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Trailing-Edge - PDP-10 Archives - bb-bt99h-bb - latser.x14
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;THIS SOFTWARE IS FURNISHED UNDER A LICENSE AND MAY ONLY BE USED
;  OR COPIED IN ACCORDANCE WITH THE TERMS OF SUCH LICENSE.
;
;COPYRIGHT (c) 1985,1986 BY
;DIGITAL EQUIPMENT CORPORATION, MAYNARD, MASS.
;ALL RIGHTS RESERVED.

IFNDEF FTOPS20,<FTOPS20==0>
IFNDEF FTOPS10,<FTOPS10==-1>
IFN FTOPS20,<	SEARCH MACSYM,MONSYM,PROLOG,TTYDEF>
IFN FTOPS10,<	SEARCH	F,S,D36PAR,MACSYM

.CPYRT<1985,1986>
	SUBTTL  TOPS10 redefinitions of TOPS20 things

	OPDEF	NOP[TRN]
	DEFINE	RESCD	<$HIGH>	;TOPS-10 EQUIVALENT
	DEFINE	SWAPCD	<$HIGH>
	DEFINE	RESDT	<$LOW>
	DEFINE	NOSKD1	<>	;DON,T HAVE TO WORRY ABOUT THESE
	DEFINE	OKSKD1	<>	;  IN TOPS10
	DEFINE	MCENT	<>	; or this one either
	EXTERN	BITTBL
	DEFINE BITS,<BITTBL>

; XCTU is used for "normal" instructions which move data from User to eXec
;	and eXec to User
;
	DEFINE	XCTU	<PXCT 4,>	;For all "normal" instructions
	DEFINE	XCTBU	<PXCT 3,>	;To load from and deposit to user
					;with byte pointer in eXec
	SUBTTL	Definitions - KS10 conditionals
IFE FTXMON,<
;
; Redefine some stuff if we running non-extended (KS10 especially)
;
	DEFINE OWGP. (SS,ADR,POS),<POINT SS,ADR,POS>

	DEFINE XBLT.(AC<T1>),<
IFN <AC>-T1,<PRINTX ? CAN'T XBLT VIA AC, USE T1>
	PUSHJ P,XBLTA##
>

>; END IFN FTXMON
	SUBTTL Symbol purging macros
;
;	Define some macros which will help purge all symbols of
;	the form ..nnnn at the end of assembly.  This will get rid
;	of about 200 useless symbols generated by .IFSKP and friends

	define	eq(a,b),<a==b>

	define	highest(sym,%tg),< ;;Macro to find highest generated symbol
	....==sixbit/%tg/&000077777777 ;;Isolate the nnnn part of ..nnnn
	eq(sym,\'....)
	purge	....>

	define	prgnum(n),<	;;Macro to purge symbol named ..nnnn
	....==sixbit/n/		;;given a number n
	ifl <n-1000>,<....==<..../100>!sixbit/0/> ;;make leading zero fill
	ifl <n-100>,<....==<..../100>!sixbit/0/>
	ifl <n-10>,<....==<..../100>!sixbit/0/>
	prgsym(..,\'....)
	purge	....>

	define prgsym(sy1,sy2),<
	purge sy1'sy2
>

	define	prgall,<	;;End product: macro to purge all symbols
if2,<				;;of the form ..nnnn
	highest XX		;;Use this just before END statement
	nn==XX
	repeat XX,<prgnum(\nn)
		nn==nn-1>

	nn==.npac
	repeat	.npac,<prgsym(.fpac,\nn)	;;get rid of .fpacN symbols
			nn==nn-1>
	purge	nn,XX,.npac>
>

;
;
; Redefine TRVAR to allocate static storage on TOPS-10
; This is so we don't have to have a frame pointer in TOPS-10
; If we ever run into a TRVAR in code, we will die
;
DEFINE TRVAR(LIST),<
IRP LIST,<
LIST:	BLOCK	1
>>

DEFINE ACDEF(N,AC),<.FPAC'N==AC>

DEFINE	FREEAC(AC),<
.NPAC==0
IRP AC,<
ACDEF(\.NPAC,AC)
.NPAC==.NPAC+1
>>

FREEAC <W,M,P1,P2,P3,P4,J>	;These are all the ACs available for ACVAR
				;Explicitly do NOT use "U" since it is used
				;for the normal TOPS-10 function to point to
				;an LDB throughout the code

DEFINE ACVAR (LIST)<
	..NAC==0		;;INIT NUMBER OF ACS USED
	IRP LIST,<
	  .ACV1 (LIST,\..NAC)		;;PROCESS ITEMS
	..NAC==..NAC+1>
	SAVEAC (<LIST>)		;;SAVE ACS USED (QUICK AND DIRTY)
	DEFINE ENDAV.<.ENAV1 <LIST>>>

DEFINE .ACV1 (ITEM,N)<
	.ACV2 (ITEM,N)>		;;PEEL OFF ANGLEBRACKETS IF ANY

DEFINE .ACV2 (NAM,N)<
   IFDEF NAM,<.IF NAM,SYMBOL,<PRINTX ACVAR NAM ALREADY DEFINED>>
	NAM==.FPAC'N	;;DEFINE VARIABLE
	$'NAM==NAM		;;FOR DDT
>

DEFINE .ENAV1 (ARGS)<
	IRP ARGS,<
	  .ENAV2 (ARGS)>>

  DEFINE .ENAV2 (ARG)<
	.ENAV3 (ARG)>

  DEFINE .ENAV3 (NAM,SIZ)<
	PURGE NAM,NAM
  >
	XOFFC=="S"-100		;XOFF CHARACTER
	XONC=="Q"-100		;XON CHARACTER
>;end IFN FTOPS10
IFN FTOPS20,<	SEARCH	NIPAR>
IFN FTOPS10,<	SEARCH	ETHPRM>
		SALL

IFN FTOPS20,<	TTITLE (LATSRV,,< -- LAT-20 Terminal Host>)>
IFN FTOPS10,<	TITLE	LATSER -- LAT-10 Terminal Host

	$RELOC

;THIS SOFTWARE IS FURNISHED UNDER A LICENSE AND MAY ONLY BE USED
;  OR COPIED IN ACCORDANCE WITH THE TERMS OF SUCH LICENSE.
;

	XP	VLATSER,1	;PUT VERSION NUMBER IN STORAGE MAP AND GLOB
>;end IFN FTOPS10

	SUBTTL	Definitions - Literals - Circuit Parameters

;
;LAT Virtual Circuit Message Types
;
	MT.RUN==0		;RUN message
	MT.STA==1		;START message
	MT.STP==2		;STOP message
	MT.MCA==^D10		;Multicast message


;LAT Virtual Circuit States
;

	CS.HLT==0		;HALTED
	CS.STA==1		;STARTING
	CS.RUN==2		;RUNNING
	CS.TRN==-1		;In transition between HALTED and STARTING
	CS.SPG==10		;STOPPING

;
;Circuit STOP message reason codes
;

	CE.NSL==1		;No slots connected on circuit
	CE.ILL==2		;Illegal message or slot format
	CE.HLT==3		;Circuit halted by local system
	CE.NPM==4		;No progress being made
	CE.TIM==5		;Time limit expired
	CE.LIM==6		;Retransmit limit exceeded
	CE.RES==7		;Insufficient resources
	CE.STO==10		;Server circuit timer out of range
	CE.SKW==11		;Protocol version skew
	CE.INV==12		;Invalid Message

;Circuit STOP reason codes of local significance only

	CE.NIH==200		;Local NI halted

	MMHDSI==^D8		;Minimum Message Header Size
	MSTMSI==^D16		;Minimum START Message Size(excluding header)

	SUBTTL	Definitions - Literals - Slot Parameters

;
;LAT Slot Types
;

	ST.DTA==0		;DATA_A slot
	ST.STA==11		;START slot
	ST.DTB==12		;DATA_B slot
	ST.ATT==13		;ATTENTION slot
	ST.REJ==14		;REJECT slot
	ST.STP==15		;STOP slot

;
;LAT Slot States
;

	SS.HLT==0		;Halted
	SS.RUN==1		;Running

;
; SLOT Reject and Stop Reason Codes
;

	SE.USR==1		;User requested disconnect
	SE.SHU==2		;System shutdown in progress
	SE.ISR==3		;Invalid slot received
	SE.SER==4		;Invalid service class
	SE.RES==5		;Insufficient resources available

;
; DATA_B Slot Control Flag Bit Definitions
; Low order bit always set to enable "HOSTSYNC" flow control ala VAX
; Other bits Enables/Disables "TTSYNC" in VAX terms.

	SL.EXF==^B0101		;Enable XON/XOFF recognition in server
	SL.DXF==^B1001		;Disable XON/XOFF recognition in server

;
; SLOT Size Definitions
;

	SLHDSI==4		;Slot header size
	ATTSIZ==SLHDSI		;ATTENTSION slot size
	DTBSIZ==SLHDSI+5	;DATA_B slot size

;
;Miscellaneous Constants
;

	LAHPV==5		;Highest protocol version supported
	LALPV==5		;Lowest protocol version supported
	PROVER==5		;Our LAT protocol version
	PROECO==0		;Our LAT protocol ECO
	MXSLSI==^D40		;Maximum slot size we will receive
	MXSLTS==^D64		;Maximum slot sessions per circuit
	LMRFSI==^D1504		;Receive buffer size
	MXHSRV==10		;Maximum number of services offered
IFN FTOPS20,<	LHPRID==6		;Product code type for TOPS-20 host>
IFN FTOPS10,<	LHPRID==7		;Product code type for TOPS-10 host

>
	SCITTY==1		;Interactive terminal service class
	MAXXBF==2		;Maximum number of transmit buffers/circuit
	CBMAXI==255		;Absolute maximum circuit id
IFN FTOPS20,<MAXCIR==^D20>	;Maximum number of simultaneous circuits
	SLHDSZ==4		;Slot header size (bytes)
	MAXCRE==2		;Maximum number of credits to extend to remote.
	MXBALC==6		;Number of ticks to wait before sending
				; unsolicited message to server

	DLL.FL==400000		;"buffer-in-DLL" flag (in UNUID)
	LS.OFF==0		;LAT Access State OFF
	LS.ON==1		;LAT Access State ON
	LS.SHT==2		;LAT Access State SHUT
	MINXBF==^D46		;Minimum transmit buffer size
	SUBTTL	MONSYM/UUOSYM Definitions

;LATOP./LATOP% Function Code Definitions

	.LASET==0	 ;Set
	.LACLR==1	 ;Clear
	.LASCH==2	 ;Show characteristics of host
	.LASTC==3	 ;Show terminal connects
	.LASAS==4	 ;Show adjacent servers
	.LASCO==5	 ;Show counters
	.LAZCO==6	 ;Zero counters

	.LAACT==0	;Argument block count
	.LAFCN==1	;LATOP% function code

	.LAPRM==2	;SET/CLEAR parameter number
	.LAVAL==3	;SET/CLEAR new parameter value

	.LABCT==2	;Buffer count
	.LABFA==3	;Buffer Address
	.LAQUA==4	;Qualifier
	.LADSC==5	;

	LA%RAT==1B0
	LA%DSC==1B1

	.LPMAC==1
	.LPMCO==2
	.LPNUM==3
	.LPLAS==4
	.LPRLI==5
	.LPTIM==6
	.LPMTI==7
	.LPCOD==10
	.LPNNM==11
	.LPNID==12
	.LPSRV==13
	.LPLOC==14

IFN FTOPS10,<
;
; Allocate some ACs for use in LATOP. UUO
; Use W, since we don't use it for anything else.
; Use M, since it is W+1 for 7.03
; We don't bother saving W, since it is useless.
; We save M at start of LATOP. UUO and restore just before end
;   because it contains the actual UUO and AC field to store to
;
		Q1==W		;redefine some TOPS-20 ACs
		Q2==M		;( = W+1)

DEFINE ITERR (ERRCOD),<
 IFB <ERRCOD>,<JRST ERRRTN>
 IFNB <ERRCOD>,<JRST [MOVEI T1,ERRCOD
		    JRST ERRRTN]>>

DEFINE RETBAD (ERRCOD),<
  IFB <ERRCOD>,<RET>
  IFNB <ERRCOD>,<JRST [MOVEI T1,ERRCOD
		     RET]>>

DEFINE .ERRT (A,B,C,D) <
	B==A
	C==A>			;internal and external name

.ERRT (00,LATX01,LABTS%,<Buffer size too small for available data>)
.ERRT (01,LATX02,LAVOR%,<LAT parameter value out of range>)
.ERRT (02,LATX03,LALNO%,<LAT is not operational>)
.ERRT (03,LATX04,LASVR%,<Invalid or unknown LAT server name>)
.ERRT (04,LATX05,LAIPN%,<Invalid LAT parameter>)
.ERRT (05,LATX06,LAIPV%,<Invalid LAT parameter value>)
.ERRT (06,LATX07,LASVC%,<Invalid or unknown LAT service name>)
.ERRT (07,LATX08,LAILR%,<Insufficient LAT Resources>)
.ERRT (10,LATX09,LAHAS%,<LAT Host name already set>)
.ERRT (11,ARGX02,LAIVF%,<Function code out of range>)
.ERRT (12,ARGX04,LAABS%,<Argument list too small>)
.ERRT (13,LATXAC,LAADC%,<Address check for argument list>)
.ERRT (14,LATXPV,LAPRV%,<No privilege for attempted operation>)

>;END IFN FTOPS10
	SUBTTL	External References

	EXT DLLUNI

IFN FTOPS20,<
	EXT DNGWDZ
	EXT DNFWDS
	EXT TTCHI
	EXT LATMCT	;CLK2TM table timer for multicast
>
IFN FTOPS10,<

	EXTERN	LAHNDB
	EXTERN	GETEWZ,GIVEWS
	EXTERN	LDBPAG,SAVE4,GETWDU,GETWD1,RTZER,STOTAC
	EXTERN	RTN,SETCHP,NTTLAH,MAXCIR,CONFIG,STANAM
	EXTERN	NSBWDS,NFRSBQ,.CPSK0,RECPTY,GETLDB,DETLDB,FRELDB
	EXTERN	LDRREM,LDBDCH,LDBISR,LDBQUH,LDBLAT
	EXTERN	LTLLAT,LDBTTW,APCLAT,LDPAPC,TTFGRT,APCUNK
	EXTERN	XMTCHR,TTIWRN,LDBTIC
	EXTERN	LDBECC,TOTAKE,L1RCHP,LDBBYT
	EXTERN	DATE,TPOPJ
	EXTERN	LDLIDL,M.LIDL,SCNADT
>





; UN Block Extension

BEGSTR	UE
	WORD LW0		;Queue Link Word for linking buffers to CB Qs
	WORD LW1		;Queue Link Word for linking buffers to NI Qs
ENDSTR

;
; Buffer offsets
;

	UNB.OF==UE.LEN		;Start of UN block for all buffers
	MDB.OF==UE.LEN+UN.LEN	;Start of MD block
	XBF.OF==UE.LEN+UN.LEN+MD.LEN
	SBF.OF==UE.LEN+UN.LEN

	SZMSTP==<XBF.OF+SZ.MHD+1>;STOP message size in words
	SZ.SHD==4		;Slot header size
	SZ.ATT==1		;Attention size
	SZ.REJ==0		;Reject slot size
	SZ.SDB==5		;DATA_B slot size
	SZ.SSP==0		;Stop slot size
	SZ.SST==6		;Start slot size
	SZ.XBF==<^D1500+3>/4
	SZ.MSP==^D10		;Start message size
	SZ.MHD==^D8		;Message header size

	ML.NNM==6		;Max length of node name
	ML.SYS==^D16		;Max length of system name
	ML.LOC==^D64		;Max length of location field
	ML.DSC==^D64		;Max length of description field
	ML.SNM==^D16		;Max length of service name
	ML.SID==^D64		;Max length of service identification field

	ML.SLN==^D16		;Max length of slot name
	ML.PNM==^D16		;Max length of port name
	ML.HMC==^D33+<1+ML.NNM>+<1+ML.DSC>+MXHSRV*<1+ML.SNM+1+ML.SID>+2
				;Host multicast message max length
	ML.HSM==^D12+<1+ML.NNM>+<1+ML.LOC>+<1+ML.SYS>+1
				;Host start message max length
	MW.SYS==<ML.SYS+4>/5	;Max length of system name in words
	MW.LOC==<ML.LOC+4>/5	;Max length of location field in words
SUBTTL	Definitions - Data Structures

;

;Host Node Data Structures
;

BEGSTR	GB			;SERVICE BLOCK
	WORD RAT		;Service Rating.
	HWORD NC		;Count of bytes in service name.
	HWORD LC		;Count of bytes in service description
	WORD NAM,<<ML.SNM+4>/5>	;Storage for up to 16 bytes of service name.
	WORD HID,<<ML.SID+4>/5>	;Storage for up to 64 bytes of service id.
ENDSTR

BEGSTR	HN			;HOST NODE Data Base
	FIELD FLG,^D18
	 BIT RUN		;NI run state (must be sign bit)
	 BIT ANY		;Reconstruct of START msg necessary
	 BIT CIP		;Virtual circuit connect in progress
	FILLER ^D10
	FIELD CFL,^D8		;Multicast message change flags
	 BIT OTH		;Something other than above changed
	 BIT FIL
	 BIT CLS		;A host service class changed
	 BIT SVD		;A host service description changed
	 BIT SVR		;A host service rating changed
	 BIT SVN		;A host service name changed
	 BIT NDD		;Host Node Description changed
	 BIT ACS		;Access Codes changed
				;START OF PARAMETERS DISPLAYED BY  .LASCH 
	HWORD MXC		;Maximum allocatable circuit blocks
	HWORD NCC		;Number of currently allocated circuit blocks
	HWORD MAC		;Maximum number of active circuits
	HWORD NAC		;Number of currently active circuits
	HWORD MCO		;Maximum number of simultaneous connects
	HWORD CON		;Current number of active connects
	HWORD NUM		;Host number
	HWORD LAS		;LAT access state
	HWORD RLI		;Virtual circuit message retransmit limit
	HWORD TIM		;Virtual circuit retransmit timer (ms)
	HWORD MTI		;Multicast timer initial value (sec)
				; END OF PARAMETERS DISPLAYED BY .LASCH 
	HWORD PRG		;Host progress timer
	HWORD NRB		;Number of receive buffers allocated
	WORD HST		;Address of state table
	WORD QAC,2		;Queue header for active circuit blocks
	WORD QIC,2		;Queue header for inactive circuit blocks
	WORD NIQ,2		;Interrupt level message queue
	WORD SCQ,2		;Scheduler level message queue
	WORD PID		;NI Portal ID
	HWORD NXI		;Next circuit block index to assign
	HWORD NSV		;Number of offered services
	WORD LOK		;Lock for HN data base
	HWORD NMC		;Host node name count
	HWORD IDC		;Host identification string count
	WORD NAM,2		;Host node name string
	WORD ID,<<ML.DSC+4>/5>	;Host identification string
	WORD SMT,<<<ML.HSM+3>/4>+SBF.OF>;Start message template
	WORD MCM,<<ML.HMC+3>/4>	;Copy of the multicast message.
	WORD SRV,<GB.LEN*MXHSRV>;Storage for service blocks
ENDSTR

BEGSTR	AC,HN.LST		;ACCESS CODES
	WORD LNG		;Access code string length in bytes
	WORD COD,^D32		;Storage for 256 bit bit-mask
ENDSTR

;LAT Circuit counters for all servers

BEGSTR	HC,AC.LST	
	WORD RCV		;Messages received
	WORD XMT		;Messages transmitted
	WORD RTR		;Messages retransmitted
	WORD SEQ		;Receive message sequence errors
	WORD IMR		;Illegal messages received
	WORD ISR		;Illegal slots received
	WORD RES		;Resource errors
	WORD MSK		;Illegal message error mask
ENDSTR

	SUBTTL	CIRCUIT BLOCK data structure definitions

BEGSTR	CB			;CIRCUIT BLOCK
	WORD LNK,2		;Queue Link words (must be first words)
	HWORD RID		;Circuit handle assigned by the remote
	HWORD LID		;Local circuit index
	FIELD FLG,3		;Virtual circuit flags
	 BIT RRF		;Reply requested flag
	 BIT MRS		;Must reply soon flag
	 BIT MRN		;Must reply now flag
	HWORD CSB		;Count since balanced
	HWORD SDC		;Number of slots with data waiting
	HWORD TSQ		;Next transmit sequence number
	HWORD RSQ		;Next expected receive sequence number
	HWORD LRA		;Sequence number of last message ack'd by remote node.
	HWORD TIM		;Current value of circuit timer.
	HWORD RTC		;Current retransmit count
	HWORD QUA		;Circuit quality
	HWORD ERR		;Reason code for last time circuit stopped
	HWORD DLL		;Number of transmit buffers in the DLL
	WORD XBQ,2		;Queue of free transmit buffers
	WORD AKQ,2		;Unacknowledged queue header
	WORD SBQ,2		;Circuit slot queue
	WORD DNI,2		;NI address of remote server
	HWORD MTF		;Maximum transmit frame size for circuit
	HWORD RPV		;Remote protocol version and ECO
	HWORD MSL		;Maximum slots allowed by remote
	HWORD NBF		;Additional transmit buffers allowed by remote
	HWORD CTI		;Value of remote's circuit timer
	HWORD KTI		;Value of remote's keep-alive timer
	HWORD PTC		;Product type code for remote node
	HWORD STA		;Virtual circuit state
	HWORD NUM		;Remote's system number
	HWORD RSC		;Remote's system name count
	HWORD RLC		;Remote's location text count
	WORD SNM,<<ML.SNM+4>/5>	;Remote's system name
	WORD LOC,<<ML.LOC+4>/5>	;Remote's location string	
	WORD KAF		;host keep-alive timer
				;<initial-value>,,<current value>
ENDSTR
BEGSTR	CC,CB.LST		;CIRCUIT COUNTERS
	WORD RCV		;Messages received
	WORD XMT		;Messages transmitted
	WORD RTR		;Messages retransmitted
	WORD SEQ		;Receive message sequence errors
	WORD IMR		;Illegal messages received
	WORD ISR		;Illegal slots received
	WORD RES		;Resource errors
	WORD MSK		;Illegal message error mask
ENDSTR

	RBFSIZ==<<LMRFSI+3>/4+UN.LEN+UE.LEN>;Receive buffer size
	XBFSIZ==<MD.LEN+SZ.XBF>;Transmit buffer length
	NBUFS==<1+<MAXXBF+1>>


;	Boundary definitions in the CB for CLEAR and SHOW
;	LAT Control Program functions.

	  CLRBEG==CB.FLG	;First clear field for .LACLR
	  CLREND==CB.DLL	;End of clear field for .LACLR
	  SASBEG==CB.DNI	;Start of .LASAS fields for single server
	  SASBG==CB.STA		;Start of .LASAS fields for multiple servers
	  SASEN==CB.SNM+<ML.SYS+4>/5 ;End of .LASAS fields for single server
	  SASEND==CB.LOC+<ML.LOC+4>/5 ;End of .LASAS fields for multiple servers

	SUBTTL	SLOT BLOCK data struction definitions

BEGSTR	SB
	WORD LNK,2		;Queue link word (must be first)
	FIELD FLG,^D18		;Flags
	  BIT SDP		;Slot data present (must be sign bit)
	  BIT REJ		;Send REJECT Slot
	  BIT STR		;Send START Slot
	  BIT FOU		;Flush output
	  BIT OUT		;Output data available
	  BIT FCC		;Flow control change
	  BIT STO		;Send STOP Slot(Must be last)
	HWORD ATS		;Maximum attention slot size
	HWORD MDS		;Maximum slot data size
	HWORD STA		;Slot state
	HWORD RID		;Remote slot id
	HWORD LID		;Local slot id
	HWORD XCR		;Transmit credits available to us
	HWORD RCR		;Receive credits still outstanding
	HWORD REA		;Reason code for stop or reject
	HWORD SNC		;Source slot name count
	HWORD OPC		;Object port name count
	HWORD SPC		;Subject port name count
	WORD SNM,<<ML.SLN+4>/5>	;Source slot name (16 characters max)
	WORD OPN,<<ML.PNM+4>/5>	;Object port name
	WORD SPN,<<ML.PNM+4>/5>	;Subject port name
	WORD TDB		;Terminal data block
	WORD CBA		;Circuit block address for this slot
IFN FTOPS10,<
	FIELD REM,^D18		;More flags for TOPS-10
	BIT TTO			;"Character in SBCHR" bit, must be sign bit
	BIT XNF			;"XON/XOF processing enabled
	HWORD CHR		;space to hold saved character
>;end ifn FTOPS10
ENDSTR

	SUBTTL Miscellaneous Structure Definitions

BEGSTR	QL			;Halfword Queue Link Word
	WORD FWD		;Next forward queue element
	WORD BWD		;Previous backward queue element
ENDSTR

	asuppress


	RESDT

IFN FTOPS10,<
OURNAM:	BLOCK	2
OURCNT:	BLOCK	1
LDPXNF:	POINT	1,LDBPAG(U),1;POINTER TO XOFFON BIT
>;end IFN FTOPS10

IFN FTOPS20,<
LAHNDB:	BLOCK 1
> ;end IFN FTOPS20
RTXTIM:	BLOCK	1		;Retransmit timer in ticks
CBVECT: BLOCK 1
SBVECT: BLOCK 1
LASDEF:	EXP LS.ON		;LAT Access Default State
NSLOTS:	BLOCK 1
IFN FTOPS10,<
LATRTQ:	BLOCK	2		;QUEUE FOR LAT LDBS
LATFRE:	BLOCK	QL.LEN		;QUEUE FOR LAT FREE CORE BLOCKS
LATLOC:: BLOCK	1		;START OF LAT FREE CORE (SET UP AT ONCE TIME)
LATMCT:	BLOCK	1		;Multicast timer (in seconds for TOPS-10)
LATNFB:	BLOCK	1		;Number of free buffers in pool
LATWFB:	BLOCK	1		;Number of free buffers wanted for new circuits
LATRFB:	BLOCK	1		;Number of buffers requested on last cycle
LASBAD::BLOCK	2		;Ethernet address of sender of last bad msg

TRVAR <MSGDID,MSGSID,MSGACK,STPCOD> ;Message header variable storage
TRVAR <SLTDID,SLTSID,SLTCNT,SLTTYP,SLTEPT>

>;end IFN FTOPS10

	SUBTTL Symbol Definitions -- Macros MIN.,MAX.,MAXENT

;
; Macro MIN. (symbol,list) - Assigns minimum arithmetic value of list of items.
;

DEFINE MIN. (SYM,LIST),
	<IRP LIST,<..X==LIST	;;Assign first value in list
		   STOPI>
	 IRP LIST,<IFL <LIST-..X>,<..X==LIST>> ;;Assign lowest in list
	 SYM==:..X>		;;Generate value

;
; Macro MAX. (symbol,list) - Assigns maximum arithmetic value of list of items.
;

DEFINE MAX. (SYM,LIST),
	<IRP LIST,<..X==LIST	;;Assign first value in list
		   STOPI>
	 IRP LIST,<IFG <LIST-..X>,<..X==LIST>> ;;Assign highest in list
	SYM==:..X>		;;Generate value

DEFINE LHDSP. (TABLE,CODE,ROUTINE) <
	.ORG <TABLE+CODE>
	IFIW ROUTINE
	.ORG>

DEFINE LSLDT. (DTBL,LTBL,CODE,ROUTINE,LNGTST,LNGADD) <
	.ORG <DTBL+CODE>
	IFIW ROUTINE
	.ORG
	.ORG <LTBL+CODE>
	EXP <LNGTST,,LNGADD>
	.ORG>

;
;	Temp storage block for LATOP.
;
	MAX. (TMPLNG,<<GB.LEN+1>,ML.NNM,ML.DSC>)
TMPBLK:	BLOCK TMPLNG
	TMPGB==TMPBLK+1

	RESCD

IFN FTOPS10,<

	SUBTTL LDBISR Dispatch Table

LATDSP::RET		;( 0)ILLEGAL NOW.  DON'T USE!!
	RET		;( 1)MODEM CONTROL
	JRST	LATSEC	;( 2)ONCE A SECOND CALL (NOT PER TTY)
	RET		;( 3)INITIALIZE
	JRST	SETCHP	;( 4)CHANGE HARDWARE PARMS (let SCNSER do it)
	RET		;( 5)LINE PARM CONTROL
	RET		;( 6)SET TERMINAL ELEMENT
	JRST	LATREM	;( 7)STUFF FOR REMOTE TERMINALS
	RETSKP		;(10)IS LINE DEFINED ON STATION (YES)

DEFINE PARTB. (PRM,MAX,MIN,CLRVAL,INSTR,FLAGS) <

	.ORG <.LP'PRM+TBRNGE>
	EXP <MAX,,MIN>
	.ORG
	.ORG <.LP'PRM+TBFLGS>
	EXP <FLAGS!CLRVAL>
	.ORG
	.ORG <.LP'PRM+TBEXEC>
   IFB <INSTR>,<
	STOR T2,HN'PRM,(Q2)
   >
   IFNB <INSTR>,<
	INSTR
   >
	.ORG
   >

	SUBTTL	LATOP% JSYS 
	
	LF%RNG==1B1		;Do range check on parameter value to set
	LF%LOK==1B2		;Lock the database before setting parameter
	LF%CLR==1B3		;Parameter may be cleared.

