/*
* Copyright (c) 2007, 2011, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
/**
* This package implements a Header-Origin-Mixed (HOM) object layout.
* <p>
* Tuples object are packed for minimal space consumption, observing alignment
* restrictions. They have a 2 word header and are layed out as shown below:
*
* <p><hr><blockquote><pre>
* cell --> +-------------+
* | misc | // monitor and hashcode
* +-------------+
* | class |
* origin/data --> +=============+
* | |
* : fields : // mixed reference and scalar data
* | |
* +-------------+
* </pre></blockquote><hr></p>
*
* Array objects have a 3 word header and are layed out as shown below:
*
* <p><hr><blockquote><pre>
* cell --> +-------------+
* | length |
* +-------------+
* | misc | // monitor and hashcode
* +-------------+
* | class |
* origin/data --> +=============+
* | |
* : elements :
* | |
* +-------------+
* </pre></blockquote><hr></p>
*
* The first word of the header (i.e. {@code misc} word for tuple objects and {@code length}
* word for arrays) encodes the type of the cell (tuple or array) in its low-order bit.
* If the bit is set, the cell contains an array otherwise it contains a tuple.
* <p>
* Unless stated otherwise, all offsets mentioned in this layout implementation are in terms of
* bytes and are relative to the origin pointer.
*/
package com.sun.max.vm.layout.hom;