1 /*
   2  *  Copyright (c) 2019, Oracle and/or its affiliates. All rights reserved.
   3  *  DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  *  This code is free software; you can redistribute it and/or modify it
   6  *  under the terms of the GNU General Public License version 2 only, as
   7  *  published by the Free Software Foundation.  Oracle designates this
   8  *  particular file as subject to the "Classpath" exception as provided
   9  *  by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  *  This code is distributed in the hope that it will be useful, but WITHOUT
  12  *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  *  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  *  version 2 for more details (a copy is included in the LICENSE file that
  15  *  accompanied this code).
  16  *
  17  *  You should have received a copy of the GNU General Public License version
  18  *  2 along with this work; if not, write to the Free Software Foundation,
  19  *  Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  *   Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  *  or visit www.oracle.com if you need additional information or have any
  23  *  questions.
  24  *
  25  */
  26 
  27 package jdk.incubator.foreign.unsafe;
  28 
  29 import jdk.incubator.foreign.MemoryAddress;
  30 import jdk.internal.foreign.MemoryAddressImpl;
  31 
  32 /**
  33  * Unsafe methods to allow interop between sun.misc.unsafe and memory access API.
  34  */
  35 public final class ForeignUnsafe {
  36 
  37     private ForeignUnsafe() {
  38         //just the one, please
  39     }
  40 
  41     // The following methods can be used in conjunction with the java.foreign API.
  42 
  43     /**
  44      * Obtain the base object (if any) associated with this address. This can be used in conjunction with
  45      * {@link #getUnsafeOffset(MemoryAddress)} in order to obtain a base/offset addressing coordinate pair
  46      * to be used with methods like {@link sun.misc.Unsafe#getInt(Object, long)} and the likes.
  47      *
  48      * @param address the address whose base object is to be obtained.
  49      * @return the base object associated with the address, or {@code null}.
  50      */
  51     public static Object getUnsafeBase(MemoryAddress address) {
  52         return ((MemoryAddressImpl)address).unsafeGetBase();
  53     }
  54 
  55     /**
  56      * Obtain the offset associated with this address. If {@link #getUnsafeBase(MemoryAddress)} returns {@code null} on the passed
  57      * address, then the offset is to be interpreted as the (absolute) numerical value associated said address.
  58      * Alternatively, the offset represents the displacement of a field or an array element within the containing
  59      * base object. This can be used in conjunction with {@link #getUnsafeBase(MemoryAddress)} in order to obtain a base/offset
  60      * addressing coordinate pair to be used with methods like {@link sun.misc.Unsafe#getInt(Object, long)} and the likes.
  61      *
  62      * @param address the address whose offset is to be obtained.
  63      * @return the offset associated with the address.
  64      */
  65     public static long getUnsafeOffset(MemoryAddress address) {
  66         return ((MemoryAddressImpl)address).unsafeGetOffset();
  67     }
  68 }