MAX. (MXSPAR,<.LPMAC,.LPMCO,.LPNUM,.LPLAS,.LPRLI,.LPTIM,.LPMTI,.LPCOD,.LPNNM,.LPNID,.LPSRV,.LPLOC>)
MIN. (MNSPAR,<.LPMAC,.LPMCO,.LPNUM,.LPLAS,.LPRLI,.LPTIM,.LPMTI,.LPCOD,.LPNNM,.LPNID,.LPSRV,.LPLOC>)


	SWAPCD

TBRNGE:	BLOCK <MXSPAR-MNSPAR+1>
TBFLGS:	BLOCK <MXSPAR-MNSPAR+1>
TBEXEC:	BLOCK <MXSPAR-MNSPAR+1>

	PARTB. (MAC,377,1,^D10,,LF%RNG!LF%CLR)
	PARTB. (MCO,NTTLAH,1,^D10,,LF%RNG!LF%CLR)
	PARTB. (NUM,177777,0,0,,LF%RNG!LF%CLR)
	PARTB. (LAS,LS.ON,LS.OFF,0,,LF%RNG!<HNOTH_^D18>)
	PARTB. (RLI,100,0,^D60,,LF%RNG!LF%CLR)
	PARTB. (TIM,^D100000,^D100,^D1000,<JRST SETRTX>,LF%RNG!LF%CLR)
	PARTB. (MTI,60,10,^D30,,LF%RNG!LF%CLR!<HNOTH_^D18>)
	PARTB. (COD,0,0,0,<JRST SETCOD>,LF%CLR!<HNACS_^D18>)
	PARTB. (NNM,0,0,0,<JRST SETNNM>,0)
	PARTB. (NID,0,0,0,<JRST SETNID>,LF%CLR!<HNNDD_^D18>)
	PARTB. (SRV,0,0,0,<JRST SSERVC>,LF%CLR)


IFN FTOPS10,<	SUBTTL	NETOP. FUNCTIONS


;NETDIL - tell user the node and port where his TTY is connected
;
;Call: (in section 1 already)
;
;	U/ LDB of LAT terminal
;	M/ Address of user's NETOP. arg list
;Return:
;	ECDX?	depending on error
;	RETSKP	node name stored in string block pointed to by user's arg list
;
;Uses P1,P2 (already saved by higher routine), T1-T4, M

NETDIL::MOVE	P1,M		;SAVE ADDRESS OF ARG LIST
	EXCTUX	<SKIPN M,5(P1)>	;POINT TO NODE NAME STRING BLOCK
	  JRST	NTDIL1		;NO STRING BLOCK FOR NAME
	PUSHJ	P,CHKSTB##	;CHECK STRING BLOCK FOR ADDRESSABILITY
	  JRST	NOPADC##	;ADDRESS CHECK
	MOVE	T3,LDBLAT##(U)	;GET ADDRESS OF SB BLOCK
	MOVE	T3,SB.CBA(T3)	;GET ADDRESS OF CORRESPONDING CB BLOCK
	LOAD	T1,CBRSC,(T3)	;GET BYTE COUNT FOR NAME
	XMOVEI	T3,CB.SNM(T3)	;GET ADDRESS OF NODE NAME
	PUSHJ	P,MOV7T8	;MOVE THE STRING
	  JRST	NOPADC##	;NOT ENOUGH ROOM
NTDIL1:	EXCTUX	<SKIPN	M,6(P1)>	;POINT TO PORT NAME STRING BLOCK
	  RETSKP		;BELIEVE IT OR NOT, WE'RE DONE
	PUSHJ	P,CHKSTB##	;CHECK THE STRING BLOCK
	  JRST	NOPADC##	;NOT THERE
	MOVE	T3,LDBLAT##(U)	;GET ADDRESS OF SB BLOCK AGAIN
	LOAD	T1,SBSPC,(T3)	;GET BYTE COUNT OF PORT NAME
	JUMPE	T1,RSKP		;Nothing to store
	XMOVEI	T3,SB.SPN(T3)	;GET ADDRESS OF PORT NAME
	PUSHJ	P,MOV7T8
	  JRST	NOPADC##	;NOT ENOUGH ROOM
	RETSKP
;
;MOV7T8 - ROUTINE TO MOVE A MONITOR 7 BIT STRING TO A USER 8 BIT STRING BLOCK
;
;CALL: M/ ADDRESS OF STRING BLOCK
;	T1/ COUNT OF SOURCE STRING
;	T3/ ADDRESS OF SOURCE STRING
;	T4/ COUNT OF DESTINATION STRING
;
;RETURN:	+1 ADDRESS CHECK
;		+2 SUCCESS
;
;	USES T1-T4
;
MOV7T8:
IFN FTXMON,<PUSHJ P,SSPCS##>	;PRESERVE PCS FOR CALLER
	PUSH	P,T1		;SAVE COUNT FOR A BIT
	MOVE	T1,M		;COPY POINTER TO STRING BLOCK
	PUSHJ	P,SXPCS##	;SETUP PCS
	  JRST	TPOPJ##		;I THOUGHT WE KNEW IT WOULD FIT?
	POP	P,T1		;RESTORE BYTE COUNT
	EXCTXU	<HRLM T1,(M)>	;STUFF BYTE COUNT INTO STRING BLOCK
	CAILE	T1,(T4)		;ENOUGH SPACE TO STORE?
	  RET			;NO
	MOVSI	T2,(<POINT 7,>!1B12)	;MAKE GLOBAL BYTE POINTER
	PUSH	P,T4+1		;SAVE A COUPLE OF ACS
	PUSH	P,T4+2		; T1 HAD BETTER BE LESS THAN 12
	MOVSI	T4+1,(<POINT 8,>!1B12)
	EXCTUX	<XMOVEI T4+2,1(M)>	;GLOBAL ADDRESS OF DEST.
	PXCT	11,[EXTEND	T1,[MOVSLJ
					0]]	;MOVE THE BYTES (I HOPE)
	  JFCL
	POP	P,T4+2
	POP	P,T4+1
	RETSKP
> ;END IFN FTOPS10
	SUBTTL	LATOP% JSYS 

.LATOP::
IFN FTOPS20,<
	MCENT
	UMOVE Q1,1		;Get the argument block address from user
>;END IFN FTOPS20
IFN FTOPS10,<
	CALL SAVE4		;Save P1-P4
	PUSH P,W		;Save the AC we use ( = Q1)
	MOVE Q1,T1		;Get the argument block address from user
;
; For TOPS10, we must address-check the arg list or else we might get
;	an IME
;
	PUSH P,M		;Save UUO for later store ( = Q2)
	MOVE J,.CPJOB##		;Also need job number
	MOVE M,T1		;Point to user's arg list
	CALL GETWRD##		;Get first word (arg count)
	  ITERR (LATXAC)	;Arg list is not addressable!
	MOVE P1,T1		;Save count of arg block
	MOVE T1,Q1		;Restore arg list address
	MOVE T2,P1		;Arg list is this long
	CALL ARNGE##		; so check it.
	  NOP			;Not addressable!
	  ITERR (LATXAC) ;Not writeable (error because must update .LABCT)
;
; From here on, we know the arg list is addressable
; so UMOVEs are no problem.
;
>;END IFN FTOPS10
IFN FTOPS20,<	UMOVE P1,.LAACT(Q1)	;Count of the argument block>
	UMOVE P2,.LAFCN(Q1)	;LAT function code.
	SKIPN Q2,LAHNDB		;If there is no data base,
	ITERR (LATX03)		; then LAT is not operational
	CAIL P2,MNLFCN		;Range check the function code
	CAILE P2,MXLFCN		; ...
	ITERR (ARGX02)		;Function code out of range
IFN FTOPS10,<
	CAIE P2,.LASET		;Is the function .LASET?
	CAIN P2,.LACLR		; or .LACLR?
	  JRST DOFUN		;Yes, these do their own address checking
	CAIN P2,.LAZCO		;or is it .LAZCO?
	  JRST DOFUN		;Yes, no show buffer for that either
;
; Here, we can do some common address checking for all functions which
;  have a SHOW buffer
	UMOVE T1,.LABFA(Q1)	;Get SHOW buffer address
	XCTU [HRRZ T2,.LABCT(Q1)] ; and buffer word count
	JUMPE T2,DOFUN		;0 length, don't bother to check.
	CALL ARNGE##		;See if all of it's addressable
	  NOP			;Not addressable
	  ITERR (LATXAC)	; or not writeable, give error
	
DOFUN:
>;END IFN FTOPS10
	CALL @LAFDSP-MNLFCN(P2)	;Dispatch to perform the function
	 ITERR ()		;Error already reported
IFN FTOPS20,<	MRETNG			;Return to user >

IFN FTOPS10,<
	POP	P,M		;RESTORE UUO
	POP	P,W		;AND SAVED AC
	RETSKP			;AND GIVE GOOD RETURN
>; END IFN FTOPS10

	MIN. (MNLFCN,<.LASET,.LACLR,.LASCH,.LASTC,.LASAS,.LASCO,.LAZCO>)
	MAX. (MXLFCN,<.LASET,.LACLR,.LASCH,.LASTC,.LASAS,.LASCO,.LAZCO>)

LAFDSP:	BLOCK <MXLFCN-MNLFCN+1>
	LHDSP. (LAFDSP,.LASET-MNLFCN,LASET) ;Set
	LHDSP. (LAFDSP,.LACLR-MNLFCN,LACLR) ;Clear
	LHDSP. (LAFDSP,.LASCH-MNLFCN,LASCH) ;Show characteristics of host
	LHDSP. (LAFDSP,.LASTC-MNLFCN,LASTC) ;Show terminal connects
	LHDSP. (LAFDSP,.LASAS-MNLFCN,LASAS) ;Show adjacent servers
	LHDSP. (LAFDSP,.LASCO-MNLFCN,LASCO) ;Show counters
	LHDSP. (LAFDSP,.LAZCO-MNLFCN,LAZCO) ;Zero counters

	SUBTTL	LATOP% JSYS - SET/CLEAR Functions

;LASET/LACLR - Set/Clear LAT Host parameters.
;Call:	Q1/ User's argument block address
;	Q2/ Host node data base address
;	P1/ User's argument block count
;	P2/ Function code

LASET:	
LACLR:
IFN FTOPS10,<
	MOVSI T1,JP.POK		;Check to see if the guy has POKE priv
	CALL PRVBIT##		; or [1,2] or JACCT
	  JRST LASET1		;Yup! non-skip means he's macho.
	RETBAD(LATXPV)		;He's a wimp, don't let him do anything.
LASET1:
>
	UMOVE T1,.LAPRM(Q1)	;Get the parameter number to set/clear.
	CAIL T1,MNSPAR		;Range check it
	CAILE T1,MXSPAR		; ...
	RETBAD (LATX06)		;Parameter number out of range
	CAIE P2,.LACLR
	IFSKP.
	  MOVX T3,LF%CLR	;Is this parameter clearable?
	  TDNN T3,TBFLGS(T1)	; ...
	  RETBAD (LATX07)	;No, return error
	  HRRZ T2,TBFLGS(T1)	;Get the value to clear to
	  JRST LASET0		; and go clear it.
	ENDIF.
	UMOVE T2,.LAVAL(Q1)	;Get the new value to set
	MOVX T3,LF%RNG		;Check if this parameter value should
	TDNN T3,TBFLGS(T1)	; be range checked.
	IFSKP.			;Yes
	  MOVE T3,TBRNGE(T1)	;Get the upper and lower ranges.
	  HRRZ T4,T3		;Lower bound
	  HLRZS T3		;Upper bound
	  CAML T2,T4
	  CAMLE T2,T3
	  RETBAD (LATX02)
	ENDIF.
LASET0:	HLRZ T3,TBFLGS(T1)	;Change flags to set.
	ANDI T3,377
	IORM T3,HN.FLG(Q2)	;Set them
	XCT TBEXEC(T1)		;Do the store.
	RETSKP

	SUBTTL	LATOP% JSYS - SET/CLEAR SERVICE

;SSERVC - Set LAT Service

;Call:	Q1/ User's parameter buffer
;	Q2/ Host node data base address
;	P2/ LATOP% function code
;Return:
;	RET -	Error return
;	RETSKP - Sucess

SSERVC:	SAVEAC <P3,P4>
	CALL FNDSRV		;(T1-T4/T1)Find the service to be set/cleared.
	 RETBAD ()
	MOVEM T1,P3		;Save the service block address
	CAIN P2,.LACLR		;Clearing rather than setting?
	JRST CSERVC		;Yes.
	SETZ P4,0		;P4 will be used to assemble the change flags
	UMOVE T1,.LAQUA(Q1)	;Get the flags and rating
	TXNN T1,LA%RAT		;Set the rating?
	IFSKP.			;Yes.
	  TXO P4,HNSVR		;Set rating change flag	  
	  HRRE T2,T1
	  MOVE T3,T2
	  AOS T2
	  CAIL T2,0		;Range check the rating.
	  CAILE T2,^D256	; ...
	  RETBAD ()		;Out of range
	  STOR T3,GBRAT,+TMPGB	;Store the rating
	ENDIF.
	TXNN T1,LA%DSC		;Set the description?
	IFSKP.
	  TXO P4,HNSVD		;Description change flag
	  UMOVE T1,.LADSC(Q1)	;Get the user's pointer to description string

IFN FTOPS10,<
	  CALL CKSTR##		;Check to see if ASCIZ string is addressable
	   RETBAD (LATXAC)	;Nope, lose
>;end ifn FTOPS10

	  MOVX T2,<POINT 7,GB.HID+TMPGB>;Where to put it.
	  MOVEI T3,ML.SID	;Maximum string count
	  CALL UMVAZS		;(T1-T3/T3)Move the string
	   RETBAD (LATX06)
	  STOR T3,GBLC,+TMPGB	;Store the description length
	ENDIF.
	SKIPN TMPBLK		;Did we add a new service?
	IFSKP.
	  OPSTRM <AOS>,HNNSV,(Q2);Yes.
	  TXO P4,HNSVN		;Flag that number of services changed.
	ENDIF.
	IORM P4,HN.FLG(Q2)	;Enter the assebled flags
	MOVEI T1,GB.LEN		;Move the new service
	XMOVEI T2,TMPGB		; to the service block
	MOVE T3,P3		; supplied by FNDSRV.
	XBLT. T1
	RETSKP


;CSERVC - Clear LAT Service

;Call:	Q1/ User's parameter buffer
;	Q2/ Host node data base address
;	T1/ Address of service block to clear
;RET -	Error return
;RETSKP - Sucess

CSERVC:	MOVE T3,T1		;Start of overlay
	LOAD T1,HNNSV,(Q2)	;Number of services before clear
	IMULI T1,GB.LEN		;Total length of service blocks
	XMOVEI T4,HN.SRV(Q2)	;Service block start address
	ADD T1,T4		;Address of first word outside service block
	XMOVEI T2,GB.LEN(T3)	;First address to move down
	SUB T1,T2		;Number of words to move down
	SKIPG T1		;Is there a service block above?
	JRST CSRVC0		;No so nothing to move
	XBLT. T1		;Compress all blocks downward
CSRVC0:	OPSTRM <SOS>,HNNSV,(Q2)	;One service less.	
	MOVEI T1,HNCLS!HNSVD!HNSVR!HNSVN
	IORM T1,HN.FLG(Q2)	;Indicate service changed.
	RETSKP

	SUBTTL	LATOP% JSYS - SET LAT RETRANSMIT TIMER

;SETRTX - Set LAT retransmit timer
;
;Call:	Q1/ User's parameter buffer
;	Q2/ Host node data base address
;Return:	+2 always
;
SETRTX:	STOR	T2,HNTIM,(Q2)		;Store millisecond value
	IMULI	T2,JIFSEC##		;Convert to ticks
	MOVE	T1,T2
	IDIVI	T1,^D1000
	MOVEM	T1,RTXTIM		;Save retransmit time in ticks
	RETSKP
	SUBTTL	LATOP% JSYS - SET LAT HOST NAME

;SETNNM - Set LAT host name

;Call:	Q1/ User's parameter buffer
;	Q2/ Host node data base address
;RET -	Error return
;RETSKP - Sucess

SETNNM:	OPSTR <SKIPE>,HNNMC,(Q2);Has one already been set?
	RETBAD (LATX09)		;Yes, illegal to reset.
	UMOVE T1,.LABFA(Q1)	;Node name string pointer from the user.

IFN FTOPS10,<
	CALL CKSTR##		;Check to see if ASCIZ string is addressable
	  RETBAD (LATXAC)	;Nope, lose
>;end ifn FTOPS10

	MOVX T2,<POINT 7,TMPBLK>;Pointer to where to build the string.
	MOVEI T3,ML.NNM		;Maximum node name count.
	CALL UMVAZS		;Move the ASCIZ string.
	  RETBAD (LATX06)
	STOR T3,HNNMC,(Q2)	;Store the actual string count
	MOVEI T1,<ML.NNM+4>/5	;Maximum number of words in the string
	XMOVEI T2,TMPBLK		;Move the string to
	XMOVEI T3,HN.NAM(Q2)	; the host node data base
	XBLT. T1		; ...
	RETSKP

	SUBTTL	LATOP% JSYS - SET/CLEAR HOST IDENTIFICATION STRING

;SETNID/CLRNID - Set/Clear host identification string.

;Call:	Q1/ User's parameter buffer
;	Q2/ Host node data base address
;RET -	Error return
;RETSKP - Sucess

SETNID:	CAIN P2,.LACLR		;Clearing rather than setting?
	JRST CLRNID		;Yes.
	UMOVE T1,.LABFA(Q1)	;Node description string pointer from the user.

IFN FTOPS10,<
	CALL CKSTR##		;Check to see if ASCIZ string is addressable
	  RETBAD (LATXAC)	;Nope, lose
>;end ifn FTOPS10

	MOVX T2,<POINT 7,TMPBLK>;Pointer to where to build the string.
	MOVEI T3,ML.DSC		;Maximum node description count.
	CALL UMVAZS		;Move the ASCIZ string.
	  RETBAD (LATX06)
	STOR T3,HNIDC,(Q2)	;Store the actual string count
	MOVEI T1,<ML.DSC+4>/5	;Maximum number of words in the string
	XMOVEI T2,TMPBLK
	XMOVEI T3,HN.ID(Q2)
	XBLT. T1
	RETSKP

CLRNID:	SETZRO HNIDC,(Q2)	;Clear the string count
	RETSKP

	SUBTTL	LATOP% JSYS - SET/CLEAR HOST GROUP CODES

; SETCOD/CLRCOD - Set/clear access codes
;Call:	Q1/ User's parameter buffer
;	Q2/ Host node data base address
;RETSKP - always, no errors.

SETCOD:

IFN FTOPS10,<
	UMOVE T1,.LABFA(Q1)	;Get address of string
	MOVEI T2,^D8		;and length
	CALL ARNGE##		;address check it
	  ITERR (LATXAC)	;not there
	  NOP			;not writeable (that's ok)
>;END IFN FTOPS10

	SAVEAC <P1>
	STKVAR <USRPTR,MSKPTR>
	SETZM TMPBLK		;Zero out the storage where mask to be built.
	XMOVEI T2,TMPBLK	;Zero the first workd
	XMOVEI T3,1(T2)		;Address of second word
	MOVEI T1,^D7		;Number of words to zero.
	XBLT. T1		;
	UMOVE T1,.LABFA(Q1)	;Group code address in user space.
	HRLI T1,441000		;Make an 8-bit byte pointer
	MOVEM T1,USRPTR		;Save it as pointer to user code string.
	MOVX T1,<POINT 8,TMPBLK>;Pointer to temporary storage for mask
	MOVEM T1,MSKPTR		;Save it too.
	MOVEI P1,^D32		;Number of bytes to do
	DO.
	  XCTBU [ILDB T1,USRPTR];Get a user group code byte
	  CALL BITSWP		;Swap the bits
	  IDPB T1,MSKPTR	;Put into mask words
	  SOJG P1,TOP.		;Continue for full count
	ENDDO.
	MOVEI T1,^D8		;32 bytes is 8 words
	XMOVEI T2,AC.COD+7(Q2)	;Address of last group code word in database
	DO.
	  MOVE T3,TMPBLK-1(T1)	;Get a mask word, going backwards
	  CAIN P2,.LACLR	;Clearing of Setting?
	  IFSKP.
	    IORM T3,(T2)	;Set the bits	    
	  ELSE.
	    ANDCAM T3,(T2)	;Clear the bits
	  ENDIF.
	  SOS T2
	  SOJG T1,TOP.
	ENDDO.
	RETSKP			;Return success.

;BITSWP - Swap all bits in an 8-bit byte
;	See Processor Reference Manual page 2-116 for algorithm
;
;Call:	T1/ Byte to swap
;Returns:
;	T1/ Swapped byte

BITSWP:	MUL T1,[100200401002]
	AND T2,[20420420020]
	ANDI T1,41
	DIVI T1,1777
	MOVE T1,T2		;put answer in T1
	RET
;UMVAZS - Get User ASCIZ String
;Call:	T1/ User's ASCIZ Pointer
;	T2/ Destination Pointer
;	T3/ Maximum string count permitted
;RET -	Error, string longer than maximum
;RETSKP	Success
;	T3/ Actual string count

	RESCD

UMVAZS:	MOVNS T3		;Make an AOBJN word
	HRLZS T3		;to count up and down at the same time
IFN FTOPS20,<
	TLC T1,-1		;Make an ASCII pointer to the
	TLCN T1,-1		; user's buffer
	HRLI T1,(<POINT 7,0>)	; if necessary.
>; END IFN FTOPS20
UMVAZ0:	XCTBU [ILDB T4,T1]	;Get a character from his string.
	JUMPE T4,UMVAZ1		;Null found so string ended
	IDPB T4,T2		;Deposit character in temp storage.
	AOBJN T3,UMVAZ0		;If we are not at the maximum, read more.
	RET			;Hit max length without seeing a null.
UMVAZ1:	HRRZS T3		;Return only the positive byte count
	RETSKP

;MMVAZS - Move ASCIZ string within monitor context
;Call:	T1/ Source ASCIZ Pointer
;	T2/ Destination Pointer
;	T3/ Maximum string count permitted
;RET -  If string longer than maximum, truncated.
;	T3/ Actual string count

MMVAZS:	STKVAR <MAXCNT>
	MOVEM T3,MAXCNT		;Save the maximum count
	SETZ T3,		;Clear the string count
MMVAZ0:	ILDB T4,T1		;Get a character from his string.
	JUMPE T4,RTN		;Null found so string ended
	IDPB T4,T2		;Deposit character at destination
	CAML T3,MAXCNT		;If we are at the maximum, read no more.
	RET
	AOJA T3,MMVAZ0		;Increment string count

	ENDSV.

	SWAPCD

	SUBTTL	LATOP% - SHOW CHARACTERISTIC HOST


;LASCH - Show LAT Host Characteristics
;Call:	Q1/ User's parameter buffer
;	Q2/ Host node data base address
;Return:
;	RET - error
;	RETSKP - success

LASCH:	UMOVE T3,.LABFA(Q1)	;User buffer address

;Check to see if the user provided buffer is large enough for all the data

	MOVEI T1,<HN.MXC-HN.MTI+<ML.LOC+3>/4+<ML.DSC+3>/4+<ML.NNM+3>/4+^D16>
	LOAD T4,HNNSV,(Q2)
	IMULI T4,GB.LEN		;Number words for service blocks
	ADD T1,T4		;Total buffer size in words
	  CALL LABFCK		;Is his buffer big enough?
	    RETBAD()		;No
;Move fixed length dynamic parameters from the host node database (HN) to the 
;user's buffer.

	MOVEI T1,<HN.MTI-HN.MXC+1>;Number words to move
	XMOVEI T2,HN.MXC(Q2)	;Address of first HN parameter to move
	XBLTXU T1

;Move static parameters to the user's buffer.

	MOVEI T1,5		;Number of words to move
	XMOVEI T2,[EXP <LAHPV,,LALPV>;Static parameter address
		   EXP <PROECO,,PROVER>
		   EXP <MXSLSI,,MXSLTS>
		   EXP <LMRFSI,,MXHSRV>
		   EXP <LHPRID,,0>]
	XBLTXU T1

;Move the access code words
	MOVEI P3,^D32		;Number of bytes for the access codes
	XMOVEI P2,AC.COD(Q2)	;Address of the access codes
	TXO P2,<OWGP. 8,0>	;Make global pointer
	MOVE P1,T3		;Current address in user's buffer.
	TXO P1,<OWGP. 8,0>	;Make a byte pointer
	DO.
	  ILDB T1,P2		;Get a byte for group codes
	  CALL BITSWP		;Swap the bits
	  XCTBU [IDPB T1,P1]	;Deposit swapped byte into user buffer.
	  SOJG P3,TOP.		;Do all bytes
	HRRZI T3,1(P1)		;Make user pointer an address again.	  
	ENDDO.

;Move Host node name and host node description

	MOVEI T1,<<ML.NNM+4>/5+<ML.DSC+4>/5+1>
	XMOVEI T2,HN.NMC(Q2)	;Address of node name and description
	XBLTXU T1
	;...


	;...

