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TOPS-20_V6.1_DECnetSrc_7-23-85
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mcb/xpt/xpefwd.bli
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module XPEFWD (
IDENT = 'X01150'
) =
begin
!
! COPYRIGHT (c) 1980, 1981, 1982
! DIGITAL EQUIPMENT CORPORATION
! Maynard, Massachusetts
!
! This software is furnished under a license and may be used
! and copied only in accordance with the terms of such license
! and with the inclusion of the above copyright notice. This
! software or any other copies thereof may not be provided or
! otherwise made available to any other person. No title to
! and ownership of the software is hereby transferred.
!
! The information in this software is subject to change
! without notice and should not be construed as a commitment
! by DIGITAL EQUIPMENT CORPORATION.
!
! DIGITAL assumes no responsibility for the use or reliability
! of its software on equipment which is not supplied by
! DIGITAL.
!
!++
! FACILITY: Transport
!
! ABSTRACT:
!
! Transport forwarding module: Forwards packets to other MCB
! routines, and terminates packets which are not to be forwarded.
!
! ENVIRONMENT: MCB
!
! AUTHOR: L. Webber , CREATION DATE: 23-Oct-79
!
! MODIFIED BY:
!
! L. Webber, 23-Oct-79 : VERSION 1.00
!
! 1.01 L. Webber, 20-Dec-79
! MCB interface modifications
!
! 1.02 L. Webber, 30-Jun-80
! Modify to use MCBLIB macros
!
! 1.03 A. Peckham, 15-Oct-80
! Take advantage of new function modifiers.
!
! 1.04 L. Webber, 17-Nov-80
! Decrement ECL quota when queuing a message to ECL.
!
! 1.05 L. Webber, 11-Dec-80
! Modify to support MCB 3.1
!
! 1.06 L. Webber, 10-Feb-81
! Change from XPTFWD to XPEFWD; all entries are now CALL$
! so they may be CALL$E'd. All entries now have a "_"
! in front of them, as: _TERMINATE.
!
! 1.07 L. Webber, 18-Feb-81
! Fix maintenance of INPUTquota.
! Add debugging code to maintain a count of DLL receive buffers
! outstanding to Transport.
!
! 1.08 L. Webber, 16-Mar-81
! Fix _TERMINATE to call UNSPAWN to clean up a spawned CCB.
!
! 1.09 L. Webber, 4-Jun-81
! Fix ECLFWD not to set C_LIN.
!
! 1.10 L. Webber, 25-Jun-81
! Have FORWARDER check for negative as well as zero values of the
! line quota (this is to accomodate some "high-priority" messages).
!
! 1.11 L. Webber, 26-Jun-81
! Fix _TERMINATE to get rid of Transport's own (usually XCP) CCB.
!
! 1.12 L. Webber, 20-Jul-81
! Modify _TERMINATE not to adjust input count when terminating a DC we
! sent (it was already adjusted when the DC was sent).
!
! 1.13 A. Peckham, 19-Sep-81
! Change CSBRT$ call to $MCB_RETURN_CCB_AND_BUFFER.
!
! 1.14 L. Webber, 23-Feb-82
! Add DLLquota maintanance.
!
! 1.15 A. Peckham, 22-Apr-82
! Eliminate GETLINE references.
!
!--
!
! INCLUDE FILES:
!
require 'XPTMAC';
!
! TABLE OF CONTENTS
!
forward routine
_SNDBUF: CALL$ novalue,
_FORWARDER: CALL$,
DLL_Q: novalue,
_ECLFWD: CALL$,
_TERMINATE: CALL$ novalue;
!
! MACROS:
!
!
! EQUATED SYMBOLS:
!
!
! OWN STORAGE:
!
!
! EXTERNAL REFERENCES:
!
external routine
UNSPAWN: novalue;
global
routine _SNDBUF (LINEb,CCB): CALL$ novalue =
!++
! FUNCTIONAL DESCRIPTION:
!
! This routine is called to unconditionally forward a packet to the
! Transport Line Interface Layer. If the packet cannot be sent, it
! will be discarded.
!
! FORMAL PARAMETERS
!
! LINEb The data base of the output line on which it is
! to be forwarded.
! CCB The CCB for the packet to be forwarded; the packet is assumed
! to be an unpaired SDB which belongs to Transport.
