void
set_my_callback(ctx, fn)
        MPV::Simple ctx
        SV *	fn
        PREINIT:
            dMY_CXT;
        CODE:
        /* Remember the Perl sub */
        if (MY_CXT.callback == (SV*)NULL)
            MY_CXT.callback = newSVsv(fn);
        else
            SvSetSV(MY_CXT.callback, fn);
    
void
_xs_set_wakeup_callback(MPV::Simple ctx)
    PREINIT:
            dMY_CXT;
    CODE:
    {
    SV* data;
    void (*rechne)(void*);
    callp_ptr = callp;
    mpv_set_wakeup_callback(ctx,callp_ptr,MY_CXT.callback);
    }