cygwin DLLs and VC (again)

["Manuel Sánchez" <icg_incubus at yahoo dot com>]

    This message follows to the one I posted on March 16.

    Following the explanations Mumit Khan kindly gave, I managed to link dinamically a cygwin GCC compiled DLL from a VC compiled exe, and using __stdcall calling specifier, it worked fine with ordinary C methods. One of the methods returned an object whose class derived the ICommon interface... well, a correct instance was returned, but then I noticed that there are some differences between VC and GCC when dealing with method calling:

 

    First of all: VC stores the object pointer in ecx before it calls the method itself, and it seems that GCC do the same in ebx.

    VC uses the eax register as storage for the returning value... I think GCC uses the stack.

    Virtual tables differ in method pointer placement in VC and GCC: when calling to one method from VC using a certain offset from the vtable it jumps to another method whose assembly it's easily recognisable (the release method), but it'snt the one it was supossed to call!!!

 

    So I wonder if is there any way of forcing both compilers to work in the same way.

 

    Thanks for reading this.

 

        Tony Sanchez