Type ASSEMBLE
Source Lines : 844
Fixes Applied : 2
Most Recent Version : Tuesday, December 12, 1978
Last Fix ID : [HRC015DS]
Module
DMSFNS
Function
TO CLOSE ONE OR MORE INPUT OR OUTPUT DISK FILE(S).
Attributes
NUCLEUS RESIDENT, REENTRANT
Operation
DMSFNSA CHECKS THE CALLER'S PARAMETER LIST FOR '*' IN
FILENAME OR FILETYPE, OR A NONALPHABETIC CHARACTER
FOR THE MODE; IF ANY OF THESE CONDITIONS ARE MET, A
FLAG IS SET TO CHECK FOR ADDITIONAL ENTRIES IN THE
ACTIVE FILE TABLE.
AFTER THIS PRELIMINARY CHECK, DMSFNSA CALLS DMSLAD TO
FIND AN AFT BLOCK
THAT MATCHES THE CALLER'S PARAMETER LIST. IF NONE IS
FOUND, AN ERROR 6 IS GIVEN AS SHOWN IN THE EXIT
CONDITIONS.
IF A MATCH IS FOUND, A CHECK IS MADE TO DETERMINE
WHETHER THE FILE IS AN ACTIVE WRITE, AN ACTIVE READ,
OR NEITHER. IF NEITHER, IT WAS PLACED THERE BY
POINT, BUT WAS NOT READ OR WRITTEN SUBSEQUENTLY.
ACTION IS TAKEN IN THESE THREE CASES AS DESCRIBED IN
THE FOLLOWING PARAGRAPHS.
ACTIVE READ FILE
IF THE FILE FOUND BY DMSLAD IS AN ACTIVE READ FILE,
DMSFNSA TAKES THE FOLLOWING
STEPS TO CLOSE THE FILE:
1. RELEASE TO FREE STORAGE THE 800-BYTE BUFFER USED
FOR THE DATA BLOCK (VIA A CALL TO FRET).
2. ALSO RELEASE EITHER THE 200- OR 800-BYTE BUFFER
CURRENTLY IN USE FOR THE CHAIN LINK.
3. IF THE FILE HAS A MODE NUMBER OF 3 (FOR EXAMPLE,
A3), IT IS NOW ERASED UNLESS THE SUBSET INITIAL-
IZATION FLAG IS ON.
THIS IS DONE BY CALLING DMSFREE TO
OBTAIN FREE STORAGE FOR A SUITABLE CALL TO
DMSERS, THEN CALLING DMSERS TO ELIMINATE THE
FILE AND THEN GIVING BACK THE FREE STORAGE VIA
DMSFRET. CARE IS TAKEN
TO PRESERVE INFORMATION TO AVOID RE-ENTERABILITY
PROBLEMS BETWEEN DMSFNSA AND DMSERS.
4. NEXT, DMSLAFFT IS CALLED TO RELEASE THIS SLOT IN
THE ACTIVE FILE TABLE.
5. FINALLY, IF EITHER THE FILENAME, FILETYPE, OR
FILEMODE INDICATED
THAT ADDITIONAL FILES SHOULD BE CHECKED.
DMSFNSA RETURNS TO THE PORTION OF CODE WHICH
CALLS DMSLAD, TO CHECK FOR ANY MORE AFT BLOCKS
THAT MAY
MATCH THE CALLER'S P-LIST.
6. FINALLY, WHEN ALL APPROPRIATE FILE(S)
HAVE BEEN CLOSED, DMSFNSA GIVES A NORMAL RETURN
AS INDICATED UNDER
EXIT CONDITIONS.
FILE ACTIVE FROM A POINT CALL
FOR THIS CASE (ACTIVE BUT NEITHER A READ NOR A
WRITE), DMSLAFFT IS CALLED, ETC.,
AS SHOWN ABOVE IN STEPS 4, 5, AND 6 FOR THE "ACTIVE
READ FILE" CASE.
