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load C code into R

3 messages · Richard Condit, Peter Dalgaard, Brian Ripley

Original
Richard Condit
# 
I am trying to load C routines into R on windows, going through the the 
book S programming and the R manual, but I know I am missing some steps.

I created a win32 DLL project in Visual C++ (ver. 6.0).  It consists of one 
simple routine named test which accepts one *integer argument and one 
*double argument and performs a trivial computation.  The dll is named 
test.dll.

In R1022 for Windows, I run

 >dyn.load("d:/programs/library/test/test.dll")
 >testr_function(a,x) 
.C"d:/programs/library/test/test",as.integer(a),as.double(x))

These are both accepted, and I can use dyn.unload as well with test.dll.  I 
notice that while loaded, Visual C++ cannot recompile test.dll.

But when I try

 >testr(10,x)

I get the message ?Error in .C("test", as.integer(a),as.double(x)) : 
C/Fortran function name not in load table?.

I know I need a link step, or an install step, but I am missing something 
in the instructions.  Perhaps just a quick piece of advice could get me to 
the next stage



Richard Condit
Smithsonian Tropical Research Institute



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Peter Dalgaard
# 
Richard Condit <rick at eno.princeton.edu> writes:
Compiling DLLs on Windows is tricky business, especially if you want
to mix and match compilers. Detailed instructions for doing it is
contained in the rw-faq file and readme.packages. There's a strong
recommendation to use the toolkit based on the Mingw32 compiler and
GNU utilities, but Visual C++ should be doable and there's a full
example in readme.packages.
Brian Ripley
#
On Sun, 10 Jun 2001, Richard Condit wrote:

            

      
      
      
    

        
Yes, that's a feature of Windows (and some other OSes).

            

      
      
      
    

        
Your .C call should be something like

.C("test", as.integer(a), as.double(x))

and "test" must be exported by your DLL.  Note: by default nothing is
exported in Visual C++: you need a .def file in the project.

I think you've missed the advice in readme.packages (in rw1023sp.zip),
which has a section `Using Visual C++'.  Despite the presence of that,
using the recommended compiler is easier....