!
! IMPLICIT INPUTS
!
! LINEstate
!
! ROUTINE VALUE:
! COMPLETION CODES:
!
! NONE.
!
! SIDE EFFECTS:
!
! NONE.
!
!--
begin
map CCB: ref block field (C_XPT_fields);
require 'XPTSYM';
!
! Make sure the output line is up
!
if ((.CCB[C_XPT_TYPE] neq INITcode)!Buffer is not from Line Support
and (.LINEstate neq RU)) ! and line is not in "run" state:
then $MCB_RETURN_CCB_AND_BUFFER(.CCB[C_XPT_ALLOCATION],.CCB) ! get rid of CCB/buffer
!
! OK - now send out the packet
!
else DLL_Q(.CCB,.LINEb);
end; !End of _SNDBUF
global
routine _FORWARDER (CCB,OLINE): CALL$ =
!++
! FUNCTIONAL DESCRIPTION:
!
! This routine is called to conditionally forward a packet to the
! Transport Line Interface Layer. If the packet cannot be forwarded
! because of unreachability or congestion, the packet is returned
! to the caller with an error code.
!
! FORMAL PARAMETERS
!
! CCB Spawned CCB for packet to be forwarded.
! OLINE Channel number for output line.
!
! IMPLICIT INPUTS
!
! LINEstate
!
! ROUTINE VALUE: "Success", "unreachable", or "congestion"
! COMPLETION CODES:
!
! CS_SUC Success: packet has been forwarded.
! CE_DIS Unreachable destination: packet is rejected.
! CE_RTE Congestion: packet is rejected.
!
! SIDE EFFECTS:
!
! NONE.
!
!--
begin
map CCB: ref block field (C_XPT_fields);
local LINEb;
require 'XPTSYM';
!
! Make sure the output line is up
!
LINEb = $XPT_GET_LINE_DB(.OLINE); ! Address line data base entry
if .LINEstate neq RU then !Output line is not in "run" state:
return (CE_DIS) ! reject the packet
!
! Check the output quota
!
else if .LINEquota leq 0 then !Quota exhausted:
return (CE_RTE) ! reject the packet
!
! OK - send out the packet
!
else begin
LINEquota = .LINEquota - 1; !Decrement the quota
CCB[C_XPT_TYPE] = FWDcode; !Set buffer type
DLL_Q (.CCB,.LINEb); !Queue up the packet
return (CS_SUC) !Return "success"
end
end; !End of _FORWARDER
routine DLL_Q (CCB,LINEb): novalue =
!++
! FUNCTIONAL DESCRIPTION:
!
! Queues a packet CCB to the Transport Line Interface Layer.
!
! FORMAL PARAMETERS
!
! CCB CCB to be queued
! LINEb Output line data base
!
! IMPLICIT INPUTS
!
! NONE.
!
! ROUTINE VALUE:
! COMPLETION CODES:
!
! NONE.
!
! SIDE EFFECTS:
!
! NONE.
!
!--
begin
map CCB: ref block field (C_XPT_fields);
require 'XPTSYM';
CCB[C_HANDLE] = .TLIhandle; ! Move in destination = TLI
CCB[C_FNC] = FC_XME; ! Function is "transmit enable"
CCB[C_MOD] = TM_DAT; ! with a side of "data"
$MCB_SCHEDULE_CCB(.CCB); ! Send the buffer
end; !End of DLL_Q
global
routine _ECLFWD (CCB,SOURCE,DEST,RTS): CALL$ =
!++
! FUNCTIONAL DESCRIPTION:
!
! This routine is called to conditionally forward a packet to a
! Transport user. If the packet cannot be forwarded because of
! congestion, the packet is returned to the caller with an error
! code.
!
! FORMAL PARAMETERS
!
! CCB CCB for packet to be forwarded.
! SOURCE Source node address
! DEST Destination node address
! RTS "Return to sender" flag to be passed to user.
!
! IMPLICIT INPUTS
!
! ECLquota
!
! ROUTINE VALUE: "Success" or "congestion"
! COMPLETION CODES:
!
! CS_SUC Success: packet has been forwarded to user.
! CE_RTE Congestion: packet is rejected.
!