ACTIVE WRITE FILE
IF THE FILE FOUND BY DMSLAD IS AN ACTIVE WRITE FILE,
DMSFNSA TAKES THE FOLLOWING
STEPS TO CLOSE THE FILE:
1. CHECKS THE POINTER (AFTPFST) IN THE AFT BLOCK TO
THE FST ENTRY (IF ANY) IN THE FST HYPERBLOCKS.
IF NONZERO, PROCEED TO STEP 2. IF ZERO (AS IS
THE CASE FOR A NEW FILE NEVER BEFORE CLOSED),
THE SPECIAL FSTLKW ENTRY TO OBTAIN AN EMPTY
40-BYTE FST ENTRY IS CALLED, AND THE AFTPFST
POINTER IS SET TO THE ADDRESS PROVIDED BY
DMSLFSW.
2. MOVES THE 40-BYTE ENTRY FROM THE AFTFST SLOT IN
THE AFT BLOCK TO ITS LOCATION WITHIN THE FST
HYPERBLOCKS, SETS THE MODE-LETTER AND CLEARS THE
FLAG-BYTE.
3. UNLESS THE FIRST FIVE LETTERS OF THE
FILETYPE=SYSUT OR CMSUT, THE TIME OF DAY AND
YEAR ARE COMPUTED IN THE SAME MANNER AS GETCLK,
AND THE DATE-TIME STORED IN FSTD IN THE FST
ENTRY, AND THE YEAR IN FSTYR. (IF THE FILETYPE
INDICATES A UTILITY FILE IS BEING FINIS'ED, THIS
STEP IS UNNECESSARY AND IS THEREFORE OMITTED.)
4. NEXT THE CURRENT DATA BLOCK POINTED TO BY AFTDBA
IS WRITTEN ON DISK.
5. THEN THE FREE STORAGE BLOCK THAT WAS USED FOR THE
DATA BLOCK IS RETURNED TO FREE
STORAGE VIA DMSFRET.
6. IF THE FIRST CHAIN LINK IS NOT RESIDENT, THE
CURRENT CHAIN LINK (UNLESS NULL) IS WRITTEN ON
DISK, AND THE FIRST CHAIN LINK BROUGHT INTO
CORE.
7. THE LINKAGE PORTION OF THE FIRST CHAIN LINK
(AFTCLB) IS MOVED FROM THE AFT BLOCK TO THE
FIRST CHAIN LINK, AND THE FIRST CHAIN LINK
WRITTEN ON DISK.
8. THEN THE FREE STORAGE BLOCK USED FOR THE CHAIN
LINK (EITHER 200 OR 800 BYTES IN LENGTH)
IS RETURNED TO FREE STORAGE VIA DMSFRET.
9. THE WRITE POINTER IS COMPUTED AS THE NUMBER OF
ITEMS PLUS ONE AND STORED IN THE FST ENTRY.
10. THE NUMBER OF ACTIVE WRITE FILES FOR THIS ACTIVE
DISK TABLE (ADTNACW) IS DECREMENTED BY ONE.
11. IF THE NUMBER OF ACTIVE WRITE FILES (ADTNACW) IS
NOW=0, THEN DMSAUDUD IS CALLED TO
UPDATE THE FILE DIRECTORY FOR THIS ACTIVE DISK
TABLE.
12. DMSLAFFT IS THEN CALLED TO RELEASE THIS SLOT IN
THE ACTIVE FILE TABLE.
13. THEN IF EITHER THE FILENAME, FILETYPE, OR
FILEMODE INDICATED THAT ADDITIONAL FILES
SHOULD BE CHECKED, DMSFNSA RETURNS TO THE
PORTION OF CODE THAT CALLS DMSLAD, TO
CHECK FOR ANY MORE AFT BLOCKS THAT MAY MATCH THE
CALLER'S P-LIST.
14. FINALLY, WHEN ALL APPROPRIATE FILE(S) HAVE BEEN
CLOSED, DMSFNSA GIVES A NORMAL RETURN
AS INDICATED UNDER EXIT CONDITIONS.
Calls to Other Routines
DMSLAFFT, DMSLAD, DMSERS, DMSFREE, DMSFRET, DMSLFSW,
DMSDIOR, DMSAUD, DMSDIOW