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Trailing-Edge - PDP-10 Archives - BB-M080V-SM_1990 - monitor-sources/swpalc.mac
There are 48 other files named swpalc.mac in the archive. Click here to see a list.
; Edit= 9021 to SWPALC.MAC on 8-Nov-88 by LOMARTIRE
;Merge Production changes to BUG text
; Edit= 8940 to SWPALC.MAC on 25-Aug-88 by GSCOTT
;Update BUG. documentation. 
; UPD ID= 8625, RIP:<7.MONITOR>SWPALC.MAC.2,  11-Feb-88 18:36:40 by GSCOTT
;TCO 7.1218 - Update copyright date.
; UPD ID= 2189, SNARK:<6.1.MONITOR>SWPALC.MAC.12,   5-Jun-85 11:08:30 by MCCOLLUM
;TCO 6.1.1406  - Update copyright notice.
; UPD ID= 1989, SNARK:<6.1.MONITOR>SWPALC.MAC.11,  17-May-85 15:59:36 by MCCOLLUM
;TCO 6.1.1238 - Fix more BUG. documentation
; UPD ID= 1934, SNARK:<6.1.MONITOR>SWPALC.MAC.10,   7-May-85 22:46:42 by MCCOLLUM
;TCO 6.1.1238 - Fix BUG. documentation
; UPD ID= 4836, SNARK:<6.MONITOR>SWPALC.MAC.9,  17-Sep-84 11:23:58 by PURRETTA
;Update copyright notice
; UPD ID= 3846, SNARK:<6.MONITOR>SWPALC.MAC.8,   5-Mar-84 09:47:13 by LOMARTIRE
;TCO 6.1955 - Change DRMAM to return +1 on failure, +2 on success
; Prevents ASGSW2 BUGHLTs when swap space is exhausted
; UPD ID= 3078, SNARK:<6.MONITOR>SWPALC.MAC.7,  25-Oct-83 13:06:28 by MILLER
;Fix typeo
; UPD ID= 3068, SNARK:<6.MONITOR>SWPALC.MAC.6,  25-Oct-83 09:58:21 by MILLER
;TCO 6.1839 once again. Must check in DRMASA as well as DRMASN
; UPD ID= 3067, SNARK:<6.MONITOR>SWPALC.MAC.5,  25-Oct-83 09:29:45 by MILLER
;TCO 6.1839. Wake up DDMP if swapping space is low
; UPD ID= 849, SNARK:<6.MONITOR>SWPALC.MAC.4,   6-Jun-82 13:28:14 by MURPHY
;TCO 6.1147 - Move bugdefs from BUGS.MAC to here and put them in-line.
; UPD ID= 1568, SNARK:<5.MONITOR>SWPALC.MAC.3,  19-Feb-81 13:58:26 by HALL
;TCO 5.1180 - MAKE THE BUGHLT IN GDSTX BE PERMANENT, BUT UNDER A
; CONDTIONAL
; UPD ID= 1197, SNARK:<5.MONITOR>SWPALC.MAC.2,  25-Oct-80 12:15:05 by HALL
;TCO 5.1180 - MOVE THE DST INTO NON-ZERO SECTION
;	GDSTX -- RETURN ADDRESS RATHER THAN OFFSET INTO DST
;	SWPINI -- CALL SETDST TO INITIALIZE PAGING STUFF
;<OSMAN.MON>SWPALC.MAC.1, 10-Sep-79 16:05:48, EDIT BY OSMAN
;TCO 4.2412 - Move definition of BUGHLTs, BUGCHKs, and BUGINFs to BUGS.MAC
;<4.MONITOR>SWPALC.MAC.1, 11-Mar-79 12:59:35, Edit by KONEN
;UPDATE COPYRIGHT FOR RELEASE 4

;	COPYRIGHT (c) DIGITAL EQUIPMENT CORPORATION 1976, 1988.
;	ALL RIGHTS RESERVED.
;
;	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 THAT IS NOT SUPPLIED BY DIGITAL.
	SEARCH PROLOG
	TTITLE(SWPALC,,< - SWAPPING SPACE ALLOCATION>)

