Type ASSEMBLE
Source Lines : 1,277
Fixes Applied : 5
Most Recent Version : Tuesday, December 12, 1978
Last Fix ID : [HRC004DS]
Module
DMSROS
Function
TO ALLOW CMS TO ACCESS, STATE, READ, NOTE, POINT AND
BACKSPACE DATA SETS RESIDING ON O/S DISKS.
Attributes
SERIALLY REUSABLE, CORE RESIDENT ONLY WHEN AN OS DISK
IS ACCESSED
Operation
ROSACC: FINALIZE ACCESS OF AN O/S DATA SET
ROSACC GETS CONTROL FROM DMSACM ONCE IT IS DETERMINED THAT
THE LABEL OF THE DISK BELONGS TO AN O/S - DISK. THE ROSACC
ROUTINE WILL READ THE FORMAT 4 DSCB OF THE DISK TO FURTHER
VERIFY THE VALIDITY OF THE O/S DISK. THE ADT IS UPDATED TO
CONTAIN THE ADDRESS OF THE HIGH EXTENT OF THE VTOC (IF THE
DISK IS DOS), OR THE ADDRESS OF THE LAST ACTIVE FORMAT ONE
DSCB (IF THE DISK IS O/S), THE NUMBER OF CYLINDERS IN THE
DISK, AND IF THE DISK IS A DOS FORMATTED DISK, A FLAG IS
SET IN THE ADT. INFORMATION MESSAGES ARE ISSUED TO NOTIFY
THE USER THE DISK HAS BEEN ACCESSED IN READ-ONLY MODE, AND
IF THE DISK IS ALREADY ACCESSED AS ANOTHER DISK, ANOTHER
INFORMATION MESSAGE IS ISSUED TO THAT EFFECT. FINALLY THE
ADTFLG1 FLAG IN THE ADT IS ZEROED, THE ADTFLG2 FLAG IS SET
TO REFLECT THAT AN O/S DISK HAS BEEN ACCESSED, AND CONTROL
RETURNS TO THE CALLER.
ROSSTT: VERIFY EXISTENCE OF AN O/S OR DOS DATA SET AND TO
VERIFY THAT THE ATTRIBUTES OF THE DATA SET ARE
SUPPORETED UNDER CMS.
ROSSTT GETS CONTROL FROM DMSSTT ONCE IT IS DETERMINED THAT
THE STATE OPERATION IS TO AN O/S OR DOS FORMATTED DISK.
THE ROSSTT ROUTINE WILL SEARCH FOR A MATCHING CMSCB OR DOSCB
ASSOCIATED TO THE DATA SET VIA A PREVIOUS FILEDEF OR DLBL.
THEN ROSSTT TRIES TO FIND IF THERE IS AN ACTIVE OSFST ASSO-
CIATED WITH THE DATA SET. IF AN ACTIVE ONE IS FOUND, CONTROL
THEN PASSES TO ROSSTRET, OTHERWISE THE DSNAME BLOCK IS BUILT,
ITS ADDRESS IS PLACED IN THE CMSCB OR DOSCB, AS MAY BE, AND
THE DATA SET NAME IS MOVED TO THE ACQURED BLOCK. THEN AN
OSFST BLOCK IS ACQUIRED AND IS CHAINED TO THE OSFST CHAIN.
THE ADDRESS OF THE OSFST BLOCK IS THEN PLACED IN THE CMSCB
OR DOSCB AS MAY BE THE CASE. SOME FIELDS IN THE OSFST ARE
INITIALIZED (DATA SET NAME, DISK ADDRESS, AND DISK MODE).
NOW, THE FORMAT 1 DSCB FOR THE DATA SET IS READ AND A CHECK
IS MADE FOR UNSUPPORTED OPTIONS ( READ PROTECT, BDAM, AND
ISAM ). ERRORS CAUSE CONTROL TO BE PASSED TO THE CALLING
ROUTINE WITH AN ERROR CODE. ALL EXTENTS OF THE DATA SET ARE
GROUPED TOGETHER (BY READING THE FORMAT 3 DSCB IF NECESSARY)
AND ARE CHECKED FOR VALIDITY. IF ANY USER LABELS EXITS, THEY
ARE BYPASSED AND A MESSAGE IS ISSUED TO THAT EFFECT.
NEXT, IF THE CMS/DOS ENVIRONMENT IS NOT ACTIVE, THE FORMAT 1
LABEL FIELDS BLKSIZE, LRECL AND RECFM ARE MOVED TO THE OSFST
AND CONTROL PASSES TO ROSSTRET.
ROSSTRET: IF THE DISK IS NOT A DOS
DISK CONTROL IS PASSED BACK TO THE CALLER. IF THE SPECIFIED
DISK IS A DOS DISK, OS FST BLKSIZE, LRECL AND RECFM
FIELDS THAT WERE NOT SPECIFIED IN THE DSCB1 ARE FILLED IN
FROM THE CMSCB OR, IF THE CMSCB FIELDS ARE ZERO, THEY
ARE DEFAULTED TO BLKSIZE= 32760, LRECL= 32760 AND RECFM= U.
CONTROL IS THEN RETURNED TO THE CALLER.
ROSRPS: READ NEXT RECORD OF OS DATA SET
UPON ENTRY TO THE ROSRPS ENTRY POINT, THE READ ROUTINE
CALLS CHKXTNT AND, IF THE CURRENT CCHHR IS XERO, SETXTNT
TO INSURE THE CCHHR AND EXTENT BOUNDARIES ARE SET CORRECT.