;Move the service blocks

	LOAD T1,HNNSV,(Q2)	;Number of services currently defined
	UMOVEM T1,(T3)		;Move to user buffer
	AOS T3			;Advance buffer address
	MOVE T1,T4		;Get back the total service block length
	XMOVEI T2,HN.SRV(Q2)	;Address of service blocks
	XBLTXU T1
	RETSKP

	SUBTTL 	LATOP JSYS - SHOW TERMINAL CONNECTS
;
; LASTC - SHOW TERMINAL CONNECTS
;
;Call:	Q1/ address of user's arg list
;	Q2/ Address of Host node database
;Return:
;	+1 error
;	+2 success
;
LASTC:	LOAD T1,HNCON,(Q2)	;How many do we think are connected?
	MOVE T4,T1		;Save count
	IMULI T1,<2+MW.SYS>	; * size of returned block
	  CALL LABFCK		;Is his buffer big enough?
	    RETBAD()		;No
	MOVEI T1,NTTLAH		;Get size of SBvect
	PUSH P,T1		;Save as a counter
	UMOVE P1,.LABFA(Q1)	;Get user's buffer address
	MOVE P2,SBVECT		;Point to table of SBs
LASTCL:	SKIPE T1,(P2)		;Is there a slot block there?
	CALL LAS1C		;Yes, move data for it to user's buffer
	  JRST LASTCN		;No, go for next one
	SOJLE T4,LASTCD		;Have we given the user as many as we said?
LASTCN:	SOSLE (P)		;Or have we exhausted SBVECT?
	AOJA P2,LASTCL		;No, just go for next data block
LASTCD:	ADJSP P,-1		;Done, adjust stack
	UMOVE T1,.LABFA(Q1)	;Get address of show buffer again
	SUB P1,T1		;Calculate number of words moved
	XCTU [HRLM P1,.LABCT(Q1)] ;and store it.
	RETSKP			;And give good return

;
;	Routine to move one connect block to user's show buffer
;Call:
;	T1/ Slot Block address
;	P1/ Next address in user's buffer
;
;Return: +1 no attached terminal or circuit block now
;	 +2 Success. Data moved to user's buffer
;
;	P1/ Updated next address to fill in user's buffer (in either case)
;
LAS1C:	SKIPE U,SB.TDB(T1)	;Any LDB associated with slot?
	SKIPN T2,SB.CBA(T1)	;Any circuit block?
	  RET			;No, skip this one
	LOAD T1,CBRSC,(T2)	;Yes, get server name string count
	LDB U,LDPLNO##		;Yes, get TTY line number
	UMOVEM U,(P1)		;Give to user
	UMOVEM T1,1(P1)		;Store count
	XMOVEI T2,CB.SNM(T2)	;and point to name string
	MOVEI T1,<MW.SYS> 	;length of string
	MOVE T3,P1		;Get current user buffer address
	ADDI T3,2		; +2 for the words we have filled
	XBLTXU T1		;Fill in the user's buffer
	MOVE P1,T3		;Point P1 to the next free place in buffer
	RETSKP			;and give good return


	SUBTTL	LATOP JSYS - SHOW SERVERS

;LASAS - Show All Known Servers
;Call:	Q1/ User's parameter buffer
;	Q2/ Host node data base address
;Return:
;	RET - error
;	RETSKP - success

LASAS:	CAIGE P1,5		;Is the user's arg block the right size?
	RETBAD (ARGX04)		;No
REPEAT 0,<
	UMOVE T1,.LAQUA(Q1)	;User's pointer to server name
	CAIN T1,-1		;Specific server wanted?
>
	XCTU [SKIPN T1,.LAQUA(Q1)]	;Specific server wanted?
	IFSKP.			;Yes.

IFN FTOPS10,<
	CALL CKSTR##		;Check to see if ASCIZ string is addressable
	  RETBAD (LATXAC)	;Nope, lose
>;end ifn FTOPS10

IFN FTOPS20,<CALL MAKPTR	;Make a valid ASCIZ pointer.>
	  CALL GTSRVR		;Find circuit block based on server name.
	   RETBAD ()		;Unknown server
	  MOVE T4,T1		;Save the circuit block address
	  MOVEI T1,<SASEND-SASBEG>;# words returned for single server
	  CALL LABFCK		;Is his buffer big enough?
	    RETBAD()		;No
 	  UMOVE T3,.LABFA(Q1)	;Get his buffer address 
	  XMOVEI T2,SASBEG(T4)	;Address of source
	  XBLTXU T1	;Move to user space
	  RETSKP		;Return successfully.
	ENDIF.
	LOAD T1,HNNCC,(Q2)	;Get the number of allocated circuit blocks
	IMULI T1,<1+MW.SYS+2>	;Compute space needed in user's buffer
	CALL LABFCK		;Is his buffer big enough
	  RETBAD()		;NO
	UMOVE T3,.LABFA(Q1)	;Get user buffer address
	MOVE T4,HN.QAC(Q2)	;First element on the active queue
	CALL SASLP		;Get all those on the active queue
	MOVE T4,HN.QIC(Q2)	;Do the same for
	CALL SASLP		; the inactive queue.
	RETSKP			;Return successfully.

SASLP:	JUMPE T4,RTN		;No more circuit blocks on this queue
	MOVE T1,CB.RSC(T4)	;get <number,,name count>
	UMOVEM T1,(T3)		;Give it to user
	ADDI T3,1		;Bump destination address
	MOVEI T1,MW.SYS		;There are 4 words of name
	XMOVEI T2,CB.SNM(T4)	;Address of first to copy
	XBLTXU T1	;Copy to user's space
	DMOVE T1,CB.DNI(T4)	;Get Ethernet address
	XCTU [DMOVEM T1,(T3)]	;Give it to the user
	ADDI T3,2		;Account for those words
	LOAD T4,QLFWD,+CB.LNK(T4);Get the next CB
	JRST SASLP		;And continue looping thru queue

	SUBTTL	LATOP% JSYS - SHOW/ZERO COUNTERS

;LASCO - Show LAT Counters
;CALL:	Q1/ User argument block address
;	Q2/ LAT host node data base address

LASCO:	CAIGE P1,5		;Is the user's arg block the right size?
	RETBAD (ARGX04)		;No
	CALL GTLCOB		;Get the counter block based on server name.
	 RET			;Error, already reported
	XCTU [HRLM T1,.LABCT(Q1)];Tell user
	XCTU [HRRZ T3,.LABCT(Q1)];Get his buffer count.
	CAMGE T3,T1		;Has user allocated large enough buffer?
	RETBAD (LATX01)		;No
	UMOVE T3,.LABFA(Q1)	;Get his buffer address 
	XBLTXU T1
	RETSKP

;LAZCO - Zero LAT Counters
;CALL:	Q1/ User argument block address
;	Q2/ LAT host node data base address

LAZCO:	CAIGE P1,5		;Is the user's arg block the right size?
	RETBAD (ARGX04)		;No
	CALL GTLCOB		;Get the counter block bases on server name.
	 RET			;Error, already reported
	SETZM (T2)		;Zero the first counter
	XMOVEI T3,1(T2)		;
	SOSLE T1		;Account for the word we just zeroed
	XBLT. T1		;Zero the block if more than 1 word
	RETSKP			;Return successfully.

;GTLCOB - Get LAT Counter Block.  Get the length and address of the LAT
; counter block based on server number.
;
;CALL:	T1/ Pointer to server name or [0,,-1]
;RET:	Error - server unknown
;RETSKP:Success with
;	T1/ Counter block length in words
;	T2/ Counter block address

GTLCOB:
REPEAT 0,<
	CAIN T1,-1		;Zero local host counters?
>
	XCTU [SKIPN T1,.LAQUA(Q1)]	;Get server name requested
	IFSKP.			;Zero a particular server's counters

IFN FTOPS10,<
	CALL CKSTR##		;Check to see if ASCIZ string is addressable
	  RETBAD (LATXAC)	;Nope, lose
>;end ifn FTOPS10

IFN FTOPS20,<CALL MAKPTR	;Make a valid pointer>
	  CALL GTSRVR		;Find circuit block based on server name
	   RETBAD ()		;Unknown server
	  XMOVEI T2,CC.BEG(T1)	;Server counter block address
	  MOVEI T1,CC.LEN	;Server counter block length
	ELSE.			;Local host counters wanted
	  MOVEI T1,HC.LEN	;Host counter block length
	  XMOVEI T2,HC.BEG(Q2)	;Host counter block address
	ENDIF.
	RETSKP

	SUBTTL	LATOP% JSYS - Utility Routines - FNDSRV

;FNDSRV - find the service block requested by the user based on the
; service name provided.

;Call:	no arguments
;Return:
;	RET - error
;	RETSKP - success, T1/ address of service block

FNDSRV:	SAVEAC <P1,P2>
	MOVEI T1,TMPLNG-1	;Zero the storage for assembling user's
	XMOVEI T2,TMPBLK	; service name.
	XMOVEI T3,TMPBLK+1	; ...
	SETZM TMPBLK		; ...
	XBLT. T1		; ...

;Get the Service Name string from the user and put it into the service
;block build area.

	UMOVE T1,.LABFA(Q1)	;Pointer to user's service name string

IFN FTOPS10,<
	CALL CKSTR##		;Check to see if ASCIZ string is addressable
	  RETBAD (LATXAC)	;Nope, lose
>;end ifn FTOPS10

IFN FTOPS20,<CALL MAKPTR	;Make a valid ASCIZ pointer>
	XMOVEI T2,TMPGB+GB.NAM	;Pointer of where to put it
	TXO T2,<OWGP. 7,0>	; ...
	MOVEI T3,<ML.SNM+4/5>	;Maximum length
	CALL UMVAZS		;Move the string to exec space
	 RETBAD (LATX07)		;Service name too long
	STOR T3,GBNC,+TMPGB	;Store the count of service name from user

;Loop through all service blocks looking for a name match.

	XMOVEI P2,HN.SRV(Q2)	;Address of start of service blocks
	OPSTR <SKIPN P1,>,HNNSV,(Q2);Number of currently defined services
	JRST FSFALS		;There are none defined.
	DO.
	  XMOVEI T1,GB.NAM(P2)	;Address of service block's service name
	  TXO T1,<OWGP. 7,0>
	  LOAD T2,GBNC,(P2)	;Count of service block's service name
	  XMOVEI T3,TMPGB+GB.NAM;Address of user's service name
	  TXO T3,<OWGP. 7,0>
	  LOAD T4,GBNC,+TMPGB	;Count of user's service name
	  CALL SCMPAR		;Compare the strings
	  IFSKP.		;MATCH FOUND
	    MOVEI T1,.LASET	;If a SET...
	    XCTU [CAME T1,.LAFCN(Q1)]
	    IFSKP.
	      MOVEI T1,GB.LEN	; then copy entire service block to the
	      XMOVEI T2,(P2)	; temporary block so that new values
	      XMOVEI T3,TMPGB	; overlay the old.
    	      XBLT. T1
	    ENDIF.
	    MOVE T1,P2		;In both cases (SET/CLEAR) return service
	    RETSKP		; block address.
	  ENDIF.
	  ADDI P2,GB.LEN	;No match here so
	  SOJG P1,TOP.		; advance to next service block
	ENDDO.

;Service block not found.  If function is SET, see if there is room for
;a new service.  If function is CLEAR, nothing further required.

FSFALS:	MOVEI T1,.LASET		;If service name not found and the function
	XCTU [CAME T1,.LAFCN(Q1)]; request is not a SET,
	RETBAD (LATX07)		; then return an error. Otherwise,
	XMOVEI T1,<GB.LEN*MXHSRV+HN.SRV>(Q2); get end of service block address
	CAML P2,T1		; and compare with first free block address
	RETBAD (LATX08)		;There is no room for new service.
	SETOM TMPBLK		;There is room.  Flag to increment # services.
	MOVE T1,P2		;Return service block address for new entry.
	RETSKP

	SUBTTL	LATOP% JSYS - Utility Routines - GTSRVR


;GTSRVR - Routine to get the circuit block address for a particular 
; server based on server name.
;
;CALL:	T1/ Pointer to server name supplied by user
;	Q2/ LAT host node data base address
;RET - 	Error, no circuit block with the requested server name
;RETSKP	Success,
;	T1/ Circuit block address for requested server

GTSRVR:	SAVEAC Q1		;Get an AC for circuit block address.
	MOVX T2,<POINT 7,TMPBLK>;Pointer to where to move name string.
	MOVEI T3,ML.DSC		;Maximum server name string length.
	CALL UMVAZS		;(T1-T3/T3)Move the ASCIZ string.
	  RETBAD (LATX04)
	MOVX T1,<POINT 7,TMPBLK>;Pointer to user's name string in local storage
	MOVE T2,T3		;Length of the user's name string.
	LOAD Q1,HNQAC,(Q2)	;Get first CB on active queue
	CALL GCBNAM		;See if desired server there
	IFSKP.
	  MOVE T1,Q1		;Return the CB address on successful
	  RETSKP		; match.
	ENDIF.
	LOAD Q1,HNQIC,(Q2)	;Get first CB on inactive queue
	CALL GCBNAM
	IFSKP.
	  MOVE T1,Q1		;Return the CB address on successful
	  RETSKP		; match.
	ENDIF.
	RETBAD (LATX04)		;Not anywhere, return error.

;GCBNUM - searches a particular queue of circuit blocks looking for a match
; on the server name.

GCBNAM: SAVEAC <T1,T2>		;Preserve string pointer and count.
	JUMPE Q1,RTN		;No more circuit blocks on this queue
	DO.
	  XMOVEI T3,CB.SNM(Q1)	;Address of server name
	  TXO T3,<OWGP. 7,0>	;Make a pointer
	  LOAD T4,CBRSC,(Q1)	;Count in name
	  CALL SCMPAR		;Do the compare
	   SKIPA		;No match
	  RETSKP		;Match
	  OPSTR <SKIPN Q1,>,QLFWD,+CB.LNK(Q1)
	  RET			;No match for any CBs on queue.
	  JRST TOP.		;Try next CB.
	ENDDO.


	SUBTTL	LATOP% JSYS - Utility Routines - SCMPAR String Compare

;SCMPAR - String Compare
;Call:	T1/ First string byte pointer
;	T2/ First string count
;	T3/ Second string byte pointer
;	T4/ Second string count
;RET 	Mismatch
;RETSKP Match

SCMPAR:	SAVEAC <T1,T2,T3,T4>	;Preserve the byte pointers.
	STKVAR <PTR1,PTR2>
	CAME T2,T4		;If lengths don't match then obviously
	RET			; the strings don't either.
	MOVEM T1,PTR1		;Save the byte pointers
	MOVEM T3,PTR2		; to the strings.
	DO.
	  ILDB T1,PTR1		;Get next character from
	  ILDB T2,PTR2		; each string.
	  CALL UPPERC		;Uppercase one.
	  EXCH T1,T2
	  CALL UPPERC		;Uppercase the other.
	  CAME T1,T2		;Compare the result.
	  RET			;Different so return failure.
	  SOJG T4,TOP.		;Match, so continue with the next.
	ENDDO.
	RETSKP			;Full match, return success.

	ENDSV.

;UPPERC - Uppercase a character
;Call:	T1/ Character
;RET	Always with T1/ uppercased character

UPPERC:	CAIL T1,"a"
	CAILE T1,"z"
	SKIPA
	SUBI T1,40
	RET

;LABFCK - Check if the user's show buffer is big enough
;Call:	T1/ Needed size
;Return:
;	+1 Not big enough
;	   T1/ LATX01
;
;	+2 OK
LABFCK:	XCTU [HRLM T1,.LABCT(Q1)];Tell user
	XCTU [HRRZ T2,.LABCT(Q1)];Get his buffer count.
	CAMGE T2,T1		;Has user allocated large enough buffer?
	RETBAD (LATX01)		;No
	RETSKP			;Yes
IFN FTOPS20,<
;MAKPTR- Make a valid ASCIZ pointer if not already

MAKPTR:	MOVE T2,T1		;Make a proper pointer in case the user
	TLC T2,-1		; supplied one of the form
	TLCN T2,-1		; -1,,address
	HRLI T1,440700		; ...
	RET
>;END IFN FTOPS20

IFN FTOPS10,<

;ERRRTN- Error return from LATOP. UUO
;	Must only be called at top level within UUO
;	i.e. the only thing on the stack is old value of M
;	Otherwise, use RETBAD and propagate error return
;
ERRRTN:	POP P,M			;Restore original UUO
	POP P,W			;Restore saved AC
	JRST STOTAC##		;Store error code and return to user

;
;	Last thing in LATOP. UUO code
;
	PURGE Q1,Q2		;undefine TOPS-20 ACs

>;end ifn FTOPS10
	SUBTTL	LATINI - LAT Initialization

;LATINI - LAT Initialization
;
;Call:	CALL LATINI
;	  Error return - resource failure
;	Normal Return
;

	ENTRY LATINI		;Keep LINK happy in library search mode

LATINI:	SE1ENT
	ACVAR <HN,XB,W1,W2>	;Reserve AC for Host Node data base address
	MOVEI T1,HC.LST+1	;Get memory for the Host Node (HN) tables
	CALL MMGTZW		;Get zeroed memory
	 JRST INIRES		;Resource failure. Should not happen.
	MOVE HN,T1		;Base address for host node database references
	SETONE HNRUN,(HN)	;Set flag that says NI not running (yet).
	MOVEM T1,LAHNDB		;Store the data base address
	MOVEI T1,CBMAXI		;Get storage for CBVECT
	CALL MMGTZW		;
	  JRST INIRES		;Resource failure.
	MOVEM T1,CBVECT		;Save the address
	MOVEI T1,NTTLAH		;Get storage for SBVECT
	CALL MMGTZW
	 JRST INIRES		;Resource failure.
	MOVEM T1,SBVECT		;Save the address
IFN FTOPS10,<
;
;	Now carve up the core we got at ONCE time
;	The free core pool will be turned into a
;	linked list of fixed length buffers from which we can allocate
;	transmit and receive buffers.
;
	SETZRO QLFWD,+LATFRE	;Clear out the queue
	SETZRO QLBWD,+LATFRE
	CALL LAGTCR		;find out how much memory we got at ONCE time
	IDIVI T1,BUFSIZ		;See how many buffers will fit
	MOVE T4,T1		;Put it where we need it later.
	MOVEM T4,LATNFB		;Remember how many we have at start
	MOVE T2,LATLOC		;Start of first one
	CALL ALCBUF		;Link them together

	MOVE T1,STANAM		;Get our node name
	CALL CVTNOD		;Convert to ASCII
>;end IFN FTOPS10
	DMOVE T1,OURNAM		;Get the local host name
	DMOVEM T1,HN.NAM(HN)	;Store in HN block
	MOVE T1,OURCNT		;Host name length in characters
	STOR T1,HNNMC,(HN)	;Store in HN block
IFN FTOPS20,<	MOVX T1,<POINT 7,SVN##>	;Pointer to MONNAM.TXT>
IFN FTOPS10,<	MOVX T1,<POINT 7,CONFIG> ;Pointer to Monitor name>
	MOVX T2,<POINT 7,HN.ID(HN)>;Where to put it.
	MOVEI T3,ML.DSC		;Maximum length allowed
	CALL MMVAZS		;Move the string
	  TRN			;Don't care, take truncated string
	STOR T3,HNIDC,(HN)	;Store real count
	MOVEI T1,^D60		;Default Host message retransmit limit
	STOR T1,HNRLI,(HN)
	MOVEI T1,^D1000		;Default host virtual circuit timer(msec)
	STOR T1,HNTIM,(HN)	;One second between retransmits
	MOVEI T1,JIFSEC##	;Same thing as above
	MOVEM T1,RTXTIM		; but in ticks instead of milliseconds
	MOVEI T2,^D30		;Default host multicast timer (secs)
	STOR T2,HNMTI,(HN)
	MOVE T1,LASDEF		;Get the default LAT Access State
	STOR T1,HNLAS,(HN)	; and store it
	CAIN T1,LS.OFF		;If default state is on, start transmitting
	IFSKP.			; multicast messages immediately.
IFN FTOPS20,<
 	  IMULI T2,^D1000	;Multicast in millisecs
>;end IFN FTOPS20
	  MOVEM T2,LATMCT	;Initialize scheduler long timer word
	ENDIF.
	MOVEI T1,MAXCIR		;Default maximum allocatable circuit blocks
	STOR T1,HNMXC,(HN)
	;...


	;...
	STOR T1,HNMAC,(HN)	;And max active circuits
	MOVEI T1,CBMAXI		;Get a random number in the range or 1 to
	CALL RANDOM		; maximum value of circuit block index
	STOR T1,HNNXI,(HN)	;Store as next CB index to assign	
	MOVEI T1,NTTLAH		;Default max number of simultaneous connects
	STOR T1,HNMCO,(HN)
	MOVEI T1,^D32		;Number of access code bytes
	STOR T1,ACLNG,(HN)
	MOVSI T1,(1B7)		;Set group 0 on
	MOVEM T1,AC.COD(HN)	;Store as first byte of access codes
	MOVEI T1,1
	STOR T1,HNNSV,(HN)	;Default number of host services offered
	XMOVEI T4,HN.SRV(HN)	;Address of the host service blocks
	STOR T1,GBRAT,(T4)
	MOVE T1,OURCNT		;Default service name is node name so
	STOR T1,GBNC,(T4)	; store the count
	DMOVE T1,OURNAM		; and the name
	DMOVEM T1,GB.NAM(T4)

IFN FTOPS10,<
	LOAD T1,HNIDC,(HN)	;get Host node id count
	CAILE T1,ML.SID
	MOVEI T1,ML.SID		;Don't exceed what's allowed in this field
	STOR T1,GBLC,(T4)	;SAVE it
	IDIVI T1,5		;Convert to word count
	SKIPE T2		;if not an even multiple of 5
	ADDI T1,1		;Round up
	XMOVEI T2,HN.ID(HN)	;Get address of host descriptor
	XMOVEI T3,GB.HID(T4)	;And address of service descriptor
	XBLT. T1		;make service descriptor the same as host
>;END IFN FTOPS10

	XMOVEI XB,HN.MCM(HN)	;Address of the multicast message block
	MOVE T1,[BYTE (8)11,0,53,0,(4)0];Store multicast address
	MOVE T2,[BYTE (8)0,17,0,0]; ...
	OPSTRM <DMOVEM T1,>,UNDAD,+UNB.OF(XB);09-00-2B-00-00-0F
	SETO T1,0		;Use random number for incarnation count
	CALL BMCFXD		;Build the first (fixed) ^D12 bytes
	CALL BMCACS		;Enter the host access code string (fixed)
	CALL BMCNID		;Enter the host node name and description
	CALL BMCSRV		;Build the services
	SETONE HNLOK,(HN)	;Initialize database lock
	STOR XB,UNRID,+UNB.OF(XB);Store for xmit complete processing
	CALL BLDSTM		;Now build the START message template
	MOVSI T1,-NSBWDS	;Initialize free slot block words to
INISBN:	SETOM NFRSBQ(T1)	; all slots free (all bits 1's)
	AOBJN T1,INISBN		; ...
	;...


	;...
	SETZRO UNCHN,+UNB.OF(XB);For now, later must read channel list
	SETZRO UNPAD,+UNB.OF(XB);We use padding
	MOVEI T1,^B0110000000000100;Protocol ID is 60-04
	STOR T1,UNPRO,+UNB.OF(XB);
	XMOVEI T1,LATCBR	;Callback routine address
	STOR T1,UNCBA,+UNB.OF(XB)
	MOVX T1,NU.OPN		;NISRV Open function
	XMOVEI T2,UNB.OF(XB)	;Use this for open as well
	CALL DLLUNI
	IFSKP.
	  LOAD T1,UNPID,+UNB.OF(XB);Get the PID return from the DLL
	  STOR T1,HNPID,(HN); and store for later calls to the DLL.
	  SKIPL UN.STA+UNB.OF(XB) ;Is returned state "running" ?
	  IFSKP.
	    SETZRO HNRUN,(HN)		;Yes, clear our flag (mark NI running)
	    CALL GETRBF			;Get a buffer for receives
	     TRN			;Will have to get buffers later
	  ENDIF.
	ENDIF.
	RET

INIRES:	
	BUG. (CHK,LATINE,LATSER,SOFT,<LATINI failed to initialize>,,<>)
	SKIPE T1,LAHNDB		;Start with a clean slate when we try
	CALL MMFREE		; to initialize later...
	SKIPE T1,CBVECT		; ...
	CALL MMFREE		; ...
	SKIPE T1,SBVECT		; ...
	CALL MMFREE		; ...
	RET

	ENDAV.

	SUBTTL	Subroutine -- CWHLAT - Type a server spec for WHERE command

;CWHLAT - Types a server spec given a LATSER-owned LDB.
;
; Call:
;	U/ Target LDB address
;	0(P)/ Command LDB address
;
; Return:
;	RET			;If success
;	via CWHNCN		;If line is not owned by LATSER
;
; Used: T1-T4

IFN FTOPS10,<
CWHLAT::POP	P,T1		;Can't call SE1ENT with junk on stack!
	SE1ENT			;So we can access NZS data
	PUSH	P,T1		;RE-save LDB of command term
	SKIPN	T1,LDBLAT##(U)	;Get slot block associated with target TTY
	  PJRST	CWHNCN##	;Not connected now.
	POP	P,U		;Point to command terminal for typeout
	PUSH	P,DEVNAM(F)	;Save TTY name
	PUSH	P,SB.CBA(T1)	; and Circuit Block address.
	CALL	TTYKLQ##	;ZAP useless TTY DDB
	CALL	INLMES##	;Type out an intro
	  ASCIZ	/LAT	/		; guess what!
	MOVE	T2,(P)		;Get LAT circuit block address
	LOAD	T1,CBRSC,(T2)	;Get server name count from it
	ADD	T2,[OWGP. 7,CB.SNM]	;Make byte pointer to name
	CALL	TCSTR		;Type a counted string
	MOVEI	T3,"("		;Separate it
	CALL	COMTYO##	; from location
	POP	P,T2		;Get CB address for last time
	LOAD	T1,CBRLC,(T2)	;Get server location count from it
	ADD	T2,[OWGP. 7,CB.LOC]	;Make byte pointer to location
	CALL	TCSTR		;Type a counted string
	CALL	INLMES##	;Close it off
	  ASCIZ	/) /		;and separate it.
	POP	P,T2		;Get TTY name
	CALL	PRNAME##	; and type it.
	PJRST	PCRLF##		;and return

;
; Routine TCSTR - type a counted ASCII string
;
;Call:	T1/ byte count
;	T2/ byte pointer
;
TCSTR:	SOJL	T1,CPOPJ##	;No chars to type
	PUSH	P,T1		;save the count in a safe place
TCST1:	ILDB	T3,T2		;Get a character
	CALL	COMTYO##	; and type it
	SOSL	(P)		;Count them down
	JRST	TCST1		; and do them all
	POP	P,T1		;trim the stack
	RET			; and return
> ;end IFN FTOPS10
	SUBTTL Once a second code (TOPS10)

IFN FTOPS10,<
LATSEC::
IFN FTMP,<
	XCT .CPSK0		;SKIP IF WE'RE ON POLICY CPU
	RET			;NO, ONLY RUN ONCE A SECOND!
>
	SKIPLE LATMCT		;IS the timer non-zero?
	SOSLE LATMCT		;Count down the timer
	  RET			;Not time to do anything yet
;	CALLRET	LATXMC		;Fall into multicast transmit code
>;end IFN FTOPS10
	SUBTTL Multicast Transmitter

;
;LATXMC	- Transmit Multicast Message
;
;CALL:	CALL LATXMC
;	Normal Return
LATXMC::
	SE1ENT
	ACVAR <HN,XB,W1,W2>
	SKIPN HN,LAHNDB		;Get the address of the HN data base
	RET			;LAT initialize not done yet.
	LOAD T1,HNMTI,(HN)	;Reset the
IFN FTOPS20,<
	IMULI T1,^D1000		; multicast
>;end IFN FTOPS20
	MOVEM T1,LATMCT		; timer
	SKIPGE HN.RUN(HN)	;is the NI running?
	  RET			;No, go no further.
	CALL GETRBF		;Get another buffer if we need one
	 NOP			;Oh well!
	XMOVEI XB,HN.MCM(HN)	;Get the address of the multicast msg
	OPSTR <SKIPE W1,>,HNCFL,(HN);If nothing changed in HN database
	OPSTR <SKIPL>,HNLOK,(HN); or something changed by db id locked
	JRST SNDMNC		; then send the old image of mc msg
	CAIE W1,HN%SVR		;Did only the ratings change?
	JRST LATXM0		;No, something else changed
	CALL BMCRAT		;Go update the ratings
	JRST LATXM2		; and send the mc msg
LATXM0:	SETZ T1,0		;So BMCFXD will increment incarnation count
	TRNE W1,HN%OTH		;Did something in fixed part of mc change?
	CALL BMCFXD		;Yes, go rebuild fixed part of mc msg
	TRNE W1,HN%ACS		;Did any access codes change?
	CALL BMCACS		;Yes, go rebuild access code field
	TRNE W1,HN%NDD		;Did the host node description change?
	CALL BMCNID		;Rebuild the node description
	TRNN W1,HN%NDD		; and the service fields
LATXM1:	TRNE W1,HN%SVN!HN%SVD!HN%SVR;Did anything in any service change?
	CALL BMCSRV		;Yes, reconstruct all service fields
LATXM2:	SETZRO HNCFL,(HN)	;Clear data base change flags
SENDMC:	MOVX T1,<POINT 8,<SBF.OF+1>(XB),23>;Pointer msg change flags
	LDB T2,T1		;Message incarnation field
	AOS T2			;Add one
	DPB T2,T1		; and put back into msg
	ILDB T2,T1		;Load current change flag settings from msg
	TDC T2,W1		;Complement those bits which represent change
	DPB T2,T1		; and put back into msg
SNDMNC:	XMOVEI T1,<SBF.OF>(XB) ;Set up one word global to buffer for
	TLO T1,(<OWGP. 8,0>)		; NISRV and
	STOR T1,UNBFA,+UNB.OF(XB); store in UN block
	LOAD T1,HNPID,(HN)	;Get the PID for the DLL
	STOR T1,UNPID,+UNB.OF(XB)
	MOVX T1,NU.XMT		;Set NI function to transmit
	XMOVEI T2,UNB.OF(XB)	;Address of arguement block for NISRV
	CALL DLLUNI		;Call NI service
	 TRN			;Ignore error
	RET			;Return

	SUBTTL	Routines to Build the Host Multicast Message - BMCFXD

;
;BMCFXD - Build fixed portion of the multicast message
;
;Call:	T1/ Incarnaction count flag
;	HN/ Host Node Data Base Address
;	XB/ Address of the multicast message block in HN
;	CALL BMCFXD
;
; This routine builds the first ^D12 bytes of the multicast message.  It is
; called either to build a new message or to update the fixed portion if any
; of the parameters in the fixed portion have changed since the last multicast
; message was transmitted.  This routine does not modify the message count.