;SWAP STORAGE ALLOCATOR

;THIS ALLOCATOR HANDLES A DEVICE OF SOME NUMBER (SWPSEC) OF SECTORS,
;AND SOME NUMBER (DRMMXB) OF TRACKS (BANDS). IT HAS A RESIDENT BIT TABLE,
;AND IS USED TO ALLOCATE SWAPPING STORAGE, EVEN IF THE PHYSICAL
;SWAPPING DEVICE IS THE SAME AS THE PHYSICAL FILE DEVICE

;PARAMETERS DRMSEC AND NTRK OF THE PHYSICAL DRUM ARE ALSO USED
;TO DETERMINE THE NUMBER OF PAGES ON THE ACTIVE PHYSICAL DRUMS

;** THE ACTUAL DRUM DRIVER IS ASSEMBLED AHEAD OF THIS ALLOCATOR **


;*** ALLOCATOR ***


EXTN <SWPSEC,DRMMXB,DRMBSZ,NPDRMS,MAXDRA,DRMBND,MDRMBD>
EXTN <DRMTPG,DRMBBT,DRMCNT,DRMBN0,DRMFRE>
EXTN <DRMSEC,NTRK,DRMINI>
;ASSIGN DRUM PAGE, FREE CHOICE
;	CALL DRMASN
; RETURN +1: DRUM FULL
; RETURN +2: PAGE ASSIGNED, A/ DRUM ADDRESS

DRMASN::SKIPG DRMFRE		;ANY SPACE ON DRUM?
	RET			;NO, FAIL
	SE1CAL
	MOVE A,DRMBN0		;GET LAST TRACK ASSIGNED
	SKIPE DRMCNT(A)		;ANY FREE ON THAT TRACK?
	JRST DRMAS3		;YES, GOOD ONE TO USE
	HRLZ A,MDRMBD		;NO, HAVE TO SEARCH. SETUP AOBJN PTR
	SKIPG DRMCNT(A)		;ANY FREE ON THIS TRACK?
	AOBJN A,.-1		;NO
	JUMPGE A,DRMBUG		;JUMP IF COULDN'T FIND ANY SPACE
DRMAS3:	MOVEI A,0(A)		;GET TRACK NUMBER
	MOVEM A,DRMBN0		;REMEMBER LAST TRACK ASSIGNED
	IMULI A,DRMBSZ		;COMPUTE INDEX TO BITS FOR THIS TRACK
	ADDI A,DRMBBT
	HRLI A,400002		;SET UP INDEX INDIRECT OF B
	MOVSI B,-DRMBSZ		;SETUP TO SCAN BIT WORDS
DRMAS2:	SKIPE C,@A		;GET BITS
	JFFO C,DRMAS1		;FREE BIT HERE?
	AOBJN B,DRMAS2		;NO, GO TO NEXT WORD
DRMBUG:	BUG.(HLT,DRMIBT,SWPALC,HARD,<DRMASN - Bit table inconsistent>,,<

Cause:	During the assignment of drum a page, DRMCNT for a track showed there
	was space on that track.  However, there was no free space available 
	according to the bit table for the track. 
>)

DRMAS1:	MOVE C,BITS(D)		;GET THE BIT JUST FOUND
	ANDCAM C,@A		;MAKE IT IN USE
	MOVEI B,0(B)		;GET WORD NUMBER WITHIN TRACK GROUP
	IMULI B,^D36		;COMPUTE SECTOR NUMBER JUST ASSIGNED
	ADDI B,0(D)
	MOVE A,DRMBN0		;RECOVER TRACK NUMBER
	SOS DRMCNT(A)		;UPDATE FREE COUNT OF TRACK
	SOS C,DRMFRE		;UPDATE FREE COUNT OF DRUM
	CAML C,DRMIN0		;Still lots of room left?
	IFSKP.			;If not
	 MOVE C,TODCLK		;Make sure DDMP wakes up
	 MOVEM C,DDTIME		;""
	ENDIF.
	CALL DRMMKA		;MAKE DRUM ADDRESS FROM TRACK AND SECTOR
	RETSKP

