open the dll in dependency walker (part of sysinternals suite) - if your functions start with underscore (_) they're almost certain cdecl, otherwise probably stdcall.
On 4/30/07, Mont Rothstein <[EMAIL PROTECTED]> wrote:
Thanks for all of the information. I'll have to dig into this more. The make file doesn't have a /Gd or a /Gz flag. I suspect I am going to have to contact the vendor about this (though I don't hold out much hope for an answer). I have C code that calls the same functions and works fine, so I know the functions work, and the DLL does nothing more than define the functions and like to the libraries them are in. Thanks again, -Mont On 4/30/07, Michael Waldinger <[EMAIL PROTECTED]> wrote: > > I have a strong recollection that when I did my P/Invoke work a few months > ago, I ran into a problem where I had to look at the calling convention. > So as I recall I think it does matter; it would stand to reason that you > would have to P/Invoke the API using the same calling convention that the > API is built to use. This may be the root of your problem. BTW, if the > DLL is being built using a makefile you will want to look for the compiler > switch /Gd for __cdecl and /Gz for __stdcall. I got this information from > the following website: > http://www.codeproject.com/cpp/calling_conventions_demystified.asp > > I have tried googling this subject using the keywords "__cdecl pinvoke" > and > I got a lot of results; many of them contradicted my earlier statement > that __cdecl is required. > > I also found this on the dotnet-cx board which sounds a lot like it > answers > your latest questions: > http://discuss.develop.com/archives/wa.exe?A2=ind0406d&L=dotnet-cx&P=730 > > Unfortunately, you have reached the limit of my knowledge on the proper > calling conventions. I don't want to give out any more bad information, > except that I think this may be your problem. Your declarations look OK > to > me but again I am unfamiliar with what it takes to get a struct back as an > out parameter. That would be the only other thing I could suggest you > look > into. A third thing to try, if you are familiar with C++, is to write a > C++ test harness to simulate the calls that you are doing in C#, and make > certain that you get the struct popuated with data. One of the earlier > posters suggested that the DLL was failing internally before it allocated > the struct, which could also be a cause of your problem. > > On Mon, 30 Apr 2007 08:44:21 -0700, Mont Rothstein > <[EMAIL PROTECTED]> wrote: > > >Thanks for the additional info. > > > >I am compiling this DLL with VS 05 form the command line. It uses a > >manually created make file and not a project. > > > >I didn't create the DLL, it is part of a package, which is why I am > unclear > >on some of this. > > > >I searched the directory where all of the source is kept for both > __stdcall > >and __decl with no hits on either. So I presume it uses whichever is > >default for VS. > > > >I guess I should ask why it matters? Might the root of this problem be > that > >the wrong calling convention is used? Or might I need to change someone > in > >my C# code based on the calling convention? > > > >Thanks, > >-Mont > > =================================== > This list is hosted by DevelopMentor(r) http://www.develop.com > > View archives and manage your subscription(s) at > http://discuss.develop.com > =================================== This list is hosted by DevelopMentor(r) http://www.develop.com View archives and manage your subscription(s) at http://discuss.develop.com
-- Cheers, Stoyan =================================== This list is hosted by DevelopMentor® http://www.develop.com View archives and manage your subscription(s) at http://discuss.develop.com
