Document revision date: 19 July 1999

This section provides programming examples that call LBR routines. Although the examples do not illustrate all the LBR routines, they do provide an introduction to the various data structures and the calling syntax.

The program examples are written in DEC Pascal and the subroutine examples are written in DEC Fortran. The listing of each program example contains comments and is followed by notes about the program. The highlighted numbers in the notes are keyed to the highlighted numbers in the examples.

Each sample program calls the LBR$INI_CONTROL routine and the LBR$OPEN routine before calling any other routine.

The sample programs require access to various symbols derived from definition macros. Use the INHERIT attribute to access these symbols from definition macros in SYS$LIBRARY:STARLET.PEN.

The LBR$INI_CONTROL routine sets up a control index; do not confuse this with a library index. The control index is used in subsequent LBR routine calls to identify the applicable library (because you may want your program to work with more than one library at a time).

Upon completion of the LBR$INI_CONTROL routine, call the LBR$OPEN routine to open the library. Open an existing library, or create and open a new library, in either the UPDATE or READ mode, checking for an error status value of RMS$_FNF. If this error occurs, open the library in CREATE mode.

When you open the library, specify the library type and pass the file specification or partial file specification of the library file.

If you are creating a new library, pass the create options array. The CRE symbols identify the significant longwords of the array by their byte offsets into the array. Convert these values to subscripts for an array of integers (longwords) by dividing by 4 and adding 1. If you do not load the significant longwords before calling LBR$INI_CONTROL, the library may be corrupted upon creation.

Finally, pass any defaults for the file specification. If you omit the device and directory parts of the file specification, the current default device and directory are used.

When you finish working with a library, call LBR$CLOSE to close the library by providing the control index value. You must close a library explicitly before updates can be posted. Remember to call LBR$INI_CONTROL again if you want to reopen the library. LBR$CLOSE deallocates all the memory associated with the library, including the control index.

The order in which you call the routines between LBR$OPEN and LBR$CLOSE depends upon the library operations you need to perform. You may want to call LBR$LOOKUP_KEY or LBR$GET_INDEX to find a key, then perform some operation on the module associated with the key. You can think of a module as being both the module itself and its associated keys. To access a module, you first need to access a key that points to it; to delete a module, you first need to delete any keys that point to it.

Example 11-1 is a sample DEC Pascal program that creates, opens, and then closes a text library. The program is summarized in the following steps:

1. Initialize the library---Call LBR$INI_CONTROL to initialize the library.
2. Open the library---Call LBR$OPEN to open the library.
3. Close the library---Call LBR$CLOSE to close the library.

Example 11-1 Creating a New Library Using DEC Pascal

PROGRAM createlib(INPUT,OUTPUT); (*This program creates a text library*) TYPE (*Data type of*) Create_Array = ARRAY [1..20] OF INTEGER; (*create options array*) VAR (*Constants and return status error codes for LBR$_OPEN & LBR$INI_CONTROL. These are defined in $LBRDEF macro*) LBR$C_CREATE,LBR$C_TYP_TXT,LBR$_ILLCREOPT,LBR$_ILLCTL, (1) LBR$_ILLFMT,LBR$_NOFILNAM,LBR$_OLDMISMCH,LBR$_TYPMISMCH : [EXTERNAL] INTEGER; (*Create options array codes. These are defined in $CREDEF macro*) CRE$L_TYPE,CRE$L_KEYLEN,CRE$L_ALLOC,CRE$L_IDXMAX,CRE$L_ENTALL, CRE$L_LUHMAX,CRE$L_VERTYP,CRE$L_IDXOPT,CRE$C_MACTXTCAS, CRE$C_VMSV3 : [EXTERNAL]INTEGER; Lib_Name : VARYING [128] OF CHAR; (*Name of library to create*) Options : Create_Array; (*Create options array*) File_Type : PACKED ARRAY [1..4] (*Character string that is default*) OF CHAR := '.TLB'; (*file type of created lib file*) lib_index_ptr : UNSIGNED; (*Value returned in library init*) status : UNSIGNED; (*Return Status for function calls*) (*-*-*-*-Function and Procedure Definitions-*-*-*-*) (*Function that returns library control index used by Librarian*) FUNCTION LBR$INI_CONTROL (VAR library_index: UNSIGNED; (2) func: UNSIGNED; typ: UNSIGNED; VAR namblk: ARRAY[l..u:INTEGER] OF INTEGER := %IMMED 0): INTEGER; EXTERN; (*Function that creates/opens library*) FUNCTION LBR$OPEN (library_index: UNSIGNED; fns: [class_s]PACKED ARRAY[l..u:INTEGER] OF CHAR; create_options: Create_Array; dns: [CLASS_S] PACKED ARRAY [l3..u3:INTEGER] OF CHAR; rlfna: ARRAY [l4..u4:INTEGER] OF INTEGER := %IMMED 0; rns: [CLASS_S] PACKED ARRAY [l5..u5:INTEGER] OF CHAR := %IMMED 0; VAR rnslen: INTEGER := %IMMED 0): INTEGER; EXTERN; (*Function that closes library*) FUNCTION LBR$CLOSE (library_index: UNSIGNED): INTEGER; EXTERN; (*Error handler to check error codes if open/create not successful*)

