	UNBSZ,(P4)	;NO BYTE COUNT MEANS MSD-STYLE CALL
;RDH	XMOVEI	T2,PCBMS1(T1)	;ADDRESS OF MSD PORTION OF PCB
;RDH	STOR	T2,UNBFA,(P4)	;STORE IN "UN" BLOCK
;RDH	SETZM	PCBNXX(T1)	;NO SECOND MSD HERE (STUPID KLNI!!!)
	MOVE	T2,PCBCTR(T1)	;COUNT OF DATA BYTES IN BUFFER
	STOR	T2,UNBSZ,(P4)	;STORE IN "UN" BLOCK
	HLLZ	T2,PCBPTR(T1)	;NOW MUST CONCOCT A TWO-WORD GLOBAL
	HRRZ	T3,PCBPTR(T1)	; BYTE POINTER FOR ETHSER
	TLO	T2,(1B12)	; OTHERWISE IT GOES DING DING DING
	DMOVEM	T2,UN.BFA(P4)	;STORE IN "UN" BLOCK
	MOVX	T2,UNA.EV	;THE DATA BUFFER IS IN EXEC VIRTUAL MEMORY
	STOR	T2,UNADS,(P4)	;STORE THAT IN "UN" BLOCK
	MOVEI	T1,NU.XMT	;FUNCTION: SEND DATAGRAM
	XMOVEI	T2,(P4)		;ADDRESS OF "UN" BLOCK
	PUSHJ	P,ETHSER##	;GIVE BUFFER TO ETHERNET SERVICE
	 JRST	D8EWR4		;FAILED - GO CHECK IT OUT
	JRST	D8EWR0		;FLUSH ALL OUTPUT INTO ETHSER

;Here on ETHSER's rejection of our output request

D8EWR4:	LOAD	T3,UNRID,(P4)	;OOPS, RETRIEVE ERRANT PCB
	NETOFF			;NO INTERRUPTS PLEASE
	HRRZ	T4,FEKOAD(J)	;GET HEAD OF STILL-TO-BE-OUTPUT PCB CHAIN
	HRRZM	T3,FEKOAD(J)	;OLD PCB GETS PUT BACK AT THE START
	HRRM	T4,PCBBLK(T3)	; OF THE FEK'S OUTPUT QUEUE
	AOS	FEKOCT(J)	;ONE MORE PCB ON THE OUTPUT QUEUE
	NETON			;SAFE AGAIN
	CAIN	T1,UNRES%	;NO RESOURCES?
	PJRST	D8EWR7		;YES, FLAG TO TRY AGAIN LATER
	STOPCD	CPOPJ,DEBUG,D8EWFU  ;++ "WRT" REQUEST FOULED UP
				; NOTE WELL: THIS LEAVES FEKBSO SET!!!!
				; EFFECTIVELY "HANGING" THIS FEK . . .
				; BUT AT LEAST IT SHOULD CAUSE NO MORE TROUBLE


;Output "blocked", try again later

D8EWR7:	MOVSI	T1,FK.STO	;THE "KICK ME" FEK FLAG
	IORM	T1,FEKBLK(J)	;ASK FOR CLOCK-DRIVEN SERVICE LATER ON
	JRST	D8EWR9		;SET FEK OUTPUT IDLE AND RETURN

D8EWR8:	NETON			;RE-ENABLE INTERRUPTS
D8EWR9:	SETOM	FEKBSO(J)	;SET OUTPUT IDLE
	POPJ	P,		;AND RETURN

;D8ECRS  --  Request the "FE" to shut down ('crash')
;
;D8ECRS is called by NETSER to forcibly terminate (i.e., shut down
;or crash) the "FE".
;
;The question remains of how we decide to "start it up" again...

D8ECRS:	PUSHJ	P,NTDSTP##	;++NULL



;D8EDWN  --  The "FE" has gone down
;
;This function is not used (rather ETHSER dispatches via D8EISR/NU.RCI)

D8EDWN:	PUSHJ	P,NTDSTP##	;++NULL



;D8EUPP  --  The "FE" is up
;
;This function is not used (rather ETHSER dispatches via D8EISR/NU.RCI)

D8EUPP:	PUSHJ	P,NTDSTP##	;++NULL



;D8ESTC  --  Station control function
;
;This function is not supported (ergo crash if get here)

D8ESTC:	PUSHJ	P,NTDSTP	;++NULL



;D8ECPS  --  Take a nap (cpu is going to sleep)
;
;This function not implemented.

