Type ASSEMBLE
Source Lines : 1,000
Fixes Applied : 6
Most Recent Version : Thursday, December 7, 1978
Last Fix ID : [HRC028DK]
Module
DMKUDR USER DIRECTORY MODULE
Function
THE USER DIRECTORY IS WRITTEN USING A PAGEABLE ACCESS
METHOD. TO MINIMIZE THE PAGEING ACTIVITY SEVERAL
CONCIDERATIONS SHOULD BE NOTED. FIRST THE USER
DIRECTORY BLOCKS ARE IN A SEPERATE PAGE OR PAGES AND
THE PAGES ARE ASSIGNED A VIRTUAL ADDRESS AT IPL
TIME. SO NO SPECIAL CONCIDERATIONS ARE NECESSARY
WHEN CALLING DMKUDRFU. THE USER MACHINE AND DEVICE
BLOCKS, ON THE OTHER HAND, ARE NOT ASSIGNED
PERMANENT VIRTUAL ADDRESSES. THE VIRTUAL ADDRESS IS
ASSIGNED THE FIRST TIME A PAGE IS REFERENCED AND
MUST BE REMEMBERED UNTIL THE CALLER IS FINISHED
WITH THAT USER. TO FACILITATE THIS THE USER MUST
PROVIDE A BUFFER, SEVEN DOUBLE WORDS LONG, WITH
THE LAST DOUBLE WORD RESERVED FOR THE DMKUDRRD,
DMKUDRFD AND DMKUDRRV ROUTINES. THE SAME BUFFER
MUST BE PROVIDED FOR EACH SUBSEQUENT RETRIEVAL.
A SECOND BUFFER MUST BE PROVIDED IF INNESTED LINKS
ARE INCOUNTERED. A MAXIMUM OF TWO BUFFERS ARE TO
BE USED AND THE BUFFER MUST HAVE THE LAST DOUBLE
WORD ZERO'S, AT ENTRY TO ANY ROUTINE FOR THE FIRST
TIME. ALL SUBSEQUENT ENTRIES TO ANY ROUTINE MUST
NOT CHANGE THIS DOUBLE WORD. AFTER A BUFFER HAS
BEEN USED FOR THE LAST TIME THE USER MUST CALL
DMKUDRRV TO RETURN THE VIRTUAL PAGE AND THEN THE
USER CAN FRET HIS BUFFER.
Attributes
REENTRANT,PAGEABLE
Operation
1. CALL DMKLOCKQ TO LOCK THE NAME ' DIRCT '.
2. MASK THE USERID, FROM THE CALLER, OFF AND
SET UP TO SCAN THE UDIRBLOK'S.
3. TRANS TO BRING IN EACH PAGE FROM THE
PAGE LIST (DMKSYSPL) UNTIL THE USERID IS
FOUND.
4. IF THE USERID IS NOT FOUND CALL DMKLOCKD TO UNLOCK
C' DIRCT ' AND EXIT CC = 1.
5. WHEN FOUND TEST IF THE USER PROVIDED
A BUFFER. IF NOT GO TO STEP 7.
6. MOVE THE UDIRBLOK INTO THE USERS BUFFER AND
UNMASK THE BLOCK.
7. CALL DMKLOCKD TO UNLOCK C' DIRECT ' AND EXIT CC = 0.
Calls to Other Routines
DMKLOCKQ - TO LOCK (QUEQE) THE USER DIRECTORY
DMKPTRAN - TO BRING A PAGE INTO STORAGE
DMKLOCKD - TO DEQUEUE THE USER DIRECTORY
DMKPTRFT - TO RELEASE A REAL STORAGE PAGE FRAME