How can I get HINSTANCE from .mex?

Good day.

My GUI contains the main .m file and .dll, which is used via .mex files, each one corresponding to a separate function from library.

Before now, each .mex contained LoadLibrary and Freelibrary functions, thus library was loaded and freed each time I called any of the dll functions.

Now I want to write 2 separate .mex files, first one loading the library and returning its HINSTANCE as output parameter so that I could use one loaded library for all functions. Second .mex must free .dll. Is it possible?

How can I return HINSTANCE form .mex into my .m file? What about type conversions?

This code returns the following error: "loadlib.cpp(45) : error C2664: 'mxCreateDoubleScalar' : cannot convert parameter 1 from 'HINSTANCE' to 'double' There is no context in which this conversion is possible "

    void mexFunction(int nlhs, mxArray* plhs[], int nrhs, const mxArray* prhs[])
    {
    const mxArray* dll_filename = prhs[0]; 

    HINSTANCE hinst = LoadLibrary((LPCSTR)mxArrayToString(dll_filename)); 

    plhs[0] = mxCreateDoubleScalar(hinst); 

    }

Answer 1

[James Tursa]

It would easier if you use just one mex routine and passed in a flag that determined the behavior. However, if you insist on passing a HINSTANCE value between mex routines, you can do this by creating a mxINT64_CLASS variable and converting your HINSTANCE from an address to a long long (e.g., via a union) and stuffing it into the mxINT64_CLASS variable in one routine and vice-versa in the other routine. Regardless of how you do it, you will have to be careful to manage all of the cleanup required (if any) via a mexAtExit function.