Re: Pascal Calling Convention

["Yannick Duchêne (Hibou57)" <yannick_duchene@yahoo.fr>]

Hello Shark,

Le Wed, 23 Mar 2011 22:37:55 +0100, Shark8 <onewingedshark@gmail.com> a  
écrit:
> I was looking around for a way to use the Pascal calling convention in
> GNAT; particularly because I thought it might be nice to do the GUI-
> stuff in good old Delphi 5 and the application itself in Ada. All
> easily doable via DLL or, possibly, through the $L compiler directive
> which specifies a .obj file to link to.
>
> -- I found a utility to convert between .o and .obj; so that's not a
> problem. Though if someone knows a way to
> -- have GNAT emit .obj files instead of .o I'd like to hear it.
You should not ask for GNAT to do it, rather to GNU ld which GNAT relies  
on (it does not have an internal linker). GNU ld does not support MS  
Windows object file format, as far as I know (the only Windows specific  
format it supports, it the one for compiled resource files data).

> The problem comes with the conventions... I'd like to be able to
> interface w/o using stdcall or cdecl calling convention and directly
> use the Pascal calling convention within my Ada texts. According to
> this page (  
> http://gcc.gnu.org/onlinedocs/gnat_ugn_unw/Stdcall-Calling-Convention.html
> ) the STDCALL convention *is* the Pascal calling convention; both are
> callee clean-up of the stack however, according to wikipedia (and
> http://www.swissdelphicenter.ch/torry/showcode.php?id=1233 ) there is
> a difference: left-to-right vs. right-to-left parameter passing.
As Delphi is Windows only, I suppose you want the Windows API calling  
convention (tell me if I'm wrong). On Windows, this is 1) Parameters  
pushed from right to left : like C 1) The callee clean the stack : like  
Pascal. This is not the same as the Pascal calling convention, which push  
parameters from left to right. I believe GNU docs is wrong here, when it  
says the Pascal calling convention is the calling convention for Windows  
API (wrong on both sides).

I never owned a Delphi compiler, so I could not tell for Delphi proper  
object files.

> This could also be a good nugget of information if I decide to use BP7
> to write an OS loader & runtime for that OS; I had an OS written in
> BP7 to the point where it could display a command-line, read
> [keyboard] commands, and change the display-mode... when trying to
> port that code to Ada apparently it failed to load properly due to the
> non-existent runtime's requirement.
The Borland Pascal 7 runtime was/is simple enough; there should be a way  
to emulate it on top of the Ada runtime, which is more complete.

> {True, it would be limited to 32-bits; but there isn't going to be a
> shortage of 32-bit CPUs for a while.}
I hope too they will live for a long time again  (I don't want to see  
millions of machines discharged and thrown away to Africa).


-- 
Si les chats miaulent et font autant de vocalises bizarres, c’est pas pour  
les chiens.
“ c++; /* this makes c bigger but returns the old value */ ” [Anonymous]