;MAKE DRUM ADDRESS FROM TRACK AND SECTOR
; A/ TRACK NUMBER
; B/ SECTOR NUMBER
;	CALL DRMMKA
; RETURN +1: ALWAYS, A/ DRUM ADDRESS

DRMMKA:	IMULI A,SWPSEC		;COMPUTE LINEAR PAGE ADDRESS
	ADD A,B
	CAML A,MAXDRA		;ON OVERFLOW DEVICE?
	JRST [	SUB A,MAXDRA	;YES, FORM ADDRESS ON OVERFLOW DEVICE
	MOVE C,STRTAB	;POINT TO SDB FOR PUBLIC STRUCTURE
		MOVE C,SDBTYP(C) ;POINT TO SIZE DATA FOR THIS DISK TYPE
		IMUL A,SECPAG(C) ;CONVERT TO SECTORS
		TXO A,DRMOB	;INDICATE OVERFLOW
		JRST DRMMK1]
	IDIVI A,DRMSEC		;CONVERT TO PHYSICAL DRUM TRACK AND SECTOR
	STOR A,DRTRK,A		;CONSTRUCT ADDRESS
	STOR B,DRSEC,A
DRMMK1:	TXO A,DRMAB		;INDICATE SWAPPING ADDRESS
	RET
;ASSIGN SPECIFIC DRUM ADDRESS
; 1/ ADDRESS TO BE ASSIGNED
;	CALL DRMASA
; RETURN +1: FAILED, ADDRESS ILLEGAL OR ALREADY ASSIGNED
; RETURN +2: SUCCESSFUL

DRMASA::SE1CAL
	CALL DRMGTS		;GET TRACK AND SECTOR
	 JRST RFALSE		;ILLEGAL ADDRESS
	PUSH P,A		;SAVE TRACK
	IMULI A,DRMBSZ		;COMPUTE INDEX TO PROPER BIT WORD
	IDIVI B,^D36
	ADDI B,0(A)
	POP P,A			;RECOVER TRACK
	MOVE C,BITS(C)		;GET BIT FOR SECTOR
	TDNN C,DRMBBT(B)	;SECTOR NOW FREE?
	JRST RTRUE		;NO. FAIL
	ANDCAM C,DRMBBT(B)	;YES, MARK IT IN USE
	SOS DRMCNT(A)		;UPDATE TRACK FREE COUNT
	SOS C,DRMFRE		;UPDATE DRUM FREE COUNT
	CAML C,DRMIN0		;Now below threshold?
	IFSKP.			;If so
	 MOVE C,TODCLK		;Get now
	 MOVEM C,DDTIME		; so DDMP wakes up ASAP
	ENDIF.
	RETSKP

;LOCAL ROUTINE TO GET TRACK AND SECTOR FROM DRUM ADDRESS
; 1/ DRUM ADDRESS
;	CALL DRMGTS
; RETURN +1: ILLEGAL ADDRESS
; RETURN +2: A/ TRACK NUMBER, B/ SECTOR NUMBER

DRMGTS:	TXZ A,-1B<POS(DRMOB)-1> ;EXTRACT ADDRESS BITS
	TXZE A,DRMOB		;OVERFLOW ADDRESS?
	JRST [	MOVE C,STRTAB	;YES. POINT TO SDB FOR PUBLIC STRUCTURE
		MOVE C,SDBTYP(C) ;POINT TO SIZE DATA FOR THIS DISK TYPE
		IDIV A,SECPAG(C) ;CONVERT TO LINEAR PAGE ADDRESS
		ADD A,MAXDRA	;SWP ADDR BASE FOR OVERFLOW DEVICE
		JRST DRMGT1]
	LOAD B,DRSEC,A		;GET SECTOR
	LOAD A,DRTRK,A		;GET TRACK
	IMULI A,DRMSEC		;COMPUTE LINEAR PAGE ADDRESS
	ADD A,B
DRMGT1:	IDIVI A,SWPSEC		;CONVERT TO TRACK AND SECTOR
	CAML A,DRMBND		;WITHIN RANGE?
	RET			;NO, FAIL
	RETSKP			;YES
;DEASSIGN DRUM ADDRESS
; 1/ DRUM ADDRESS
;	CALL DASDRM
; RETURN +1: ALWAYS (BUGCHK IF BAD OR UNASSIGNED ADDRESS)

DASDRM::SE1CAL
	CALL DEDRM		;DO THE WORK
	 BUG.(CHK,ILDRA1,SWPALC,HARD,<DASDRM - Illegal or unassigned drum address>,,<

Cause:	DASDRM was called to deassign a drum address, but the drum address
	provided by the caller is invalid or already unassigned.

