Writing Externals in Pascal?

[Peter W A Wood]

Hi Scott

I am also be interested in being able to develop externals in Free Pascal. At the moment, I am testing calling a dynamic load library written in Free Pascal from Rebol (a language written in C) using C calling conventions.

> It is impossible to get the level
> of granularity of compiler options with Borland's compilers
> (C++ Builder, Delphi) to get the combination of:
> 1. no leading underscore

You get to name the function in FPC. Here is an extract from my dll:

{$ifndef Darwin}
exports  
  version name 'version';
{$else}
exports
  version name '_version';
{$endif}

> 2. mixed case exported symbols

I tested with a mixed case function name:

exports
  accountingformat name '_accountingFormat',
  version name '_version';


> 3. C-style parameter passing (first to last)
> 4- C-style stack frames (calling program cleans up
> the stack)

FPC includes a modifier for the cdecl calling convention (which I believe answers 3 & 4). Here is an example:

procedure version(var answer: shortstring);cdecl;
begin
  answer := CurrentVersion;
end;

Regards

Peter Wood