Type ASSEMBLE
Source Lines : 3,942
Fixes Applied : 11
Most Recent Version : Tuesday, December 12, 1978
Last Fix ID : [R13560DS]
Module
DMSCPY (COPYFILE)
Function
TO COPY DISK FILES, SPECIFYING VARIOUS CONVERSIONS.
Attributes
REENTRANT, DISK RESIDENT
Operation
OPERATION TAKES PLACE IN SEVERAL STEPS.
STEP 1. THE WORK SPACE IA ALLOCATED VIA 'GETMAIN'
AND ITS FIELDS ARE INITIALIZED.
STEP 2. THE FILE NAME LIST IS SCANNED. A FLAG BYTE
IS SET UP FOR EACH FILE NAME, INDICATING THE FIELDS,
IF ANY, IN WHICH AN ASTERISK OR AN EQUAL SIGN OCCURS.
STEP 3. THE OPTION LIST IS SCANNED. FOR EACH OPTION
IN THE USER-SUPPLIED LIST, A SPECIAL ROUTINE IS
ENTERED TO HANDLE IT. THE HANDLING ROUTINE CAN SET A
FLAG, AND CAN HANDLE SUB-FIELDS OF THE OPTION NAME.
STEP 4. ADDITIONAL OPTION PROCESSING. THIS
INCLUDES:
CHECKING FOR OPTION CONFLICTS.
SETTING MULTIPLE OR SINGLE MODE, AS SPECIFIED.
READING 'SPECS' LIST, IF THAT OPTION WAS
GIVEN.
SETTING UP TRANSLATE TABLE, IF NECESSARY.
READING TABLE FOR TERMINAL IF 'TRANSLATE'
SPECIFIED.
STEPS 4 AND 5. PERFORM THE ACTUAL COPYING OPERATION.
DUE TO THE NUMBER OF OPTIONS AND MODES AVAILABLE, IT
WAS FELT THAT A STRAIGHTFORWARD CODING OF THE COPYING
STEP WOULD LEAD TO VERY COMPLEX AND HARD-TO-MANAGE
CODE. IN ORDER TO AVOID THIS PROBLEM, A DIFFERENT
SCHEME WAS USED. THIS SCHEME WAS DESIGNED WITH THE
FOLLOWING OBJECTIVES IN MIND:
FAST EXECUTION SPEED
EASY TO DEBUG CODE
EASY TO MODIFY CODE
THE IDEA BEHIND THE COPYING OPERATION IS THE
FOLLOWING: THE COPYING OPERATION IS BROKEN UP INTO A
LARGE NUMBER OF SMALL ROUTINES, HANDLING THE VARIOUS
TASKS TO BE PERFORMED AS PART OF THE COPYING
OPERATION. EACH OF THE ROUTINES IS MADE TO BE AS
STRAIGHT-LINE AS POSSIBLE, SO THAT IT WON'T DEPEND ON
WHICH OPTIONS HAVE BEEN SPECIFIED.
IT MUST, THEREFORE, BE DETERMINED IN ADVANCE WHICH OF
THESE ROUTINES ARE TO BE EXECUTED. A ONE-BYTE CODE IS
ASSIGNED TO EACH OF THE ROUTINES, AND TABLES ARE MADE
UP, DEPENDING UPON THE OPTIONS WHICH WERE SPECIFIED,
TO CALL ONLY THE ROUTINES WHICH SHOULD BE INVOKED FOR
THE SPECIFIED OPTIONS.
STEP 4, THEN, SETS UP THE CODE STRINGS, DEPENDING
UPON WHICH OPTIONS WERE SPECIFIED. THE CODE STRINGS
ARE GROUPED INTO 'PHASES', REPRESENTING THE DIFFERENT
LOGICAL PHASES OF THE COPYING OPERATION. (PHASES ARE
NECESSARY FOR A DIFFERENT REASON: THEY REPRESENT THE
ONLY REAL MEANS FOR PROVIDING FOR CONDITIONAL
BRANCHES AMONG ROUTINES DURING THE COPYING OPERATION
- A CONDITIONAL BRANCH IS ACCOMPLISHED BY A
CONDITIONAL CHANGE OF PHASE.)
STEP 5 PERFORMS THE ACTUAL COPYING OPERATION BY
BRANCHING TO THE ROUTINES, IN TURN, AS SPECIFIED BY
THE CODE TABLES.
Calls to Other Routines
STRINIT: TO INITIALIZE STORAGE
GETMAIN (OS MACRO): TO ALLOCATE STORAGE AND BUFFERS
WAITRD: TO READ FORM THE CONSOLE
FSTLKP: TO FIND THE FST FOR A FILE
ADTLKP: TO FIND ADT FOR OUTPUT DISK (TO SEE IF IT'S RDONLY)
RDBUF: TO READ A RECORD FROM A DISK FILE
WRBUF: TO WRITE A RECORD TO A DISK FILE
FREEMAIN (OS MACRO): TO FREE ALLOCATED STORAGE
FINIS: TO RELEASE ACTIVE FILES
ERASE: TO ERASE FILES
DMSERR: TO TYPE OUT INFORMATION ERROR MESSAGES
ALTER: TO ALTER TEMP FILE NAME TO REAL OUTPUT FILE NAME