Hello Mirko,

On Tue, Jun 25, 2013 at 1:56 AM, Mirko Vukovic <mirko.vukovic@gmail.com> wrote:
> I am trying to link to a VISA library (VISA is used to control data
> acquisition instruments), visa32.lib compiled for Windows. The library is
> shipped with Tektronix software.

I'm surprised loading it works. That sounds like a static library.

> Using `nm' I did find:
> 00000000 I __imp__viOpenDefaultRM@4
> 00000000 T _viOpenDefaultRM@4

This looks like the stdcall calling convention. (See "Name-decoration
convention" in <http://msdn.microsoft.com/en-us/library/zxk0tw93(v=vs.71).aspx>.)
Passing ":convention :stdcall" to DEFCFUN should work.

As a side point, I'm not sure if cffi-libffi works with stdcall. I think I put the code in, but having nothing to test it on, I have no idea if it works. If you have some structures-by-value functions to call, it would be good to test it (but you'll have to do the debugging if it fails).

Liam