PROCEDURE Open_Error; (3) BEGIN WRITELN('Open Not Successful'); (*Now check specific error codes*) IF status = IADDRESS(LBR$_ILLCREOPT) THEN WRITELN(' Create Options Not Valid Or Not Supplied'); IF status = IADDRESS(LBR$_ILLCTL) THEN WRITELN(' Invalid Library Index'); IF status = IADDRESS(LBR$_ILLFMT) THEN WRITELN(' Library Not In Correct Format'); IF status = IADDRESS(LBR$_NOFILNAM) THEN WRITELN(' Library Name Not Supplied'); IF status = IADDRESS(LBR$_OLDMISMCH) THEN WRITELN(' Old Library Conflict'); IF status = IADDRESS(LBR$_TYPMISMCH) THEN WRITELN(' Library Type Mismatch') END; (*of procedure Open_Error*) BEGIN (* *************** DECLARATIONS COMPLETE ************************* *************** MAIN PROGRAM BEGINS HERE ********************** *) (*Prompt for Library Name*) WRITE('Library Name: '); READLN(Lib_Name); (*Fill Create Options Array. Divide by 4 and add 1 to get proper subscript*) Options[IADDRESS(CRE$L_TYPE) DIV 4 + 1] := IADDRESS(LBR$C_TYP_TXT); Options[IADDRESS(CRE$L_KEYLEN) DIV 4 + 1] := 31; (4) Options[IADDRESS(CRE$L_ALLOC) DIV 4 + 1] := 8; Options[IADDRESS(CRE$L_IDXMAX) DIV 4 + 1] := 1; Options[IADDRESS(CRE$L_ENTALL) DIV 4 + 1] := 96; Options[IADDRESS(CRE$L_LUHMAX) DIV 4 + 1] := 20; Options[IADDRESS(CRE$L_VERTYP) DIV 4 + 1] := IADDRESS(CRE$C_VMSV3); Options[IADDRESS(CRE$L_IDXOPT) DIV 4 + 1] := IADDRESS(CRE$C_MACTXTCAS); (*Initialize library control index*) status := LBR$INI_CONTROL (lib_index_ptr, (5) IADDRESS(LBR$C_CREATE), (*Create access*) IADDRESS(LBR$C_TYP_TXT)); (*Text library*) IF NOT ODD(status) THEN (*Check return status*) WRITELN('Initialization Failed') ELSE (*Initialization was successful*) BEGIN (*Create and open the library*) status := LBR$OPEN (lib_index_ptr, Lib_Name, Options, (6) File_Type); IF NOT ODD(status) THEN (*Check return status*) Open_Error (*Call error handler*) (7) ELSE (*Open/create was successful*) BEGIN (*Close the library*) status := LBR$CLOSE(lib_index_ptr); IF NOT ODD(status) THEN (*Check return status*) WRITELN('Close Not Successful') END END END. (*of program creatlib*)

Each item in the following list corresponds to a number highlighted in Example 11-1:

1. Use the INHERIT attribute to access the LBR and CRE symbols from SYS$LIBRARY:STARLET.PEN.
2. Start the declarations of the LBR routines that are used by the program. Each argument to be passed to the Librarian is specified on a separate line and includes the name (which just acts as a placeholder) and data type (for example: UNSIGNED, which means an unsigned integer value, and PACKED ARRAY OF CHAR, which means a character string). If the argument is preceded by VAR, then a value for that argument is returned by the LBR to the program.
3. Declare the procedure Open_Error, which is called in the executable section if the Librarian returns an error when LBR$OPEN is called. Open_Error checks the Librarian's return status value to determine the specific cause of the error. The return status values for each routine are listed in the descriptions of the routines.
4. Initialize the array called Options with the values the Librarian needs to create the library.
5. Call LBR$INI_CONTROL, specifying that the function to be performed is create and that the library type is text.
6. Call LBR$OPEN to create and open the library; pass the Options array initialized in item 5 to the Librarian.
7. If the call to LBR$OPEN was unsuccessful, call the procedure Open_Error (see item 4) to determine the cause of the error.

