Get a structure pointer from perl's SV containing T_PTRREF

pointer_madness.xs

typedef struct datum {
	int number;
} datum;

typedef datum * table;

TYPEMAP: <<END
table	T_PTRREF
END

data
init()
  INIT:
    unsigned int SIZE = 10;
    table t = (table)malloc(SIZE*sizeof(datum));
    int i;
  CODE:
    for (i = 0; i < SIZE; i++) {
      datum d;
      d.number = i*i;
      t[i]=d;
    }
    RETVAL = t;
  OUTPUT:
    RETVAL

void
dealloc(self)
	HV *self;
	CODE:
		SV** table = hv_fetch(self, "table", 5, 0);
		IV t = SvIV( (SV*)SvRV( *table ) );
		genetic_code foo = INT2PTR( table, t );

		printf(">>%d\n",foo[4].number);
		free(t);