Action:	If this BUGCHK can be reproduced, change it to a BUGHLT and submit an
	SPR along with instructions on reproducing the problem.
>)
	RET

;DEASSIGN DRUM ADDRESS
; 1/ DRUM ADDRESS
;	CALL DEDRM
; RETURN +1: BAD OR UNASSIGNED DRUM ADDRESS
; RETURN +2: SUCCESS, ADDRESS DEASSIGNED

DEDRM::	SE1CAL
	CALL DRMGTS		;GET TRACK AND SECTOR FROM ADDRESS
	 RET			;ILLEGAL ADDRESS, FAIL
	PUSH P,A		;SAVE TRACK
	IMULI A,DRMBSZ		;COMPUTE INDEX TO PROPER BIT WORD
	IDIVI B,^D36
	ADDI B,0(A)
	POP P,A			;RECOVER TRACK
	MOVE C,BITS(C)		;GET BIT FOR SECTOR
	TDNE C,DRMBBT(B)	;NOW ASSIGNED?
	RET			;NO, FAIL
	IORM C,DRMBBT(B)	;MARK IT FREE
	AOS DRMCNT(A)		;UPDATE TRACK FREE COUNT
	AOS DRMFRE		;UPDATE DRUM FREE COUNT
	RETSKP
;ASSIGN MULTIPLE CONTIGUOUS DRUM ADDRESSES
; 1/ NUMBER OF CONTIGUOUS PAGES DESIRED
;	CALL DRMAM
; RETURN +1: FAILURE, DRUM IS FULL
;	 +2: SUCCESS, WITH:
;  A/ NUMBER OF CONTIGUOUS PAGES ACTUALLY FOUND
;  B/ ADDRESS OF FIRST OF GROUP OF CONTIGUOUS PAGES

;PAGES ARE NOT ACTUALLY ASSIGNED HERE, CALLER MUST ASSIGN PAGES
;INDIVIDUALLY AS THEY ARE SUBSEQUENTLY USED

;AC USAGE:
; Q1 - AOBJN PTR TO SCAN TRACKS
; Q2 - DESIRED N FROM CALLER
; Q3 - MAX CONTIGUOUS PAGES FOUND SO FAR
; P1 - TRACK,,SECTOR  OF FIRST PAGE OF BEST CONTIGUOUS GROUP

DRMAM::	SKIPG DRMFRE		;ANY SPACE ON DRUM?
	RET			;NO, FAIL
	SE1CAL
	PUSH P,Q1
	PUSH P,Q2
	PUSH P,Q3
	PUSH P,P1
	MOVEM A,Q2		;SAVE DESIRED COUNT
DRMAM6:	HRLZ Q1,MDRMBD		;SETUP TO SCAN TRACKS
	SETZ Q3,		;INIT MAX
DRMAM2:	CAMG Q2,DRMCNT(Q1)	;ENOUGH FREE PAGES THIS TRACK FOR REQUEST?
	JRST DRMAM3		;YES, GO CHECK IT
DRMAM4:	AOBJN Q1,DRMAM2		;LOOP OVER TRACKS
	JUMPG Q3,DRMAM5		;JUMP IF HAVE FOUND SOMETHING
	ASH Q2,-1		;FOUND NO TRACK WITH N, REDUCE N
	JUMPG Q2,DRMAM6		;TRY AGAIN UNLESS N NOW 0
	BUG.(HLT,DRMNFR,SWPALC,HARD,<DRMAM - Cannot find page when DRMFRE non-0>,,<

Cause:	During assignment of multiple contiguous drum addresses, DRMFRE said
	there was space on the drum.  However, none of the DRMCNT's for each
	track showed any free space.
>)

;HERE WHEN HAVE A TRACK WITH .GE. N FREE PAGES.  PAGES MAY OR MAY NOT
;BE CONTIGUOUS HOWEVER.

