#define PERL_NO_GET_CONTEXT

#include "EXTERN.h"
#include "perl.h"
#include "XSUB.h"

SV * dubble(pTHX_ SV * in) {
 return newSViv(SvIV(in) * 2);
}

MODULE = FOO	PACKAGE = FOO	

SV *
dubble (in)
	SV *	in
CODE:
  RETVAL = dubble(aTHX_ in);
OUTPUT:
  RETVAL