D8ECPS:	POPJ	P,		;DON'T WORRY ABOUT IT



;D8ECPW  --  Time to wake up (cpu awakened)
;
;This function not implemented.

D8ECPW:	POPJ	P,		;DON'T WORRY ABOUT IT

;D8ECFK  --  Create new slave FEK (new Ethernet NCL node)
;
;D8ECFK called when a NODEID has been received (from the master FEK)
;for a new node. Master FEK address in J.
;
;Returns new slave FEK address in T1 (or 0 if couldn't create a new
;FEK block).

D8ECFK:	PUSHJ	P,D8EFGN	;CREATE A NEW FEK BLOCK
	JRST	[SETZ	T1,		;CAN'T, FLAG FAILURE
		POPJ	P,]		;AND RETURN NOW
	MOVSI	T2,FK.NID	;THE "NODEID-SENT" FLAG
	IORM	T2,FEKBLK(T1)	;ALWAYS SET IN SLAVES (ONLY MASTER DOES NODEIDS)
	MOVSI	T2,FK.ONL	;THE "ON-LINE" FEK FLAG
	TDNE	T2,FEKBLK(J)	;IS THE MASTER ON LINE?
	IORM	T2,FEKBLK(T1)	;YES, THEN SO IS THE SLAVE
	POPJ	P,		;RETURN WITH T1/FEK



;D8EDFK  --  Destroy old slave FEK
;
;Called with slave FEK address in J

D8EDFK:	NETOFF			;NO INTERRUPTS WHILST DIDDLING FEK CHAIN
	MOVE	T2,FEKNIF(J)	;START WITH SLAVE'S MASTER FEK ADDRESS
D8EDF1:	MOVE	T1,T2		;SAVE PRECEDING FEK ADDRESS
	HRRZ	T2,FEKBLK(T2)	;LINK TO NEXT FEK IN CHAIN
	CAIN	T2,0		;BAD NEWS IF CAN'T FIND SLAVE FEK IN FEK CHAIN
	STOPCD	D8EDF9,DEBUG,D8EFNC  ;++ SLAVE FEK NOT IN FEK CHAIN
	CAME	T2,J		;IS THIS THE FEK TO BE DELETED?
	JRST	D8EDF1		;NO
D8EDF3:	HRRZ	T3,FEKBLK(T2)	;ADDRESS OF NEXT FEK IN CHAIN
	HRRM	T3,FEKBLK(T1)	;SPLICE OUT OLD SLAVE FEK
	NETON			;SAFE AGAIN
	PUSH	P,T1		;SAVE ADDRESS OF PRECEDING FEK
;	MOVSI	T1,FK.ONL	;THE FEK-IS-ONLINE FLAG
;	ANDCAM	T1,FEKBLK(J)	;THE FEK IS NO LONGER ONLINE
	MOVEI	T1,FI.DWN	;THIS FEK IS DOWN FER SUR
	PUSHJ	P,FEKINT##	;TELL NETSER TO RECOMPUTE TOPOLOGY
	MOVEI	T1,FEKLEN	;LENGTH OF FEK BLOCK
	MOVE	T2,J		;ADDRESS OF FEK BLOCK
	PUSHJ	P,GIVZWD##	;DEALLOCATE FEK BLOCK MEMORY
	PJRST	JPOPJ##		;RETURN, J/PRECEDING FEK ADDRESS
				; (E.G., FOR NETSER/FEK ONCE/SECOND, ETC.)


D8EDF9:	NETON			;CLEAR NETSER INTERLOCK
	POPJ	P,		;AND RETURN

	SUBTTL	FEK "Interrupt" service

;D8EISR - Interrupt service dispatch from ETHSER
;Call is:
;
;	MOVEI	T1,<FNC>
;	MOVX	T2,<UNB>
;	MOVX	T3,<STS>
;	PUSHJ	P,D8EISR
;	 return
;
;Where <FNC> is the ISR (or 'callback' in Etherese) function; <UNB>
;is the ETHSER-supplied 'UN' argument block; and <STS> is the function
;status (if any).
;
;Return is CPOPJ always.