DRMAM3:	CALL DRMBG		;GET MAX CONTIGUOUS GROUP ON THIS TRACK
	CAMLE A,Q3		;BEST GROUP SO FAR?
	JRST [	MOVEM A,Q3	;YES, SAVE COUNT
		MOVEM B,P1	;SAVE SECTOR NUMBER
		HRLM Q1,P1	;SAVE TRACK NUMBER
		JRST .+1]
	CAMGE Q3,Q2		;ENOUGH TO SATISFY REQUEST?
	JRST DRMAM4		;NO, KEEP LOOKING
DRMAM5:	HLRZ A,P1		;GET TRACK
	HRRZ B,P1		;GET SECTOR
	CALL DRMMKA		;MAKE DRUM ADDRESS
	MOVE B,A		;RETURN IT IN B
	MOVE A,Q3		;GET COUNT TO RETURN
DRMAMX:	POP P,P1
	POP P,Q3
	POP P,Q2
	POP P,Q1
	RETSKP			;RETURN SUCCESS
;LOCAL ROUTINE TO FIND LARGEST CONTIGUOUS CLUSTER OF PAGES ON
;A TRACK.
; Q1/ TRACK NUMBER
;	CALL DRMBG
; RETURN +1: ALWAYS,
;  A/ MAX NUMBER OF CONTIGUOUS PAGES FOUND
;  B/ SECTOR NUMBER OF FIRST PAGES OF GROUP

;AC USAGE:
; A/ NUMBER OF BITS LEFT TO EXAMINE IN CURRENT WORD
; B/ CURRENT BIT WORD
; C/ RESULT OF JFFO
; D/ NUMBER OF CONTIGUOUS BITS FOUND IN THIS GROUP
; Q1/ AOBJN PTR TO LOOP THROUGH ALL BIT WORDS FOR THIS TRACK
; Q2/ LH: SECTOR NUMBER OF FIRST SECTOR OF BEST GROUP SEEN
;     RH: SECTOR NUMBER OF FIRST SECTOR OF CURRENT GROUP
; P1/ NUMBER OF CONTIGUOUS BITS IN BEST GROUP SEEN SO FAR

DRMBG:	PUSH P,Q1
	PUSH P,Q2
	PUSH P,P1
	MOVEI Q1,0(Q1)		;GET TRACK NUMBER
	IMULI Q1,DRMBSZ		;COMPUTE INDEX TO BITS WORDS FOR THIS TRK
	HRLI Q1,-DRMBSZ		;CONSTRUCT AOBJN PTR
	SETZB Q2,P1		;INIT MAX COUNT AND SECTOR NUMBER
	SETZ D,			;INIT CURRENT COUNT
DRMBG3:	MOVE B,DRMBBT(Q1)	;GET BIT WORD
	MOVEI A,^D36		;WE HAVE 36 BITS TO EXAMINE IN THIS WORD
DRMBG2:	SETCA B,		;COMPLEMENT SO JFFO WILL FIND 0'S
	JFFO B,.+2		;SKIP OVER 1'S TO FIND FIRST 0
	MOVEI C,0(A)		;NO 0'S, REST OF WORD IS 1'S
	ADD D,C			;ADD COUNT TO COUNT FROM PREVIOUS WORDS
	CAMLE D,P1		;MAX COUNT SEEN SO FAR?
	JRST [	MOVEM D,P1	;YES, REMEMBER IT
		HRLM Q2,Q2	;AND REMEMBER FIRST SECTOR NUMBER
		JRST .+1]
	SUB A,C			;REDUCE BIT COUNT BY BITS JUST PASSED
	JUMPLE A,DRMBG1		;JUMP IF NO MORE BITS IN THIS WORD
	SETCA B,		;GET TRUE WORD BACK
	LSH B,0(C)		;SHIFT OUT BITS JUST PASSED
	ADDM D,Q2		;UPDATE SECTOR NUMBER FOR BITS NOW PASSED
	SETZ D,			;SET NO BITS IN PREVIOUS WORD
	JFFO B,.+2		;SKIP 0'S TO FIND A 1
	MOVEI C,0(A)		;NO 1'S IN REST OF WORD
	SUB A,C			;REDUCE BIT COUNT BY BITS JUST PASSED
	ADDM C,Q2		;UPDATE SECTOR NUMBER FOR BITS JUST PASSED
	LSH B,0(C)		;SHIFT OUT 0'S JUST PASSED
	JUMPG A,DRMBG2		;JUMP IF MORE BITS IN THIS WORD
DRMBG1:	AOBJN Q1,DRMBG3		;LOOK AT ALL BIT WORD FOR THIS TRACK
DRMBG4:	MOVE A,P1		;GET MAX COUNT SEEN
	HLRZ B,Q2		;GET SECTOR NUMBER
	POP P,P1
	POP P,Q2
	POP P,Q1
	RET
;CONVERT DRUM ADDRESS INTO INDEX INTO DST


