void callp( )
{
    int new_perl = 0;
    
    dTHX;
    if ( my_perl != NULL )
         printf ("my_perl == %ul\n", my_perl);
      else
      {
         printf ("my_perl was NULL\n");
         PERL_SET_CONTEXT(mine);
         perl_for_cb = perl_clone(mine, CLONEf_KEEP_PTR_TABLE);
         PERL_SET_CONTEXT(perl_for_cb);
         
         // The following seems not necessary
         //CLONE_PARAMS clone_param; clone_param.stashes = NULL; clone_param.flags = 0; clone_param.proto_perl = perl_for_cb;
         
         new_perl = 1;
      } 
    
    dSP;
    SV* callback = get_sv("MPV::Simple::callback",0);
    SV* data = get_sv("MPV::Simple::callback_data",0);
    
    ENTER; SAVETMPS; 
    PUSHMARK(SP);
    
    EXTEND(SP,1);
    PUSHs(sv_2mortal(newSVsv(data)));
    
    PUTBACK;
    
    perl_call_sv(callback,G_DISCARD);
    SPAGAIN;
    
    PUTBACK;FREETMPS;LEAVE;
    
    // I don't know whether this is important
    if ( new_perl ) {
        perl_free(my_perl);
        PERL_SET_CONTEXT(mine);
    }
}

##</code><code>##

void
_xs_set_wakeup_callback(MPV::Simple ctx, SV* callback)
    CODE:
    {
    void (*callp_ptr)(void*);
    callp_ptr = callp;
    mpv_set_wakeup_callback(ctx,callp_ptr,NULL);
    }