BMCFXD:	STKVAR <INCFLG>		;Save the incarnaction
	MOVEM T1,INCFLG		; flag.
	MOVX T1,<POINT 8,<SBF.OF>(XB)> ;Byte pointer to start of msg
	STOR T1,UNBFA,+UNB.OF(XB); is needed to fill in the msg header
	MOVEI T1,MT.MCA_2	;Message type for multicast message
	OPSTRM <IDPB T1,>,UNBFA,+UNB.OF(XB)	
	MOVEI T1,^D8		;Set 80ms preferred server circuit timer
	OPSTRM <IDPB T1,>,UNBFA,+UNB.OF(XB)
	MOVEI T1,LALPV_^D8+LAHPV;Highest and lowest permitted protocol version
	CALL LAP2B0
	MOVEI T1,PROECO_^D8+PROVER ;Enter current protocol version and ECO
	CALL LAP2B0
	OPSTR <ILDB T1,>,UNBFA,+UNB.OF(XB);Get old incarnation count and assume
	AOS T1			; we just want to increment it.
	SKIPN INCFLG		;If this is initialization, we want a "random"
	IFSKP.			; incarnation count instead.
	  MOVEI T1,^D255	;Maximum value incarnation count can have.
	  CALL RANDOM		; the initial message incarnation count.
	ENDIF.
	OPSTRM <DPB T1,>,UNBFA,+UNB.OF(XB); and put back
	LOAD T1,HNCFL,(HN)	;Get the change flags
	OPSTRM <IDPB T1,>,UNBFA,+UNB.OF(XB)
	MOVEI T1,LMRFSI+^D14	;Receive buffer size (including E-net header)
	CALL LAP2B0
	LOAD T1,HNMTI,(HN)	;Get the multicast timer interval
	OPSTRM <IDPB T1,>,UNBFA,+UNB.OF(XB)
	MOVEI T1,0		;Set status indicating accepting new sessions.
	LOAD T2,HNLAS,(HN)	;Get the current LAT access state
	CAIE T2,LS.ON		;Is it on?
	MOVEI T1,1		;No, indicate not accepting new sessions.
	OPSTRM <IDPB T1,>,UNBFA,+UNB.OF(XB)
	RET

	SUBTTL	Routines to Build the Host Multicast Message - BMCFXD

;
;BMCACS - Enter Access Codes into the Multicast Message - BMCACS
;
;Call:	HN/ Host Node Data Base Address
;	XB/ Address of the multicast message block in HN
;	CALL BMCACS
;	Normal Return
;
; This routine builds ^D32 bytes of host access codes.  It is called either to
; build a new message or to update the fixed length access code field if any of
; the access codes have changed since the last multicast message was
; transmitted.  This routine does not modify the message count.

BMCACS:
	MOVX T1,<POINT 8,<SBF.OF+^D12/4>(XB)> ;ACs start at a fixed location
	STOR T1,UNBFA,+UNB.OF(XB);Store as byte pointer to message buffer
	LOAD T1,ACLNG,(HN)	;Count of the access code string
	MOVX T2,<POINT 8,AC.COD(HN)> ;Source string byte pointer
	CALL PTCST0		;Transfer the string to the message
	RET

	SUBTTL	Routines to Build the Host Multicast Message - BMCNID

;
;BMCNID - Enter Access Codes into the Multicast Message - BMCNID
;
;Call:	HN/ Host Node Data Base Address
;	XB/ Address of the multicast message block in HN
;	CALL BMCNID
;	Normal Return
;
; This routine enters the host node name and descriptor strings into the 
; multicast message block.  It is called either to build a new message or to
; update the fixed length access code field if the node name or descriptor 
; has changed since the last multicast message was transmitted.  If this
; routine is called, the rest of the multicast message must be rebuilt.  This
; routine does not modify the message count.

BMCNID:
	MOVX T1,<POINT 8,<SBF.OF+^D12/4+^D32/4>(XB),7> ;Node name starts here
	STOR T1,UNBFA,+UNB.OF(XB);Store as byte pointer to message buffer
	LOAD T1,HNNMC,(HN)	;Host name count
	MOVX T2,<POINT 7,HN.NAM(HN)> ;Source string byte pointer
	CALL PTCST0		;Transfer the host node name to m.c.msg
	LOAD T1,HNIDC,(HN)	;Count of host node description string
	MOVX T2,<POINT 7,HN.ID(HN)> ;Move the host node id string to the
	CALL PTCST0		; m.c. message
	RET

	SUBTTL	Routines to Build the Host Multicast Message - BMCSRV

;
;BMCSRV - Build the Available Host Services Data - BMCSRV
;
;Call:	HN/ Host Node Data Base Address
;	XB/ Address of the multicast message block in HN
;	CALL BMCSRV
;	Normal Return
;
; This routine enters all service blocks and the service classes into the
; multicast message block.  It is called either to build a new message or to
; update the message when any service name or description has changed since
; the last multicast message was transmitted.  This routine does modify the
; message count.

BMCSRV:	SAVEAC <W1,W2>
	MOVEI T4,^D12+^D33+1	;Initialize msg count
	MOVX T3,<POINT 8,<SBF.OF+^D12/4+^D32/4>(XB),7>;Get pointer to node name
	ILDB T1,T3		;Get node name count
	ADDI T4,1(T1)		;Include in total msg count
	ADJBP T1,T3		;Adjust to node descriptor
	ILDB T3,T1		;Get the node description count
	ADDI T4,1(T3)		;Include in total msg count
	ADJBP T3,T1		;Adjust pointer to start of Service Block
	STOR T4,UNBSZ,+UNB.OF(XB);Store msg count so far
	STOR T3,UNBFA,+UNB.OF(XB);Current message byte pointer
	LOAD W1,HNNSV,(HN)	;Get the total number of offered services
	OPSTRM <IDPB W1,>,UNBFA,+UNB.OF(XB);Already counted
	XMOVEI W2,HN.SRV(HN)	;Address of start of service blocks
SRVLP:	OPSTR <SKIPGE T1,>,GBRAT,(W2) ;Get the service rating
	CALL DYNRAT		;If negative, get the dynamic rating
	OPSTRM <AOS>,UNBSZ,+UNB.OF(XB);Account for rating in the byte count
	OPSTRM <IDPB T1,>,UNBFA,+UNB.OF(XB);Store in mc msg
	LOAD T1,GBNC,(W2)	;Get the service name count
	MOVX T2,<POINT 7,GB.NAM(W2)> ;Pointer to service name
	CALL PTCSTR		;Move name string to mc msg
	LOAD T1,GBLC,(W2)	;Get the service description count
	MOVX T2,<POINT 7,GB.HID(W2)>;Pointer to the service description string
	CALL PTCSTR		;Move to mc msg
	ADDI W2,GB.LEN		;Address of next block
	SOJN W1,SRVLP		;Loop through all services
	MOVEI T1,1_^D8+1	;Service class 1 only
	CALL LAP2BY
	RET

	SUBTTL	Routines to Build the Host Multicast Message - BMCRAT

;
;BMCRAT - Build the Available Host Services Data - BMCRAT
;
;Call:	HN/ Host Node Data Base Address
;	XB/ Address of the multicast message block in HN
;	CALL BMCRAT
;	Normal Return
;
; This routine enters all service blocks and the service classes into the
; multicast message block.  It is called either to build a new message or to
; update the message when any service name or description has changed since
; the last multicast message was transmitted.  This routine does modify the
; message count.

BMCRAT:	SAVEAC <W1,W2>
	MOVX T3,<POINT 8,<SBF.OF+^D12/4+^D32/4>(XB),7>;Get pointer to node name
	ILDB T1,T3		;Get node name count
	ADJBP T1,T3		;Adjust to node descriptor
	ILDB T3,T1		;Get the node description count
	ADJBP T3,T1		;Adjust pointer to start of Service Block
	ILDB W1,T3		;Get number of services from msg
	XMOVEI W2,HN.SRV(HN)	;Address of start of service blocks
RATLP:	OPSTR <SKIPGE T1,>,GBRAT,(W2) ;Get the service rating
	CALL DYNRAT		;If negative, get the dynamic rating
	IDPB T1,T3		;Store updated rating in mc msg
	LOAD T1,GBNC,(W2)	;Get the service name count
	OPSTR <ADD T1,>,GBLC,(W2);Add the service description count
	ADDI T1,2		;Account for the 2 count fields
	ADJBP T1,T3		;Adjust the pointer
	MOVE T3,T1		;Put adjusted pointer back where we want it
	ADDI W2,GB.LEN		;Address of next block
	SOJN W1,RATLP		;Loop through all services
	RET

	SUBTTL

;BLDSTM - Build the START Message Template
;
;Call:	HN/ Address of the Host Node Data Base
;	CALL BLDSTM
;	Normal Return
;
; This routine builds the "static" portions of the start message:  those
; fields which do not change very frequently. Fields which change frequently
; are set up by the transmitting routines.  This routine also sets up the
; message size in UNBSZ of the NISRV UN block.

BLDSTM:	SAVEAC <W1>
	XMOVEI XB,HN.SMT(HN)	;Address of START message template
	MOVX T1,<POINT 8,<SBF.OF+<SZ.MHD>/4>(XB)>;Point beyond the msg header
	STOR T1,UNBFA,+UNB.OF(XB); since it will change with each transmission.
	MOVEI W1,^D20		;Count of fixed fields (including count fields)
	MOVEI T1,LMRFSI+^D14	;Minimum receive buffer size
	CALL LAP2B0		;Store in msg
	MOVEI T1,PROECO_^D8+PROVER ;Enter current LAT protocol version
	CALL LAP2B0		; and ECO
	LOAD T1,HNMCO,(HN)	;System-wid maximum LAT connects allowed
	CAILE T1,MXSLTS		; compared to max slots per virtual circuit
	MOVEI T1,MXSLTS		;Get the smaller of the two
	CALL LAP2B0
	MOVEI T1,0		;Timers are non-zero when from server
	CALL LAP2B0		; only.
	LOAD T1,HNNUM,(HN)	;Get the host number
	CALL LAP2B0		; and store as 2 bytes in msg
	MOVEI T1,LHPRID		;LAT Host product ID is TOPS-20 Host
	CALL LAP2B0		; and store as 2 bytes in msg
	LOAD T1,HNNMC,(HN)	;Host Node Name count
	ADDI W1,1(T1)		;Add to the total message byte count
	MOVX T2,<POINT 7,HN.NAM(HN)>;Host node name source string
	CALL PTCST0		;Put into start message as NODE NAME
	LOAD T1,HNNMC,(HN)	;Host Node Name count
	ADDI W1,1(T1)		;Add to the total message byte count
	MOVX T2,<POINT 7,HN.NAM(HN)>;Host node name source string
	CALL PTCST0		;Put into start message as SYSTEM NAME
	LOAD T1,HNIDC,(HN)	;Count of description string
	ADDI W1,1(T1)		;Add to the total message byte count
	MOVX T2,<POINT 7,HN.ID(HN)>;Description string source pointer
	CALL PTCST0		;Put into start message
	MOVEI T1,0		;There are no parameters
	OPSTRM <IDPB T1,>,UNBFA,+UNB.OF(XB); is zero
	ADDI W1,1		;Include in total count
	CAIG W1,MINXBF		;Send at least the minimum 
	MOVEI W1,MINXBF		; size.
	STOR W1,UNBSZ,+UNB.OF(XB);Store message byte count
	STOR XB,UNRID,+UNB.OF(XB);Store buffer address for completion routines.
	RET

	ENDAV.

	SUBTTL	LAINTR - LAT DLL Callback Routinea

;LATCBR - dispatch to routine to handle DLL callback
;
;Call:	T1/ NU.RCV
;	T2/UN block address
;	CALL LATCBR
;	Normal return
;

LATCBR:	ACVAR <HN,XB,RB>	;Reserve some registers
	MOVE HN,LAHNDB		;Get the host node data base address
	MOVE T4,T3		;Save NISRV's error register
	CAIL T1,MINCBF		;Validate the callback function code
	CAIG T1,MAXCBF
	 CALLRET @CBRDSP-MINCBF(T1);Valid, call the proper routine
	BUG. (CHK,LATICB,LATSER,SOFT,<LATCBR called from NISRV with illegal callback function code>,<<T1,CODE>>,<
NISRV has called the LATSER callback routine with an invalid function code.
	>)
ILLCBR:	
	RET

	MIN. (MINCBF,<NU.XMT,NU.RCV,NU.RCI,NU.SCA,NU.RCC>) ;Minimum callback function
	MAX. (MAXCBF,<NU.XMT,NU.RCV,NU.RCI,NU.SCA,NU.RCC>) ;Maximum callback function

CBRDSP:	REPEAT <MAXCBF-MINCBF+1>,<
	IFIW	ILLCBR>			;Catch undefined call-back codes

	LHDSP. (CBRDSP,NU.XMT-MINCBF,LAINTX) ;Datagram transmit complete
	LHDSP. (CBRDSP,NU.RCV-MINCBF,LAINTR) ;Datagram received
	LHDSP. (CBRDSP,NU.RCI-MINCBF,LATLSC) ;Link state change
	LHDSP. (CBRDSP,NU.SCA-MINCBF,ILLCBR) ;Illegal callback, not used by LAT
	LHDSP. (CBRDSP,NU.RCC-MINCBF,ILLCBR) ;Illegal callback, not used by LAT

	SUBTTL	LAINTR - Interrupt Level Virtual Circuit Message Receiver

;LAINTR - Processes a circuit message at NI interrupt level
;
;Call:	T1/ NU.RCV
;	T2/UN block address
;	T4/NISRV's T3
;	CALL LAINTR
;	Normal return
;

LAINTR:	LOAD RB,UNRID,(T2)	;Get address of message block
	JUMPE T4,LANTR1	;If error code is 0 proceed
;
; Here, there was an error on receive.  Don't wait for tick time
;  to turn the buffer around.
;
	MOVE T1,RB		;Get address of receive buffer
	CALL RBPOSS		;Repost it now (preserving T1-T4)
	  JRST LANTR1		;Couldn't re-post. Process it later.
	RET			;Buffer re-posted. That's all we need to do.
LANTR1:	MOVEI T1,UN.LEN		;Length of the block to copy
	XMOVEI T3,UNB.OF(RB)	;Address of where to copy the UN block
	XBLT. T1		;Copy the UN block to buffer header
	MOVEI T1,NU.RCV		;Scheduler needs to know buffer type.
	MOVE T2,RB		;Address of element to put onto queue
	CALL LAINT0		;Do common actions
	RET			;And return to NISRV dismissing interrupt

	SUBTTL	LAINTX - Interrupt Level Virtual Circuit Message Receiver

;LAINTX - Processes a circuit message at NI interrupt level
;
;Call:	T1/ NU.XMT
;	T2/UN block address
;	T4/NISRV's T3
;	CALL LAINTX
;	Normal return
;

LAINTX:	LOAD XB,UNRID,(T2)	;Get the buffer address
	LOAD T3,UNDAD,+UNB.OF(XB);Get first 4 bytes (low order) of NI address
	TXNE T3,1B7		;Is the multicast bit on?
	RET			;Yes, nothing to do
	MOVX T3,<POINT 8,<SBF.OF>(XB)>;Point to the msg header
	ILDB T2,T3		; and get the message type
	LSH T2,-2		;Shift off M and RRF bits
	CAIE T2,MT.STA		;If a START message,
	IFSKP.			; then release lock on the START message
	  SETZRO HNCIP,(HN)	; template and return.
	  RET
	ENDIF.
	MOVE T2,XB
	CALL LAINT0		;Do common actions
	RET

; Routine to perform interrupt level actions common to both receive data and
; transmit complete.

LAINT0:	STOR T1,UNCBA,+UNB.OF(T2);Store callback type for scheduler processing
	STOR T4,UNSID,+UNB.OF(T2);Save NISRV's error return
	ETHLOK			;Interlock queue access
	OPSTR <SKIPN T3,>,HNNIQ,+1(HN);Is the Q currently empty?
	IFSKP.			;NO
	  STOR T2,UELW1,(T3)	;New forward for old Q tail element
	  SETZRO UELW1,(T2)	;New tail's forward link is zero.
	ELSE.			;YES
	  STOR T2,HNNIQ,(HN)	;New queue header forward pointer
	ENDIF.
	STOR T2,HNNIQ,+1(HN)	;New queue header tail pointer
	ETHULK			;Release interlock
	RET

	ENDAV.

	SUBTTL LARSCH - Scheduler Level Virtual Circuit Message Receiver

;LARSCH - Complete circuit message processing at scheduler level

LARSCH::
IFN FTOPS10,<
LATSTO::

IFN FTMP,<
	XCT .CPSK0		;SKIP IF WE'RE ON POLICY CPU
	RET			;NO, ONLY RUN ONCE A SECOND!
>
>; END FTOPS10
	SE1ENT
	ACVAR <HN,XB,RB,CB,SB,W1,W2>;Get a set of dedicated ACs
IFN FTOPS20,<
	TRVAR <MSGDID,MSGSID,MSGACK,STPCOD> ;Message header variable storage
>; END FTOPS20
	SKIPN HN,LAHNDB		;Get the host node database address
	RET			;If none, not initialized yet.
	CALL MOVNIQ		;Move all messages from NI to Scheduler queue
IFN FTOPS10,<
	SETZM LATWFB		;Say we don't want more buffers yet
>;end IFN FTOPS10
MSGNXT:	OPSTR <SKIPN T2,>,HNSCQ,(HN);Get first element on the scheduler Q
	CALLRET LAMUX		;No more so call the slot multiplexor
	OPSTR <SKIPN T3,>,UELW1,(T2);Get new head or queue if any
	STOR T3,HNSCQ,+1(HN)	;None, so clear the queue header tail pointer
	STOR T3,HNSCQ,(HN)	;Set new queue header forward pointer
	SETZRO UELW1,(T2)	;Clear link word
	LOAD T1,UNCBA,+UNB.OF(T2)	
	CAIE T1,NU.XMT		;Is this a transmit complete?
	IFSKP.			;Yes...
	  CALL XMTDON		;Go do scheduler level transmit done stuff
	  JRST MSGNXT		; and continue with next message
	ENDIF.
	MOVE RB,T2		;Message address obtained
	SKIPE T1,UN.SID+UNB.OF(RB);Was there an error?
	JRST MSGDON		;Re-post and ignore
	OPSTRM <AOS>,HCRCV,(HN)	;Increment count of received messages
	OPSTR <ILDB W1,>,UNBFA,+UNB.OF(RB);Get the message type from the buffer
	OPSTR <ILDB T1,>,UNBFA,+UNB.OF(RB);Get number of slots in message
	MOVEM T1,NSLOTS
	MOVX T1,-2		;Reduce the residual byte count by 2 for
	OPSTRM <ADDM T1,>,UNBSZ,+UNB.OF(RB); type and slots fields
	CALL LAG2BY		;Get the destination ID from msg (2 bytes)
	MOVEM T1,MSGDID
	CALL LAG2BY		;Get the source id from the msg
	MOVEM T1,MSGSID
	CALL LAG2BY		;Get the ACK/SEQ field from msg
	MOVEM T1,MSGACK
	MOVE T1,W1
	LSH T1,-2		;Shift off the M and RRF bits
	CAIL T1,MINMTY		;Range check message type
	CAILE T1,MAXMTY		;...
	IFNSK.
	  BUG. (INF,LATIMT,LATSER,SOFT,<LAT Illegal Message Type>,<<T1,MSGID>>,<

Cause:	LAT virtual circuit message received with message type out of range.

Action:

>)
	ELSE.
	  TRNN W1,2		;Test the Master/Slave bit
	  JRST MSGDON		;This a message from a host. 
	  CALL @MSGDSP-MINMTY(T1) ;Dispatch to process the message
	ENDIF.
MSGDON:	CALL RELRBF		;else ignore for now
	JRST MSGNXT


	MIN. (MINMTY,<MT.RUN,MT.STA,MT.STP>) ;Minimum message type code
	MAX. (MAXMTY,<MT.RUN,MT.STA,MT.STP>) ;Maximum message type code

MSGDSP:	BLOCK <MAXMTY-MINMTY+1>
	LHDSP. (MSGDSP,MT.RUN-MINMTY,HMRUN) ;RUN message received
	LHDSP. (MSGDSP,MT.STA-MINMTY,HMSTRT) ;START message received
	LHDSP. (MSGDSP,MT.STP-MINMTY,HMSTOP) ;STOP message received


;MOVNIQ - Move all messages on the NI queue to the Scheduler queue
;
;Call:	T1/ Pointer to head of NIQ 
;	T2/ Pointer to tail of NIQ
;	CALL MOVNIQ
;	Normal return
;
;Uses: T3,T4 

MOVNIQ:	
	ETHLOK			;No interruptions, please!
	DMOVE T1,HN.NIQ(HN)	;Get the header contents
	SETZM HN.NIQ(HN)	;Clear the queue begin pointer
	SETZM HN.NIQ+1(HN)	;Clear the end pointer
	ETHULK			;Ok, interrupt me now
	OPSTR <SKIPN T3,>,HNSCQ,+1(HN);Is there anything on the queue?
	IFSKP.			;YES
	  STOR T1,UELW1,(T3)	;Add new elements at the queue tail.
	ELSE.			;NO
	  STOR T1,HNSCQ,(HN)	;New queue header forward pointer
	ENDIF.
	STOR T2,HNSCQ,+1(HN)	;New queue header tail pointer.
	RET

	SUBTTL	LATLSC - Ethernet Link State Change Callback

;LATLSC - Process an asynchronous link state change
;
;Call:	T1/ NU.RCI
;	T2/UN block address
;	Normal return
;

LATLSC:	MOVX T3,HNRUN
	OPSTR <SKIPL>,UNSTA,(T2)	;Is NI running?
	IFSKP.
	  ANDCAM T3,HN.FLG(HN)	;NI is up
	  MOVEI T1,1		;So if multicast timer
	  SKIPLE LATMCT		; is running...
	  MOVEM T1,LATMCT	;  set it to ring soon.
	ELSE.
	IORM T3,HN.FLG(HN)	;NI went down.
	ENDIF.
	RET

	SUBTTL	Message Receiver - HMSTRT

;HMSTRT - Process a Received START Message
;
;Call:	RB/ Address of Message Block
;	CALL HMSTRT
;	 Error Return - error processing completed, message processing aborted.
;	Normal Return

HMSTRT:	TMNN HNCIP,(HN)		;If the START message template is locked
	SKIPN MSGSID		;or source's message handle is 0
	 RET			; ignore since server will persist.
	LOAD T1,HNLAS,(HN)	;If LAT access state is not ON, ignore the
	CAIE T1,LS.ON		; START message. 
	 RET			; ...
	LOAD T1,HNNAC,(HN)	;If the addition of this circuit brings total
	OPSTR <CAML T1,>,HNMAC,(HN); over the maximum number of active circuits
	 JSP T2,NOCRES		; then reject it.
	CALL HSTRCB		;Find the CB associated with this circuit.
	 RET			;None.  Error action already taken.
	LOAD T1,CBSTA,(CB)	;Get the current circuit state
	CAIE T1,CS.RUN		;If the state is running, 
	IFSKP.
	  CALL RELSBS		; release all current slots before continuing
	  CALL RFXBFS		;Release all buffers on free queue.
	  CALL MDLXBF		;Mark all buffers on ACK queue for later release
	ENDIF.
	CALL GETXBH		;Get the necessary number of transmit buffer
	 SKIPA			; headers (+MSD pointers)
	CALL GETRBF		;Go see if we need more receive buffers
	 JSP T2,NOCRES		;Could not get the necessary buffer quota
	CALL CBINIT		;Initialize all host CB parameters
	 RET			;START message format bad. Error action done.
	CALL MTTSTR		;Send a START message
	MOVEI T1,CS.STA		;Put the circuit into the
	STOR T1,CBSTA,(CB)	; STARTING state.
IFN FTOPS20,<	RET		; and return. >
IFN FTOPS10,<
	MOVEI T1,MAXXBF+1	;New circuit, add some buffers
	CAMLE T1,LATNFB		;Are there already enough free buffers?
	  ADDM T1,LATWFB	;No, ask for some more
	RET
>;END IFN FTOPS10
	SUBTTL 	HSTRCB

;HSTRCB - Find the circuit block for a received START msg on a LAT host.
;
;Call:	RB/ address of received message block
;	CALL HSTRCB
;	 Error Return - CB not found
;	Normal Return
;	CB/ Circuit Block address

HSTRCB:	XMOVEI T1,HN.QIC(HN)	;Search the inactive CB queue first
	CALL CMNIAD		;Look for NI address match
	 SKIPA			;Not found on the inactive CB queue
	JRST CBIFND		;Correct CB found on inactive CB queue
NFND1:	XMOVEI T1,HN.QAC(HN)	;Not on inactive Q, try active Q
	CALL CMNIAD		;Look for NI address match
	 SKIPA			;Not on active queue either
	JRST CBAFND		;Active CB has been found
NFND2:	LOAD T2,HNNAC,(HN)	;Get number of currently active CBs
	OPSTR <CAML T2,>,HNMXC,(HN) ;Compare with maximum allowed
	IFSKP.			;Not at maximum number of CBs allowed
	  MOVEI T1,CC.LST	;The number of words to get for a CB
	  CALL MMGTZW		;Go get them
	   JSP T2,NOCRES	;Failed
	  MOVE CB,T1		;This is the new CB address
	  MOVEI T1,CS.HLT	;Don't assume that the halted state
	  STOR T1,CBSTA,(CB)	; is zero.
	  OPSTRM <AOS>,HNNCC,(HN) ;Count number of allocated CBs 
	  JRST CBALNW		;Allocated new CB successfully
	ENDIF.
	OPSTR <SKIPN CB,>,QLBWD,+HN.QIC(HN);Check inactive Q for free CB
	JSP T2,NOCRES		;None, so can't reuse an inactive CB
CBIFND:	MOVE T2,CB		;(T1)Remove from inactive CB queue
	CALL LAUNQ
CBALNW:	CALL CBGNIX		;Get next assignable index for the CB
	XMOVEI T1,HN.QAC(HN)	;Put at the front of the active
	MOVE T2,CB		; CB
	CALL LAQUE		; queue
	OPSTRM <AOS>,HNNAC,(HN)	;New active circuit. Count it.
	SETONE CBSTA,(CB)	;Set state to non-HALTED since now active
	OPSTRM <AOS>,CCRCV,(CB)	;Increment per server count
	OPSTR <DMOVE T1,>,UNSAD,+UNB.OF(RB);Move the source NI address from
	OPSTRM <DMOVEM T1,>,CBDNI,(CB)  ; message to the CB
CBAFND:	RETSKP			;Return success