Example 11-2 illustrates the insertion of a module into a library from a DEC Pascal program. The program is summarized in the following steps:

1. Ensure that the module does not already exist by calling LBR$LOOKUP_KEY. The return status should be LBR$_KEYNOTFND. This step is optional.
2. Construct the module by calling LBR$PUT_RECORD once for each record going into the module. Pass the contents of the record as the second argument. LBR$PUT_RECORD returns the record file address (RFA) in the library file as the third argument on the first call. On subsequent calls, you pass the RFA as the third argument, so do not alter its value between calls.
3. Call LBR$PUT_END after the last call to LBR$PUT_RECORD.
4. Call LBR$INSERT_KEY to catalog the records you have just put in the library. The second argument is the name of the module.

Example 11-2 Inserting a Module into a Library Using DEC Pascal

PROGRAM insertmod(INPUT,OUTPUT); (*This program inserts a module into a library*) TYPE Rfa_Ptr = ARRAY [0..1] OF INTEGER; (*Data type of RFA of module*) VAR LBR$C_UPDATE, (*Constants for LBR$INI_CONTROL*) LBR$C_TYP_TXT, (*Defined in $LBRDEF macro*) LBR$_KEYNOTFND : [EXTERNAL] INTEGER;(*Error code for LBR$LOOKUP_KEY*) Lib_Name : VARYING [128] OF CHAR; (*Name of library receiving module*) Module_Name : VARYING [31] OF CHAR; (*Name of module to insert*) Text_Data_Record : VARYING [255] OF CHAR; (*Record in new module*) Textin : FILE OF VARYING [255] OF CHAR; (*File containing new module*) lib_index_ptr : UNSIGNED; (*Value returned in library init*) status : UNSIGNED; (*Return status for function calls*) txtrfa_ptr : Rfa_Ptr; (*For key lookup and insertion*) Key_Not_Found : BOOLEAN := FALSE; (*True if new mod not already in lib*) (*-*-*-*-Function Definitions-*-*-*-*) (*Function that returns library control index used by Librarian*) FUNCTION LBR$INI_CONTROL (VAR library_index: UNSIGNED; func: UNSIGNED; typ: UNSIGNED; VAR namblk: ARRAY[l..u:INTEGER] OF INTEGER := %IMMED 0): INTEGER; EXTERN; (*Function that creates/opens library*) FUNCTION LBR$OPEN (library_index: UNSIGNED; fns: [class_s]PACKED ARRAY[l..u:INTEGER] OF CHAR; create_options: ARRAY [l2..u2:INTEGER] OF INTEGER := %IMMED 0; dns: [CLASS_S] PACKED ARRAY [l3..u3:INTEGER] OF CHAR := %IMMED 0; rlfna: ARRAY [l4..u4:INTEGER] OF INTEGER := %IMMED 0; rns: [CLASS_S] PACKED ARRAY [l5..u5:INTEGER] OF CHAR := %IMMED 0; VAR rnslen: INTEGER := %IMMED 0): INTEGER; EXTERN; (*Function that finds a key in index*) FUNCTION LBR$LOOKUP_KEY (library_index: UNSIGNED; key_name:[CLASS_S] PACKED ARRAY [l..u:INTEGER] OF CHAR; VAR txtrfa: Rfa_Ptr): INTEGER; EXTERN; (*Function that inserts key in index*) FUNCTION LBR$INSERT_KEY (library_index: UNSIGNED; key_name:[CLASS_S] PACKED ARRAY [l..u:INTEGER] OF CHAR; txtrfa: Rfa_Ptr): INTEGER; EXTERN; (*Function that writes data records*)

