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+/****************************************************************************
+**
+** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
+** Contact: Qt Software Information (qt-info@nokia.com)
+**
+** This file is part of the documentation of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** No Commercial Usage
+** This file contains pre-release code and may not be distributed.
+** You may use this file in accordance with the terms and conditions
+** contained in the either Technology Preview License Agreement or the
+** Beta Release License Agreement.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 2.1 requirements
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Nokia gives you certain
+** additional rights. These rights are described in the Nokia Qt LGPL
+** Exception version 1.0, included in the file LGPL_EXCEPTION.txt in this
+** package.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3.0 as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU General Public License version 3.0 requirements will be
+** met: http://www.gnu.org/copyleft/gpl.html.
+**
+** If you are unsure which license is appropriate for your use, please
+** contact the sales department at qt-sales@nokia.com.
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+/*!
+ \page atomic-operations.html
+ \title Implementing Atomic Operations
+ \ingroup architecture
+ \ingroup qt-embedded-linux
+ \brief A guide to implementing atomic operations on new architectures.
+
+ Qt uses an optimization called \l {Implicitly Shared
+ Classes}{implicit sharing} for many of its value classes.
+
+ Starting with Qt 4, all of Qt's implicitly shared classes can
+ safely be copied across threads like any other value classes,
+ i.e., they are fully \l {Thread Support in Qt#Reentrancy and
+ Thread-Safety}{reentrant}. This is accomplished by implementing
+ reference counting operations using atomic hardware instructions
+ on all the different platforms supported by Qt.
+
+ To support a new architecture, it is important to ensure that
+ these platform-specific atomic operations are implemented in a
+ corresponding header file (\c qatomic_ARCH.h), and that this file
+ is located in Qt's \c src/corelib/arch directory. For example, the
+ Intel 80386 implementation is located in \c
+ src/corelib/arch/qatomic_i386.h.
+
+ Currently, Qt provides two classes providing several atomic
+ operations, QAtomicInt and QAtomicPointer. These classes inherit
+ from QBasicAtomicInt and QBasicAtomicPointer, respectively.
+
+ When porting Qt to a new architecture, the QBasicAtomicInt and
+ QBasicAtomicPointer classes must be implemented, \e not QAtomicInt
+ and QAtomicPointer. The former classes do not have constructors,
+ which makes them POD (plain-old-data). Both classes only have a
+ single member variable called \c _q_value, which stores the
+ value. This is the value that all of the atomic operations read
+ and modify.
+
+ All of the member functions mentioned in the QAtomicInt and
+ QAtomicPointer API documentation must be implemented. Note that
+ these the implementations of the atomic operations in these
+ classes must be atomic with respect to both interrupts and
+ multiple processors.
+
+ \warning The QBasicAtomicInt and QBasicAtomicPointer classes
+ mentioned in this document are used internally by Qt and are not
+ part of the public API. They may change in future versions of
+ Qt. The purpose of this document is to aid people interested in
+ porting Qt to a new architecture.
+*/