TYPEMAP
Crypt_GCrypt		T_PTROBJ_SPECIAL
Crypt_GCrypt_MPI	T_PTROBJ_SPECIAL

INPUT
T_PTROBJ_SPECIAL
	if (sv_derived_from($arg, \"${(my $ntt=$ntype)=~s/_/::/g;\$ntt}\")) {
		IV tmp = SvIV((SV*)SvRV($arg));
		$var = ($type) tmp;
	} else
		croak(\"$var is not of type ${(my $ntt=$ntype)=~s/_/::/g;\$ntt}\");

OUTPUT
T_PTROBJ_SPECIAL
	sv_setref_pv($arg, \"${(my $ntt=$ntype)=~s/_/::/g;\$ntt}\",
		(void *)$var);