; 2/ DRUM ADDRESS
;	CALL GDSTX
; RETURN +1: ALWAYS, 2/ ADDRESS WITHIN DST
;PRESERVES T1 AND T4

GDSTX::	

;IF THE CALLER OF THIS ROUTINE IS RUNNING IN SECTION 0 ON AN EXTENDED
;ADDRESSING MACHINE, THERE MAY BE TROUBLE LATER WHEN THE CALLER USES
;THE ADDRESS RETURNED BY THIS ROUTINE. THIS ROUTINE RETURNS AN ADDRESS
;IN A NON-ZERO SECTION, AND THE CALLER PROBABLY DOES AN INDEXED REFERENCE
;TO THAT ADDRESS. IN SECTION 0, THE LEFT HALF OF THE AC WILL BE IGNORED.
;THE CODE UNDER THE CONDTIONAL TESTS FOR THIS CASE AND BUGHLT'S, THUS
;AVERTING LATER DISASTER.

   IFN SEC0SW,<			;IF TESTING FOR RUNNING IN SECTION 0
	MOVX CX,VSECNO		;GET SECTION NUMBER MASK FOR PC
	TDNN CX,0(P)		;CHECK THE CALLING PC
	BUG.(HLT,GDSTX0,SWPALC,SOFT,<GDSTX Called from section 0>,<<0(P),PC>>,<

Cause:	A routine in SWPALC that provides an address in the DST was called from
	section 0 on a machine that runs extended addressing.  This is
	dangerous because the routine returns a 30-bit address, and the caller
	will probably use the address in an index register, thus losing the
	section number.

	It is essential that any code that references the DST run in a non-zero
	section.  The long-term solution is to study the entire stack and make
	all the code run in section 1.  For the short term, it may be possible
	to insert an SE1CAL at the beginning of the routine that called GDSTX.
	Note that this may lead to other problems, including slower performance
	and ILMNRF BUGHLTs.

Action:	If this BUGCHK can be reproduced, change it to a BUGHLT and submit an
	SPR along with instructions on reproducing the problem.

Data:	PC - the PC from which GDSTX was called

>)
>				;END OF IFN SEC0SW

	TLNN 2,14		;INSIST ON REGULAR DRUM ADDRESS
	TLNN 2,2
	BUG.(HLT,ILGDA1,SWPALC,SOFT,<GDSTX - Bad address>,,<

Cause:	A bad drum address was given to the GDSTX routine, which converts drum
	address into indexes into the DST table.  Consequently, the GDSTX
	routine did not try to compute the index.
>)
	TXZ 2,-1B<POS(DRMOB)-1> ;EXTRACT ADDRESS BITS
	TXZE 2,DRMOB		;AN OVERFLOW ADDRESS?
	JRST [	MOVE C,STRTAB	;YES. POINT TO SDB FOR PUBLIC STRUCTURE
		MOVE C,SDBTYP(C) ;POINT TO SIZE DATA FOR THIS DISK TYPE
		IDIV 2,SECPAG(C) ;CONVERT TO PAGE UNITS
		ADD 2,MAXDRA	;SWP ADDR BASE FOR OVERFLOW DEVICE
		JRST GDSTX1]
	LOAD C,DRSEC,B		;GET SECTOR
	LOAD B,DRTRK,B		;GET TRACK
	IMULI B,DRMSEC		;COMPUTE LINEAR PAGE ADDRESS
	ADD B,C
GDSTX1:	CAIL 2,NDST
	BUG.(HLT,ILGDA2,SWPALC,SOFT,<GDSTX - Bad address>,,<