	SUBTTL	CBINIT - Circuit Block Initialization

;
;CBINIT - Initialize a Circuit Block from the Contents of a START Message
;
;Call:	CB/ Address of Circuit Block
;	RB/ Address of Message Block
;	CALL CBINIT
;	 Error Return - START Message content in error.
;	Normal Return

CBINIT:	MOVEI T1,MSTMSI		;Check to see if the message is at least
	OPSTR <CAMLE T1,>,UNBSZ,+UNB.OF(RB); the minimum size for a START msg
	JSP T2,ILLMESS		;No, too short.
	SETZM CLRBEG(CB)	;Clear the region which must be initialized
	MOVEI T1,<CLREND-CLRBEG>; to zero when a circuit block is 
	XMOVEI T2,CLRBEG(CB)	; re-used.
	XMOVEI T3,CLRBEG+1(CB)	; ...
	XBLT. T1		; ...
	MOVE T1,MSGSID		;Move source's circuit ID from message
	STOR T1,CBRID,(CB)	; to circuit block
	CALL LAG2BY		;Get the maximum transmit frame size which
	STOR T1,CBMTF,(CB) ; the remote will allow
	OPSTR <ILDB T1,>,UNBFA,+UNB.OF(RB);LAT protocol version used by remote
	CAIL T1,LALPV		;Check if in the range of version supported
	CAILE T1,LAHPV		; by this node
	JSP T2,LVSKEW		;Out of range, return error
	OPSTR <ILDB T2,>,UNBFA,+UNB.OF(RB);Remote's protocol ECO level
	LSH T2,^D9		;Shift protocol version
	IOR T1,T2		;OR version and ECO level
	STOR T1,CBRPV,(CB) ;	; and store as single unit
	OPSTR <ILDB T1,>,UNBFA,+UNB.OF(RB);Maximum number of slots in VC message
	STOR T1,CBMSL,(CB)	; permitted by remote
	OPSTR <ILDB T1,>,UNBFA,+UNB.OF(RB);Number of additional receive buffers
	STOR T1,CBNBF,(CB)	; queued by remote for this circuit
	OPSTR <ILDB T1,>,UNBFA,+UNB.OF(RB);Remote's circuit timer value
	STOR T1,CBCTI,(CB)	;
	OPSTR <ILDB T1,>,UNBFA,+UNB.OF(RB);Remote's keep-alive timer value
	STOR T1,CBKTI,(CB) 	;Which is in seconds.
	IMULI T1,JIFSEC##	;CONVERT TO Jiffies
	HRLZM T1,CB.KAF(CB)
	MOVX T1,-^D6		;Decrement residual message count by what we
	OPSTRM <ADDM T1,>,UNBSZ,+UNB.OF(RB); have read so far.
	CALL LAG2BY		;Get the "facility number"
	STOR T1,CBNUM,(CB)
	CALL LAG2BY		;Get the product type code
	STOR T1,CBPTC,(CB)
	CALL IGCSTR		;Skip the circuit name
	 JSP T2,ILLMES		;Illegally formatted message
	MOVEI T1,ML.SYS		;Maximum length of system's name string
	MOVX T2,<POINT 7,<CB.SNM>(CB)> ;Copy the name string
	CALL GTCSTR
	 JSP T2,ILLMES		;Illegally formatted message
	STOR T1,CBRSC,(CB) ;Save the length of the name string
	MOVEI T1,ML.LOC		;Maximum length of the system's location string
	MOVX T2,<POINT 7,<CB.LOC>(CB)>;Copy the location string
	CALL GTCSTR
	 JSP T2,ILLMES		;Illegally formatted message
	STOR T1,CBRLC,(CB) 	;Save the length of the location string
	RETSKP

	SUBTTL	CMNIAD - Find CB base on NI address

;CMNIAD - search the CBs on a CB queue looking for one which has the same
;	NI address as the source NI address in the incoming message.
;
;Call:	T1/ Queue header of CB queue to search
;	RB/ Address of the circuit message
;	CALL CMNIAD
;	 Not found return
;	Success return
;	T1/ unchanged
;	CB/ circuit block address if found, 0 otherwise

CMNIAD:	LOAD CB,QLFWD,(T1)	;Get the first queue entry
CMLOOP:	JUMPE CB,RTN		;Is this last entry?
	LOAD T3,CBDNI,(CB)	;First 4 bytes of remote NI address from CB
	LOAD T4,CBDNI,+1(CB)	;Last 2 bytes
	OPSTR <CAMN T3,>,UNSAD,+UNB.OF(RB);Compare with message destination adr
	OPSTR <CAME T4,>,UNSAD,+<UNB.OF+1>(RB) ;...
	IFNSK.
	  LOAD CB,QLFWD,+CB.LNK(CB); Get next forward CB
	  JRST CMLOOP		;Try again
	ENDIF.
	RETSKP			;Return success
		

;
;CBGNIX - Get the next assignable index for a CB
;
;Call:	CB/ address of circuit block
;	CALL CBGNIX
;	Normal Return
;
; This routine is called each time a CB is to be used for a new LAT
; virtual circuit.  The old index vector (CBVECT) pointer to the CB
; is deleted and a new index is generated.

CBGNIX:	MOVE W1,CBVECT		;Get the address of the CB index vector
	OPSTR <SKIPN T2,>,CBLID,(CB);Get the old circuit index, if any.
	IFSKP.
	  ADD T2,W1		;Get the address of the pointer to this CB
	  SETZM (T2)		; in the CB index vector and clear it.
	ENDIF.
	LOAD T2,HNNXI,(HN)	;Get the next available index to assign
	STOR T2,CBLID,(CB)	;Set the new index in the CB
	MOVE T1,W1		;Address of teh CB index vector
	ADD T1,T2		;Offset into this vector for new index
	MOVEM CB,(T1)		;Set the new pointer to point to new CB
CBGNX0:	AOS T2			;Increment the next available index
	AOS T1			; and the corresponding index vector pointer
	CAIG T2,CBMAXI		;Time to wrap around?
	IFSKP.			;Yes
	  MOVEI T2,1		;Always start at 1
	  XMOVEI T1,1(W1)	;and vector+1
	ENDIF.
	SKIPE (T1)		;Is this vector entry free?
	JRST CBGNX0		;No, try next
	STOR T2,HNNXI,(HN)	;Store new "next assignable index"	
	RET

	SUBTTL -- HMRUN -- 

;HMRUN - Process a Host RUN Message
;
;Call:	
;	CALL HMRUN
;	 Error return
;	Normal return

HMRUN:	CALL HRUNCB		;Get the circuit block address
	 RET			;None, error action already comleted
	SKIPE T2,MSGDID		;Destination and source circuit IDs from
	SKIPN T1,MSGSID		; the message may not be zero
	JSP T2,ILLMES		;If so, it is illegal
	LOAD T3,CBRID,(CB)	;Get the remote's circuit index from the CB
	LOAD T4,CBLID,(CB)	; and our circuit index from the CB must match
	CAMN T1,T3		; the source id and
	CAME T2,T4		; the destination id from the msg.
	JSP T2,INVRUN		;Invalid RUN msg, go terminate the circuit.
	HLLZS CB.KAF(CB)	;Clear the host keep-alive timer.
	MOVEI T1,CS.RUN		;Put in RUNNING state if not there already
	STOR T1,CBSTA,(CB)	;Store state in CB
	MOVE T1,MSGACK		;Get the SEQ/ACK number
	MOVE W1,T1		;
	ANDI T1,377		;Received message sequence number
	LSH W1,-^D8		;Last message ack'd by remote
	LOAD T3,CBRSQ,(CB)	;Previous recv SEQ number
	AOS T3			;Increment
	ANDI T3,377		;Modulo 256
	CAME T1,T3		;Is is the expected sequence number
	IFSKP.
	  STOR T1,CBRSQ,(CB)	;Update expected sequence number for next time
	ELSE.
	  SETZM NSLOTS		;No, ignore any slots in this message
	  OPSTRM <AOS>,HCSEQ,(HN);Increment Host's count
	  OPSTRM <AOS>,CCSEQ,(CB);Increment per-server count
	ENDIF.
	LOAD T3,CBLRA,(CB)	;Previous "last ACK from remote"
	STOR W1,CBLRA,(CB)	;New "last ACK from remote"
	CAMGE W1,T3		;Is new ACK less than old ACK?
	ADDI W1,^D256		;Yes, new ACK has wrapped around
	SUB W1,T3		;Number of messages ACK'd by this msg
	CAILE W1,MAXXBF		;Range check it and if out of range
	JSP T2,ILLMES		; treat as an illegal message
	SKIPN W1		;If anything got ACK'd
	IFSKP.
	  SETZRO CBRTC,(CB)	
	ENDIF.
NXTACK:	JUMPE W1,ACKDON		;No new messages ACK'd
	MOVE XB,CB.AKQ(CB)	;Get first buffer on ack queue
	CALL RELXBF		;Release buffer, since we got an ack
	XMOVEI T1,CB.AKQ(CB)	;Unqueue the now acknowledged buffers
	CALL UNQ1WF		; from the ACK wait queue
	  JSP T2,ILLMES	;Should not happen
	XMOVEI T1,CB.XBQ(CB)	;Queue  them back to the transmit buffer
	CALL QUE1WB		; queue.
	SOJA W1,NXTACK
ACKDON:	OPSTR <SKIPN>,CBAKQ,(CB);If all messages ack'd
	SETZRO CBTIM,(CB)	; clear the circuit timer.
	SETONE CBMRS,(CB)	;Indicate we must respond to this msg "soon"
	CALL LSDMUX		;Go process all slots in the RUN message
	  CALL MTTSTP		;Illegal slot, kill the circuit
	RET			;All slots processed, return.


	SUBTTL 	HSTRCB

;
;HRUNCB - Find the circuit block for a received RUN/STOP msg on a LAT host.
;
;Call:	RB/ address of received message block
;	CALL HRUNCB
;	 Error Return - CB not found
;	Normal Return
;	CB/ Circuit Block address
;

HRUNCB:	SKIPN CB,MSGDID		;Index to CB from received message
	JSP T2,ILLMS0		;Zero message destination index is illegal	
	CAIG CB,CBMAXI		;If CB index is greater than our max
	IFSKP.
	  SETZ	CB,		;it's also illegal, so flag no circuit
	  JSP	T2,ILLMS0	;and go send a stop message
	ENDIF.
	ADD CB,CBVECT		;Add address of vector of pointers to CBs
	SKIPN CB,(CB)		;The real circuit block address
	  JSP T2,INVRUN		;Circuit probably went away.
	OPSTR <DMOVE T3,>,CBDNI,(CB);All 6 bytes of remote NI address from CB
	OPSTR <CAMN T3,>,UNSAD,+UNB.OF(RB);Compare with message destination adr
	OPSTR <CAME T4,>,UNSAD,+<UNB.OF+1>(RB) ;...
	 SKIPA			;Not the right CB
	JRST HRNFND			;Found the CB	
	XMOVEI T1,HN.QAC(HN)	;Try searching the active Q
	CALL CMNIAD
	 SKIPA			;Not there either
	JRST HRNFND		;Found the CB
	XMOVEI T1,HN.QIC(HN)	;Try searching the inactive Q
	CALL CMNIAD
	 JSP T2,ILLMES		;Non-existent CB. Treat as illegal message.
HRNFND:	OPSTRM <AOS>,CCRCV,(CB)	;Increment per-server count
	RETSKP			;Found the CB


	SUBTTL -- HMSTOP -- 

HMSTOP:	CALL HRUNCB		;Get the CB for this STOPS message
	 RET			;None, error action already done
	SKIPE MSGSID		;Is the source ID in MSG non-zero?
	 JSP T2,ILLMES		;Yes, that's not legal
	LOAD T1,CBLID,(CB)	;Get our local ID for circuit. It must be
	LOAD T2,CBSTA,(CB)	;Current circuit state
	CAME T2,CS.HLT		;Is it halted or
	CAME T1,MSGDID		; an invalid STOP message?
	  RET			;Yes, just ignore it.
	CALLRET CBKILL		;Else, release all CB resources and
				; put on inactive Q

; Routines to terminate a circuit because of some error.  T1 contains
; the error to be entered into the STOP message.

ILLMES: OPSTRM <AOS>,CCIMR,(CB)	;Increment per-server count
ILLMS0:	OPSTRM <AOS>,HCIMR,(HN)	;Increment host count
	MOVEI T1,CE.ILL		;Illegally formatted message received
	JRST INFSTP		;Join common code to kill off circuit

LVSKEW:	MOVEI T1,CE.SKW		;Version skew between server and host,
	JRST INFSTP		; cannot support connection.

NOCRES: OPSTRM <AOS>,CCIMR,(CB)	;Increment per-server count
NOCRE0:	OPSTRM <AOS>,HCIMR,(HN)	;Increment host count
	MOVEI T1,CE.RES		;Insufficient resources to support new circuit.
	JRST INFSTP

XMTLIM: MOVEI T1,CE.LIM		;Retransmit limit exceeded. Server probably
	JRST INFSTP		; has gone away.

IDLHLT:	MOVEI T1,CE.NSL		;Circuit halted because there are no more slots
	JRST MTTSTP

LCLHLT: MOVEI T1,CE.HLT		;Circuit halted by local system. Either stopped
	JRST MTTSTP		; by operator or last slot has disconnected.

IFN FTOPS20,<
NIHALT:	MOVEI T1,CE.NIH		;NI halted
	SETZ T2,0		;PC meaningless
	JRST INFSTP
>; END IFN FTOPS20

INVRUN:	MOVEI T1,CE.INV		;Invalid message
	JRST INFSTP

INFSTP:	PUSH P,T2		;Save PC of error
	OPSTR <DMOVE T2,>,UNSAD,+UNB.OF(RB) ;Source NI address from recvd msg
	DMOVEM T2,LASBAD	;Save ethernet address of sender of bad msg
	POP P,T2		;Restore PC of caller for typeout
	BUG. (INF,LATNSC,LATSER,SOFT,<LAT Host node stopped circuit>,<<T1,CODE>,<T2,PC>,<LASBAD,EADDR1>,<LASBAD+1,EADDR2>>,<

Cause:	LAT Host node stopped the circuit.

Action: Look at the Reason Code in T1 and the PC in T2, and the
	Ethernet address in EADDR1 and EADDR2.  This error, if
	relatively infrequent is nothing to be concerned about.  If it occurs
	frequently, use the CODE and PC to determine further action.
>)
	JRST MTTSTP

	SUBTTL	Message Transmit Routines

;MTTSTR - transmit a START message
; 
;Call:	CALL MTTSTR
;	Normal Return
;
; This routine builds the START message header in the template from the host
; node data base and transmits it. It sets the interlock so that the template
; cannot be changed at process level by the LATOP% JSYS.  The message count
; is not changed since it is already correct (hence LAP2B0 is called instead of
; LAP2BY).  Cannot fail after this point since sending a STOP will clobber
; the START msg template.

MTTSTR:	SETONE HNCIP,(HN)	;Set interlock on the msg template
	XMOVEI XB,HN.SMT(HN)	;Address of start message template
	MOVX T1,<POINT 8,<SBF.OF>(XB)>;Set pointer to the message header
	STOR T1,UNBFA,+UNB.OF(XB); for BMSGHD.
	MOVEI T1,<MT.STA_2>	;Build a START
	CALL BMSGHD		; message header
	XMOVEI T1,<SBF.OF>(XB)	;Build the one word global
	TLO T1,(<OWGP. 8,0>)	; byte pointer.
	STOR T1,UNBFA,+UNB.OF(XB);
	OPSTR <DMOVE T1,>,CBDNI,(CB);
	OPSTRM <DMOVEM T1,>,UNDAD,+UNB.OF(XB);
	LOAD T1,HNPID,(HN)	;Get the Portal ID for NISRV
	STOR T1,UNPID,+UNB.OF(XB)
	MOVX T1,NU.XMT		;Go transmit but don't
	XMOVEI T2,UNB.OF(XB)	; use the usual routine
	CALL DLLUNI		; ...
	IFSKP.
	  OPSTRM <AOS>,HCXMT,(HN);Increment host count
	  OPSTRM <AOS>,CCXMT,(CB);Increment per-server count
	ELSE.
	  SETZRO HNCIP,(HN)	;Release the lock
	ENDIF.
	RET



;CBKILL - Kill a circuit by releasing all slots and buffers
;
;Call:	CB/ address of the circuit block
;	CALL CBKILL
;	Normal return

CBKILL:	CALL RELSBS		;Release all slots asssociated with this CB
	CALL RFXBFS		; Release all buffers on
	CALL MDLXBF		; free queue and mark all those in DLL
;	CALLRET CBDACT		;and move CB to the inactive queue

;CBDACT - Deactivate CB by moving to inactive queue
;
;Call:	CB/ address of the circuit block
;	CALL CBDACT
;	Normal return

CBDACT:	JUMPE CB,RTN		;If there is no CB, don't do the following
	SETZRO CBRID,(CB)	;Clear remote circuit index
	MOVEI T1,CS.HLT		;If the current circuit state is not halted
	OPSTR <CAMN T1,>,CBSTA,(CB); move CB from active to inactive queue
	RET			; otherwise CB is already on inactive queue
	STOR T1,CBSTA,(CB)	;Set the state to halted now
	XMOVEI T1,HN.QAC(HN)	;Remove 
	MOVE T2,CB		; the circuit block
	CALL LAUNQ		; from the active queue
	XMOVEI T1,HN.QIC(HN)	; and queue to 
	MOVE T2,CB		;Need the CB address again.
	CALL LAQUE		; the inactive queue
	OPSTRM <SOS>,HNNAC,(HN)	;Reduce the number of active circuits
	RET

;MDLXBF - Remove all buffers from ACK Wait queue, and mark them
;		for deletion at transmit complete.
;
;Call:	CB/ circuit block address
;	CALL MDLXBF
;	Normal return
;

MDLXBF:	SETZRO CBDLL,(CB)	;No buffers in DLL now
MDLXB1:	XMOVEI T1,CB.AKQ(CB)	;Address of the ACK wait queue
	CALL UNQ1WF		;Unqueue next buffer on Q
	 RET			;Done
	MOVEI T1,0		;Mark buffer for freeing at xmit done
	EXCH T1,UN.UID+UNB.OF(T2) ;and get current "DLL" flag
	JUMPL T1,MDLXB1		;If in DLL, it will be freed at XMTDON
	MOVE XB,T2		; else we have to free it now.
	CALL RELXBH
	JRST MDLXB1


;MTTSTP - transmit a STOP message ;
;Call:	T1/ stop reason code
;	XB/ address of transmit buffer
;	RB/ address of recieve buffer
;	CB/ address of circuit block (may be 0)
;	CALL MTTSTP
;	Normal return
;

MTTSTP:	MOVEM T1,STPCOD		;Save the stop reason.
	JUMPE CB,MTTSP0		;If there is not CB, just send stop msg.
	STOR T1,CBERR,(CB)	;Store reason for the stop in the CB
	LOAD T1,CBRID,(CB)	;Get the id to which to send the STOP
	SKIPE T1	;If it is 0, assume MSGSID already contains correct ID
			;This may prevent sending an illegal STOP with 0
			;in the destination ID field.
	MOVEM T1,MSGSID		; and put where we want it below
	CALL CBKILL		;Free all circuit resources.
;
;	Here to actually send a stop message
;	Always get a temp xmit buffer.
;	Then send the message with a 0 in UNUID so that
;	XMTDON will always just release the buffer.
;
MTTSP0:	SKIPGE HN.RUN(HN)	;If the NI is no longer running
	 RET			;We're done.
	MOVEI T1,SZMSTP		;There will be no buffers so get one
	CALL MMGTZW
	 RET			;Couldn't. Assume we did.
	MOVE XB,T1		;Transmit buffer for STOP message
	MOVX T1,<POINT 8,<XBF.OF>(XB)>;Byte pointer to start of msg
	STOR T1,UNBFA,+UNB.OF(XB);Store byte ptr to use building STOP msg
	MOVEI T1,MT.STP_2	;Message type (STOP) and number of slots (=0)
	CALL LAP2B0		; to message
	MOVE T1,MSGSID		;Get the source ID from the received message
	CALL LAP2B0		; and enter as destination ID to msg to send.
	MOVEI T1,0		;Get a 0 source ID
	CALL LAP2B0		; and enter into msg to send
	CALL LAP2B0		;Ack and sequence number must be zero also.
	MOVE T1,STPCOD		;Enter Disconnect reason and Reason text byte
	CALL LAP2B0		; (=0 since text field not used) to msg.
	XMOVEI T1,<XBF.OF>(XB)	;Set up 1 word global byte pointer
	TLO T1,(<OWGP. 8,0>)	; to the transmit data for NISRV
	STOR T1,UNBFA,+UNB.OF(XB); and store in UN block
	MOVEI T1,MINXBF		;Initialize to zero
	STOR T1,UNBSZ,+UNB.OF(XB); the message count
	CALLRET XMTMSN		;Go give the message to the DLL.
				; It will be freed at XMTDON


;MTTRUN - transmit a RUN message
;Call:	XB/ address of the transmit buffer
;	CALL MTTRUN
;	Normal return

MTTRUN:	JUMPE XB,RTN		;No message to transmit
	XMOVEI T1,CB.XBQ(CB)	;Unqueue the transmit buffer
	CALL UNQ1WF		; from the free Q
	 NOP
	SETZ T1,		;No flag set yet
	SKIPN CB.XBQ(CB)	;Is this our last transmit buffer?
	  MOVX T1,CBRRF		;Yes, set flag
	IORB T1,CB.RRF(CB)	;Stuff flag and get result
	MOVE CX,RTXTIM		;Value for circuit timer
	TXNE T1,CBRRF		;Is flag set for any reason?
	  STOR CX,CBTIM,(CB)	;Yes, start circuit timer ticking.
	XMOVEI T1,CB.AKQ(CB)	; and queue to the end
	CALL QUE1WB		; of the ACK queue
	LOAD T1,CBTSQ,(CB)	;Get the transmit sequence number
	AOJ T1,			; and increment it by one before
	ANDI T1,377		;Counter is only 8 bits
	STOR T1,CBTSQ,(CB)	; using it in the next transmitted msg.
	MOVX T1,<POINT 8,<XBF.OF>(XB)>;Set message pointer to point to
	STOR T1,UNBFA,+UNB.OF(XB); the RUN message header.
	MOVEI T1,MT.RUN_2	;Message type for the header.
	CALL BMSGHD		;Build the message header
	MOVEI T1,SZ.MHD		;Store the message header length
	SKIPN MD.NXT+MDB.OF(XB); which if there is no slot data
	MOVEI T1,MINXBF		; must be the minimum NI datagram size.
	STOR T1,MDBYT,+MDB.OF(XB); in the appropriate place
	SETZRO UNBSZ,+UNB.OF(XB);MBZ for MSD type transmits
	XMOVEI T1,<MDB.OF>(XB)	;Address of the first MSD block
	STOR T1,UNBFA,+UNB.OF(XB);stored where usually byte pointer goes.
	CALL XMTMSG		;No, go transmit a single buffer XB
	RET


;TMRCHK - Host circuit timer check routine.  This routine performs actions
; base on the state of the circuit timer.
;Call:	CB/ circuit block address
;Return:
;	RET - no further action required for this circuit
;	RESKSP - continue processing

TMRCHK:	OPSTR <SKIPN T1,>,CBTIM,(CB);Is the circuit timer running?
	RETSKP			;No, continue processing circuit
	SOSE T1			;Decrement the timer.
	IFSKP.			;Circuit timer has expired.
	  LOAD T1,HNRLI,(HN)	;Get the retransmit limit.
	  OPSTR <CAMG T1,>,CBRTC,(CB);Have we reached the limit?
	  IFSKP.		;No, so
	    CALL XUNAKQ		; and retransmit the unack queue
	    MOVE T1,RTXTIM	; Reset the timer
	    STOR T1,CBTIM,(CB)	; in the circuit block
	  ELSE.
	    JSP T2,XMTLIM	; otherwise, terminate the circuit
	  ENDIF.		; cause communication broken with remote.
	  RET
	ENDIF.
	STOR T1,CBTIM,(CB)	;Restore decremented timer to CB
	RETSKP
	

;XUNAKQ - Transmit all messages on the unacknowledged queue

XUNAKQ:	OPSTR <SKIPN>,CBDLL,(CB);Don't retransmit if already transmitting
	OPSTR <SKIPN XB,>,QLFWD,+CB.AKQ(CB) ;First msg to retransmit
	RET			;Should be
	OPSTRM <AOS>,HCRTR,(HN)	;Increment host count
	OPSTRM <AOS>,CCRTR,(CB)	; and per-server count
	OPSTRM <AOS>,CBRTC,(CB)	;Increment retransmit count
XMTALL:	OPSTRM <AOS>,CBDLL,(CB)	;Increment buffers in DLL
	MOVX T1,NU.XMT		;Transmit function
	XMOVEI T2,UNB.OF(XB)	;UN block
	CALL DLLUNI
	IFNSK.
	  OPSTRM <SOS>,CBDLL,(CB)
	ENDIF.
	SKIPE XB,UE.LW0(XB)	;Next XB on queue to (re)transmit
	JRST XMTALL		;Still more, continue to give buffers to DLL
	RET


; BMSGHD - Build a LAT Virtual Circuit Message Header

;Call:	T1/ <Message type>_2
;	XB/ Message buffer address
;	CB/ Address of the Circuit Block

BMSGHD:	MOVE T2,NSLOTS		;Number of slots in message
	LSH T2,^D8		;Shift to left byte position
	IOR T1,T2		;Or in message type (shifted)
	OPSTR <SKIPE>,CBRRF,(CB);If the Reply Request Flag is set
	IORI T1,1		; set it in message header
	CALL LAP2B0		;Enter as 1st 2 bytes of header
	LOAD T1,CBRID,(CB)	;Get the remote's circuit index
	CALL LAP2B0		; and enter as 2 byte field
	LOAD T1,CBLID,(CB)	;Get our circuit index
	CALL LAP2B0		; and enter as 2 byte field
	LOAD T1,CBRSQ,(CB)	;ACK number
	LSH T1,^D8		;Shift to left byte position
	LOAD T2,CBTSQ,(CB)	;Send Seq Number
	IOR T1,T2
	CALL LAP2B0
	RET	
	SUBTTL	Message Transmitter - XMTMSG

;
;XMTMSG - Transmit a LAT Message
;
;Call:	CB/ 0 or Circuit Block Address
;	XB/ Address of the UN block/Transmit Buffer
;	RB/ Address of Receive Buffer if XB/0
;	UNBSZ/ Message byte count
;	CALL XMTMSG
;	Normal Return
;
; This routine sets up the UN block for NISRV and issues the transmit
; function.  Only UNBSZ must be set by the caller.  If there is no CB,
; the information is taken from the receive buffer, otherwise from the
; circuit block.
;
;If there is no possibility of an ACK (such as sending a STOP message),
; then call XMTMSN, which will set UNUID to 0 so that the buffer will
; just be returned to free memory after NISRV has sent it.
;

XMTMSN:	TDZA T1,T1		;Enter here if you just want to free the buffer
				;  when transmit is done.
XMTMSG:	MOVE T1,CB
	TLO T1,DLL.FL		;set "buffer-in-DLL" flag
	STOR T1,UNUID,+UNB.OF(XB);Save the CB address for completion action
	JUMPE CB,XMNOCB		;Case with no assigned circuit block
	LOAD T1,HNPID,(HN)	;Portal ID
	OPSTR <DMOVE T2,>,CBDNI,(CB) ;Get destination NI adr from CB
	OPSTRM <AOS>,CBDLL,(CB) ;Increment # buffers in the DLL
	JRST XMTMS0		;Go do common code
XMNOCB:	LOAD T1,UNPID,+UNB.OF(RB);Get the portal ID
	OPSTR <DMOVE T2,>,UNSAD,+UNB.OF(RB) ;Source NI address from recvd msg
XMTMS0:	STOR T1,UNPID,+UNB.OF(XB);Store in xmit buffer
	OPSTRM <DMOVEM T2,>,UNDAD,+UNB.OF(XB) ; to the xmit buffer
	STOR XB,UNRID,+UNB.OF(XB);Remember the buffer address
	MOVEI T1,UNA.EV
	STOR T1,UNADS,+UNB.OF(XB);Tell NISRV we are using EXEC virtual memory
	MOVX T1,NU.XMT		;NI transmit function code
	XMOVEI T2,UNB.OF(XB)	;UN block address
	CALL DLLUNI
	 JRST XMTMS1		;Function failed, clean up
	OPSTRM <AOS>,HCXMT,(HN) ;Count total messages transmitted
	JUMPE CB,RTN		;and if there is a CB,
	OPSTRM <AOS>,CCXMT,(CB) ;count messages xmitted on that circuit
	RET
XMTMS1:	MOVSI T1,DLL.FL	;get "buffer-in-DLL" flag
	ANDCAB T1,UN.UID+UNB.OF(XB) ;clear it in message
	JUMPE T1,RELXBH	;If no CB for this one, just return buffer
 	OPSTRM <SOS>,CBDLL,(CB);Failed so put back count where is was
	RET

	SUBTTL	Message Transmitter - XMTDON

;XMTDON - Message Transmitter Transmit Done Scheduler Level Routine
;
;Call:	T1/ NU.XMT
;	T2/ UN block address
;	CALL XMTDON
;	Normal return
;
;  If the UNRID is zero, there is no longer a CB for this buffer because the
; circuit went away and we don't care what happens at transmit complete.  Just
; release the buffer.  If the CB state is stopping, complete the stopping of
; the circuit which could not be done earlier because all xmit buffers were in
; the DLL.

