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Message-ID: <4AB683DF.7000206@gmail.com>
Date: Sun, 20 Sep 2009 21:34:55 +0200
From: Matthieu Dubuget <matthieu.dubuget@gmail.com>
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To: caml-list@inria.fr
Subject: External DLL call with mingw OCaml
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X-Spam: no; 0.00; matthieu:01 dubuget:01 matthieu:01 dubuget:01 mingw:01 ocaml:01 mingw:01 ocaml:01 def:01 def:01 lib:01 --dllname:01 ocamlc:01 stub:01 ocamlmklib:01 

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).
I'd like to know if there is a more simple way?

Here is the way I found, after asking some questions to internet:

1/ First I had to create a .def file for the third party DLL:
pexports.exe Visa32.dll > visa.def

2/ Then I had to edit the visa.def file, in order to add @nn to symbol 
names.

3/ Import lib generation
dlltool --input-def visa.def --dllname Visa32.dll --output-lib libvisa.a -k

4/ My C-stub, that give access to the functions of Visa32.dll to OCaml
ocamlc -c test_stub.c

Is then turned into a library that depends on Visa32.dll
ocamlmklib -o test_dll -lvisa test_stub.o

5/ Test module compilation
ocamlc -c test.ml
ocamlc -a -o test.cma -dllib dlltest_dll test.cmo

6/ Load test.cma into toplevel


The main problem is that it is a trial error process in order to find 
the @nn to add into visa.def.
I deduce them from the error message I receive (I don't remember if this 
is at step 5/ or 6/) about
visa_function@nn that can't be found.

Salutations

Matthieu Dubuget