D8EISR:	PUSHJ	P,SAVJW##	;PROTECT ETHSER'S REGS
	CAIL	T1,NU.MIN	;RANGE CHECK THE FUNCTION
	CAILE	T1,NU.MAX	;  CODE AND STOP IF BAD
D8EIS0:	STOPCD	.,STOP,D8EISF	;++ BAD ISR FUNCTION CODE
	JRST	@D8EIST-NU.MIN(T1) ;DISPATCH ON ISR ('CALLBACK') FUNCTION


;ISR function dispatch table

DEFINE	DISP(CODE,ADDR),<
IF1,<IFN <CODE-NU.MIN-<.-D8EIST>>,<PRINTX ?Table D8EIST entry CODE is out of order>>
	IFIW	ADDR		;CODE
>; END DEFINE DISP

D8EIST:	DISP	NU.OPN,D8EIS0	;NU.OPN - 01 - UNDEFINED
	DISP	NU.CLO,D8ECLO	;NU.CLO - 02 - PORTAL CLOSED
	DISP	NU.RCV,D8ERCV	;NU.RCV - 03 - DATAGRAM RECEIVED
	DISP	NU.XMT,D8EXMT	;NU.XMT - 04 - DATAGRAM TRANSMITTED
	DISP	NU.EMA,D8EIS0	;NU.EMA - 05 - MULTICAST ADDRESS ENABLED
	DISP	NU.DMA,D8EIS0	;NU.DMA - 06 - MULTICAST ADDRESS DISABLED

	DISP	NU.RCL,D8EIS0	;NU.RCL - 07 - READ CHANNEL LIST
	DISP	NU.RCI,D8ERST	;NU.RCI - 10 - CHANNEL STATE CHANGE
	DISP	NU.RCC,D8EIS0	;NU.RCC - 11 - READ CHANNEL COUNTERS
	DISP	NU.SCA,D8ESCA	;NU.SCA - 12 - CHANNEL ADDRESS CHANGED

	DISP	NU.RPL,D8EIS0	;NU.RPL - 13 - READ PORTAL LIST
	DISP	NU.RPI,D8EIS0	;NU.RPI - 14 - READ PORTAL INFO
	DISP	NU.RPC,D8EIS0	;NU.RPC - 15 - READ PORTAL COUNTERS

	DISP	NU.RKL,D8EIS0	;NU.RKL - 16 - READ PORTAL LIST
	DISP	NU.RKI,D8EIS0	;NU.RKI - 17 - READ PORTAL INFO
	DISP	NU.RKC,D8EIS0	;NU.RKC - 20 - READ PORTAL COUNTERS

IF1,<IFN <NU.MAX-NU.MIN+1-<.-D8EIST>>,<PRINTX ?Table D8EIST is missing entries>>

;D8ECLO  --  ETHSER 'Portal' closed
;
;This function handles the ISR-level notification of the FE's having
;'CLOSEd' the ethernet 'Portal' (i.e., the FE is shut down).

D8ECLO:	PUSHJ	P,NTDSTP##	;++ WE DON'T EVER CLOSE THE PORTAL

;D8ERCV  --  Message received
;
;D8ERCV is the ISR-level receipient of a successfully-filled (and
;previously "posted" via D8ERDD) receive buffer from the ethernet.

D8ERCV:	LOAD	T1,UNRID,(T2)	;RETRIEVE PCB ADDRESS
	LOAD	J,UNUID,(T2)	;AND MASTER FEK ADDRESS
	MOVEM	T1,FEKIDN(J)	;SET RECEIVED PCB ADDRESS (NI-FEK ONLY)
	SOS	FEKNIQ(J)	;ONE FEWER PCB QUEUED IN ETHSER
	JUMPN	T3,D8ERC5	;GO HANDLE ERRORS
D8ERC1:	LOAD	T3,UNBSZ,(T2)	;GET RECEIVED BYTE COUNT
D8ERC2:	MOVEM	T3,PCBCTR(T1)	;SAVE IT WITH THE PCB
	DMOVE	T3,UN.BFA(T2)	;GET ETHSER'S RETURNED BYTE POINTER
	TLZE	T3,(1B12)	;CLEAR 2-WORD FORMAT FLAG
	HRR	T3,T4		;AND MAKE IT A ONE-WORD LOCAL BYTE POINTER
	MOVEM	T3,PCBPTR(T1)	;SAVE IT WITH THE PCB
				; AS OF THIS WRITING, THE KLNI LEAVES THE
				; TWO-BYTE COUNT FIELD IN THE DATA BUFFER,
				; AND ETHSER INCREMENTS THE POINTER PAST
				; THE TWO BYTES, BUT THAT MAY CHANGE SOME-
				; DAY, SO WE MUST PICK UP ETHSER'S BYTE
				; POINTER RATHER THAN TRUSTING THE ORIGINAL
				; PCB BYTE POINTER . . .
	DMOVE	T3,UN.SAD(T2)	;GET SOURCE ETHERNET NODE ADDRESS
	DMOVEM	T3,PCBNIA(T1)	;SAVE IT WITH THE PCB
	MOVEI	T1,FI.IDN	;FUNCTION: INPUT DONE (FEKIDN)
	PJRST	FEKINT##	;GIVE THE PCB TO NETSER

