[Back to MISC SWAG index] [Back to Main SWAG index] [Original]

    (*
    YK>1) I'm going to write a program in pascal that calls a function.
    YK>2) That function is going to be written in C.
    YK>3) Link them together to make one EXE file.

    YK>Is there anyway to do this or am I just dreaming? <g>  Thanks for
    YK>any insight in this.

    Yes, it is possible.  You will need to compile object code modules with
    your Pascal and C compilers, and then link them with a linker program.
    Unusually, for a programming tool, the program you use for linking usually
    has the obvious name of LINK.EXE (as compared to such things as "grep",
    "awk", "yacc" or "bison").

    The second edition of Turbo C++ includes a set of example files for just
    this situation.

    First, a fragment of the C code called by the Pascal program.

    typedef unsigned int word;
    typedef unsigned char byte;
    typedef unsigned long longword;

    extern void setcolor(byte newcolor);  /* procedure defined in
                                             Turbo Pascal program */
    extern word factor;    /* variable declared in Turbo Pascal program */

    word sqr(int i)
    {
      setcolor(1);
      return(i * i);
    } /* sqr */

    word multbyfactor(word w)
    {
      setcolor(9);        /* note that this function accesses the Turbo Pascal */
      return(w * factor); /* declared variable factor */
    } /* multbyfactor */

    ----8<---------

    The command line compiler uses the following .CFG file

    ---8<---------

    -wrvl
    -p
    -k-
    -r-
    -u-
    -zCCODE
    -zP
    -zA
    -zRCONST
    -zS
    -zT
    -zDDATA
    -zG
    -zB

    ---8<------------

    Finally, the Pascal code

    *)
    program CPASDEMO;
    (*
      This program demonstrates how to interface Turbo Pascal and Turbo C++.
      Turbo C++ is used to generate an .OBJ file (CPASDEMO.OBJ). Then
      this .OBJ is linked into this Turbo Pascal program using the {$L}
      compiler directive.

      NOTES:
        1. Data declared in the Turbo C++ module cannot be accessed from
           the Turbo Pascal program. Shared data must be declared in
           Pascal.

        2. If the C functions are only used in the implementation section
           of a unit, declare them NEAR.  If they are declared in the
           interface section of a unit, declare them FAR.  Always compile
           the Turbo C++ modules using the small memory model.

        3. Turbo C++ runtime library routines cannot be used because their
           modules do not have the correct segment names.  However, if you
           have the Turbo C++ runtime library source (available from
           Borland), you can use individual library modules by recompiling
           them using Pascal conventions.  If you do recompile them, make
           sure that you include prototypes in your C module for all C
           library functions that you use.

        4. Some of the code that Turbo C++ generates are calls to internal
           routines. These cannot be used without recompiling the relevant
           parts of the Turbo C++ runtime library source code.

      In order to run this demonstration program you will need the following
      files:

        TCC.EXE and CTOPAS.CFG or
        TC.EXE and CTOPAS.TC

      To run the demonstration program CPASDEMO.EXE do the following:

      1. First create a CPASDEMO.OBJ file compatible with Turbo Pascal 4.0
         or later using Turbo C++.

        a) If you are using the Turbo C++ integrated environment (TC.EXE)
           then at the DOS prompt execute:

           TC CTOPAS.PRJ

           then create the .OBJ file by pressing ALT-F9.

        b) If you are using the Turbo C++ command line version (TCC.EXE)
           then at the DOS prompt execute:

           TCC +CTOPAS.CFG CPASDEMO.C

           Note: Use the same configuration file (CTOPAS.CFG or CTOPAS.PRJ)
                 when you create your own Turbo C++ modules for use with
                 Turbo Pascal

      2. Compile and execute the Turbo Pascal program CPASDEMO.PAS

      This simple program calls each of the functions defined in the Turbo C++
      module. Each of the Turbo C++ functions changes the current display color
      by calling the Turbo Pascal procedure SetColor. }
    *)

    uses Crt;

    var
      Factor : Word;

    {$F+}  { Force Far Calls for calling to and from Turbo C }

    {$L CPASDEMO.OBJ}  { link in the Turbo C++-generated .OBJ module }

    function Sqr(I : Integer) : Word; external;
    { Change the text color and return the square of I }

    function MultByFactor(W : Word) : Word; external;
    { Change the text color and return W * Factor - note Turbo C++'s access of }
    { Turbo Pascal's global variable.                                        }

    procedure SetColor(NewColor : Byte); { A procedure that changes the current }
    begin                                { display color by changing the CRT    }
      TextAttr := NewColor;              { variable TextAttr                    }
    end; { SetColor }

    begin
      Writeln(Sqr(10));                  { Call each of the functions defined   }
                                         { passing it the appropriate info.}

      Factor :=100;
      Writeln(MultbyFactor(10));
      SetColor(LightGray);

    end.
    {
    ------8<----------

    To save space, I've edited a lot of the functions out of both source
    files.  I hope this works.  I don't have a DOS Pascal compiler :(
    }

[Back to MISC SWAG index] [Back to Main SWAG index] [Original]