HP 3000 Manuals

HP Pascal/iX Programmer's Guide

How Non-Pascal Programs Call Pascal Routines 

A program written in C, COBOL II, FORTRAN 66/V, FORTRAN 77, or SPL can
call an external routine written in HP Pascal.  You must match the formal
parameters and result type of the HP Pascal routine with those that the
calling program specifies.

The matching rules are:

   *   Corresponding formal parameter lists must have the same number of
       parameters in the same order.  If the Pascal routine requires
       hidden parameters, the non-Pascal routine must have actual
       parameters that correspond to them (see Chapter 7  for
       details).

   *   Corresponding formal parameters must be of corresponding types.
       Correspondence depends upon the source language of the external
       routine.  See the parameter descriptions in "EXTERNAL Directive"
       .

   *   Corresponding formal parameters can have different names.

Example 1 

This C program calls the external Pascal procedure pas:

     main()
     { extern void pas();  /*This is non ANSI C  */

       char carr[21];
       short sint1, sint2;
       short sum;

       strcpy(carr, "Add these 2 numbers ");
       sint1 = 25;
       sint2 = 15;
       pas(carr, sint1, sint2, &sum);
     }

This Pascal program contains the procedure pas:

     $SUBPROGRAM$
     PROGRAM Pas_Proc;
     TYPE
        arr = PACKED ARRAY [1..21] OF char;

     PROCEDURE pas (VAR carr  : arr;
                        sint1 : shortint;
                        sint2 : shortint;
                    VAR sum   : shortint);
     BEGIN
        carr := 'Sum of two numbers: '#0;
        sum := sint1 + sint2;
     END;

     BEGIN
     END.

Example 2 

The COBOL II program COBOL-TO-PASCAL calls the external Pascal procedure
pasprog.

COBOL II program:

     IDENTIFICATION DIVISION.
     PROGRAM-ID. COBOL-TO-PASCAL.
     AUTHOR. BP.
     DATA DIVISION.
     WORKING-STORAGE SECTION.
     77 ASTRING   PIC X(16) VALUE "A COBOL STRING!".
     77 ANUM      PIC 9(04) USAGE COMP.
     77 ANUM2     PIC 9(04) USAGE COMP.
     77 RESULT    PIC -ZZZZ.
     PROCEDURE DIVISION.
     FIRST-PARA.
       MOVE 9999 TO ANUM.
       DISPLAY ASTRING.
       CALL "PASPROG" USING ASTRING, \ANUM\, ANUM2.
       MOVE ANUM2 TO RESULT.
       DISPLAY ASTRING, RESULT.
       STOP RUN.

Pascal procedure:

     $SUBPROGRAM$
     PROGRAM pas_proc;
     TYPE
        charstr = PACKED ARRAY [1..16] OF char;

     PROCEDURE pasprog(VAR astr : charstr;
                           num : short_int;
                       VAR num2 : short_int);
     BEGIN
        astr := 'A PASCAL STRING!';
        num2 := num;
     END;
     BEGIN
     END.

Example 3 

The following FORTRAN 66/V program calls the external Pascal procedure
pas:

     INTEGER INT1, INT2, ISUM
     CHARACTER CSTR*20

     CSTR = "Add these 2 numbers"
     INT1 = 25
     INT2 = 15

     DISPLAY CSTR, INT1, INT2
     CALL PAS(CSTR,\INT1\,\INT2\,ISUM)
     DISPLAY CSTR, ISUM

     STOP
     END

Pascal procedure:

     $SUBPROGRAM$
     PROGRAM example(input,output);
     TYPE
        arr = PACKED ARRAY [1..20] OF char;
        small_int = -32768..32767;

     PROCEDURE pas $CHECK_ACTUAL_PARM 0; CHECK_FORMAL_PARM 0$
        (VAR carr : arr;
             sint : small_int;
             sint2 : small_int;
         VAR sum : small_int);

     BEGIN
         carr := 'Sum of two numbers: ';
         sum := sint1 + sint2;
     END;

     BEGIN
     END.

Example 4 

The following FORTRAN77 program calls the external Pascal procedure pas:

     $ALIAS PAS(%REF,%VAL,%VAL,%REF)
            INTEGER INT1, INT2, ISUM
            CHARACTER CSTR*20

            CSTR = "Add these 2 numbers"
            INT1 = 25
            INT2 = 15

            PRINT *, CSTR, INT1, INT2
            CALL PAS(CSTR, INT1, INT2, ISUM)
            PRINT *, CSTR, ISUM

            STOP
            END

Pascal procedure:

     $SUBPROGRAM$
     PROGRAM example;
     TYPE
        arr = PACKED ARRAY [1..20] OF char;
        small_int = -32768..32767;

     PROCEDURE pas(VAR carr : arr;
                       sint : small_int;
                       sint2 : small_int;
                   VAR sum : small_int);

     BEGIN
        carr := 'Sum of two numbers: ';
        sum := sint1 + sint2;
     END;

     BEGIN
     END.

Example 5 

The following SPL program calls the external Pascal procedure pas:

     BEGIN
       LOGICAL ARRAY chr(0:9) := "Add these 2 numbers:";
       BYTE ARRAY bchr(*) = chr;
       INTEGER sint:=15,sint2:=25,len;
       INTEGER int, int2, sum;
       BYTE ARRAY csum(0:1), cint(0:1), cint2(0:1);

       INTRINSIC PRINT,ASCII
       PROCEDURE pas(chr,sint,sint2,sum);
         VALUE sint,sint2;
         INTEGER sint,sint2,sum;
         BYTE ARRAY chr;
         OPTION EXTERNAL;

       PRINT(chr,10,0);
       len := ASCII(sint,-10,cint);
       len := ASCII(sint2,-10,cint2);
       PRINT(cint,-2,0);
       PRINT(cint2,-2,0);

       pas(chr,sint,sint2,sum);

       PRINT(chr,10,0);
       len := ASCII(sum,-10,csum);
       PRINT(csum,-2,0);
     END.

Pascal procedure:

     $HP3000_16$
     $SUBPROGRAM$
     PROGRAM example;
     TYPE
        arr = PACKED ARRAY [1..20] OF char;
        small_int = -32768..32767;

     PROCEDURE pas(VAR carr : arr;
                       sint : small_int;
                       sint2 : small_int;
                   VAR sum : small_int);
     BEGIN
        carr := 'Sum of two numbers: ';
        sum := sint1 + sint2;
     END;
     BEGIN
     END.

MPE/iX 5.0 Documentation