D8ERC5:	STOPCD	.+1,DEBUG,D8ERCE  ;++ ISR-LEVEL INPUT ERROR
	SETZ	T3,		;RETURN BYTE COUNT OF ZERO
	JRST	D8ERC2		;TO INDICATE USELESS (BUT NOT LOST) PCB

;D8EXMT  --  Message transmitted
;
;D8EXMT is the ISR-level receipient of a successfully-transmitted
;(and previously "queued" via D8EWRT) transmit buffer.

D8EXMT:	LOAD	T1,UNRID,(T2)	;RETRIEVE ADDRESS OF PCB
	HLRZ	J,PCBFEK(T1)	;RETRIEVE ORIGINATING FEK'S ADDRESS
	MOVEM	T1,FEKODN(J)	;SET OUTPUT-DONE PCB ADDRESS
	JUMPN	T3,D8EXM5	;GO HANDLE ERRORS
D8EXM1:	MOVEI	T1,FI.ODN	;FUNCTION: OUTPUT-DONE
	PJRST	FEKINT##	;RETURN BUFFER TO NETSER

D8EXM5:	CAIE	T3,UNDNS%	;IF DATAGRAM NOT SENT
	CAIN	T3,UNEXC%	;OR TOO MANY COLLISIONS (SAME EFFECT)
	JRST	D8EXM1		;JUST LET NETSER TIME IT OUT AND RETRANSMIT
	STOPCD	.+1,DEBUG,D8EXME  ;++ ISR-LEVEL OUTPUT ERROR
	JRST	D8EXM1		;BLUNDER ONWARDS

;D8ERST  --  Ethernet channel ("FE") state change
;
;D8ERST is called by ETHSER whenever the 'Portal' (the logical "FE")
;changes state (i.e., goes online/offline/etc).

D8ERST:	LOAD	J,UNUID,(T2)	;RETRIEVE ADDRESS OF ASSOCIATED MASTER FEK
	PUSHJ	P,D8EOOF	;CHECK/SET ON/OFF LINE FEK STATUS
	 PUSHJ	P,NTDSTP##	;CAN'T (WELL, SHOULDN'T) HAPPEN
	JUMPE	T1,CPOPJ##	;IF NOTHING EXCITING HAPPENED, IGNORE IT

;FEK changed state, tell NETSER as appropriate

D8ERS1:	PUSHJ	P,SAVE4##	;NEED SOME NETSER-PRESERVED ACS HERE
	MOVE	P1,J		;SAVE A COPY OF THE MASTER FEK ADDRESS
	TDNN	T1,FEKBLK(J)	;IS MASTER FEK NOW ONLINE?
	JRST	D8ERS6		;OFFLINE, SET ALL SLAVES OFFLINE ALSO


;Master FEK is now online

D8ERS2:	MOVSI	T2,4		;INITIAL BROADCAST TIMER INTERVAL
	MOVEM	T2,FEKNIT(J)	;RESET BROADCAST INTERVAL TIMER
	SETZM	FEKNIS(J)	;REINITIALIZE NODEID SERIAL NUMBER
	POPJ	P,		;NOTHING MORE TO DO FOR NOW


;Master FEK is offline, set all slaves offline also

D8ERS6:	MOVE	J,P1		;START SEARCHING AT THIS MASTER FEK
D8ERS7:	HRRZ	J,FEKBLK(J)	;NEXT POTENTIAL SLAVE FEK
	JUMPE	J,D8ERS8	;EXIT WHEN NO MORE SLAVE FEKS
	CAME	P1,FEKNIF(J)	;SLAVE BELONG TO THIS MASTER?
	JRST	D8ERS7		;NO, SKIP IT
	PUSHJ	P,D8EDFK	;DESTROY DEAD SLAVE FEK
				; (THIS TELLS NETSER TO BLAST TOPOLOGY)
	JRST	D8ERS7		;LOOP FOR ALL SLAVES ON THIS MASTER

D8ERS8:	MOVEI	T1,FI.DWN	;FUNCTION: FEK OFFLINE
	PJRST	FEKINT##	;TELL NETSER MASTER FEK IS NOW OFFLINE

;D8ESCA  --  Ethernet channel address changed
;
;D8ESCA is called by ETHSER whenever the 'Channel' address associated
;with a 'Portal' changes.