XMTDON:	SAVEAC <CB>
	MOVE XB,T2		;Move transmit buffer adr to conventional AC.
	MOVSI CB,DLL.FL		;Get "buffer-in-DLL" flag
	ANDCAB CB,UN.UID+UNB.OF(T2) ;Clear it and load result
	JUMPE CB,RELXBH	;If there is no CB, release buffer and header and return
	OPSTRM <SOS>,CBDLL,(CB)	;One less buffer in the DLL
	RET

	SUBTTL - Receive Message Handling Routines

;LAG2BY - obtains two bytes from the message which is assumed to be a 16-bit
; quantity.
;
;Call:	MA/ Message base address
;	CALL LAG2BY
;	Normal Return
;Changes T2
;	T1/ 16-bit quantity

LAG2BY:	MOVX T1,-2		;Amount to decrement the count by
	OPSTR <ADDM T1,>,UNBSZ,+UNB.OF(RB);Update message count
	OPSTR <ILDB T1,>,UNBFA,+UNB.OF(RB);Get low order byte
	OPSTR <ILDB T2,>,UNBFA,+UNB.OF(RB);Get high order byte
	LSH	T2,^D8		;Shift high order byte left
	IOR	T1,T2		;Make a 16-bit quantity
	RET			;Return with result

;GTCSTR - Move Counted String from a Message
;
;Call:	T1/ Maximum count to move
;	T2/ Destination byte pointer for string
;	RB/ Message base address
;Changes T1,T2,T3,T4

IGCSTR:	SETZ T1,		;Here to ignore a counted string
GTCSTR:	SAVEAC <W1,W2>		;Get two work registers
	OPSTR <SKIPN T3,>,UNBSZ,+UNB.OF(RB);Byte count left in message
	RET			;Return error. Message unexpectedly truncated
	OPSTR <ILDB W1,>,UNBFA,+UNB.OF(RB);Count of the counted string
	SUBI T3,1(W1)		;Calculate new residual message count
	JUMPL T3,RTN		;Message truncated
	STOR T3,UNBSZ,+UNB.OF(RB);Store back into message header
	SKIPE W1		;A null string?
	IFSKP.
	  MOVEI T1,0		;Yes, return zero count
	  RETSKP		; successfully
	ENDIF.
	MOVE T3,W1		;Copy of the actual string count
	CAMLE T3,T1		;Get the minimum of (actual string count,
	MOVE T3,T1		; maximum string count) for copy loop index
	MOVEM T3,T1		; and store as actual count copied
	LOAD T4,UNBFA,+UNB.OF(RB);Save initial value of byte pointer
	JUMPE T1,GTCDON		;Skipping over this field
GTCSLP: OPSTR <ILDB W2,>,UNBFA,+UNB.OF(RB);Fetch a source byte
	IDPB W2,T2		;Store as destination byte
	SOJN T3,GTCSLP		;Loop till all bytes copied
GTCDON:	ADJBP W1,T4		;Adjust byte pointer properly in case less than
	STOR W1,UNBFA,+UNB.OF(RB); the full string was copied
	RETSKP			;Return success, T1/ count of string fetched

	SUBTTL - Transmit Message Handling Routines

;LAP2BY - Put 2 bytes to message
;
;Call:	XB/ Address of the transmit buffer
;	T1/ 16-bit quantity to ouput
;	CALL LAP2BY or CALL LAP2B0
;	Normal return
;T1 perserved, T2 used
;
; This routine enters a 16-bit quantity as two bytes from T1 into the transmit
; buffer with the least significant entered first.  It assumes that UNBFA is
; set up with the proper byte pointer to the message buffer. The alternate
; entry LAP2B0 differs from LAP2BY in that LAP2B0 does not increment the
; message byte count whereas LAP2BY does.

LAP2BY:	MOVEI T2,2		;Amount to increment the message count by
	OPSTRM <ADDM T2,>,UNBSZ,+UNB.OF(XB);Update the count in message header
LAP2B0:	MOVE T2,T1		;In order to return T1 preserved.
	OPSTR <IDPB T2,>,UNBFA,+UNB.OF(XB);Low order byte entered first
	LSH T2,-^D8		;Shift hi byte into position
	OPSTR <IDPB T2,>,UNBFA,+UNB.OF(XB);High order byte goes to b buffer
	RET

;
;PTCSTR - put counted string to message buffer
;
;Call:	XB/ Address of the transmit buffer
;	T1/ Count to enter into buffer
;	T2/ Source string byte pointer

PTCSTR:	MOVEI T3,1(T1)		;Increment to include count byte
	OPSTRM <ADDM T3,>,UNBSZ,+UNB.OF(XB);Increment count in buffer
PTCST0:	OPSTR <IDPB T1,>,UNBFA,+UNB.OF(XB);Put the string count to buffer
	MOVE T3,T1		;Save copy of count for decrementing
PTCSTL:	JUMPE T3,RTN		;If count exhausted, done with copying
	ILDB T4,T2		;Get the next source string byte
	OPSTR <IDPB T4,>,UNBFA,+UNB.OF(XB);Put it to buffer
	SOJA T3,PTCSTL		;Continue til string count zero

;
;PTUSTR - put uncounted string to message buffer
;
;Call:	XB/ Address of the transmit buffer
;	T1/ Count to enter into buffer
;	T2/ Source string byte pointer

PTUSTR:	OPSTRM <ADDM T1,>,UNBSZ,+UNB.OF(XB);Increment count in buffer
	MOVE T3,T1		;Save copy of count for decrementing
PTUSTL:	JUMPE T3,RTN		;If count exhausted, done with copying
	ILDB T4,T2		;Get the next source string byte
	OPSTR <IDPB T4,>,UNBFA,+UNB.OF(XB);Put it to buffer
	SOJA T3,PTUSTL		;Continue til string count zero


;RBPOST - Return Receive Buffer to DLL
;
;Call:	T1/ Message block address
;	CALL RBPOST
;	Normal Return
;
;Call at RBPOSS if you need to preserve T1-T4

RBPOSS:	CALL SAVT##	;Preserve T1-T4
RBPOST:	MOVEI T2,LMRFSI		;Size of the buffer
	STOR T2,UNBSZ,+UNB.OF(T1);Store in UN block for NISRV
	XMOVEI T2,<SBF.OF>(T1) ;Set up 1 word global byte pointer
	TLO T2,(<OWGP. 8,0>)	; to the transmit data for NISRV
	STOR T1,UNRID,+UNB.OF(T1);Store the buffer address for callback
	STOR T2,UNBFA,+UNB.OF(T1); and store in UN block
	LOAD T2,HNPID,(HN)	;Get the Portal ID for NISRV
	STOR T2,UNPID,+UNB.OF(T1)
	MOVEI T2,UNA.EV
	STOR T2,UNADS,+UNB.OF(T1);Tell NISRV we are using EXEC virtual memory
	XMOVEI T2,UNB.OF(T1)	;UN block address
	MOVX T1,NU.RCV		;Post receive buffer function code
	CALLRET DLLUNI		;Do it and return +1 or +2 to caller

repeat 0,<
	IFNSK.
	  BUG. (CHK,LAPRBF,LATSER,SOFT,<Specify Receive Buffer Failure>,<<T1,DLLERC>>,<
LATSER received an error from NISRV while attempting to post a receive buffer>)
	  RET
	ENDIF.
	RETSKP
> ;end repeat 0


	SUBTTL	Slot Demultiplexor - LSDMUX

;
;LSDMUX - Process all slots in a received RUN message
;
;Call:	RB/ Address of RUN message
;	CALL LSDMUX
;	 Error return - illegal slot encountered
;	Normal return

	MIN. (MINSTY,<ST.DTA,ST.STA,ST.STP,ST.DTB,ST.ATT,ST.REJ>) ;Minimum slot type code
	MAX. (MAXSTY,<ST.DTA,ST.STA,ST.STP,ST.DTB,ST.ATT,ST.REJ>) ;Maximum slot type code

LSDMUX:	
IFN FTOPS20,<
	TRVAR <SLTDID,SLTSID,SLTCNT,SLTTYP,SLTEPT> ;Assign some variables on stack
>; END IFN FTOPS20
	SKIPN T1,NSLOTS		;Any slots left to process?
	RETSKP			;No, return successfully
NXTSLT:	OPSTR <ILDB T2,>,UNBFA,+UNB.OF(RB);Get the destination id
	MOVEM T2,SLTDID
	OPSTR <ILDB T2,>,UNBFA,+UNB.OF(RB);Get the source id
	MOVEM T2,SLTSID
	OPSTR <ILDB T2,>,UNBFA,+UNB.OF(RB);Get the slot count
	MOVEM T2,SLTCNT
	LOAD T3,UNBSZ,+UNB.OF(RB);Get the current message count
	AOS T1,T2		;Round up to nearest even number
	TRZ T1,1		;Since there may be 1 pad byte in slot
	SUBI T3,SLHDSZ(T1)	;Subtract the total slot size
	STOR T3,UNBSZ,+UNB.OF(RB);Store back in msg header as updated msg count
	JUMPL T3,ILLSLT		;Error if message has ended prematurely
	OPSTR <ILDB T2,>,UNBFA,+UNB.OF(RB);Get the slot type/credits/reason
	MOVEM T2,SLTTYP		;and save it
	ADJBP T1,UN.BFA+UNB.OF(RB) ;Point to next slot
	MOVEM T1,SLTEPT		;In case we need to skip later
	LSH T2,-4		;Shift off the credits field
	CAIL T2,MINSTY		;Range check slot type
	CAILE T2,MAXSTY
	CALLRET ILLSLT		;Slot ID out of range, illegal slot
	CALL @SLTDSP-MINSTY(T2)	;Dispatch to proper routine
	 JRST ILLSLT
	SOSG NSLOTS		;Indicate one less slot to process
	RETSKP			;Count went to zero, so done.
	MOVE T1,SLTEPT		;Get pointer to next slot's data
	MOVEM T1,UN.BFA+UNB.OF(RB) ;and force pointer to there
	JRST NXTSLT		;Still some left, go do next

SLTDSP:	REPEAT <MAXSTY-MINSTY+1>,<
	IFIW	ILLSLT>		;Catch undefined slot types

	LHDSP. (SLTDSP,ST.DTA-MINSTY,HSDATA)
	LHDSP. (SLTDSP,ST.DTB-MINSTY,HSDATB)
	LHDSP. (SLTDSP,ST.STA-MINSTY,HSSTRT)
	LHDSP. (SLTDSP,ST.ATT-MINSTY,IGNSLT)
	LHDSP. (SLTDSP,ST.REJ-MINSTY,ILLSLT)
	LHDSP. (SLTDSP,ST.STP-MINSTY,HSSTOP)

 	SUBTTL

;HSSTRT  Process a received START slot
;
;Call:
;	CALL HSSTRT
;	 Error Return - Terminate slot loop
;	Normal Return - Continue to next slot
;

HSSTRT:	SKIPE SLTSID		;Source ID 0 is illegal
	SKIPE SLTDID		;Destination ID of non-0 is illegal
	CALLRET ILLSLT		;Report an illegal slot received
	OPSTR <ILDB T2,>,UNBFA,+UNB.OF(RB);Get the service class requested
	CAIE T2,SCITTY		;Only interactive terminal class permitted
	CALLRET ILLSLT		;If not, slot is illegal.
	CALL SBALOC		;Allocate a slot block
	 RETSKP			;Ignore since server should persist and we
				; assume we should almost always get an SB
	OPSTR <ILDB T2,>,UNBFA,+UNB.OF(RB);Attention slot size maximum
	STOR T2,SBATS,(SB)
	OPSTR <ILDB T2,>,UNBFA,+UNB.OF(RB);Data slot size maximum
	STOR T2,SBMDS,(SB)
	MOVE T1,SLTCNT		;Get slot data count
	SUBI T1,3		;Account for the 3 bytes already read
	EXCH T1,UN.BSZ+UNB.OF(RB) ;Put it where it's useful for GTCSTR
	PUSH P,T1		;and save real message byte count
	MOVEI T1,ML.SNM		;Max length of service name
	MOVX T2,<POINT 7,<SB.SNM>(SB)> ;Point to slot name string
	CALL GTCSTR		;Get a counted string
	  SETZ T1,		;Ran out of message
	STOR T1,SBSNC,(SB)	;Store actual length of name
	CALL IGCSTR		;Ignore the subject service name
	  JRST HSSTR3		;No more data in message
;
; Now we are into the variable parameter part of a START SLOT
; Loop and record whatever fields we think are important.
;
HSSTR1:	SOSL T1,UN.BSZ+UNB.OF(RB)	;Count down bytes in slot
	ILDB T1,UN.BFA+UNB.OF(RB)	;Get Parameter number
	JUMPLE T1,HSSTR3	;Either ran out of bytes, or hit end of parms
	CAILE T1,SBPRMX		;Greater than max parm we know about?
	 SETZ T1,		;Yes, we will just ignore it.
	PUSHJ P,@SBPRTB(T1)	;Call routine to deal with parameter
	 JRST HSSTR3		;Ran out of message
	JRST HSSTR1		;Get next parameter from slot
HSSTR3:	POP P,T1		;Restore real message byte count
	EXCH T1,UN.BSZ+UNB.OF(RB) ;to its rightful place
	MOVEM T1,SLTCNT		;And put new remaining slot count where it goes

IFN FTOPS10,<
;First, check to see if remote TTYs can connect

	MOVE T1,STATES##	;Get system states word
	TRNE T1,ST.NRT		;Are remote TTYs allowed?
	 JRST SLSHUT		;Nope, reject the connection
> ;end IFN FTOPS10
	CALL GETTDB		;Get a terminal data block and start a job
	 JRST SLRESF		;No terminal data blocks available
	MOVX T1,SBSTR!SBFCC	;Flag this slot as waiting to send a START
	CALL SSBDAV		; and a DATA_B slot when MUX runs.
	RETSKP			;Return success

SLSHUT:	SKIPA T2,[SE.SHU]	;Reject reason is "Shut down"
SLRESF:	MOVEI T2,SE.RES		;Indicate insufficient resource as reject code
	STOR T2,SBREA,(SB)	; and save for later when REJ slot built
	MOVX T1,SBREJ		;Flag this slot as waiting to send
	CALL SSBDAV		; a REJECT slot when MUX runs
	RETSKP			;Return success
	SUBTTL	Process parameters from a received START slot
;
; Dispatch table of routines to deal with parameters from start slot
;
SBPRTB:	IFIW	IGCSTR		;Ignore ones we don't know about
	IFIW	IGCSTR		;Parameter 1
	IFIW	IGCSTR		;2
	IFIW	IGCSTR		;3
	IFIW	GETOPN		;OBJECT_PORT_NAME
	IFIW	GETSPN		;SUBJECT_PORT_NAME
SBPRMX=.-SBPRTB-1

GETOPN:	MOVE T2,[POINT 7,SB.OPN(SB)]	;Get object_port_name
	MOVEI T1,ML.PNM			;Set up max length of port name
	CALL GTCSTR			;Go get the string
	  TDZA T1,T1		;zero the count and give non-skip return
	AOS (P)			;PROPAGATE SKIP
	STOR T1,SBOPC,(SB)	;SAVE COUNT
	RET

GETSPN:	MOVE T2,[POINT 7,SB.SPN(SB)]	;Get Subject_port_name
	MOVEI T1,ML.PNM			;Set up max length of port name
	CALL GTCSTR			;Go get the string
	  TDZA T1,T1		;zero the count and give non-skip return
	AOS (P)			;PROPAGATE SKIP
	STOR T1,SBSPC,(SB)	;SAVE COUNT
	RET
	SUBTTL Slot Processing Routines - STOP Slots

;HSSTOP - Process a STOP Slot.
;
;Call:	SB/ Slot block address
;	CALL HSSTOP
;	 Error return - 
;	Normal return

HSSTOP:	SKIPN T2,SLTDID		;Destination ID cannot be zero
	CALLRET IGNSLT		;  but if it is zero, just ignore it.
	SKIPN SLTSID		;Source ID must be zero
	CAILE T2,NTTLAH		;Is the SBVECT index in range?
	CALLRET ILLSLT		;No. Slot is illegal
	MOVE T1,SBVECT		;Get the slot block address from
	ADD T1,T2		; the destination slot id
	SKIPE SB,(T1)		;If the SB address is zero
	OPSTR <CAME CB,>,SBCBA,(SB); or CB address has changed then
	JRST IGNSLT		; ignore the slot since already gone.
	CALL RELSB		;Release all slot resources	
	RETSKP			;Return success

	SUBTTL	Slot Processing Routines - DATA_A,DATA_B Slots

;HSDATA - Process a DATA_A Slot
;
;Call:  SB/ Slot block address
;	CALL HSDATA
;	 Error return - illegal slot
;	Normal return

HSDATA:	CALL HDRDAT		;Go process data slot header
	 RET			;Illegal slot, error return
	SKIPN W1,SLTCNT		;Get the number of characters in the slot
	RETSKP			;None, return
IFN FTOPS10,<
	LOAD U,SBTDB,(SB)	;Get line data block address
>;end IFN FTOPS10
IFN FTOPS20,<
	LOAD T2,SBTDB,(SB)	;Terminal dynamic data base
	DYNST			;Get the line number
>;end IFN FTOPS20
NXSLCH:
IFN FTOPS20,<
	OPSTR <ILDB T1,>,UNBFA,+UNB.OF(RB);Get a character.
	CALL TTCHI		;Call TTYSRV to enter into input buffer
	 TRN			;Ignore error
>;end IFN FTOPS20
IFN FTOPS10,<
	OPSTR <ILDB T3,>,UNBFA,+UNB.OF(RB);Get a character.
	CALL RECPTY		;Call SCNSER to enter into input buffer
>;end IFN FTOPS10
	SOJG W1,NXSLCH		;If still more, continue
	RETSKP			;Otherwise return success

HSDATB:				;Process received DATA_B slot (NOP)

HDRDAT:	SKIPE T2,SLTDID		;Destination ID cannot be zero
	CAILE T2,NTTLAH		; or greater than maximum slot index
	CALLRET ILLSLT		;Illegal slot
	MOVE T3,SLTSID		;Source ID from the slot
	MOVE T1,SBVECT		;Get the address of the SB
	ADD T1,T2		; based on the remote slot id from 
	SKIPN SB,(T1)		; the message 
	CALLRET IGNSLT		;No slot block.
	OPSTR <CAME T3,>,SBRID,(SB) ;Is slot source ID equal to SB remote ID?
	CALLRET IGNSLT		;No, ignore the slot
	LOAD T3,SBSTA,(SB)	;Get the slot state
	CAIN T3,SS.RUN		;If the slot state is not running or
	OPSTR <CAME CB,>,SBCBA,(SB) ; the circuit block address has changed
	CALLRET IGNSLT		; then slot disappeared already so ignore.
	MOVE T3,SLTTYP		;See if remote extended us any transmit
	ANDI T3,17		; credits. If so, add them to what we already
	OPSTRM <ADDM T3,>,SBXCR,(SB); have.
	SKIPN SLTCNT		;Do remote credit check only if there was
	RETSKP			; data in the slot.
	OPSTR <SOSGE T3,>,SBRCR,(SB) ;Decrement the receive credits
	JRST ILLSLT		;Illegal, server sent data with no credits	
	STOR T3,SBRCR,(SB)	;Store back updated credits count
	SKIPE T3		;If receive credits have gone to zero,
	IFSKP.			; then indicate we need to grant more credits
	  MOVX T1,SBOUT		; by setting setting data available
	  CALL SSBDAV		; for MUX when it runs next time.
	ENDIF.
	RETSKP

	SUBTTL	Slot Block Allocation and Deallocation Routines

;SBALOC - Slot Block Allocation Routine
;
;Call:	CB/ circuit block address
;	CALL SBALOC
;	 Error Return
;	Normal Return
;	SB/ Address of allocated slot block
;
; This routine allocates and initializes a new slot block.

SBALOC:	MOVEI T1,SB.LEN		;Number of words to allocate for a slot blk
	CALL MMGTZW		;Try to get them
	  RET			;Can't
	MOVE SB,T1		;Put address in proper AC
	MOVSI T4,-NSBWDS	;Look for a free slot block index
SBANXT:	SKIPE T1,NFRSBQ(T4)	; by examining the free slot block words
	JFFO T1,SBAGO		; for the first 1 bit.  This represents
	AOBJN T4,SBANXT		; the first free slot block index
	  RET			;No slot block available
SBAGO:	HRRZS T4		;Clear out left half
	MOVE T3,BITS(T2)	;Clear the bit since the index is
	ANDCAM T3,NFRSBQ(T4)	; no longer free
	IMULI T4,^D36		;Compute the slot block index
	ADDI T2,1(T4)		;Cannot be zero
	STOR T2,SBLID,(SB)	;Store in SB as local slot index
	MOVE T1,SBVECT		;Now store the address of the slot block
	ADD T1,T2		; in the vector of slot block address, which
	MOVEM SB,(T1)		; is indexed by slot block index
	XMOVEI T1,CB.SBQ(CB)	;Queue the SB to the circuit block's 
	MOVE T2,SB		; queue of slot blocks.
	CALL LAQUE		;
	MOVEI T1,CS.STA		;Set the slot state
	STOR T1,SBSTA,(SB)	; to starting.
	STOR CB,SBCBA,(SB)	;Store the circuit block address in SB
	MOVE T1,SLTSID		;Get the remote's slot id
	STOR T1,SBRID,(SB)	;Store as our remote id
	MOVE T1,SLTTYP		;Get the Slot type/credits from recv's slot
	ANDI T1,17		;Keep only the number of credits extended to us
	STOR T1,SBXCR,(SB)	;Store is slot block as our transmit credits
	MOVEI T1,MAXCRE		;Maximum credits to extend to remote
	STOR T1,SBRCR,(SB)	; to current number of remote credits
	OPSTRM <AOS>,HNCON,(HN)	;Count one more active connect
	RETSKP			;Return successfully


;SSBDAV - Set Slot BLock Data Available
;
;Call:	T1/ Bit to set in SB.FLG
;	SB/ Slot block address
;	CALL SSBDAV
;	Normal Return

SSBDAV:	SKIPGE T2,SB.FLG(SB)	;Is there already data available?
	IFSKP.			;No, so set it now
	  OPSTRM <AOS>,CBSDC,(CB);Increment number of slots waiting
	  TLO T2,400000		; and indicate this slot now waiting	 
	ENDIF.
	IOR T2,T1		;OR in new reason for waiting
	MOVEM T2,SB.FLG(SB)	; and store back
	RET			;Return

;CSBDAV - Clear Slot BLock Data Available
;
;Call:	T1/ Bit to clear in SB.FLG
;	SB/ Slot block address
;	CALL SSBDAV
;	Normal Return

CSBDAV:	SKIPL T2,SB.FLG(SB)	;Is "data available" already clear?
	RET			;Yes
	ANDCM T2,T1		;Clear the desired bit
	TLNE T2,377777		;Are all bits off now?
	IFSKP.
	  OPSTRM <SOS>,CBSDC,(CB)
	  MOVEI T2,0
	ENDIF.
	HLLM T2,SB.FLG(SB)
	RET


;RELSBS - Release all Slot Blocks and their Resources for a virtual circuit
;
;Call:	CB/ Address of the circuit block
;	CALL RELSBS
;	Normal Return
;

RELSBS:	JUMPE CB,RTN		;No slots to release if no circuit block
	OPSTR <SKIPN SB,>,QLFWD,+CB.SBQ(CB);Get the address of first SB on Q
	RET			;If zero, there are no more on the queue
	CALL RELSB		;Release the slot block
	JRST RELSBS		;Go do the next
	RET

;RELSB - Release a Slot Block and its Resources
;
;Call:	CB/ Address of the circuit block for slot
;	SB/ Address of the slot block to release
;	CALL RELSB
;	Normal Return
;	SB/ address of previous slot or listhead

RELSB:
IFN FTOPS20,<	OPSTR <SKIPN T2,>,SBTDB,(SB) ;Is there a terminal data base
	JRST RELSB0		;No, go just release the SB resources
	SETZM TTDEV(T2)		;Clear the slot block address in the TDB.
	SETZRO TTPRM,(T2)	;TDB no longer permanent
	DYNST			;Get the static line number
	CALL NTYCOF		;Go detach the job
	LOAD T2,SBTDB,(SB)	;Get the TDB address again.
	LOAD T1,TCJOB,(T2)	;If there is a controlling job, don't release
	CAIE T1,-1		; the TDB since this will be done
	JRST RELSB0		; later by JOBCOF.
	DYNST			;No controlling job so we must release the
	CALL TTYDE0		; the dynamic data base here.
	  TRN			;TTYSRV already reports this.
>;end IFN FTOPS20
IFN FTOPS10,<
	OPSTR <SKIPN U,>,SBTDB,(SB) ;Is there a terminal data base
	JRST RELSB0		;No, go just release the SB resources
	PUSH P,J			;NGVLDB blows J (our W2)
	CALL NGVLDB		;Give the LDB back to SCNSER
	POP P,J				;Get our AC back
>;end IFN FTOPS10
RELSB0:	OPSTR <XMOVEI T1,>,CBSBQ,(CB) ;Point to the CB SBQ header
	MOVE T2,SB		; and 
	CALL LAUNQ		; release the SB from this queue
	SKIPL SB.FLG(SB)	;Did this SB have any data waiting?
	IFSKP.			;Yes
	  OPSTRM <SOS>,CBSDC,(CB) ;Reduce number of slots with data waiting
	ENDIF.
	CALL RLSBID		;Release the SB local id.
	MOVE T1,SB
	OPSTR <SKIPN SB,>,QLBWD,(SB);Set up so the slot mux gets the correct
	XMOVEI SB,CB.SBQ(CB)	; next slot.
	CALL MMFREE		;Free the memory
	OPSTRM <SOS>,HNCON,(HN)	;One less connected session
	RET
;RLSBID - Release a Slot Block's local id.
;
;Call:	SB/ Address of the SB
;	CALL RLSBID
;	Normal Return
;

RLSBID:	OPSTR <SKIPN T1,>,SBLID,(SB);Get the SB local index
	RET			;Already zero. Nothing to do.
	MOVE T2,SBVECT		;Clear the pointer to SB
	ADD T2,T1		; in the vector of SB addresses
	SETZM (T2)		; ...
	SOS T1			;Normalize to zero
	IDIVI T1,^D36		;Now clear the bit to indicate that the
	MOVE T3,BITS(T2)	; slot block index is now free
	IORM T3,NFRSBQ(T1)	; ...
	SETZ T1,		;Clear the local
	STOR T1,SBLID,(SB)	; SB ID.
	RET

;GETTDB - get terminal dynamic data base
;
;Call:	SB/ slot block address
;	CALL GETTDB
;	 Error return
;	Normal return
;	


GETTDB:
IFN FTOPS20,<
	SAVEAC <W1,W2>
	MOVE W1,TT1LIN+TT.LAH
GTTDB0:	LOAD T1,TTSTY,(W1)	;Get the line type
	CAIE T1,TT.LAH
	 RET
	MOVE T2,W1
	CALL STADYN
	 JUMPE T2,GTTDB2
GTTDB1:	AOJA W1,GTTDB0		;Try next line
GTTDB2:	MOVE T2,W1
	CALL TTYASC
	 JRST GTTDB1
	CALL STADYN
	 JRST GTTDB1
	STOR T2,SBTDB,(SB)
	MOVEM SB,TTDEV(T2)
	SETONE TCJOB,(T2)
	SETONE TTPRM,(T2)
	MOVEI T1,.CHCNC
	MOVE T2,W1
	CALL TTCHI
	  NOP
	RETSKP
>;end IFN FTOPS20

IFN FTOPS10,<

; Get a remote LDB and make it mine
;
;
; Return:
;	RET			;FAILED
;	RETSKP			;SUCCESS
;

	SAVEAC <W>		;SCNSER/NETSER WILL USE THIS

;Allocate an LDB

	MOVSI T1,LTLLAT		;FLAG A NEW LAT TERMINAL
	MOVEI T3,LATDSP		;LAT'S ISR DISPATCH TABLE
	CALL GETLDB		;GET A REMOTE TTY LDB, POINTER IN U
	 RET			;GO ANNOUNCE THE FAILURE

;Finish making this a LAT LDB

	MOVEI T1,LATRTQ		;GET POINTER TO OUTPUT Q HEADER
	HRLZM T1,LDBQUH(U)	;STORE FOR SCNSER (TOPOKE/TOTAKE)
	STOR U,SBTDB,(SB)	;REMEMBER OUR LDB
	MOVEM SB,LDBLAT(U)	;STORE SB PTR IN LDB TOO
	MOVEI T1,APCLAT		;GET LATSER CODE
	DPB T1,LDPAPC		;SET ASYNC PORT CHARACTERISTIC
	MOVEI T1,M.LIDL		;GET MAX. IDLE TIME FOR LAT LINES
	CALL SCNADT		;SET THE TIMER GOING
	LDB T1,LDPXNF		;Find out our XON/XOF setting
	STOR T1,SBXNF,(SB)	;And make LAT's setting agree (we will also
				;send a DATA_B slot to inform LATbox).

