[gambit-list] FFI float/int interoperability?

Is there a way to make Gambit behave like C when passing floats/ints to and from foreign functions? I mean to have them automatically converted as they would be if I were programming in C.

I've run into a problem where I have 2 variables (in Scheme) to keep track of my OpenGL window's width and height, but the calls to OpenGL expect floats (gluOrtho2D) while the calls to SDL expects ints (SDL_SetVideoMode).

If there isn't a way to convert automatically, is there a Scheme function to convert between these two types? I suppose I could write them myself, but since I'm already asking...

TJ