From: "David Allsopp" <dra-news@metastack.com>
To: "'Matthieu Dubuget'" <matthieu.dubuget@gmail.com>, <caml-list@inria.fr>
Subject: RE: [Caml-list] External DLL call with mingw OCaml
Date: Sun, 20 Sep 2009 21:37:14 +0100 [thread overview]
Message-ID: <002001ca3a32$24167db0$6c437910$@metastack.com> (raw)
In-Reply-To: <4AB683DF.7000206@gmail.com>
Matthieu Dubuget wrote:
> Hello,
>
> recently, I had to call a third-party DLL (Windows, mingw flavour of
> OCaml).
> It was not easy, because of symbol names decorations (I think).
It is indeed not easy - fortunately, it's a once-only thing (for each DLL)
> I'd like to know if there is a more simple way?
Not as far as I'm aware - no site I've ever seen gives a reasonable
explanation for why the "@nn" decorations are necessary (gcc or any other
compiler should be able to infer it from the header at link time, but
neither gcc nor the MS compilers provide a way to do this)
<snip>
> 3/ Import lib generation
> dlltool --input-def visa.def --dllname Visa32.dll --output-lib
> libvisa.a -k
The irony is that the -k (--kill-at) removes the @nn from the symbols :o)
<snip>
> The main problem is that it is a trial error process in order to find
> the @nn to add into visa.def.
This shouldn't be trial and error - you can work out the numbers from the C
definitions (which presumably you know as you're writing stubs). For the
most part for 32-bit code, it'll be 4 x the number of parameters to the
function but in more exact terms it's the number of bytes occupied by the
parameters (so sizeof the *type* of each arg) which you can deduce from the
.h file. Alternatively, you can just put them all as @0 initially and use
the error messages - it'll always give you the correct one (provided that
your headers are correct)
Hope this reassures, even if it doesn't offer an easier way!
David
PS This is the site I used originally -
http://www.emmestech.com/moron_guides/moron1.html though I'm not sure you'd
ever find a moron who wanted/needed to do this kind of thing!!
prev parent reply other threads:[~2009-09-20 20:37 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-09-20 19:34 Matthieu Dubuget
2009-09-20 20:37 ` David Allsopp [this message]
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