;Initialize the TTY with .HELLO force command

	CALL TTFGRT		;GO FORCE .HELLO/.RESTART
	RETSKP 			;SUCCESS RETURN
	SUBTTL Subroutines -- NGVLDB - Give an LDB back to SCNSER

;NGVLDB - Give an LDB back to SCNSER
;
; Call:	U/ Pointer to LDB
;
; Return:
;	RET			;ALWAYS

NGVLDB:	SETZM	LDBLAT(U)	;CLEAR OUT BY-NOW-STALE POINTER
	MOVEI	T1,IONND%	;"NODE DOWN" (PATH LOST/ETC) ERROR
	CALL	DETLDB		;DETACH THE LDB/DDB
	CALLRET	FRELDB		;RETURN LDB TO SCNSER FREE POOL
>;end IFN FTOPS10
	SUBTTL	Slot Multiplexor - Main Loop

;LAMUX Slot Multiplexor Main Loop
;
;Call:	CALL LAMUX
;	Normal return
;

LAMUX:
IFN FTOPS10,<
	CALL LATSCN		;Scan active LDBs
>;end IFN FTOPS10
	LOAD CB,QLFWD,+HN.QAC(HN) ;Get the first CB on the active queue
LANXCB:
IFN FTOPS20,<	JUMPE CB,RTN		;All CBs processed, return>
IFN FTOPS10,<	JUMPE CB,CHKWFB	;All CBs processed, check if we need buffers>
IFN FTOPS20,<
	SKIPL HN.RUN(HN)		;Is the NI still running?
	IFSKP.
	  CALL NIHALT		;No, so deallocate all resources
	  JRST MXNXCB
	ENDIF.
> ;END IFN FTOPS20
	SETZM NSLOTS		;Initialize number of slots in this msg
	LOAD T1,CBSTA,(CB)	;Consider only those circuits which are
	CAIE T1,CS.RUN		; in the running state
	JRST MXNXCB		; ...
	OPSTR <SKIPN>,CBSBQ,(CB);If there are no slots for this circuit or
	  JRST [CALL IDLHLT
		JRST MXNXCB]	;Kill it and look at next one.
	LOAD T1,HNLAS,(HN)	;Get the current access state.
	CAIN T1,LS.OFF		;If the access state is now off,
	  JRST MXNXC2		;  kill this circuit and look at next.
	SETZRO CBRRF,(CB)	;No RRF set yet
	CALL TMRCHK		;Check for circuit timer related functions.
	 JRST MXNXCB		;Continue with next circuit.
	TMNN CBMRN,(CB)		;Must we go balanced (reply to server) now?
	JRST LMNMRN		;No

; We have received a message from the server and must respond message now.  If
; there is a free transmit buffer and there is slot data waiting to be sent,
; then build the slots in a large MSD transmit buffer and send it.  If the MSD
; buffer is not available or there is no slot data waiting, just send a RUN
; message header.  If there are no free transmit buffers, retransmit the queue
; of unacknowledged messages.

	MOVX T1,CBMRS!CBMRN!CBRRF;Clear all flags
	ANDCAM T1,CB.FLG(CB)	; since we will reply now.
	SETZRO CBCSB,(CB)	;Clear count since balanced
	SKIPN XB,CB.XBQ(CB)	;Is there a transmit buffer header free?
	JRST LMNOXB		;No, go transmit unACK'd Q
	OPSTR <SKIPE >,CBSDC,(CB);There is a buffer, is there data waiting?	
	CALL BLDMSL		;Everything there so build slots in buffer
	  NOP			;No slots, but don't care
	CALL MTTRUN		;Transmit either hdr only or full message
	JRST MXNXCB		;Go to next circuit block
LMNOXB:	CALL XUNAKQ		;Transmit all messages on the unack'd Q
	JRST MXNXCB

; Check to see if we just received a message from the server.  If so,
; flag to force a reply at the next sheduler cycle.  We wait one cycle in
; case user programs are controlling echoing in the hopes that response
; will be smoother.

LMNMRN:	TMNN CBMRS,(CB)		;Must reply soon?
	JRST LMUNSL
	SETONE CBMRN,(CB)	;Yes, set to force reply on next cycle	
	JRST MXNXCB


; We are in balanced mode, i.e. the response to the latest server message
; has already been sent.  Check here to see if we ought to send an unsolicited
; message.  We are allowed one.  We wait at least MXBALC scheduler cycles since
; last going balanced.  If after that period there is slot data waiting, we
; send an unsolicited message to the server.
; If we have not data to send, wait another MXBALC cycles before trying again.

LMUNSL:	LOAD T1,CBCSB,(CB)	;Number of cycles to wait before sending
	CAIL T1,MXBALC		;Have we waited long enough?
	IFSKP.			;No, so
	  AOJ T1,		; increment the count
	  STOR T1,CBCSB,(CB)	; and wait
	  JRST MXNXCB		; some more.
	ENDIF.

; We have waited long enough. If there is slot data waiting and resouces
; available, send an unsolicited message to the server

	SKIPN XB,CB.XBQ(CB)	;Is there a transmit buffer header free?
	JRST MXNXCB		;No, so don't send anything
	SETZRO CBCSB,(CB)	;We might send data, reset the ticker.
	OPSTR <SKIPE >,CBSDC,(CB);Is there slot data waiting?
	CALL BLDMSL		;Build a message full of slots
	  JRST MXNXC1		; If no slots, do keep-alive timing.
	CALL MTTRUN		;There are slots in the message so send it.
MXNXCB:	LOAD CB,QLFWD,(CB)	;Index of the next CB on active queue
	JRST LANXCB		;Continue looping
	RET
;
; We don't have any unsolicited data to send, check if we have heard
; from the server within the last few SERVER_KEEP_ALIVE_TIMER seconds.
; If not, we will assume the server died, and we will kill the circuit.

MXNXC1:	AOS T1,CB.KAF(CB)	;Count keep-alive timer
	HLRZ T2,T1		;Get limit value of timer
	HRRZS T1		; and isolate timer part
	CAML T1,T2		;Have we hit limit yet?
MXNXC2:	CALL LCLHLT		;Yes, we have not heard from the server
	JRST MXNXCB		;in a long time, so kill the circuit.

	SUBTTL 
;BLDMSL - Build RUN Message Slots
;
;Call:	CB/ Address of Circuit Block
;	CALL BLDMSL
;	Normal return
;
; This routine scans through all slots associated with a LAT virtual circuit
; and builds RUN message slots for those which have data waiting to be sent 
; to the remote node.  SBFLGS contains a bits mask which indicates which
; type of slot must be built for the slot block. More than one bit may be set.

BLDMSL:	OPSTR <SKIPN SB,>,QLFWD,+CB.SBQ(CB);Get addr of first slot for this CB
	RET			;There are none
	SETZRO UNBSZ,+UNB.OF(XB); and message count
	SETZM MD.NXT+MDB.OF(XB)		;No transmit buffer yet.
BLSLOP:	SKIPL W1,SB.FLG(SB)	;Does this slot have data waiting?
	JRST MXNXSL		;No, loop to next slot
	HLLZS W1		;Clear all but flags
	TLZ W1,400000
BLNXSL:	JFFO W1,BLSDSP		;Find first flags bit which is lit.
MXNXSL:	OPSTR<SKIPE SB,>,QLFWD,(SB);Get next slot's index and
	JRST BLSLOP		; continue with the next slot
BLSLCP:	SKIPN NSLOTS		;Check to see if any slots entered at all
	RET			;None.

;If we couldn't get through all slots, rotate this circuit's slot queue so
;that we resume next time with the slot we did not complete this time.

	SKIPN SB		;Did we get through the whole queue?
	IFSKP.			;NO
	  OPSTR <CAMN SB,>,QLFWD,+CB.SBQ(CB);Is slot already at the Q head?
	  IFSKP.		;NO
	    LOAD T3,QLFWD,+CB.SBQ(CB);Get old queue head
	    LOAD T4,QLBWD,+CB.SBQ(CB);Get old queue tail
	    STOR T3,QLFWD,(T4)	;Joint them together
	    STOR T4,QLBWD,(T3)	; ...
	    LOAD T3,QLBWD,(SB)	;Get new Q tail from new Q head
	    SETZRO QLFWD,(T3)	;Clear new tail's forward ptr
	    SETZRO QLBWD,(SB)	;Clear new head's backward ptr
	    STOR SB,QLFWD,+CB.SBQ(CB);New head
	    STOR T3,QLBWD,+CB.SBQ(CB);New tail
	  ENDIF.
	ENDIF.

;Compute final byte count padding to minimum NI datagram size if necessary.

	LOAD T1,UNBSZ,+UNB.OF(XB);Store the larger of the final real message
	CAIG T1,MINXBF-MMHDSI	; count and the minimum count as the message
	MOVEI T1,MINXBF-MMHDSI	; count.
	MOVE T3,MD.NXT+MDB.OF(XB)		;Get MSD address
	STOR T1,MDBYT,(T3)	;and store count in MSD
	RETSKP


; Check first to see if adding a new slot causes the number of slots in a
; message to exceed the maximum permitted by remote.

BLSDSP:	LOAD T3,CBMSL,(CB)	;Get the maximum permitted by remote
	CAMG T3,NSLOTS		; and compare with number of slots so far.
	JRST BLSLCP		;At maximum, stop processing this circuit.

; Check to see if there is enough room remaining in the transmit buffer to
; include this slot.

	HLRZ T1,SLLNTB-1(W2)	;Minimum bytes required for this slot type.
	LOAD T3,UNBSZ,+UNB.OF(XB);Current number of bytes in the buffer.
	ADD T1,T3		;Count if we include this new slot.
	CAILE T1,SZ.XBF		;Compare with total transmit buffer capacity.
	JRST BLSLCP		;Will not fit so stop processing this circuit.

; Call the routine to build the slot.  It may or may not be entered into the
; message. At this point however it is always marked as having been processed.

	MOVE T1,BITS(W2)	;Get the mask for the bit
	ANDCM W1,T1		;Indicate that this slot has been processed.
	CALL @SLBDSP-1(W2)	;Build the slot.
	  JRST BLNXSL		;Slot not entered. Try next.

; Slot successfully entered into the transmit buffer. Update the buffer counts.
; Terminal character count has already been added.

	HRRZ T1,SLLNTB-1(W2)	;Get the count for the slot header.	
	OPSTR <ADD T1,>,UNBSZ,+UNB.OF(XB);Get the message count so far
	TRNN T1,1		;Is the count even?
	IFSKP.			;No, must pad to even number
	  OPSTR <IDPB T1,>,UNBFA,+UNB.OF(XB);Put fill byte into message
	  AOS T1		;Increment total in message
	ENDIF.
	STOR T1,UNBSZ,+UNB.OF(XB);
	AOS NSLOTS		;Increment number of slots in the message.
	JRST BLNXSL		;Get next slot request.

	MIN. (MINSFL,<^L<SBREJ>,^L<SBSTR>,^L<SBSTO>,^L<SBOUT>,^L<SBFOU>,^L<SBFCC>>)
	MAX. (MAXSFL,<^L<SBREJ>,^L<SBSTR>,^L<SBSTO>,^L<SBOUT>,^L<SBFOU>,^L<SBFCC>>)


SLBDSP:	BLOCK <MAXSFL-MINSFL+1>
SLLNTB:	BLOCK <MAXSFL-MINSFL+1>
	LSLDT. (SLBDSP,SLLNTB,^L<SBREJ>-1,XSLREJ,<SZ.SHD+SZ.REJ>,<SZ.SHD+SZ.REJ>)
	LSLDT. (SLBDSP,SLLNTB,^L<SBSTR>-1,XSLSTA,<SZ.SHD+SZ.SST>,<SZ.SHD+SZ.SST>)
	LSLDT. (SLBDSP,SLLNTB,^L<SBSTO>-1,XSLSTP,<SZ.SHD+SZ.SSP>,<SZ.SHD+SZ.SSP>)
	LSLDT. (SLBDSP,SLLNTB,^L<SBOUT>-1,XSLDTA,<SZ.SHD>,<SZ.SHD>)
	LSLDT. (SLBDSP,SLLNTB,^L<SBFOU>-1,XSLATT,<SZ.SHD+SZ.ATT>,<SZ.SHD+SZ.ATT>)
	LSLDT. (SLBDSP,SLLNTB,^L<SBFCC>-1,XSLDTB,<SZ.SHD+SZ.SDB>,<SZ.SHD+SZ.SDB>)

	SUBTTL	Slot Formatting Routines

;XSLSTA - Format a START Slot in the Transmit Buffer
;
;Call:	SB/ Slot Block Address
;	CB/ Circuit Block Address
;	XB/ Transmit Buffer Address
;	CALL XSLSTA
;	Normal Return
;

XSLSTA:	CALL XBFCHK		;Do we have a transmit buffer yet?
	  RET			;No, and can't get any.
	MOVEI T1,SS.RUN		;Put the slot in the
	STOR T1,SBSTA,(SB)	; RUNNING state.
	MOVEI T1,<<ST.STA_^D12>!<MAXCRE_^D8>!SZ.SST>;COUNT/TYPE/CREDITS fields
	CALL BSLTHD		;Build the slot header	
	MOVEI T1,SCITTY		;Only available service class currently
	OPSTR <IDPB T1,>,UNBFA,+UNB.OF(XB)
	MOVEI T1,MXSLSI		;Maximum slot size for all slot types
	OPSTR <IDPB T1,>,UNBFA,+UNB.OF(XB);As maximum attention slot size
	OPSTR <IDPB T1,>,UNBFA,+UNB.OF(XB);As maximum data slot size
	MOVEI T1,0
	CALL LAP2B0		;Zero slot names
	OPSTR <IDPB T1,>,UNBFA,+UNB.OF(XB);No parameters either
	MOVX T1,SBSTR		;Indicate that this slot request successfully
	CALL CSBDAV		; and entirely completed.
	RETSKP

;XSLREJ - Format a REJECT Slot in the Transmit Buffer
;
;Call:	SB/ Slot Block Address
;	CB/ Circuit Block Address
;	XB/ Transmit Buffer Address
;	CALL XSLREJ
;	Normal Return
;

XSLREJ:	CALL XBFCHK		;Do we have a transmit buffer yet?
	  RET			;No, and can't get any.
	LOAD T1,SBREA,(SB)	;Get the reject reason code
	LSH T1,^D8
	MOVEI T1,<ST.REJ_^D12!SZ.REJ>(T1) ;COUNT/TYPE/REASON fields
	CALL BSLTHD		;Go build the slot header
	MOVX T1,SBREJ		;Indicate that this slot request successfully
	CALL CSBDAV		; and entirely completed.
	CALL RELSB		;Release the slot.
	RETSKP			;That's all there is to a REJECT slot.

	SUBTTL	Slot Formatting Routines

;XSLSTP - Format a STOP Slot in the Transmit Buffer
;
;Call:	SB/ Slot Block Address
;	CB/ Circuit Block Address
;	XB/ Transmit Buffer Address
;	CALL XSLSTP
;	Normal Return
;

XSLSTP:	CALL XBFCHK		;Do we have a transmit buffer yet?
	  RET			;No, and can't get any.
	CALL RLSBID		;Release the local slot block ID.
	LOAD T1,SBREA,(SB)	;Get the stop reason code
	LSH T1,^D8
	MOVEI T1,<ST.STP_^D12!SZ.SSP>(T1) ;COUNT/TYPE/REASON fields
	CALL BSLTHD		;Go build the slot header
	MOVX T1,SBSTO		;Indicate that this slot request successfully
	CALL CSBDAV		; and entirely completed.
	CALL RELSB		;Now go release the slot
	RETSKP

;XSLATT - Format a ATTENTION Slot in the Transmit Buffer
;
;Call:	SB/ Slot Block Address
;	CB/ Circuit Block Address
;	XB/ Transmit Buffer Address
;	CALL XSLATT
;	Normal Return
;

XSLATT:	CALL XBFCHK		;Do we have a transmit buffer yet?
	  RET			;No, and can't get any.
	MOVEI T1,<ST.ATT_^D12!SZ.ATT>;COUNT/TYPE fields
	CALL BSLTHD		;Go build the slot header
	MOVEI T1,1B30
	OPSTRM <IDPB T1,>,UNBFA,+UNB.OF(XB);Deposit control flags
	MOVX T1,SBFOU		;Indicate that this slot request successfully
	CALL CSBDAV		; and entirely completed.
	RETSKP

	SUBTTL	Slot Formatting Routines

;XSLDTA - Format a DATA_A Slot in the Transmit Buffer
;
;Call:	W1/ Slot Block Flags
;	SB/ Slot Block Address
;	CB/ Circuit Block Address
;	XB/ Transmit Buffer Address
;	CALL XSLDTA
;	Normal Return

; If we have transmit credit available, compute the maximum number of terminal
; output characters which may be entered into the slot.  If we no longer have
; credit, set the character count to zero.

XSLDTA:	SAVEAC <W1,W2>
IFN FTOPS10,<
	LOAD	U,SBTDB,(SB)	;Get address of LDB.
				;We will carry this in U for a while
>;end IFN FTOPS10
	OPSTR <SKIPN>,SBXCR,(SB);Do we still have any transmit credit?
	IFSKP.
	  MOVEI W1,SZ.XBF-SZ.SHD;Get the residual buffer (minus slot header)
	  OPSTR <SUB W1,>,UNBSZ,+UNB.OF(XB); count.
IFN FTOPS20,<
	  LOAD T2,SBTDB,(SB)	;Get address of TDB
	  CAMLE W1,TTOCT(T2)	;Smaller of residual count - 4 and TTOCT
	  MOVE W1,TTOCT(T2)	;TTOCT was smaller
>;end IFN FTOPS20
	  OPSTR <CAMLE W1,>,SBMDS,(SB) ;Compare with maximum DATA_A slot size
	  LOAD W1,SBMDS,(SB)	;Maximum allowed by remote is less.
	ELSE.
	  MOVEI W1,0		;No transmit credits so can't send data.
	ENDIF.

IFN FTOPS20,<

; Determine if the remote needs more credits and if we can give him any.  If
; he doesn't or we can't and there is no terminal output data to be sent(count
; from above is 0) , exit without building the slot since there is no need to
; send one.  Otherwise at least a DATA_A slot header will be sent.  If it is 
; extending credit, there may or may not be output data.

	CALL CRECHK		;Check if we can grant more credit remote
	 SKIPE W1		;Can't or don't need to so if there is no data
	SKIPA			; either, no need to send a slot. Otherwise,
	JRST XSLDA3		; send at least empty slot granting new credit.
	MOVE W2,T1		;Save CRECHK result
	CALL XBFCHK		;Do we have a transmit buffer yet?
	  JRST XSLDA3		;No, and can't get any.
	MOVE T1,W2		;Retrieve CHECHK results
	IORI T1,<ST.DTA_^D12>(W1);Fill in the rest of last 2 slot header bytes.
	CALL BSLTHD		;Go build the slot header
	JUMPE W1,XSLDA2		;No slot data and no credits used.
	OPSTRM <ADDM W1,>,UNBSZ,+UNB.OF(XB);Update the total message count.
	JRST XSLDA1		;Enter output data into slot if there is any. 
XSLDA0:	LOAD T2,SBTDB,(SB)	;Dynamic TT data base
	CALL TTSND		;Get a character from the buffer
	  RET			;Probably PAGE STOP
	OPSTR <IDPB T1,>,UNBFA,+UNB.OF(XB);Enter character into buffer
XSLDA1:	SOJGE W1,XSLDA0		;Continue if more characters
	LOAD T1,SBXCR,(SB)	;Get our transmit credit count
	SOS T1			;Decrement since we may consume one credit now.
	STOR T1,SBXCR,(SB)	; send data so store decremented credit count.

; Determine whether to slot request was FULLY completed.  If not, don't
; clear the request bit since it will have to be completed next time around.

XSLDA2:	LOAD T2,SBTDB,(SB)	;Get the TDB address back
	SKIPE TTOCT(T2)		;If there is more data to output, return
	RETSKP			; successfully. Do not clear request bit.
	SETZRO TTOTP,(T2)	;Clear TTY output active if not more data.
	OPSTR <SKIPN>,SBRCR,(SB);If remote has zero credit for transmits 
	RETSKP			; return successfully without clearint request.
	MOVX T1,SBOUT		; Otherwise mark this request as complete.
	CALL CSBDAV
	RETSKP

XSLDA3:	LOAD T2,SBTDB,(SB)	;Get the TDB address
	SKIPE TTOCT(T2)		;If there is no terminal output, clear
	RET			; the TTOTP bit.
	SETZRO TTOTP,(T2)	; ...
	RET			; ...

>;end ifn ftops20
IFN FTOPS10,<
; Determine if the remote needs more credits and if we can give him any.
; If he doesn't or we can't and there is no terminal output data to be
; sent, exit without building the slot since there is no need to send
; one. Otherwise at least a DATA_A slot header will be sent. If it is
; extending credit, there may or may not be output data. We don't know
; at this point how many characters SCNSER has for us to send, so just
; keep trying to get chars until we fill the slot or run out of
; characters
;
;	at this point:
;	W1/ max characters we can send
;
	MOVNS W1		;Make into
	HRLZS W1		;AOBJN word
;
;	now:
;	W1/ -max,,0
;
	JUMPE W1,NOCHR		;We don't have credit to send. Don't get a char
	SKIPGE SB.TTO(SB)	;Is there saved character? (SBTTO is sign bit)
	  JRST GOTCHR		;Yes
	CALL XMTCHR		;No, try to get a character from SCNSER
	  JRST NOCHR		;SCNSER doesn't have any for us.
	SETONE SBTTO,(SB)	;SCNSER does have one, remember we got it
	STOR T3,SBCHR,(SB)	;and save it away
GOTCHR:	AOBJN W1,.+1		;Got a char, count it
NOCHR:	CALL CRECHK		;Check if we can grant more credit remote
	  TRNE W1,777777	;Can't or don't need to. See if any data?
	SKIPA			;Got data or can grant credit, send a slot
	  RET			;No slot to send, just return
	MOVE W2,T1		;Save CRECHK result
	CALL XBFCHK		;Do we have a transmit buffer yet?
	  RET			;No, and can't get any.
	LOAD T1,SBXCR,(SB)	;Get our transmit credit count
	SOS T1			;Decrement since we may consume one credit now
	TRNE W1,777777		;If data count is not zero, we will definitely
	  STOR T1,SBXCR,(SB)	;Store updated credit count
;
;Can't build slot header yet, since we don't know how many characters
; we will send.  Save a pointer to the slot character count, and
; call BSLTHD anyway.  We will stuff the char count later.
;
;At this point, the slot byte pointer points to the DST_SLOT_ID
;
	MOVEI T1,3		;the byte count is the 3rd byte of the slot
	OPSTR <ADJBP T1,>,UNBFA,+UNB.OF(XB) ;so make a DPB pointer to it
	PUSH P,T1		;save first word of byte pointer
	PUSH P,T2		;and possible second word
;
;Now build the slot header
;
	MOVE T1,W2		;get CRECHK results
	LSH T1,^D8		;Shift to proper position
	IORI T1,<ST.DTA_^D12>	;fill in the flag
	CALL BSLTHD		;build the slot header (with bad char count)
	TRNN W1,777777		;Is there some data?
	  JRST XSLDA2		;No, no characters to move
	LOAD T3,SBCHR,(SB)	;Yes, get saved character.
	SETZRO SBTTO,(SB)	;And remember we got it.
	OPSTR <IDPB T3,>,UNBFA,+UNB.OF(XB) ;Stuff first character into buffer
	JUMPGE W1,XSLDA2	;if (heaven help us) there was only space for
				;one character, stop now.
XSLDA0:	CALL XMTCHR		;Get a character from SCNSER
	  JRST XSLDA2		;None left
	OPSTR <IDPB T3,>,UNBFA,+UNB.OF(XB) ;Stuff a character into buffer
	AOBJN W1,XSLDA0		;Count characters done
;
; Here we have either filled up the slot or run out of characters.
; Stuff the actual character count into the slot header.
;
XSLDA2:	POP P,T2		;retrieve pointer to slot header
	POP P,T1		; byte count
	DPB W1,T1		;and stuff actual character count
	HRRZ T1,W1		;get character count by itself
	OPSTRM <ADDM T1,>,UNBSZ,+UNB.OF(XB) ;and update total message count.
	OPSTRM <ADDB W2,>,SBRCR,(SB) ;Update his credit count. (remember total)
	JUMPE W1,RSKP		;If we don't have any transmit credits, or
	SKIPE W2		;If the remote has zero credits for transmits
	SKIPL LDBDCH(U)		;Or if SCNSER doesn't think line is idle
		.CREF LDLIDL	;(really checking this bit)
	  RETSKP		;Return successfully without clearing request
	MOVX T1,SBOUT		;Otherwise, mark this request as complete.
	CALL CSBDAV
	RETSKP
	SUBTTL	Slot Formatting Routines

;XSLDTB - Format a DATA_B Slot in the Transmit Buffer
;
;Call:	SB/ Slot Block Address
;	CB/ Circuit Block Address
;	XB/ Transmit Buffer Address
;	CALL XSLDTB
;	Normal Return
;

XSLDTB:	OPSTR <SKIPE>,SBXCR,(SB);Do we still have any transmit credit?
	CALL XBFCHK		;Check if we have a transmit buffer yet.
	 RET			; Didn't and can't get one.
	LOAD T1,SBXCR,(SB)	;Current number of transmit credits available
	SOS T1			;Decrement since this slot will consume one.
	STOR T1,SBXCR,(SB)	;Store updated credit count
IFN FTOPS10,<
	LOAD	U,SBTDB,(SB)	;Point to LDB
>;end IFN FTOPS10
	CALL CRECHK		;Does remote need credits?
	 NOP			;Dont't care if he did and we can't provide
	LSH T1,^D8		;Shift to proper position.
	IORI T1,<ST.DTB_^D12>!SZ.SDB;Fill in rest of last 2 header bytes.
	CALL BSLTHD		;Go build the slot header
	MOVEI T1,SL.DXF		 ;Assume disabling XOFF recognition	
IFN FTOPS20,<
	LOAD T2,SBTDB,(SB)	;Get the terminal data base address
	TMNE TT%PGM,TTFLGS(T2)	
>;end IFN FTOPS20
IFN FTOPS10,<
	LOAD U,SBTDB,(SB)	;Get LDB address
	LDB T2,LDPXNF		;Get XON/XOF flag
	SKIPE T2		;disabling XON/XOF recognition?
>;end IFN FTOPS10
	MOVEI T1,SL.EXF		 ;No, enabling	
	OPSTR <IDPB T1,>,UNBFA,+UNB.OF(XB);Enter control flags to buffer	
	MOVEI T1,<XONC_^D8!XOFFC> ;XON and XOFF characters
	CALL LAP2B0		;Enter them into buffer
	CALL LAP2B0		;Also input XON/XOFF characters
	MOVX T1,SBFCC
	CALL CSBDAV
	RETSKP

BSLTHD:	MOVE T3,T1		;Save input arg
	LOAD T1,SBLID,(SB)	;Remote slot ID
	LSH T1,^D8		;Shift to second byte
	OPSTR <IOR T1,>,SBRID,(SB) ;Local slot ID into first byte
	CALL LAP2B0		;(Clobbers T2 only.)
	MOVE T1,T3		;Get original argument back
	CALL LAP2B0		;Enter count/slot type/credits
	RET


;CRECHK - Remote Credit Check Routine
;
;Call:	SB/ Slot Block Address
;	CALL CRECHK
;	 No-Grant return
;	Grant return
;	T1/ <Number to grant>

; If the remote has less than the maximum number of transmit credits, try to
; compute the number of additional credits to grant him and return in T1, 
;  We can only grant credit
; if there is room for a non-zero integral number of full slot buffers (of
; length MXSLSI).

