Hi all,

I hope some have knowledge of PascalScript because I'm having quite a weird and complex problem. I'll demonstrate it here very simply so if some have ideas...

*Problem*
I'm exporting some classes (originally a TBitmap; now a custom class) to the ROPS engine and then interacting with the class in the scripting engine. Everything works, except for some functions that behave very strange. They skip/duplicate the parameters and invert parameters.

*Simple example*
All the following code is typed in the e-mail.

TMyClass
public
  procedure DrawRectangle(left, top, right, bottom: Extended);
end;
//
procedure TMyClass.DrawRectangle(left, top, right, bottom: Extended);
begin
  ShowMessage('left='+FloatToStr(left)+' top='+FloatToStr(top)+
    ' right='+FloatToStr(right)+' bottom='+FloatToStr(bottom));
end;
//
var
  MyClass: TMyClass; //I create it later

Now I call a function in the script defined as procedure OnMyClass(myclass: TMyClass); Then I pass the class in parameters.

*Example of script*
procedure OnMyClass(myclass: TMyClass);
begin
  myClass.DrawRectangle(1,2,3,4);
end;

*Results of all that*
We would expect to have a nice message displaying 'left=1 top=2 right=3 bottom=4', but in fact I'm getting 'left=4 top=3 right=2 bottom=2'. So parameter order is reversed and I'm always loosing the first (last!?!) parameter and the second one is duplicated to the first.

The ROPS units are compiled in delphi mode in there units. My application is pure fpc. I'm under winXP.

I'm still doing many other tests meanwhile.

Best regards.

Try declaring the methods as "stdcall" (although I'm not sure whether this works for methods).

Jonas

2006/8/8, Jonas Maebe :

This causes External SIGFPE. Seeing the call, I'm not sure this is the problem. I must say that what I explaned here is also true (and doing the same thing) with Bitmap.Canvas.Rectangle() method.

2006/8/8, Michael Van Canneyt :

I was exactly thinking about the stack. But I don't know how it work. Ok, now Bitmap.Canvas.Rectangle uses Integer and it has the same behaviour. So it is probably not only a matter of extended? Now I would gladly answer that question, but Carlo Kok is in vacation (he is The guy about ROPS). Well, I like what you bring - I'm no stack expert
- but if you want you can speculate more :) I can try to find answers in the code.

That won't work. Delphi doesn't use stdcall by default, so the ROPS engine doesn't expect this.

The problem is more likely that all arguments are extended, which probably means that the stack is used differently. Are they pushed on the FPU stack ?

Michael.

2006/8/8, Michael Van Canneyt :

The problem is more likely that all arguments are extended, which probably means that the stack is used differently. Are they pushed on the FPU stack ?

Ok, I found this procedure that is used to handle parameters... Maybe this is the actual asm code who is not good... ???

procedure PutOnFPUStackExtended(ft: extended);
asm
  fstp tbyte ptr [ft]
end;
And here is a part of the monstruous function MyAllMethodsHandler2
that work with the arguments:
//...
  if (Res  nil) then
  begin
    Params.DeleteLast;
    if (ResultAsRegister(Res.FType)) then
    begin
      if (res^.FType.BaseType = btSingle) or (res^.FType.BaseType = btDouble) or
      (res^.FType.BaseType = btCurrency) or (res^.Ftype.BaseType =
btExtended) then
      begin
        case Res^.FType.BaseType of
          btSingle: PutOnFPUStackExtended(PPSVariantSingle(res).Data);
          btDouble: PutOnFPUStackExtended(PPSVariantDouble(res).Data);
          btExtended: PutOnFPUStackExtended(PPSVariantExtended(res).Data);
          btCurrency: PutOnFPUStackExtended(PPSVariantCurrency(res).Data);
        end;
        DestroyHeapVariant(Res);
        Res := nil;
      end else
      begin
{$IFNDEF PS_NOINT64}
        if res^.FType.BaseType  btS64 then
{$ENDIF}
          CopyArrayContents(Pointer(Longint(Stack)-8),
@PPSVariantData(res)^.Data, 1, Res^.FType);
      end;
    end;
    DestroyHeapVariant(res);
  end;
//...

The actual procedure that is called. It does some asm processing and then calls the MyAllMethodsHandler2 that works with parameters. Maybe this is there that there is a problem? (This is all in the uPSRuntime.pas file)

procedure MyAllMethodsHandler;
// On entry:
// EAX = Self pointer
// EDX, ECX = param1 and param2
// STACK = param3... paramcount
asm
push 0
push ecx
push edx
mov edx, esp
add edx, 16 // was 12
pop ecx
call MyAllMethodsHandler2
pop ecx
mov edx, [esp]
add esp, eax
mov [esp], edx
mov eax, ecx
end;

2006/8/8, Alexandre Leclerc :

2006/8/8, Alexandre Leclerc :

The actual procedure that is called. It does some asm processing and then calls the MyAllMethodsHandler2 that works with parameters. Maybe this is there that there is a problem? (This is all in the uPSRuntime.pas file)

For the records, issue has been fixed by Carlo Kok in svn tree of ROPS at revision 11 (as of 2006/08/18). It now works great in FPC!