Help with Windows DLL linking

[Robert Hansen Crystal Software]

GCC Help,
I am trying to help some developers that are using GCC to develop a linux 
application that will run on windows. They would like to link into several 
functions in a dll that I provide under windows that provides serial 
communication in windows.

My build tools for the windows dll is Microsoft C/C++ version 6 Visual 
Studio. I create with the Microsoft tools the windows DLL, and
LIB file for linking windows C programs. I obviously also have Microsoft 
compliant .def files for the dll and header files. The dll that is created 
using the Microsoft tools is linked with the following lib files in its 
construction: kernel32.lib user32.lib gdi32.lib winspool.lib comdlg32.lib 
advapi32.lib shell32.lib ole32.lib oleaut32.lib uuid.lib odbc32.lib 
odbccp32.lib winmm.lib.

Now I need to link a simple little .c program to the dll using the gcc 
tools.

1st approach: use the def file that I already have using the tool to create 
a .a file to link to my compiled c program
The command "dlltool -def foo.def -dllname fll.dll -output-lib foo.a" 
appears to work, but when I try to use the command
"gcc -o myprog myprog.c -L./ -lfoo" I get an error for each one of the 
functions that the program calls in the foo dll that states that they are 
undefined.

2nd approach: create a def file using the gcc tools by..
Echo EXPORTS > foo.def
nm foo.dll | grep ' T _' | sed 's/.* T _//' >> foo.def

This simply tells me that foo.dll has no symbols, even if I use the 
Microsoft debug version of the dll.

3rd approach: compile the dll using gcc. Unfortunately there is the issue of 
all of the lib files that the dll needs to link with and I have a circular 
problem.

How can I approach this successfully?

Robert Hansen  Crystal Software
crystalcom@direcway.com
crystalcom@hughes.net
crystalrh@comcast.net
crystal@up.net
329 Fire Lake Road
Crystal Falls, MI 49920
(906) 822-7994
(906) 250-5031 Cell