Re: bug or wrong usage of external functions

[Martin Sjölund]

Hi,

It seems this is indeed an OpenModelica bug. The prototype and function 
call are done properly. But when copied into the result structure, the 
order is mixed up:

  rv_ext = exttest(omega_ext, Position_ext, &outx_ext, PPP_ext);
  out.targ1 = (modelica_integer)outx_ext;
  out.targ2 = (modelica_integer)rv_ext;

--
Martin Sjölund

Kiel, Dr. Henning wrote:
Hi list,
 
the Modelica Laguage Spec 3.1 has an example for external function with 
two output values (one via return other via pointer parameter) in 
chapter 12.9.5.3.
 
I'm trying to simulate an electronic device which reacts on hall pulses 
generated by a motor.
I implemented a DC-motor in modelica and am calling my "device" 
(external C function "fexttest") via algorithm:
 
  algorithm
    if HallSignal <> pre(HallSignal) then
      (Check, BBR) := fexttest(omega, HallPos, table);
 
This basically works. Has anyone a better construct?
 
Now to the real problem:
I wrote code that should do the same as in the example, but what I see 
is that the return value and the pointer parameter values are swapped 
(see plot).
In the external function I just return constants to be sure to to know 
what I return. I would expect the two values to be just the other way round.
Is this a bug, or am I doing something wrong?
I attached all required files.
 
    function fexttest
      input Real omega;
      input Integer Position;
      input demoPack_Data PPP;
      output Integer rv;
      output Integer outx;
      external "C" rv = exttest(omega, Position, outx, PPP) 
annotation(Library="exttest.o",Include="#include \"exttest.h\"");
    end fexttest;
 
Regards,
Henning

 

 

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