When the XREFFILE file cannot be used by the XREFANALYZER program, the following error message is printed:

########## XREF ERROR: <error number> ##########

Then, one of the following messages is printed and the XREFANALYZER program is terminated.

Example 1

This example shows an ALGOL program with its corresponding cross-reference listing.

    00000100 $SET XREF
    00000200 BEGIN
    00000300 REAL B, C, MEAN;
    00000400 INTEGER I;
    00000500 ARRAY R[1:3];
    00000600 DEFINE  ONEE=    1;,
    00000700         TWOO=    2;,
    00000800         THREEE=  3;;
    00000900
    00001000 PROCEDURE ONE;
    00001100   BEGIN
    00001200   MEAN:= 2;
    00001300   FOR I:= 0 STEP 1 UNTIL 5 DO
    00001400      MEAN:= MEAN * B;
    00001500   C:= C * MEAN;
    00001600   END ONE;
    00001700
    00001800
    00001900 R[ONEE]:= 1;
    00002000 R[TWOO]:= 2;
    00002100 R[THREEE]:= R[ONEE] + R[TWOO];
    00002200 B:= 3;
    00002300 C:= 25;
    00002400 ONE;
    00002500 B:= 5;
    00002600 ONE;
    00002700 END.
    B---REAL AT (2,2)---DECLARED AT 00000300
               00001400  *00002200  *00002500
    B.0000 - PROCEDURE AT (1,2) - DECLARED AT 0000200 ENDS AT 00002700
    C---REAL AT (2,3)---DECLARED AT 00000300
              *00001500  *00002300
    I---INTEGER AT (2,5)---DECLARED AT 00000400
              *00001300
    MEAN---REAL AT (2,4)---DECLARED AT 00000300
              *00001200  *00001400   00001500
    ONE - PROCEDURE AT (2,7) - DECLARED AT 00001000   ENDS AT 00001600
               00002400   00002600

    ONEE---DEFINE---DECLARED AT 00000600
               00001900   00002100
    R---REAL ARRAY AT (2,6)---DECLARED AT 00000500
              *00001900  *00002000  *00002100
    THREEE---DEFINE---DECLARED AT 00000800
               00002100
    TWOO---DEFINE---DECLARED AT 00000700
               00002000   00002100

Each reference consists of an 8-digit sequence number, preceded by either an E if the reference appears in an address equation or an asterisk (*) if the value might be changed by the statement.

The sequence number is followed by a number sign (#) if the reference occurs as part of an expanded define.

Example 2

This example shows a FORTRAN program with its corresponding cross-reference listing.

   00000100 $SET XREF
   00000200       REAL B, C, MEAN
   00000300       INTEGER I
   00000400       DIMENSION R(3)
   00000500       R(1) = 1
   00000600       R(2) = 2
   00000700       R(3) = R(1) + R(2)
   00000800       B = 3
   00000900       C = 25
   00001000       CALL ONE
   00001100       B = 5
   00001200       CALL ONE
   00001300       END
   00001400       SUBROUTINE ONE
   00001500          MEAN = 2
   00001600          DO 10 I=0,5,1
   00001700             MEAN = MEAN * B
   00001800             C = C * MEAN
   00001900  10      CONTINUE
   00002000       RETURN
   00002100       END

    B     ---REAL---DECLARED AT 00000200
              *00000800  *00001100
    B     ---REAL---DECLARED AT 00001700
    C     ---REAL---DECLARED AT 00000200
              *00000900
    C     ---REAL---DECLARED AT 00001800
              *00001800
    I     ---INTEGER---DECLARED AT 00000300
    I     ---INTEGER---DECLARED AT 00001600
              *00001600
    MEAN  ---REAL---DECLARED AT 00000200
    MEAN  ---INTEGER---DECLARED AT 00001500
              *00001500  *00001700   00001800
    ONE   ---SUBROUTINE---DECLARED AT 00001000
               00001200   00001400
    R     ---REAL ARRAY---DECLARED AT 00000400
              *00000500  *00000600  *00000700
    10    ---LABEL---FORWARD AT 00001600      OCCURS AT 00001900

Each reference consists of an 8-digit sequence number, preceded by an asterisk (*) if the value might be changed by the statement.

Example 3

This example shows a job that runs XREFANALYXER explicitly to generate the files that are necessary for Editor and INTERACTIVEXREF to perform cross-referencing commands.

1000 ?BEGIN JOB WBM;
2000 INTEGER TASKVAL;
3000 TASK T;
4000 TASKVAL:= -1;
5000 COMPILE OBJ/WBM/1 ALGOL [T] LIBRARY;
6000 C DATA
7000 $SET NOXREFLIST XREF

8000 BEGIN
9000 INTEGER I;
10000 I:= 0;
12000 END.
13000 ?%END OF ALGOL DATA
14000 IF T IS COMPILEDOK THEN
15000    BEGIN
16000    RUN SYSTEM/XREFANALYZER (0);
17000    VALUE=TASKVAL;
18000    FILE XREFFILE (TITLE=XREF/OBJ/WBM/1);
19000    FILE REFERENCES (SECURITYTYPE=PUBLIC,SECURITYUSE=IO);
20000    FILE DECLARATIONS (SECURITYTYPE=PUBLIC,SECURITYUSE=IO);
21000    END;
22000 ?END JOB

The title of the ALGOL program is WBM/1. When compiled, it generates cross-reference information containing a list of all identifiers that appear in the program and saves it as the XREF file. Since NOXREFLIST is TRUE, XREFANALYZER is not initiated by the ALGOL compiler and consequently no cross-reference listing is printed. When XREFANALYZER is run explicitly, the TASKVALUE equal to –1 causes the DECS and REFS files to be created and saved. Since the LINEWIDTH parameter is equal to 0, no printed output is produced.

Example 4

The following ALGOL code excerpt can be used to invoke XREFANALYZER with an XREFFILE file equated to KIND=PORT:

BEGIN
 ...
 FILE XREFFILE(KIND=PORT, MYUSE=OUT, MAXRECSIZE=510,
               BLOCKSTRUCTURE=EXTERNAL, YOURNAME="XREFFILE.");
 INTEGER REF_COUNT, XSZ;
 ARRAY   XSTUF[0:510];
 TASK    XT;  % TASK FOR XREFANALYZER
 PROCEDURE Z(LSIZ); VALUE LSIZ; REAL LSIZ;
   EXTERNAL;
 ...
 REPLACE XREFFILE.MYNAME BY ...; % XREF/<file name>
 REF_COUNT := ...;               % High approx of # references
 ...
 REPLACE XT.NAME BY ="*SYSTEM/XREFANALYZER.";
 REPLACE XT.FILECARDS BY MYSELF.FILECARDS;
 REPLACE P:XSTUF BY 
  "FILE XREFFILE(KIND=PORT, DEPENDENTSPECS, MYNAME=XREFFILE, "
                "YOURNAME=", XREFFILE.MYNAME;
 REPLACE P:P-1 BY ")" 48"00";
 REPLACE XT.FILECARDS BY POINTER(XSTUF);
 XT.TASKVALUE := NABS(REF_COUNT);
 XT.JOBSUMMARY := VALUE(CONDITIONAL);
 PROCESS Z (0) [XT];
 ...
 OPEN(XREFFILE, WAIT);
 XSZ := XREFFILE.ACTUALMAXRECSIZE;
 ...
   WRITE(XREFFILE, SZ, XSTUF); % usually within a loop
 ...
 LOCK(XREFFILE);
 WHILE XT.STATUS > 0 DO
   WAITANDRESET((5), MYSELF.EXCEPTIONEVENT);
END