! SIDE EFFECTS:
!
! NONE.
!
!--
begin
map CCB: ref block field (C_XPT_fields);
require 'XPTSYM';
local CCB_P: ref block field(C_FIELDS);
!
! Check the ECL quota
!
if .ECLquota eql 0 then !Quota exhausted:
return (CE_RTE) ! return "congestion"
else ECLquota = .ECLquota - 1; !Otherwise - decrement
!
! OK - forward to user
!
CCB[C_FNC] = FC_RCP; !Function is "receive complete"
CCB[C_MOD] = XM_DAT; !Modifier is "data message"
CCB[C_XPT_SOURCE] = .SOURCE; ! and source node address
CCB[C_XPT_DESTINATION] = .DEST; ! and destination node address
CCB[C_STS] = (if .RTS then CE_DIS !Status = "return to sender"
else CS_SUC); ! or "regular packet"
begin
local NODEb: ref NODEblock;
NODEb = $XPT_GET_NODE_DB(.DEST);
CCB[C_PIX] = .User; !Move in destination PIX
end;
$MCB_SCHEDULE_CCB (.CCB); !Queue to the destination process
return(CS_SUC) !Return "success"
end; !End of _ECLFWD
global
routine _TERMINATE (CCB,CODE): CALL$ novalue =
!++
! FUNCTIONAL DESCRIPTION:
!
! This routine is called to "terminate" a CCB or spawned/pass-through
! CCB pair. "Termination" consists of releasing the spawned CCB and its
! SDB (if either exist) and returning the pass-through CCB to its owning
! process with a specified success or error code.
!
! FORMAL PARAMETERS
!
! CCB First or only CCB to terminate.
! CODE Success/failure code to return to the originating process.
! This value is only used if the originating process is a
! Transport user; if the terminated CCB is sent back to the
! Data Link Layer, no status is returned.
!
! IMPLICIT INPUTS
!
! NONE.
!
! ROUTINE VALUE:
! COMPLETION CODES:
!
! NONE.
!
! SIDE EFFECTS:
!
! NONE.
!
!--
begin
map CCB: ref block field (C_XPT_fields);
local LINEb;
require 'XPTSYM';
local ADJ;
local CCB_P: ref block field(C_XPT_fields);
!
! Process spawned CCB if any
!
if ((.CCB[C_OWN] eql PD_XPT) and !Parameter
(.CCB[C_STK] neq 0)) then begin ! is a
CCB_P = .CCB[C_STK]; ! spawned CCB:
UNSPAWN(.CCB); ! clean it up
end
else CCB_P = .CCB; !Parameter is pass-through CCB
!
! Return pass-through CCB to a Transport user
!
if .CCB_P[C_FNC] eql FC_XME then begin
INPUTquota = .INPUTquota + 1; !Increase admission quota
CCB_P[C_FNC] = FC_XCP; !Function = "transmit complete"
CCB_P[C_STS] = .CODE; !Move in success/failure code
LLCRS$ (.CCB_P); !Return CCB to user
end
!
! Return pass-through CCB to the Transport Line Interface Layer
!
else if .CCB_P[C_FNC] eql FC_RCP then begin
LINEb = $XPT_GET_LINE_DB(.CCB_P[C_LIX]); ! Address line data base entry
if .CCB[C_XPT_TYPE] neq NOcode then
begin !Decrement receive
INPUTcount = .INPUTcount - 1; ! buffer count
DLLquota = .DLLquota + 1; ! and global quota
end;
CCB_P[C_FNC] = FC_RCE; !Function = "receive enable"
LLCRS$ (.CCB_P); !Queue CCB back to DLL
end
!
! Return our own CCB to the pool
!
else if .CCB_P[C_OWN] eql PD_XPT
then begin
if .CCB_P[C_XPT_ALLOCATION] neq 0
then begin
MAP$(.CCB_P[C_BIAS]);
$MCB_RETURN_BUFFER(.CCB_P[C_XPT_ALLOCATION],.CCB_P[C_ADDR]);
end;
$MCB_RETURN_CCB(.CCB_P);
end
!
!
! How did we get here?
!
else BPT(XPT$_IFC,CCB_P[C_FNC]);
end; !End of _TERMINATE
end !End of Module XPEFWD
eludom