FUNCTION LBR$PUT_RECORD (library_index: UNSIGNED; (*to modules*) textline:[CLASS_S] PACKED ARRAY [l..u:INTEGER] OF CHAR; txtrfa: Rfa_Ptr): INTEGER; EXTERN; (*Function that marks end of a module*) FUNCTION LBR$PUT_END (library_index: UNSIGNED): INTEGER; EXTERN; (*Function that closes library*) FUNCTION LBR$CLOSE (library_index: UNSIGNED): INTEGER; EXTERN; BEGIN (* *************** DECLARATIONS COMPLETE ************************* *************** MAIN PROGRAM BEGINS HERE ********************** *) (*Prompt for library name and module to insert*) WRITE('Library Name: '); READLN(Lib_Name); WRITE('Module Name: '); READLN(Module_Name); (*Initialize lib for update access*) status := LBR$INI_CONTROL (lib_index_ptr, (1) IADDRESS(LBR$C_UPDATE), (*Update access*) IADDRESS(LBR$C_TYP_TXT)); (*Text library*) IF NOT ODD(status) THEN (*Check error status*) WRITELN('Initialization Failed') ELSE (*Initialization was successful*) BEGIN status := LBR$OPEN (lib_index_ptr, (*Open the library*) Lib_Name); IF NOT ODD(status) THEN (*Check error status*) WRITELN('Open Not Successful') ELSE (*Open was successful*) BEGIN (*Is module already in the library?*) status := LBR$LOOKUP_KEY (lib_index_ptr, (2) Module_Name, txtrfa_ptr); IF ODD(status) THEN (*Check status. Should not be odd*) WRITELN('Lookup key was successful.', 'The module is already in the library.') ELSE (*Did lookup key fail because key not found?*) IF status = IADDRESS(LBR$_KEYNOTFND) THEN (3) Key_Not_Found := TRUE END END;

(******If LBR$LOOKUP_KEY failed because the key was not found (as expected), we can open the file containing the new module, and write the module's records to the library file*******) IF Key_Not_Found THEN BEGIN OPEN(Textin,Module_Name,old); RESET(Textin); WHILE NOT EOF(Textin) DO (*Repeat until end of file*) BEGIN (4) READ(Textin,Text_Data_Record); (*Read record from external file*) status := LBR$PUT_RECORD (lib_index_ptr, (*Write*) Text_Data_Record, (*record to*) txtrfa_ptr); (*library*) IF NOT ODD(status) THEN WRITELN('Put Record Routine Not Successful') END; (*of WHILE statement*) IF ODD(status) THEN (*True if all the records have been successfully written into the library*) BEGIN status := LBR$PUT_END (lib_index_ptr); (*Write end of module record*) IF NOT ODD(status) THEN WRITELN('Put End Routine Not Successful') ELSE (*Insert key for new module*) BEGIN (5) status := LBR$INSERT_KEY (lib_index_ptr, Module_Name, txtrfa_ptr); IF NOT ODD(status) THEN WRITELN('Insert Key Not Successful') END END END; status := LBR$CLOSE(lib_index_ptr); IF NOT ODD(status) THEN WRITELN('Close Not Successful') END. (*of program insertmod*)

Each item in the following list corresponds to a number highlighted in Example 11-2:

1. Call LBR$INI_CONTROL, specifying that the function to be performed is update and that the library type is text.
2. Call LBR$LOOKUP_KEY to see whether the module to be inserted is already in the library.
3. Call LBR$LOOKUP_KEY to see whether the lookup key failed because the key was not found. (In this case, the status value is LBR$_KEYNOTFND.)
4. Read a record from the input file, then use LBR$PUT_RECORD to write the record to the library. When all the records have been written to the library, use LBR$PUT_END to write an end-of-module record.
5. Use LBR$INSERT_KEY to insert a key for the module into the current index.

Example 11-3 illustrates the extraction of a library module from a DEC Pascal program. The program is summarized in the following steps:

1. Call LBR$LOOKUP_KEY to locate the module. Specify the name of the module as the second argument. LBR$LOOKUP_KEY returns the RFA of the module as the third argument; do not alter this value.
2. Call LBR$GET_RECORD once for each record in the module. Specify a character string to receive the extracted record as the second argument. LBR$GET_RECORD returns a status value of RMS$_EOF after the last record in the module is extracted.