D8ESCA:	POPJ	P,		;DUH?

	SUBTTL	Miscelleaneous support routines

;D8EFGN  --  Create a new Ethernet FEK
;Call is:
;
;	MOVE	J,<MFEK>
;	PUSHJ	P,D8EFGN
;	 Error return
;	Normal return
;
;Where <MFEK> is the address of the "master" (or prototype) FEK from which
;the new FEK is to be modeled (FEKDSP, FEKUNI, FEKNIF).
;
;On error return there was insufficient ANF free core to allocate for
;the FEK block.
;
;On normal return, T1 contains address of newly-created FEK in CLNFEK (i.e.,
;pristine) condition, and linked into the system FEK chain.

D8EFGN:	MOVEI	T2,FEKLEN	;LENGTH OF ETHERNET-STYLE FEK BLOCK
	PUSHJ	P,GETZWD##	;GET SOME ANF FREE CORE
	 POPJ	P,		;NO FREE CORE, NO FEK BLOCK
	PUSH	P,J		;SAVE MASTER FEK INDEX
	MOVE	J,T1		;SET ADDRESS OF NEWLY-CREATED FEK
	PUSHJ	P,NTFONC##	;"ONCE-ONLY" THE FEK
	MOVE	T1,J		;REPOSITION NEWLY-CREATED FEK ADDRESS
	POP	P,J		;AND RESTORE MASTER/PROTOTYPE FEK ADDRESS
	MOVSI	T2,FK.ETH	;THE "ETHERNET-FEK" FLAG
	IORM	T2,FEKBLK(T1)	;PUT OUR BRAND ON THIS LITTLE FEKKY
	MOVE	T2,FEKDSP(J)	;PROTOTYPE "DISP" WORD
	MOVEM	T2,FEKDSP(T1)	;SET FEK DISPATCH SERVICE VECTOR
	MOVE	T2,FEKUNI(J)	;PROTOTYPE CPU/UNIT WORD
	MOVEM	T2,FEKUNI(T1)	;SET FEK CPU AND UNIT WORD
	SETZM	FEKNIA(T1)	;NO ETHERNET REMOTE ADDRESS YET
	SETZM	FEKNIA+1(T1)	;NO ETHERNET REMOTE ADDRESS YET
	SETZM	FEKNIC(T1)	;NO ETHERNET CHANNEL ID YET
	SETZM	FEKNID(T1)	;NO ETHERNET PORTAL ID YET
	MOVEM	J,FEKNIF(T1)	;SET MASTER/PROTOTYPE FEK ADDRESS
	SETZM	FEKNIS(T1)	;NO ETHERNET NODEID SERIAL NUMBER
	MOVE	T2,%NTNIJ##	;ETHERNET SLAVE FEK KEEP-ALIVE TIMER
	MOVEM	T2,FEKNIT(T1)	;INITIALIZE KEEP-ALIVE FOR THIS FEK
	NETOFF			;PREVENT RACES
	HRRZ	T2,FEKBLK(J)	;ADDRESS OF REST OF FEK CHAIN
	HRRM	T1,FEKBLK(J)	;SPLICE NEWLY-CREATED FEK INTO
	HRRM	T2,FEKBLK(T1)	;SYSTEM FEK CHAIN
	NETON			;OK TO RACE NOW
	JRST	CPOPJ1##	;SUCCESS RETURN WITH T1/FEK

;D8EGUN - Get a "UN" block
;Call is:
;
;	PUSHJ	P,D8EGUN
;	 Error return
;	Normal return
;
;On error return no UN blocks are available (and no network free core
;is available to make a new UN block).
;
;On normal return register P4 contains a UN block address.
;
;D8EGUN co-routines back to its caller, and automatically frees up the
;UN block on caller's exit.
;
;Uses T1.

