###########################
TYPEMAP

#string (char*) with automatic NULL<->undef conversion on input/output
char *			T_STR_OR_NULL
const char *		T_STR_OR_NULL

#pointer with automatic NULL<->undef conversion on input/output
unsigned char *		T_PTR_OR_NULL
Ihandle *		T_PTR_OR_NULL
cdCanvas *		T_PTR_OR_NULL
#xxxIcallback		T_PTR_OR_NULL
#xxxvoid *		T_PTR_OR_NULL

#structs with automatic conversion to perl classes
cdBitmap *		O_OBJECT
IUPinternal_cdPalette * O_OBJECT
IUPinternal_cdPattern * O_OBJECT
IUPinternal_cdStipple * O_OBJECT

cdImage *		O_OBJECT
cdState *		O_OBJECT
cdContext *		O_OBJECT

###########################
INPUT

T_PTR_OR_NULL
	$var = (SvIOK($arg)) ? INT2PTR($type,SvIVX($arg)) : NULL;

T_STR_OR_NULL
	$var = (SvOK($arg)) ? SvPV_nolen($arg) : NULL;

T_PTROBJ
	if (SvROK($arg) && sv_derived_from($arg, \"${ntype}\")) {
	    IV tmp = SvIV((SV*)SvRV($arg));
	    $var = INT2PTR($type,tmp);
	}
	else
	    Perl_croak(aTHX_ \"%s: %s is not of type %s\",
			${$ALIAS?\q[GvNAME(CvGV(cv))]:\qq[\"$pname\"]},
			\"$var\", \"$ntype\") 

O_OBJECT
	if( sv_isobject($arg) && (SvTYPE(SvRV($arg)) == SVt_PVMG) ) {
           void** pointers = (void**)(SvIV((SV*)SvRV( $arg ))); 
           $var = ($type)(pointers[0]);
        } else if ($arg == 0) {
           XSRETURN(0);
        } else {
           XSRETURN_UNDEF;
        }

###########################
OUTPUT

T_PTR_OR_NULL
	if ($var==NULL) XSRETURN_UNDEF;
	else sv_setiv($arg, PTR2IV($var));

T_STR_OR_NULL
	if ($var==NULL) XSRETURN_UNDEF;
	else sv_setpv($arg, $var);

T_PTROBJ
        sv_setref_pv($arg, \"${ntype}\", (void*)$var);
        
# The Perl object is blessed into 'CLASS', which should be a char* having the name of the package for the blessing.
O_OBJECT
        if ($var) {
          void** pointers = malloc(2 * sizeof(void*));
          pointers[0] = (void*)$var;
          pointers[1] = (void*)PERL_GET_CONTEXT;
  	  sv_setref_pv( $arg, CLASS, (void*)pointers );
        } else {
          XSRETURN_UNDEF;
        }