/******** VIRTUAL DISK HANDLER ********
/LAST EDIT: 23-MRT-76, ELC (DSK0 REMOVED, RENAMED RKB0=DSK0)
/LAST EDIT:  5-AUGUST-75, JV
/CREATED: 27-JULY-75, JV

/THIS HANDLER IMPLEMENTS 8 VIRTUAL DISKS. THESE ARE
/FILES, WHICH ARE USED AS FILE-STRUCTURED DEVICES.
/
/THE FILES MUST BE ON SYS, OR ON A DEVICE WHOSE HAND-
/LER IS CORESIDENT WITH SYS (LIKE RKB0). FIRST A
/LOOKUP IS DONE TO THE FILE, THEN THE STARTING BLOCK
/OF THE FILE IS ADDED TO THE REQUESTED BLOCK NUMBER.
/ONCE FOUND, THE STARTING BLOCK IS REMEMBERED, THUS
/NO SECOND LOOKUP IS NEEDED. HOWEVER, WHEN TRANSFER-
/ING DATA FROM ONE VIRTUAL DISK TO ANOTHER, ANY NEW
/CALL TO THIS HANDLER CAUSES A NEW LOOKUP TO BE DONE.
/
/THE PROBLEM IS, THAT THE FIRST CALL TO THIS HANDLER
/WILL COME IN MOST OF THE CASES FROM OR VIA USR.
/IF THE CALLER HAS SAVED CORE TO GET USR, WE CANNOT
/USE THE DISK AGAIN FOR SAVING HIS VERSION OF USR.
/THUS THESE HANDLERS WORK ONLY IF BIT 11 OF THE JSW0000-11777 ARE SAVED, ANKUP THE FILE DSKN.M8 ON  ON RKB0 (N IS THE REQUERETURN FROM USR, 10000-11777 IS WRITTEN BACK.
/IF THE FILE IS NOT FOUND, THE ERROR RETURN IS TAKEN.
/
/THESE HANDLERS PROVED TO WORK PROPERLY FOR MOST
/OS/8 V3 PROGRAMS (PIP,EDIT,PAL8,ABSLDR,FOTP,DIRECT,
/RESORCBOOT,FORT,SABR,E.O. IT
ELY THROUGH THE ERROR RERAMS: ASK THE AUTHOR OF  OF THE JSW MAY BE A 1.

VERSION=1
RK8E=1	/IF NO RK8E, DO NOT DEFINE RK8E !
/NOTEST=1/DEFINE IT, IF YOU DON'T LIKE A LENGTH TEST

/DIRECTIONS FOR CHANGES IN NAMES:
/FILENAMES:	SEE LABEL DKFILN
/   NOTE: CHAR 3 MUST BE "K", CHAR 4 AN OCTAL DIGIT !
/DEVICE NAMES:	SEE NEXT PAGE (PAGE ZERO) OR WITH THE
/		BUILD COMMAND $NA DSK1=...
/DEVICE RKB0:	SEE LABEL DKDVNR, AND PREV. LOCAT.
	*0
	-7		/7 DEVICE HANDLERS

	DEVICE VDSK	/GROUP NAME IS VDSK (VIRTUAL
	DEVICE DSK1	/DISK)
	4510		/FILE#STRUCTURED, DEV # 51
	DSK1		/ENTRYPOINT OFFSET
	ZBLOCK 2

