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TITLE LNKOVS - COMMON SUBROUTINES FOR OVERLAY MODULES
SUBTTL	D.M.NIXON/DMN/JBC/JNG/DZN/PAH	6-Dec-83


;COPYRIGHT (C) 1973, 1983 BY
;DIGITAL EQUIPMENT CORPORATION, MAYNARD, MASS.
;
;
;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.

SEARCH	LNKPAR,LNKLOW,OVRPAR,MACTEN,UUOSYM,SCNMAC
SALL

ENTRY	TR.WLK


CUSTVR==0		;CUSTOMER VERSION
DECVER==5		;DEC VERSION
DECMVR==1		;DEC MINOR VERSION
DECEVR==2026		;DEC EDIT VERSION

VERSION


SEGMENT

SUBTTL	REVISION HISTORY


;START OF VERSION 2
;135	ADD OVERLAY FACILITY
;136	FIX VARIOUS BUGS
;174	MAKE RELOCATABLE OVERLAYS WORK

;START OF VERSION 2B
;363	UPDATE MINOR VERSION #

;START OF VERSION 2C
;557	Clean up listing for release.

;START OF VERSION 3A
;560	Release on both TOPS-10 and TOPS-20 as LINK version 3A(560)


;START OF VERSION 4
;731	SEARCH MACTEN,UUOSYM
;765	Release on both TOPS-10 and TOPS-20 as LINK version 4(765)

;START OF VERSION 4A
;1174	Label and clean up all error messages.
;1217	Clean up the listings for release.
;1220	Release on both TOPS-10 and TOPS-20 as version 4A(1220).

;START OF VERSION 5
;1400	Use OVRPAR.MAC.

;Start of Version 5.1
;2026	Update copyright notice.

SUBTTL	TREE WALK ROUTINE


;ENTER WITH REQUIRED LINK IN P1 (RH)
;START AT FSTLNK
;SCAN ALL TREE UNTIL REQUIRED LINK IS FOUND
;RETURNS ADDRESS IN P1 (LH), LINK # IN (RH)
;RETURNS TOTAL NO. OF LINKS IN SUB-TREE IN P2
;ADDRESS IN P1 IS EITHER THAT OF REQUIRED NODE 
; OR ITS FATHER IF REQUIRED NODE IS TERMINAL

TR.WLK:	MOVE	T2,BRNMAX	;LONGEST POSSIBLE BRANCH
	ADDI	T2,1		;SPACE FOR TERMINATOR
	PUSHJ	P,DY.GET##	;GET SPACE FOR PD STACK
	SPUSH	<T1,T2>		;SAVE SO WE CAN GIVE BACK
	MOVN	T2,T2		;-LENGTH
	HRL	T1,T2		;FORM PDP
	MOVE	P2,T1		;SAFE PLACE
	PUSH	P2,[0]		;START WITH A ZERO TERMINATOR
	MOVE	T1,FSTPTR	;GET START
TRWLK1:	HLL	T1,(T1)		;FORM AOBJN
	ADD	T1,[2,,2]	;BYPASS HEADER AND BACK PTR
TRWLK2:	MOVS	T2,(T1)		;PTR ,, #
	CAIN	P1,(T2)		;ONE WE WANT?
	JRST	TRWLKF		;YES
	TLNE	T2,-1		;IS IT A TOP LINK?
	JRST	TRWLK3		;NO, FOLLOW IT
	AOBJP	T1,.+3		;GET NEXT ITEM IN LIST
	SKIPE	(T1)		;UNLESS NULL
	JRST	TRWLK2		;TRAVEL ITS PATH
	POP	P2,T1		;GET TOP ITEM OFF STACK
	JUMPE	T1,TRWLKZ	;NOT IN TREE (MIGHT BE SUB-TREE)
	JRST	TRWLK2		;AND FOLLOW PREVIOUS

TRWLK3:	MOVE	T2,T1		;GET A COPY TO PLAY WITH
	AOBJP	T2,.+3		;SEE IF WE NEED TO STACK
	SKIPE	(T2)
	PUSH	P2,T2		;YES, RETURN HERE
	MOVE	T1,(T1)		;GET ADDRESS
	JRST	TRWLK1		;AND FOLLOW