Example 11-3 Extracting a Module from a Library Using DEC Pascal

PROGRAM extractmod(INPUT,OUTPUT,Textout); (*This program extracts a module from a library*) TYPE Rfa_Ptr = ARRAY [0..1] OF INTEGER; (*Data type of RFA of module*) VAR LBR$C_UPDATE, (*Constants for LBR$INI_CONTROL*) LBR$C_TYP_TXT, (*Defined in $LBRDEF macro*) RMS$_EOF : [EXTERNAL] INTEGER; (*RMS return status; defined in $RMSDEF macro*) Lib_Name : VARYING [128] OF CHAR; (*Name of library receiving module*) Module_Name : VARYING [31] OF CHAR; (*Name of module to insert*) Extracted_File : VARYING [31] OF CHAR; (*Name of file to hold extracted module*) Outtext : PACKED ARRAY [1..255] OF CHAR; (*Extracted mod put here,*) Outtext2 : VARYING [255] OF CHAR; (* then moved to here*) i : INTEGER; (*For loop control*) Textout : FILE OF VARYING [255] OF CHAR; (*File containing extracted module*) nullstring : CHAR; (*nullstring, pos, and len used to*) pos, len : INTEGER; (*find string in extracted file recd*) lib_index_ptr : UNSIGNED; (*Value returned in library init*) status : UNSIGNED; (*Return status for function calls*) txtrfa_ptr : Rfa_Ptr; (*For key lookup and insertion*) (*-*-*-*-Function Definitions-*-*-*-*) (*Function that returns library control index used by Librarian*) FUNCTION LBR$INI_CONTROL (VAR library_index: UNSIGNED; func: UNSIGNED; typ: UNSIGNED; VAR namblk: ARRAY[l..u:INTEGER] OF INTEGER := %IMMED 0): INTEGER; EXTERN; (*Function that creates/opens library*) FUNCTION LBR$OPEN (library_index: UNSIGNED; fns: [class_s]PACKED ARRAY[l..u:INTEGER] OF CHAR; create_options: ARRAY [l2..u2:INTEGER] OF INTEGER := %IMMED 0; dns: [CLASS_S] PACKED ARRAY [l3..u3:INTEGER] OF CHAR := %IMMED 0; rlfna: ARRAY [l4..u4:INTEGER] OF INTEGER := %IMMED 0; rns: [CLASS_S] PACKED ARRAY [l5..u5:INTEGER] OF CHAR := %IMMED 0; VAR rnslen: INTEGER := %IMMED 0): INTEGER; EXTERN; (*Function that finds a key in an index*) FUNCTION LBR$LOOKUP_KEY (library_index: UNSIGNED; key_name:[CLASS_S] PACKED ARRAY [l..u:INTEGER] OF CHAR; VAR txtrfa: Rfa_Ptr): INTEGER; EXTERN;

(*Function that retrieves records from modules*) FUNCTION LBR$GET_RECORD (library_index: UNSIGNED; var textline:[CLASS_S] PACKED ARRAY [l..u:INTEGER] OF CHAR): INTEGER; EXTERN; (*Function that closes library*) FUNCTION LBR$CLOSE (library_index: UNSIGNED): INTEGER; EXTERN; BEGIN (* *************** DECLARATIONS COMPLETE ************************* *************** MAIN PROGRAM BEGINS HERE ********************** *) (* Get Library Name, Module To Extract, And File To Hold Extracted Module *) WRITE('Library Name: '); READLN(Lib_Name); WRITE('Module Name: '); READLN(Module_Name); WRITE('Extract Into File: '); READLN(Extracted_File); status := LBR$INI_CONTROL (lib_index_ptr, (1) IADDRESS(LBR$C_UPDATE), IADDRESS(LBR$C_TYP_TXT)); IF NOT ODD(status) THEN WRITELN('Initialization Failed') ELSE BEGIN status := LBR$OPEN (lib_index_ptr, Lib_Name); IF NOT ODD(status) THEN WRITELN('Open Not Successful') ELSE BEGIN (2) status := LBR$LOOKUP_KEY (lib_index_ptr, Module_Name, txtrfa_ptr); IF NOT ODD(status) THEN WRITELN('Lookup Key Not Successful') ELSE BEGIN (3) OPEN(Textout,Extracted_File,new); REWRITE(Textout) END END END; WHILE ODD(status) DO BEGIN nullstring := ''(0); FOR i := 1 TO 255 DO (4) Outtext[i] := nullstring; status := LBR$GET_RECORD (lib_index_ptr, Outtext); IF NOT ODD(status) THEN BEGIN (5) IF status = IADDRESS(RMS$_EOF) THEN WRITELN(' RMS end of file') END

ELSE BEGIN (6) pos := INDEX(Outtext, nullstring); (*find first null in Outtext*) len := pos - 1; (*length of Outtext to first null*) IF len >= 1 THEN BEGIN Outtext2 := SUBSTR(Outtext,1,LEN); WRITE(Textout,Outtext2) END END END; (*of WHILE*) status := LBR$CLOSE(lib_index_ptr); IF NOT ODD(status) THEN WRITELN('Close Not Successful') END. (*of program extractmod*)

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