IT THEN CALLS DISKIO AND IF NECESSARY CHKSENSE AND
GETALT TO READ THE NEXT RECORD. IF THERE ARE NO ERRORS
OR IF AN UNRECOVERABLE ERROR WAS ENCOUNTERED, CONTROL
IS RETURNED TO THE USER WITH EITHER A ZERO (I/O OK)
OR AN EIGHTY (I/O ERROR) IN REG15. IF A RECOVERABLE
ERROR IS ENCOUNTERED, THE CCW'S AND BUFFER POINTERS
ARE UPDATED AS NECESSARY AND CHKXTNT AND DISKIO
ARE RECALLED TO READ THE NEXT RECORD.
ROSFIND: SET CCHHR TO POINT TO MEMBER SPECIFIED IN
FCBMEMBR OR, IF FCBMVPDS BIT IS ON, SET CCHHR
TO POINT TO NEXT MEMBER HIGHER THAN FCBMEMBR
AND SET NEW MEMBER NAME IN FCBMEMBR.
UPON ENTRY, ROSFND SETS UP A CCW TO SEARCH FOR A HIGHER
MEMBER NAME IF THE FCBMVPDS BIT IS ON OR AN EQUAL
MEMBER NAME IF THE FCBMVPDS BIT IS NOT ON. IT
THEN CALLS SETXTNT, DISKIO AND IF NEEDED CHKSENSE,
AND GETALT TO READ IN THE DIRECTORY BLOCK THAT CONTAINS
THE MEMBER NAME REQUESTED. AFTER THE BLOCK HAS BEEN
READ, IT IS SEARCHED FOR THE REQUESTED MEMBER NAME.
IF THE MEMBER NAME IS NOT FOUND, AN ERROR CODE 4 IS
PASSED BACK TO THE CALLER. IF AN I/O ERROR IS EN-
COUNTERED TRYING TO READ THE PDS BLOCK, AN ERROR
CODE 8 IS PASSED BACK TO THE CALLER. IF THE MEMBER
NAME IS FOUND, TTRCNVRT IS CALLED TO CONVERT THE
RELATIVE TRAK ADDRESS TO A CCHH AND THE ADDRESS OF THE
MEMBER ENTRY IS PASSED BACK TO THE CALLER.
ROSNTPTB: GET CURRENT TTR, SET CURRENT CCHHR TO TTR,
BACKSPACE TO PREVIOUS RECORD
UPON ENTRY TO ROSNTPTB, A CHECK IS MADE TO
SEE IF A NOTE, POINT OR BSP FUNCTION HAS BEEN
REQUESTED. IF REG 0 IS ZERO, A NOTE IS ASSUMED.
THE NOTE ROUTINE CALLS CHRCNVRT TO CONVERT THE CCHH
TO A RELATIVE TRACK AND RETURNS CONTROL TO THE
CALLER WITH THE TTR IN REG 0. IF REG 0 WAS
POSITIVE ON ENTRY TO DMSROS, A POINT IS ASSUMED
AND A TTR IS LOADED FROM THE ADDRESS SPECIFIED IN
R0 AND TTRCNVRT AND SETXTNT ARE CALLED TO CONVERT
THE TTR TO A CCHHR AND CONTROL IS RETURNED TO THE
CALLER. IF REG 0 WAS NEGATIVE ON ENTRY TO DMSROS, A
BSP (BACKSPACE) IS ASSUMED. THE BACKSPACE CODE CHECKS
IF THE CURRENT POSITION IS THE BEGINNING OF A TRACK.
IF NOT, THE RECORD NUMBER IS DECREMENTED BY ONE AND
CONTROL IS RETURNED TO THE CALLER. IF THE CURRENT
POSITION IS THE BEGINNING OF A TRACK, CHRCNVRT IS
CALLED TO GET THE CURRENT RELATIVE TRACK, THE RELATIVE
TRACK IS DECREMENTED BY ONE AND TTRCNVRT IS CALLED
TO GET THE CURRENT CCHH. RDCNT IS THEN CALLED TO
GET THE CURRENT RECORD NUMBER OF THE LAST RECORD ON
THE NEW TRACK, SETXTNT IS CALLED TO SET THE NEW EXTENT
BOUNDARIES AND CONTROL IS RETURNED TO THE CALLER.
ROUTINES COMMON TO ALL OF DMSROS:
CHRCNVRT: CONVERTS A CCHH ADDRESS TO A RELATIVE TRACK
ADDRESS.
TTRCNVRT: CONVERTS A RELATIVE TRACK ADDRESS TO AN
ACTUAL ADDRESS (CCHHR).
CHKSENSE: IF A UNIT CHECK IS ENCOUNTERED, CHECKS
SENSE BITS TO DETERMINE IF THE ERROR IS
RECOVERABLE.
CHKXTNT: CHECKS TO SEE IF END OF SPLIT CYL OR END OF
ENTENT HAS BEEN REACHED AND IF SO UPDATES TO
THE NEXT SPLIT CYL OR EXTENT.
DISKIO: STARTS I/O ON CCW STRING VIA A DIAGNOSE X'20'
GETALT: SWITCHES FROM ALTERNATE TRACK TO PRIME TRACK
AND FROM PRIME TRACK TO ALTERNATE TRACK.
RDCNT: READS COUNT FIELDS ON TRACK TO DETERMINE
LAST RECORD NUMBER ON TRACK.
SETXTNT: SET OSFSTEND TO END OF EXTENT AND, IF A NEW
EXTENT IS SPECIFIED, SETS CCHHR TO THE START
OF THE EXTENT.
Calls to Other Routines
DMSERR, ADTNXT, DMSFREE, DMSFRET