D8EGUN:	PUSH	P,P4		;SAVE CALLER'S P4 FOR LATER RESTORATION
	NETOFF			;MUST DO THIS INTERLOCKED
	SKIPN	P4,D8EUNL	;GOT A FREE UN BLOCK?
	JRST	D8EGU4		;NO, MUST ALLOCATE ONE
	MOVE	T1,(P4)		;YES, ADDRESS OF NEXT UN BLOCK IN FREE LIST
	MOVEM	T1,D8EUNL	;IT BECOMES THE NEW FIRST FREE
	NETON			;SAFE NOW
D8EGU1:	SETZM	(P4)		;CLEAR FIRST WORD OF UN BLOCK
	MOVSI	T1,(P4)		;CONCOCT
	HRRI	T1,1(P4)	; A BLT POINTER TO
	BLT	T1,UN.LEN-1(P4)	;  CLEAR OUT THE UN BLOCK
	AOS	-1(P)		;"SKIP"
	PUSHJ	P,@-1(P)	; CO-ROUTINE BACK TO OUR CALLER
	 CAIA			;NON-SKIP RETURN TO CALLER'S CALLER
	AOS	-2(P)		;SKIP RETURN TO CALLER'S CALLER
	NETOFF			;MUST INTERLOCK AGAIN
	EXCH	P4,D8EUNL	;PUT THIS UN BLOCK AT HEAD OF CHAIN
	MOVEM	P4,@D8EUNL	;AND LINK REST OF CHAIN TO NEW FIRST FREE
	NETON			;SAFE AGAIN
	POP	P,P4		;RESTORE CALLER'S P4
	POP	P,(P)		;POP JUNK ADDRESS
	POPJ	P,		;RETURN TO CALLER'S CALLER

;HERE TO ALLOCATE A NEW UN BLOCK

D8EGU4:	NETON			;RESTORE INTERRUPTABILITY
	PUSHJ	P,D8EGUX	;GET A CORE BLOCK
	 JRST	P4POPJ##	;RESTORE P4 AND ABORT
	JRST	D8EGU1		;RETURN UN BLOCK TO CALLER

D8EGUX:	PUSHJ	P,SAVT##	;SAVE CALLER'S TEAS
	MOVEI	T2,UN.LEN	;LENGTH OF A UN BLOCK
	PUSHJ	P,GETZWD##	;ASK NETSER FOR A HUNK OF MEMORY
	 POPJ	P,		;NONE AVAILABLE
	MOVE	P4,T1		;GOT ONE!
	JRST	CPOPJ1##	;SUCCESSFUL RETURN (RESTORING THE TEAS)

;D8EOOF - Set FEK ON- or OFF-LINE
;Call is:
;
;	MOVX	T2,<UN>
;	PUSHJ	P,D8EOOF
;	 Error return
;	Normal return
;
;Where <UN> is the address of the "UN" block to/from ETHSER.
;
;Error return is not used.
;
;On normal return the FEK block is "ON-" or "OFF-LINE" based on the
;state of the "RUN" bit in the UN status word. T1 contains the FEK
;status-change flag, 0 if no change in FEK status, FK.ONL if the FEK
;changed ON/OFF status.

D8EOOF:	MOVSI	T1,FK.ONL	;THE FEK "ON-LINE" FLAG
	TMNN	UNRUN,(T2)	;IS "RUN" BIT SET IN UN STATUS FIELD?
	JRST	D8EOO3		;NO, "OFF-LINE"
	TDNE	T1,FEKBLK(J)	;YES, "ON-LINE", WAS FEK ALREADY ON-LINE?
	JRST	D8EOO5		;NO CHANGE, JUST RETURN
	IORM	T1,FEKBLK(J)	;WAS OFF-LINE, FLAG ON-LINE
	JRST	CPOPJ1##	;AND TAKE SUCCESSFUL RETURN WITH CHANGE FLAG

D8EOO3:	TDNN	T1,FEKBLK(J)	;WAS FEK ALREADY OFF-LINE?
	JRST	D8EOO5		;NO CHANGE, JUST RETURN
	ANDCAM	T1,FEKBLK(J)	;WAS ON-LINE, FLAG OFF-LINE
	JRST	CPOPJ1##	;AND TAKE SUCCESSFUL RETURN WITH CHANGE FLAG

D8EOO5:	SETZ	T1,		;FLAG NO CHANGE IN FEK STATUS
	JRST	CPOPJ1##	;AND TAKE SUCCESSFUL RETURN

	$LIT

	$LOW

D8EUNL:	BLOCK	1		;FIRST FREE "UN" BLOCK

D8EBLK:	BLOCK	RSBLEN		;RANDOM SCRATCH BLOCK

D8EEND::!END