Cause:	Bad index into the DST was computed from a drum address that was given
	to GDSTX for conversion.
>)
	ADD 2,DSTLOC		;MAKE IT AN ADDRESS
	RET

;INCREMENT DRUM ADDRESS - USED TO GET NEXT ADDRESS IN GROUP WHEN
;CONSTRUCTING MULTIPLE-PAGE SWAP
; 1/ DRUM ADDRESS
;	CALL DRMIAD
; RETURN +1: ALWAYS, A/ DRUM ADDRESS 1 PAGE BEYOND ARGUMENT

DRMIAD::SE1CAL
	CALL DRMGTS		;GET TRACK AND SECTOR
	 BUG.(HLT,ILDRA2,SWPALC,SOFT,<DRMIAD - Illegal drum address>,,<

Cause:	AN illegal drum address was given to the DRMIAD subroutine, which
	computes disk tracks and sectors.
>)
	ADDI B,1		;INCREMENT SECTOR
	CAIL B,SWPSEC		;BEYOND END OF TRACK?
	JRST [	SETZ B,		;YES, RESET TO SECTOR 0
		AOJA A,.+1]	;GO TO NEXT TRACK
	CALLRET DRMMKA		;RECONSTRUCT ADDRESS AND RETURN
;ROUTINE TO INITIALIZE BIT TABLE FOR A TRACK
; A/ TRACK NUMBER
;	CALL DRMTKI
; RETURNS +1: ALWAYS, ALL PAGES ON TRACK SET FREE

DRMTKI:	MOVEI B,SWPSEC		;INIT COUNT FOR TRACK
	MOVEM B,DRMCNT(A)
	IMULI A,DRMBSZ		;COMPUTE INDEX TO FIRST WORD OF BITS
	ADDI A,DRMBBT
	HRLI A,400002		;SET UP INDIRECT B
	MOVSI B,-DRMBSZ		;SETUP AOBJN PTR TO INIT ALL BIT WORDS
	SETOM @A		;SET ALL PAGES FREE IN THIS WORD
	AOBJN B,.-1
	MOVEI B,SWPSEC
	IDIVI B,^D36		;COMPUTE NUMBER BITS IN LAST WORD
	JUMPE C,R		;PERHAPS NONE
	MOVNI B,-1(C)		;SETUP TO CONSTRUCT BIT WORD
	MOVX C,1B0		;GET A BIT
	ASH C,0(B)		;REPLICATE IT
	MOVEI B,DRMBSZ-1	;MAKE PTR TO LAST BIT WORD
	MOVEM C,@A		;SET LAST (PARTIAL WORD
	RET

;ROUTINE TO ASSIGN ALL PAGES FOR A TRACK IN CASE TRACK BAD
; A/ TRACK NUMBER
;	CALL DRMTLK
; RETURN +1: ALWAYS, TRACK SET TO 0 FREE

DRMTLK:	SETZM DRMCNT(A)		;SET COUNT TO 0
	IMULI A,DRMBSZ		;GET PTR TO FIRST WORD OF BITS
	ADDI A,DRMBBT
	HRLI A,400002		;SET UP FOR @A
	MOVSI B,-DRMBSZ		;SETUP TO REF ALL BIT WORDS
	SETZM @A		;CLEAR ALL BITS
	AOBJN B,.-1
	RET
;INITIALIZE DRUM BIT TABLES