TRWLKF:	SETZ	P2,		;HOLD COUNT OF NODES IN SUB-TREE
	TLNN	T2,-1		;IS IT TERMINAL?
	AOJA	P2,.+2		;YES, ACCOUNT FOR IT
	HLR	T1,T2		;NO, USE PTR
	SKIPL	(T1)		;POINTING TO AOBJN WORD
	SOJA	T1,.-1		;NOT YET
	HRL	P1,T1		;SAFE PLACE
	SPOP	<T2,T1>
	PUSHJ	P,DY.RET##	;RETURN STACK
	MOVS	T1,P1		;GET POINTER
	HRRZ	T2,(T1)		;GET LINK#
	JUMPE	T2,CPOPJ	;FINISHED WHEN BACK TO 0
	MOVE	T1,1(T1)	;GET NEXT
	AOJA	P2,.-3		;LOOP

TRWLKZ:	SETZB	P1,P2		;NO DEPTH, NO PTR
	SPOP	<T2,T1>
	PJRST	DY.RET##	;RETURN STACK AND GIVE UP

SUBTTL	RELOCATABLE OVERLAY ROUTINES


;RT.P2 - ROUTINE TO SETUP RT.PT AND MAKE SURE ENOUGH SPACE
;ENTER WITH
;P2 = UPPER ADDRESS
;P3 = LOWER ADDRESS
;USES T1, T2

RT.P2::	MOVE	T1,P2		;GET UPPER ADDRESS
	SUB	T1,PH+PH.ADD	;[1400] MINUS BASE
	IDIVI	T1,^D18		;2 BITS PER BYTE
	SKIPE	T2		;REMAINDER?
	ADDI	T1,1		;YES
	SUB	T1,OVLOFF	;INCASE BASE NOT IN CORE
	ADD	T1,RT.LB	;MAKE ABS
	CAMG	T1,RT.AB	;WILL IT FIT?
	JRST	RT.P3		;YES, SET BYTE PTR
	PUSHJ	P,RT.INC	;NO, EXPAND
	JRST	RT.P2		;MAKE SURE ITS OK NOW

;RT.P3 - ROUTINE TO SETUP RT.PT (BYTE PTR TO STORE RELOCATION INFO)
;ENTER WITH
;P3 = LOWER ADDRESS
;USES T1, T2

RT.P3::	MOVE	T1,P3		;GET LOWER ADDRESS
	SUB	T1,PH+PH.ADD	;[1400] MINUS BASE
	IDIVI	T1,^D18		;2 BITS PER BYTE
	SUB	T1,OVLOFF	;INCASE BASE NOT IN CORE
	IOR	T1,RTBTAB(T2)	;GET CORRECT BYTE
	ADD	T1,RT.LB	;MAKE ABS
	MOVEM	T1,RT.PT	;NEW IDPB PTR
	POPJ	P,

	SALL
RTBTAB:	POINT 2,
	ZZ==1
REPEAT ^D17,<
	POINT 2,0,ZZ
ZZ==ZZ+2>

RT.INC::PUSHJ	P,.SAVE2##	;SAVE P1 & P2
	MOVEI	P1,RT.IX	;AREA
	MOVEI	P2,.IPS		;SIZE
	PUSHJ	P,LNKCOR##	;EXPAND
	  PUSHJ	P,E$$MEF##	;[1174] SHOULD NOT HAPPEN
	HRLI	T1,(POINT 2)	;RESET BYTE PTR
	HLLM	T1,RT.PT
	MOVEI	T1,^D18*.IPS	;AND BYTE COUNT
	MOVEM	T1,RT.FR
CPOPJ:	POPJ	P,

SUBTTL	COMMON MESSAGES


;IOWD FOR PREAMBLE SECTION

IFN FTKIONLY,<
PHIOWD::IOWD	PH.ZZ,PH	;[1400]
	0
>

E$$IOV::PUSH	P,[OC]		;[1174]
	.ERR.	(ST,,V%L,L%F,S%F,IOV,<Input error for overlay file>)

E$$OOV::PUSH	P,[OC]		;[1174]
	.ERR.	(ST,,V%L,L%F,S%F,OOV,<Output error for overlay file>)

E$$LNM::.ERR.	(MS,.EC,V%L,L%F,S%F,LNM,<Link number >) ;[1174]
	.ETC.	(DEC,.EC!.EP,,,,P2)
	.ETC.	(STR,,,,,,< not in memory>) ;[1174]

SUBTTL	THE END


	END