void
sub_from_xs(SV *num, SV *str)
	INIT:
		if ((!SvROK(num)))
			croak("not a reference");
		
		if ((!SvROK(str)))
			croak("not a reference");
			
		int nx;
		char *sx;
	CODE:
		nx = get_nx();
		sv_setiv_mg(SvRV(num), nx);
		sx = get_sx();
		sv_setpv_mg(SvRV(str), sx);