SWPINI::
	CALL SETDST		;SET UP THE SECTION MAP AND DSTLOC
	SETZM NPDRMS		;DECLARE 0 PHYSICAL UNLESS DRMINI CHANGES
	CALL DRMINI		;INIT DEVICE DRIVER, COUNT PHYSICAL UNITS
	MOVE A,NPDRMS		;GET NUMBER OF PHYSICAL UNITS
	IMULI A,NTRK*DRMSEC	;COMPUTE NUMBER OF PAGES OF PHYS UNITS
	MOVEM A,MAXDRA		;IT MARKS BOUNDARY BETWEEN DRUM AND DISK SWAP
	CALL DRMISP		;INIT STORAGE PARAMETERS
	HRLZ D,MDRMBD		;SETUP TO INIT ALL TRACKS
	MOVEI A,0(D)		;GET TRACK NUMBER
	CALL DRMTKI		;INIT THE TRACK
	AOBJN D,.-2
	MOVE A,DRMTPG		;GET TOTAL NUMBER PAGES ON DRUM
	CAILE A,NDST		;CHECK AGAINST DST
	BUG.(HLT,DST2SM,SWPALC,SOFT,<SWPINI - DST too small>,,<

Cause:	There are more pages for swapping than there are entries in the DST.

Action:	Either rebuild the monitor after changing STG.MAC to have a larger
	value for NDST or use a boot structure with less swapping pages.
>)
	MOVEM A,DRMFRE
	CALL SETSSP		;SETUP LIMITS BASED ON DRUM SPACE
	SKIPG DRUMP		;REAL DRUM ON SYSTEM?
	RET			;NO, DON'T ASSIGN RESERVED ADDRESSES
	PUSH P,Q1
	MOVSI Q1,-NDRMBA	;SETUP TO ASSIGN BAD ADDRESSES
DRMIN2:	MOVE A,DRMBAT(Q1)	;GET A BAD ADDRESS
	JUMPL A,DRMIN1		;JUMP IF END OF LIST
	CALL DRMASA		;ASSIGN THE ADDRESS
	 BUG.(CHK,ASGSWB,SWPALC,SOFT,<SWPINI - Cannot assign bad address>,,<

Cause:	Cannot assign bad drum address because it is an illegal address or
	already assigned.

Action:	There could be a problem with the boot structure on this system.  If
	this problem is reproducable with a healthy boot structure, and this
	BUGCHK can be reproduced, change it to a BUGHLT and submit an SPR along
	with instructions on reproducing the problem.
>)
	AOBJN Q1,DRMIN2
DRMIN1:	POP P,Q1
	RET

;SETUP SWAP STRUCTURE PARAMETERS BASED ON NDST

DRMISP:	MOVEI A,NDST		;GET MAX NUMBER PAGES FOR SWAPPING
	MOVE B,NSSUN		;GET # OF DISK SECTORS RESERVED
	MOVE C,STRTAB		;POINT TO SDB FOR PUBLIC STRUCTURE
	MOVE D,SDBTYP(C)	;POINT TO SIZE DATA FOR THIS DISK TYPE
	IDIV B,SECPAG(D)	;CONVERT NUMBER SWAP SECTORS TO PAGES
	MOVE C,STRTAB		;POINT TO SDB FOR PUBLIC STRUCTURE
	IMUL B,SDBNUM(C)	;GET TOTAL DSK PAGES RESERVED
	ADD B,MAXDRA		;ADD DRUM PAGES AVAILABLE
	CAMLE A,B		;GET MINIMUM AMOUNT
	MOVE A,B		;LIMITED TO SPACE RESERVED ON DISK & DRUM
	MOVEM A,DRMTPG		;SAVE TOTAL DRUM PAGES
	IDIVI A,SWPSEC		;COMPUTE TOTAL NUMBER TRACKS
	MOVEM A,DRMBND
	MOVNM A,MDRMBD		;KEEP NEGATIVE ALSO FOR CONVENIENCE
	RET

;BAD AND RESERVED ADDRESS TABLE

DRMBAT:	-1			;MARK END OF LIST
	BLOCK 6			;PATCH SPACE FOR ADDITIONAL BAD ADRS
NDRMBA==.-DRMBAT

	TNXEND			;BUGSTRINGS, ETC.
	END