CRECHK:	MOVEI T1,MAXCRE		;Maximum number of credits remote may have.
	OPSTR <SUB T1,>,SBRCR,(SB);His deficiency.
	JUMPE T1,RTN		;Can't grant him more-- he already has limit.
	MOVE T3,T1		;Save remote's credit deficiency.
IFN FTOPS20,<
	LOAD T4,SBTDB,(SB)	;Get the terminal dynamic pointer
	LOAD T1,TIMAX,(T4)	;Maximum that will fit in an input buffer
	SUB T1,TTICT(T4)	;Subtract current input count to get whats left
>;end IFN FTOPS20
IFN FTOPS10,<
	MOVEI T1,TTIWRN		;Get max characters for an input buffer
	SUB T1,LDBTIC(U)	;Minus number that have been echoed
	SUB T1,LDBECC(U)	;Also minus number that have not yet echoed
>;end IFN FTOPS10
	IDIVI T1,MXSLSI		;Compute number of slot buffer that would fit
IFN FTOPS10,<
	JUMPE T1,RTN	 	;None, so can't grant more.
>;end IFN FTOPS10
IFN FTOPS20,<
	JUMPE T1,[SETONE TTFWK,(T4);None, so can't grant more so force
		  JRST RTN]	; the process to wake.
>;end IFN FTOPS20
	CAMLE T1,T3		;Make sure he never gets a total of more than
	MOVE T1,T3		; the maximum allowed.
	RETSKP


IGNSLT:	SETZM SLTCNT		;Force data to be ignored.
	RETSKP			;This is a good return.

ILLSLT:	OPSTRM <AOS>,HCISR,(HN)	;Increment host count
	OPSTRM <AOS>,CCISR,(CB)	; and the per-server count
	RET			;Give a bad return

	SUBTTL -  Queue Handling Routines

;LAQUE - Add an element to the front of a queue
;
;Call:	T1/ Address of Queue Header
;	T2/ Address of Element to Add
;	CALL LAQUE
;	Normal Return
; This routine is used to queue either CBs or SBs.  The queue headers
; and link words are always two words, and are described by the BEGSTR QL.
; All elements are linked in both forward and backward directions.

LAQUE:	MOVE T4,T1		;Save queue header address
	OPSTR <SKIPE T3,>,QLFWD,(T1)	;Get old first queue element if any.
	MOVE T1,T3		; Old first element or Q header backward
	STOR T2,QLBWD,(T1)	; pointer points to new element
	STOR T2,QLFWD,(T4)	;Store new first queue element
	SETZRO QLBWD,(T2)	;Zero its backward pointer
	STOR T3,QLFWD,(T2)	;Set up its forward pointer
	RET

;LAUNQ - Dequeue a queue element
;
;Call:	T1/ Address of queue header
;	T2/ Address of queue element to be unqueued
;	CALL LAUNQ
;	Normal return
;
;Uses:	T3,T4

LAUNQ:	LOAD T3,QLBWD,(T2)	;Get elements backward pointer
	LOAD T4,QLFWD,(T2)	;Get its forward ptr also.
	SKIPN T2,T4		;Remove the element from the backward list
	XMOVEI T2,QL.FWD(T1)	; by updating the backward
	STOR T3,QLBWD,(T2)	; ptr of either next Q element or Q head
	SKIPE T3		;If backward ptr 0 update Q head forward ptr
	XMOVEI T1,QL.FWD(T3)	; otherwise  update that of the previous Q
	STOR T4,QLFWD,(T1)	; element
	RET

	

;QUE1WB - Routine to queue and element to the back of a 1 directional queue.
;
;Call:	T1/ address of Q header block
;	T2/ address of queue element to add to queue
;	CALL QUE1WB
;	Normal return

QUE1WB:	OPSTR <SKIPN T3,>,QLBWD,(T1);Address of first element on Q
	MOVE T3,T1		;Zero, Q header fwd ptr points to new element
	STOR T2,QLFWD,(T3)	;Update forward ptr of Q hdr or old Q tail
	SETZRO QLFWD,(T2)	;Zero new elements forward ptr
	STOR T2,QLBWD,(T1)	;New tail ptr
	RET

;UNQ1WF - Routine to remove an element from the front of a 1 directional queue.
;
;Call:	T1/ address of the Q header block
;	CALL UNQ1WF
;	 Error return - queue emtpy	
;	Normal return
;	T2/ address of element

UNQ1WF:	OPSTR <SKIPN T2,>,QLFWD,(T1);Address of first element on Q
	RET			;Zero, so queue is empty
	OPSTR <SKIPN T3,>,QLFWD,(T2);If only 1 element on Q then update
	STOR T3,QLBWD,(T1)	; the Q headers tail ptr (set to 0)
	STOR T3,QLFWD,(T1)	;There is a new head of the Q (or 0)
	RETSKP			;Return with the Q element in T2

	SUBTTL - Buffer Handling Routines - Transmit Buffers

;GETXBH - Get the necessary number of transmit buffer headers
;
;Call:	CB/ Address of the circuit block
;	CALL GETXBH
;	  Error return - insufficient resources
;	Normal return

GETXBH:	MOVSI W1,-MAXXBF	;Number of buffers to get
GTXNXT:	MOVEI T1,<<MINXBF+3>/4+XBF.OF>;Buffer length to get
	CALL MMGTZW		;Go get the storage
	 JRST GTXFL		;Failed to get all that are needed
	MOVX T2,<POINT 8,0>
	STOR T2, MDAUX,+MDB.OF(T1);
	MOVEI T2,SZ.MHD		;The message header always has 
	STOR T2,MDBYT,+MDB.OF(T1); 8 bytes.
	MOVEI T2,VMC.XC		;Always use exec virtual paging
	STOR T2,MDVMC,+MDB.OF(T1)		; ...
	XMOVEI T2,<XBF.OF>(T1)	;
	STOR T2,MDALA,+MDB.OF(T1);Address of start of header
	MOVE T2,T1		;Now queue to circuit blocks queue of free
	XMOVEI T1,CB.XBQ(CB)	; transmit buffers
	CALL QUE1WB		; ...
	AOBJN W1,GTXNXT		;Get as many as required
	RETSKP

; Failed to get the nececessary number of buffers. Must free those
; which we did get.

GTXFL:	XMOVEI T1,CB.XBQ(CB)	;Unqueu each from the transmit free Q
	CALL UNQ1WF		; ...
	 RET			;No more there so return with error
	MOVE T1,T2		;Give back the buffer to the memory
	CALL MMFREE		; manager
	JRST GTXFL		; and continue looping til all returned


;GETXBF - Get one long transmit buffer for real data
;
;Call:	CB/ Address of the circuit block
;	XB/ Address of the 1st MSD (header)	
;	CALL GETXBH
;	  Error return - insufficient resources
;	Normal return
;	T3/ MSD address (also saved in MD.NXT+MDB.OF(XB))

GETXBF:	MOVEI T1,XBFSIZ		;Buffer length to get
IFN FTOPS20,<CALL MMGTZW>
IFN FTOPS10,<CALL GETZBF>	;Go get the storage
	  RET			;No luck!
	MOVE T3,T1
	SETZ T1,
	MOVX T2,<POINT 8,0>
	STOR T2,MDAUX,(T3);Byte pointer to message
	MOVEI T1,SZ.XBF
	STOR T1,MDBYT,(T3);Zero length
	MOVEI T1,VMC.XC		;Always use exec virtual paging
	STOR T1,MDVMC,(T3); ...
	XMOVEI T1,<MD.LEN>(T3)	;
	MOVEM T3,MD.NXT+MDB.OF(XB) ;Link header MSD to this
	STOR T1,MDALA,(T3)	;Message address
	RETSKP


;XBFCHK - Check for Transmit buffer
;
;Call:	XB/
;	CALL XBFCHK
;	 Error Return
;	Normal Return

XBFCHK:	SKIPE T3,MD.NXT+MDB.OF(XB)		;If we already have one,
	  RETSKP		;return
	CALL GETXBF		;Get an MSD transmit buffer
  	  RET			;None available, return failure
	XMOVEI T1,<MD.LEN>(T3)	;Make a one word 8 bit
	TLO T1,(<OWGP. 8,0>)		;Global byte pointer and save as
	STOR T1,UNBFA,+UNB.OF(XB); message byte pointer.
	RETSKP


;RFXBFS - Release all free transmit buffers
;
;Call:	CB/ circuit block address
;	CALL RFXBFS
;	Normal return
;

RFXBFS:	XMOVEI T1,CB.XBQ(CB)	;Address of the free xmit buffer queue
	CALL UNQ1WF		;Unqueue the head of the Q
	 RET
	MOVE XB,T2		;Put buffer address where RELXBH wants it
	CALL RELXBH		;Go release it
	JRST RFXBFS		;Get next

;RELXBF - Release Transmit Buffer
;
;Call:	XB/ Address of buffer header
;	CALL RELXBF
;	Normal return

RELXBF:	MOVEI T1,0
	EXCH T1,MD.NXT+MDB.OF(XB);If there is no MSD style buffer
	JUMPE T1,RTN			; then just return
IFN FTOPS20,<CALLRET MMFREE>
IFN FTOPS10,<CALLRET GIVBF>	; and free the MSD's storage.

;RELXBH - Release Transmit Buffer Header and Buffer
;
;Call:	XB/ Address of buffer header
;	CALL RELXBH
;	Normal return

RELXBH:	CALL RELXBF		;Release the buffer first
	MOVE T1,XB		;Now the header
	CALL MMFREE
	RET

	SUBTTL - Buffer Handling Routines - Receive Buffers

;GETRBF - Get a Receive buffer
;
;Call:	CALL GETRBF
;	 Error return - no receive buffers
;	Normal Return
;
; This routine checks to see if enough receive buffers have been posted
; to the NI DLL to support the number of currently active circuits plus
; a new one.  If  buffers are needed and can be obtained, they are posted
; directly to the NI DLL.  If some are needed, and cannot be obtained,
; the error return is taken.

GETRBF:	LOAD T1,HNNRB,(HN)	;Do check to see if we need more buffers.
	LOAD T2,HNNAC,(HN)
	CAIL T1,1(T2)
	  RETSKP		;No additional are needed. Return success.
	MOVEI T1,RBFSIZ		;Receive buffer size
IFN FTOPS20,<CALL MMGTZW>
IFN FTOPS10,<CALL GETZBF>	;Get the number of required buffers
	  RET			;Can't, return error.
	CALL RBPOSS		;Post the receive buffer to NISRV
IFN FTOPS10,<CALLRET GIVBF>
IFN FTOPS20,<CALLRET MMFREE>	;Couldn't post it so free it.
	OPSTRM <AOS>,HNNRB,(HN);Increment the number of receive buffers
	RETSKP		;Return success

;RELRBF - Release a Receive buffer
;
;Call:	RB/ Address of the buffer to release
;	CALL RELRBF
;	Normal Return
;
; This routine frees a receive buffer if there is already a sufficient number
; posted to the NI DLL otherwise the buffer is re-posted to the NI DLL.

RELRBF:	LOAD T1,HNNRB,(HN)	;Do we still need this buffer?
	LOAD T2,HNNAC,(HN)
	CAILE T1,1(T2)
	 JRST RELRB0		;No, so free it
	MOVE T1,RB		;Yes, so
	CALL RBPOST		; re-post it to NISRV
	 JRST RELRB0		;NISRV could not accept it?! Release it.
	RET			;Successfully re-posted. Return.
RELRB0:	MOVE T1,RB		;Here to free the buffer.
IFN FTOPS10,<CALL GIVBF>
IFN FTOPS20,<CALL MMFREE>
	OPSTRM <SOS>,HNNRB,(HN)	;Reduce the number of receive buffers
	RET

IFN FTOPS10,<
	SUBTTL	SCNSER DEVICE DEPENDANT ROUTINES
;
;	TOPS10 does not call a device dependant routine for each output
;	  character. Nor does it call a routine to change TTY PAGE.
;	At each scheduler interval, we scan all LDBs in LATSER's queue
;	to see what must be done with each one.
;
LATSCN:	MOVEI T1,LATRTQ			;Get SCNSER's queue header
	CALL TOTAKE			;Get next active LDB on the chain
	  RET				;None. Just return.
	SKIPN SB,LDBLAT(U)		;Get slot block address
	  RET				;None. This guy's a loser so punt.
	MOVEI T1,0			;T1 will get Slot flags
	MOVEI T3,L1RCHP
	TDNE T3,LDBBYT(U)		;Need to change parameters?
	  PUSHJ P,LATCHP		;Yes. See what needs change and set T1
	TXO T1,SBOUT		;Always set flag for output. Check later anyway
;
; Here if we MIGHT have characters to output, or need to change TTY PAGE
;
	MOVE CB,SB.CBA(SB)	;And associated circuit block address
	CALL SSBDAV		;And set this slot's flags
	JRST LATSCN		;Look at next LDB in the queue
;
;Routine to see if we need to change recognition of XON/XOFF
;
;Call:	U/ LDB address
;
;Return:	Flag SBFCC set in T1 if we need to change
;
LATCHP:	ANDCAM T3,LDBBYT(U)	;Turn off CHP bit to show we checked
	LDB T2,LDPXNF		;Get TTY PAGE bit
	LOAD T3,SBXNF,(SB)	;Get bit that says what the LAT knows
	CAMN T2,T3		;Are they already the same?
	 RET			;Yes, no need to send a message, then
	TXO T1,SBFCC		;Different. Need to send a message
	STOR T2,SBXNF,(SB)	;AND remember what we are now.
	RET
>;end IFN FTOPS10
	ENDAV.

IFN FTOPS20,<
	SUBTTL	TTYSRV DEVICE DEPENDENT ROUTINES

LTSTRO::MOVX T1,SBOUT
	SETONE TTOTP,(T2)	;Set output active
	JRST LTSSDC
LTCOBF::MOVX T1,SBFOU
	JRST LTSSDC
LTEXF::	MOVX T1,SBFCC
LTSSDC:	ACVAR <HN,XB,RB,CB,SB,W1,W2>
	NOSKD1
	CHNOFF DLSCHN
	SKIPN SB,TTDEV(T2)	;Get the slot data base from TDB if not 0
	JRST LTSSD0
	MOVE CB,SB.CBA(SB)	;Get the circuit data base from slot block.
	SAVEAC <T2>		;TTYSRV needs T2 returned intact
	CALL SSBDAV
LTSSD0:	CHNON DLSCHN
	OKSKD1
	RET

; TTYSRV Device Dependent Routine to see if SENDAL should be done on this
; line.  
; Call:	T2/ Line Number
;	Non-skip Return/ Skip SENDALL to this Line
;	Skip Return    / Do SENDALL to this Line

LTSALL::SKIPG TTACTL(T2)	;Is line fully active?
	RET			;No, don't do SENDALL
	RETSKP			;Yes, do the SENDALL

; TTYSRV device dependent routine to perform hang-up action
;
;Call:	T2/ Line Number

LTHNGU::SAVEAC <T2>		;Caller wants this back intact
	CALL STADYN		;Get the dynamic data base
	 RET			;There is none
	MOVX T1,SBSTO		;Mark to send STOP slot if necessary
	CALL LTSSDC		;(CALLRET won't work here)
	RET

; TTYSRV device dependent routine to see if output is possible on a line
;
; Call:	T2/ TDB Address
;	Non-skip Return/ Output not possible
;	Skip Return    / Output possible

LTTCOU::RETSKP

; TTYSRV device dependent routine to set LAT Host terminal lines as 
; high speed lines.
;
;RETSKP always with:
;	T3/ ^D9600 to simulate high speed output
;	T4/ IBFRC1 the high speed terminal characteristics word

LTSOF::	MOVEI T3,^D9600		;Fake 9600 baud
	MOVE T4,IBFRC1		;High speed buffer word
	RETSKP			;Always
>;end IFN FTOPS20

IFN FTOPS10,<
	SUBTTL  More SCNSER device dependant routines

;Routine LTHNGU - LAT "disconnect" function
;Called by SCNSER thru ISRREM entry point in dispatch vector with
; a function code if IRRDSC in T3
;
;	U/ LDB address
;	T3/IRRDSC
;	CALL LTHNGU
;	Returns +2 always (note: there is no "error" return)
;
LTHNGU:	MOVX T1,SBSTO		;Yes, we want to stop this slot
	CALL LTSSDC		;SO do it
	RETSKP			;And indicate success to SCNSER
;
;Routine LATREM
;Called from SCNSER through dispatch vector element ISRREM (7)
;
;	U/ LDB address
;	T3/ Function code
;		Possible values are:
;		(1) Input buffer low (ignored)
;		(2) Input character not stored (ignored)
;		(IRRSCG) Eat all output characters
;		(IRRDSC) Disconnect LAT terminal
;		(IRRTMO) Disconnect idle terminal
;
LATREM:	CAIN T3,IRRDSC		;Is the the "disconnect" function?
	  CALLRET LTHNGU	;Yes, do it.
	CAIN T3,IRRTMO		;Is it the "timeout" function?
	  CALLRET LTHNGU	;Yes, do it.
	CAIE T3,IRRSCG		;Is it "send character gobbler"?
	  RET			;No, those are all we know about
LTCOBF:	MOVX T1,SBFOU		;User hit ^O, tell remote to gobble output
LTSSDC:	ACVAR <HN,XB,RB,CB,SB,W1,W2>
	ETHLOK			;Interlock against races
	SKIPN SB,LDBLAT(U)	;Get slot data base from LDB
	  JRST LTSSD0		;Not there any more, ignore
	MOVE CB,SB.CBA(SB)	;Get circuit data base from slot block.
	CALL SSBDAV
LTSSD0:	ETHULK			;Release interlock
	RET
>;end IFN FTOPS10
				

	SUBTTL	General Untility Routines

;
;RANDOM - get a "random" number
;
;Call:	T1/ Maximum number allowed
;	CALL RANDOM
;	Normal Return
;	T1/ Random Number

RANDOM:	MOVE T4,T1		;Save for modulo
IFN FTOPS20,<
	CALL LGTAD		;Get internal time and date
>;end IFN FTOPS20
IFN FTOPS10,<
	MOVE T1,DATE		;get TOPS-10 time and date
>;end IFN FTOPS10
	ANDI T1,777777		;Time only
	IDIV T1,T4		;MODULO max, (which is the remainder in T2)
	SKIPN T1,T2		;GET remainder
	MOVEI T1,1		;But if it's zero, make it 1
	RET

	ENDAV.

DYNRAT:
IFN FTOPS20,<	FIXR T1,RJAV+2		;15 minute load average>
IFN FTOPS10,<	MOVEI	T1,1		;FOO>
	RET


	SUBTTL	LAGTCR - LAT memory management routines

;
;	Subroutine to tell COMMON how much core LAT needs at ONCE time
;
;Call:	CALL LAGTCR
;
;Return: +1 always with T1/ size of memory LAT needs, which is:
;
;		Space for 1 outstanding receive buffer +
;		 for each possible open circuit: MAXXBF transmit buffers
;		  + 1 receive buffer

;	MAX.(BUFSIZ,<RBFSIZ,XBFSIZ>)	;BUFSIZ is size of largest buffer
;	BUFSIZ==BUFSIZ+QL.LEN		;we need + 2 words for linking list
	BUFSIZ==PAGSIZ##	;Oh, the hell with it! receive buffers have
				;to be contiguous, so don't bother to
				;split a buffer across a page boundary.
				;Luckily, the actual size of a buffer
				;is slightly smaller than a page.
;


LAGTCR::
	MOVEI T1,<BUFSIZ*NBUFS>
	RET

;
;	Routine to ask for more memory from user free core
;	We should get it a tick or two later.
;
CHKWFB:	SKIPE T1,LATWFB		;Do we want any more buffers?
	SKIPE LATRFB		;And have we not yet aksed for them?
	  RET			;No to either, don't get memory now.
;
;	Here we have finally decided it's our turn to ask for some memory
;
	IMULI T1,BUFSIZ		;Calculate how many words
	TRZE T1,PG.BDY##	;Round up to page bound
	ADDI T1,PAGSIZ##
	MOVEM T1,LATRFB		;Remember how many words we asked for.
	LSH T1,W2PLSH##		;Convert to pages
	HRLI T1,(MS.SCA)	;Section to allocate from
	JSP T2,GETCLP##		;Ask for the space and wait for it
				;T2 contains callback routine address
;
;	CHKRFB - Routine called when VMSER gave us memory
;		If so, link it into free buffer list
;
CHKRFB:	MOVE T4,T1		;Get address of start
	SETZ T1,		;Get a zero
	EXCH T1,LATRFB		;Get number of pages we wanted (and clear it)
	IDIVI T1,BUFSIZ		;Convert to number of buffers
	ADDM T1,LATNFB		;Indicate that we've got more
	MOVE T2,T4		;Get address of first buffer
	MOVE T4,T1		;save buffer count
ALCBUF:	MOVEI T1,LATFRE		;QUEUE header for LAT free core
	CALL QUE1WB		;Link this buffer to the list.
	ADDI T2,BUFSIZ		;Point to next one.
	SOJG T4,ALCBUF		;Until all buffers have been allocated.
	RET
;
;	GETZBF - Routine to get a receive or transmit buffer and zero it.
;
;Call:	T1/ required size
;Return: +1 failure
;	 +2 success T1/ address of buffer
;
GETZBF:	PUSH P,T1		;Save size wanted
	MOVEI T1,LATFRE		;Address of queue header for free pool
	CALL UNQ1WF		;Get a buffer
	  JRST TPOPJ		;Couldn't, restore T1 and return.
	SOS LATNFB		;One less free buffer
	PUSH P,T2		;SAVE ADDRESS OF BUFFER
	XMOVEI T3,1(T2)		;POINT TO SECOND WORD
	SETZM (T2)		;ZERO FIRST WORD
	MOVEI T1,BUFSIZ-1	;SET UP TO ZERO THE WHOLE BLOCK
	XBLT. T1		;DO IT
	POP P,T2		;RESTORE ADDRESS
	POP P,T1		;Restore size
	HRLI T1,'LAT'		;check word
	MOVEM T1,(T2)		;save <'LAT',,size> as first word
	HRRZ T3,T1		;Isolate size
	ADD T3,T2		;Point to end of buffer
	HRLI T1,'END'
	MOVEM T1,1(T3)
	XMOVEI T1,1(T2)		;POINT to address of data portion
	RETSKP

;
;	GIVBF - Routine to give back a buffer to free pool
;
;Call:	T1/ address of data portion of buffer
;Return: +1 always
;
GIVBF:	SUBI T1,1		;Point to size word
	HLRZ T2,(T1)		;Get check code
	HRRZ T3,(T1)		;Get size
	ADD T3,T1		;Point to near end of buffer
	HLRZ T3,1(T3)		;Get ending check code
	CAIN T3,'END'		;See if either end has been wiped out
	CAIE T2,'LAT'		;Is it still there?
	  BUG. (CHK,LATMEM,LATSER,SOFT,<LAT buffer overwritten>,<<T1,ADDRESS>>,<
While trying to return a buffer, LATSER discovered it had been overwritten.>)
	MOVE T2,T1		;Now return the buffer
	MOVEI T1,LATFRE		;To the queue of free buffers
	AOS LATNFB		;Count one more buffer available
	CALLRET QUE1WB		;For re-use

MMGTZW:
IFN FTOPS20,<
	CALL DNGWDZ
	  RET
	RETSKP
>;END IFN FTOPS20
IFN FTOPS10,<
	MOVEI T2,1(T1)		;Going to ask for 1 more word for check
	PUSH P,T2		;save requested size
	CALL GETEWZ		;Get zeroed core from ethernet free pool
	  JRST TPOPJ		;No luck
	POP P,T2		;Get back requested size
	ADDI T1,1		;Point to data portion of block
	MOVEM T2,-1(T1)		;save length as first word of block
	RETSKP			;And return it to caller

MMFREE:
IFN FTOPS20,<
	CALL DNFWDS
	RET	
>
IFN FTOPS10,<
	XMOVEI T2,-1(T1)	;Point to block-1
	HRRZ T1,(T2)		;Which contains length of block
	CALLRET GIVEWS		;and give it back to ethernet free pool.
;
;	Subroutine to convert SIXBIT nodename to ASCII
;
;Call:	T1/ SIXBIT node name
;
;Return: +1 always with ASCII in OURNAM, OURNAM+1
;	and character in OURCNT
;
CVTNOD:	SETZM OURCNT		;No characters yet
	SETZM OURNAM		;Or name
	SETZM OURNAM+1		; ...
	JUMPE T1,RTN		;Done if no characters left
	MOVE T3,[POINT 7,OURNAM]	;Where to put node name
CVTNO1:	SETZ T2,		;Zap the temp AC
	ROTC T1,6		;Get next character into T2
	ADDI T2,40		;Convert to ASCII
	AOS OURCNT		;Count characters done
	IDPB T2,T3		;Put the character into the name
	JUMPN T1,CVTNO1		;Continue
	RET			;Done

	XLIST
	LIT

	define	.xcrf1(syms),<
	irp	syms,<purge syms>>
	.xcmsy			;Purge some stupid MACSYM symbols
	PRGALL			;Purge all ..nnnn symbols

>;end IFN FTOPS10
	END