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