Type ASSEMBLE
Source Lines : 885
Fixes Applied : 2
Most Recent Version : Tuesday, December 12, 1978
Last Fix ID : [R14929DS]
Module
DMSLFS
Function
TO FIND A SPECIFIED 40-BYTE FST ENTRY WITHIN THE FST
TABLES FOR READ-ONLY OR READ-WRITE DISK(S).
Attributes
NUCLEUS RESIDENT, REENTRANT
Operation
DMSLFS CHECKS TO ENSURE THAT R1 IS NOT ZERO (A
CALLING ERROR), AND INITIALIZES
TO TEST FOR EITHER A READ-ONLY OR READ-WRITE DISK.
THEN THE PARAMETER LIST IS CHECKED TO ENSURE THAT THE
FILENAME AND FILETYPE ARE PRESENT (CALLING ERROR IF
NOT), AND CHECKS TO SEE IF THE MODE-LETTER IS
ALPHABETIC, AND IF SO WHETHER A MODE-NUMBER IS GIVEN.
IF THE MODE IS ALPHABETIC, DMSLAD IS CALLED TO CHECK
FOR A DISK WHOSE MODE-LETTER
ADTM MATCHES THE PARAMETER LIST. IF THE MODE IS *-*
OR EQUIVALENT (NOT ALPHABETIC), DMSLADN IS CALLED TO
CHECK FOR ANY AVAILABLE DISK. AN ERROR RETURN FROM
DMSLAD OR DMSLADN TRIGGERS A 'FILE NOT FOUND' RETURN
FROM DMSLFS. ON A SUCCESSFUL RETURN, DMSLFS CHECKS TO
MAKE SURE THE DISK FOUND IS LOGGED IN
(AS EITHER READ-ONLY OR READ-WRITE OR IF DMSLFS WAS
CALLED BY DMSSTT, OS READ ONLY). IF NOT, THE
LOGIC CONTINUES AS DESCRIBED BELOW, WHERE THE GIVEN
FST ENTRY WAS NOT FOUND ON THE DISK.
IF THE DISK IS AN OS DISK, DMSLFS CALLS ROSSTT IN
DMSROS TO VERFIY THAT THE DATA SET EXISTS AND THAT THE
ATTRIBUTES OF THE DATA SET ARE SUPPORTED. UPON RETURN
FROM DMSROS, A RETURN CODE OF 88 INDICATES THAT
THE DATA SET WAS NOT FOUND AND DMSLFS INITIATES THE
SEARCH AGAIN USING THE NEXT DISK IN ORDER. ANY OTHER
ERRORS SUCH AS RETURN CODE 80 CAUSE DMSLFS TO EXIT
IMMEDIATELY.
A RETURN CODE OF 0 FROM DMSROS INDICATES THAT THE DATA
SET WAS FOUND ON THE SPECIFIED DISK AND DMSLFS CONTINUES
AS IT DOES WHEN A CMS FST IS FOUND.
IF THE DISK FOUND BY DMSLAD OR DMSLADN IS LOGGED IN,
DMSLFS CHECKS THROUGH THE VARIOUS
FST HYPERBLOCKS IN CORE TO FIND A MATCHING FST ENTRY
FOR THE FILENAME (IF GIVEN IN THE PARAMETER LIST) AND
FILETYPE (IF GIVEN). NOTE - IF R1 WAS NEGATIVE AT
ENTRY TO DMSLFS, SEARCHING FOR THE GIVEN FST RESUMES
FROM THE POINT LAST SEARCHED, AS INDICATED BY
THE ADTCHBA (CURRENT HYPERBLOCK ADDRESS) AND ADTCFST
(CURRENT FST ENTRY DISPLACMENT) POINTERS IN THE
ACTIVE DISK TABLE FOR THE GIVEN DISK.
IF THE FILENAME AND FILETYPE ARE BOTH GIVEN AND MATCH
EXPLICITLY, THE FILE IS DEEMED 'FOUND' IRRESPECTIVE
OF ANY MODE-NUMBER IN THE PARAMETER LIST. IF EITHER
(OR BOTH) WAS '*' IN THE PARAMETER LIST, HOWEVER, AND
THE MODE-NUMBER WAS GIVEN, THEN THE MODE-NUMBER IN
THE PARAMETER LIST MUST MATCH THE MODE-NUMBER IN THE
FST ENTRY.
THUS, FOR EXAMPLE, A CALL TO DMSLFS FOR "SOME FILE
A5" WOULD CONSIDER "SOME FILE A1"
(ON THE A-DISK) A MATCH EVEN THOUGH THE MODE-NUMBER
IS WRONG. (THIS LOGIC IS PURPOSELY PROVIDED TO AVOID
MISLEADING THE USER, SINCE YOU CANNOT HAVE TWO FILES
ON THE SAME DISK WITH SAME FILENAME AND FILETYPE, BUT
DIFFERENT MODE NUMBERS.) A SEARCH FOR "* FILE A5",
HOWEVER, WOULD NOT CONSIDER "SOME FILE A1" TO MATCH,
SINCE THE MODE NUMBER DIFFERS.
(NOTE - THIS LOGIC IS NOW CONSISTENT THROUGHOUT CMS.
THAT IS, IF THE FILENAME AND FILETYPE MATCH
EXPLICITLY, THE MODE NUMBER NEED NOT BE CORRECT FOR A
MATCH; BUT IF THE FILENAME AND/OR FILETYPE IS '*' AND
THE MODE-NUMBER IS GIVEN, THEN IT MUST EQUAL THE FST
MODE-NUMBER TO BE CONSIDERED A MATCH.)
IF DMSLFS FINDS THE MATCHING FILE ON THE GIVEN DISK,
IT RETURNS THE ADDRESSES OF THE ACTIVE
DISK TABLE (ADT) AND THE FST ENTRY IN R0 AND R1 AS
SHOWN IN EXIT CONDITIONS, AND REMEMBERS WHERE IT
FOUND THE FILE IN THE ADTCHBA AND ADTCFST POINTERS IN
THE ADT BLOCK.
FST ENTRY NOT FOUND ON THE DISK
IF THE FST ENTRY WAS NOT FOUND ON THE DISK JUST
CHECKED, DMSLFS CHECKS THE MODE SUPPLIED IN THE
P-LIST. IF IT WAS '*' (OR EQUIVALENT), DMSLADN IS
CALLED AND THE NEXT
DISK (IF ANY) IS CHECKED AS ABOVE FOR THE MATCHING
FILE.
IF THE MODE, ON THE OTHER HAND, WAS ALPHABETIC,
DMSLADN IS CALLED TO DETERMINE IF ANOTHER
DISK IS AVAILABLE FOR CHECKING. IF SO, THE ADTMX
EXTENSION-MODE-LETTER IS CHECKED TO SEE IF IT MATCHES
THE MODE GIVEN IN THE PARAMETER LIST. IF IT MATCHES,
THIS INDICATES THAT THE NEW DISK IS A READ-ONLY
EXTENSION OF THE ONE PREVIOUSLY CHECKED, AND THE
GIVEN FILE IS LOOKED UP ON THIS DISK. IF FOUND,
SUCCESSFUL RETURN IS GIVEN POINTING TO THIS DISK AND
THE FST ENTRY FOUND. IF NOT, THIS PROCESS IF
REPEATED UNTIL A MATCH IS FOUND, OR UNTIL NO MORE
DISK(S) WITH A MATCHING ADTMX LETTER ARE FOUND.
DMSLFS (FSTLKP)
Calls to Other Routines
DMSLAD, DMSLADN, DMSROS