	DEVICE VDSK
	DEVICE DSK2
	4520
	DSK2
	ZBLOCK 2

	DEVICE VDSK
	DEVICE DSK3
	4530
	DSK3
	ZBLOCK 2

	DEVICE VDSK
	DEVICE DSK4
	4540
	DSK4
	ZBLOCK 2

	DEVICE VDSK
	DEVICE DSK5
	4550
	DSK5
	ZBLOCK 2
	DEVICE VDSK
	DEVICE DSK6
	4560
	DSK6
	ZBLOCK 2

	DEVICE VDSK
	DEVICE DSK7
	4570
	DSK7
	ZBLOCK 2


/WE MAKE USE OF THE FACT, THAT THE SECOND 12-BIT
/WORD OF FILENAME DSK#.M8 IS EQUAL TO 13 TAD DSK#, IF DSK1 IS ATUNIT = - (TAD DSK#) = - 0		/HOLDS RETURN ADDRESS ETC.
DSK2,	ISZ DKUNIT
DSK3,	ISZ DKUNIT
DSK4,	ISZ DKUNIT
DSK5,	ISZ DKUNIT
DSK6,	ISZ DKUNIT
DSK7,	ISZ DKUNIT
	CLA CLL
	TAD DKUNIT
DKJMP,	JMP DKSTRT
*200
DKJSW,	JSW		/MUST BE AT 200 (FOR DK3600)
JSW=7746	/	-TAD-DSK7	/6411=-1367
	DCA DKTAD
	TAD (-TAD-DXT CALL.
	DCA DKUNIT
	D DKTAD
	DCA DKDCA
DKTAD,	  HLT		/TAD DSK#
	DCA DSK0	/DSK0 WILL POINT TO DTV
	TAD (ISZ DKUNIT
DKDCA,	  HLT		/RESET DSK# FOR NEXT CALL.
	TAD I DSK0
	ISZ DSK0
	DCA DKFUNC	/TRANSFER DTV TO THIS PAGE
	TAD I DSK0
	ISZ DSK0
	DCA DKADDR	/THAT'S 2
	TAD I DSK0
	ISZ DSK0	/POINTS TO ERROR RETURN
	DCA DKBLCK	/THAT'S 3
	RDF
	TAD DK6203	/PREPARE RETURN
	DCA DKEXIT
	CDF 10
	TAD I (7700	/17700 MAY HOLD SPECIAL CODE.
DK6203,	CDF CIF 0
	DCA DKTEM
DKTEM=DKDCA
	TAD DKTAD	/"TAD DSK#" = 1360+# =  "K#"
	CIA
	TAD DKFILN+1	/GET LAST FILE WE LOOKED UP
	SNA CLA		/IS IT THE SAME ONE ?
			/(FIRST TRY MUST ALWAYS FAIL)
	 JMP DKSECN	/YES, THAT'S EASY (NO LOOKUP)
	TAD I DKJSW	/JOB STATUS WORD
	CLL RAR		/BIT 11 TO LINK
	SNL
	 JMP DKEREX	/THIS IS TOO DANGEROUS
	CLL RAL		/SET BACK WITH BIT 11 ZERO
DK3600,	DCA I DKJSW	/SO THAT USR WILL SAVE CORE
	TAD DKTAD
	DCA DKFILN+1	/THE BIG DEAL
	JMS DKSETP	/PUT THE REAL ADDRESS OF
			/FILPTR IN SETPTR. (RELOCAT.)
DKFILN,	FILENA NAMES LOOKED UP
DKSETTH REAL ADDRESS
IFDEF R7700
	   10		/USRIN, LOAND HANDLER TO 7607 (SYS:)
	DCA DKHAND
	CLA IAC		/SET DEV # TO 1
	DCA DKDVNR	>
DKRTRY,	TAD DKSETP	/TAD (DKFILN
	DCA DKFBLK
IFDEF RK8E <
	TAD DKDVNR	/FOR RK8E: TRY SYS: AND RKB0:
	CIF 10
	JMS I (200	/USR IS I	/FOR NON-RK8E IT'S EASIYS HAS DEVICE # 1
	CIF S AND
	JMS I (7700	/RES	   2		/LOOKUP
DKFBLK,	   DKFILN	/OVERLAYED BY STARTING BLOCK
DKFILG,	   0		/OVERLAYED BY MINUS LENGTH.
IFDEF RK8E <
	 JMP DKRKB0	/TRY RKB0: OR GIVE ERROR >
IFNDEF RK8E <
	 JMP DKERST	/NOT FOUND: ERROR. >
	JMS DKRSET
DKSECN,
IFNDEF NOTEST <		/TEST MAY BE OMITTED BY DE-
	TAD DKFUNC	/FINING NOTEST >
	TAD (7700
	AND DK3600
	CLL RTL		/FIRST GET # OF BLOCKS
	RTL
	RTL		/ONE BLOCK TOO FEW, LINK=0
	TAD DKBLCK
	TAD DKFILG
	SZL CLA		/USE IT AS CONSTANT !
	 JMP DKEREX	/DON'T GO OUTSIDE FILE >
	TAD DKBLCK
	TAD DKFBLK	/ADD STARTING BLOCK OF FILE
	DCA DKBLCK
	JMS I DKHAND	/SYSTEM HANDLER, (OR RKB0:)
DKFUNC,	   0		/HERE THE CALLING SEQUENCE
DKADDR,	   0		/IS COPIED.
DKBLCK,	   0		/THE BLOCK # SPECIFIED + THE
			/START. BLOCK # OF THE FILE.
	 JMP DKEREX	/ERROR ON SYSTEM DEVICE !!
	ISZ DSK0
DKEXIT,	  HLT		/RETURN, CDF CIF CALL. FLD.
	JMP I DSK0
IFDEF RK8E <
DKRKB0,	STA
	TAD DKDVNR	/IS THIS THE FIRST TRY ?
	SZA CLA
	 JMP DKERST	/BOTH SYS: AND RKB0: FAT KNOW THE INTERNAL
	JMB0.
	   12		/INQUIRE
/003-1	/DSK0: (RENAME RKBOVERLAYED BY DEVICE NUMBER
DKHAND,	   7607		/OVERLAYED BY 7621 FOR RKB0
	 JMP DKERST	/RKB0: NOT FOUND, ERROR RETURN
	JMP DKRTRY	/NOW RKB0NR MUST BE NONZERO >

DKERST,JMS DKRSET	/ERROR WHEN DATA NEED BE RESET
	DCA DKFILN+1	/NEXT ONE MUST LOOKUP AGAIN!
DKEREX,	STA
	JMP DKEXIT

DKRSET,	0
IFDEF RK8E <
	CIF 10
	JMS I (200
	   11		/USROUT, GET CORE AGAIN >
	ISZ I DKJSW
	TAD DKTEM
	CDF 10
	DCA I (7700	/THIS LOCATION MAY HOLD DATA
	CDF 0
	JMP I DKRSET
IFNDEF RK8E <
DKHAND,	7607		>

O=DSK0	/DON'T FORGET LOCATIONS 360-371
O=DKJMP	/ARE ALREADY IN USE AS ENTRY POINTS !

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