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/****************************************************************************
**
** Copyright (C) 2012 Digia Plc and/or its subsidiary(-ies).
** Contact: http://www.qt-project.org/legal
**
** This file is part of the documentation of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and Digia. For licensing terms and
** conditions see http://qt.digia.com/licensing. For further information
** use the contact form at http://qt.digia.com/contact-us.
**
** 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, Digia gives you certain additional
** rights. These rights are described in the Digia Qt LGPL Exception
** version 1.1, 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.
**
**
** $QT_END_LICENSE$
**
****************************************************************************/
/*!
\page qt-embedded-porting-operatingsystem.html
\title Porting Qt for Embedded Linux to Another Operating System
\ingroup qt-embedded-linux
\l{Qt for Embedded Linux} is reasonably platform-independent, making use of
the standard C library and some POSIX functions, but only a Linux
implementation is publically available. If you are looking for a
non-Linux commercial implementation, it is worth contacting \l
{mailto:qt-info@nokia.com}{qt-info@nokia.com} to see if we can
help.
There are several issues to be aware of if you plan to do your own
port to another operating system. In particular you must resolve
\l{Qt for Embedded Linux}'s shared memory and semaphores (used to share
window regions), and you must provide something similar to
Unix-domain sockets for inter-application communication. You must
also provide a screen driver, and if you want to implement sound
you must provide your own sound server. Finally you must modify
the event dispatcher used by \l{Qt for Embedded Linux}.
Contents:
\tableofcontents
\section1 Shared Memory and Semaphores
\l{Qt for Embedded Linux} uses System V IPC (shared memory and semaphores)
to share window regions between client and server. When porting,
something similar must be provided; otherwise it will not be
possible to run multiple applications.
System V semaphores are also used for synchronizing access to the
framebuffer.
\list
\o Modify \c qsharedmemory_p.cpp
\o Modify \c qlock_qws.cpp
\o Modify \c qwslock.cpp
\endlist
\section1 Inter-Application Communication
To communicate between applications, \l{Qt for Embedded Linux} uses the
Unix-domain sockets. When porting, something similar must be
provided; otherwise it will not be possible to run multiple
applications.
It should be possible to use message queues or similar mechanisms
to achieve this. With the exception of QCOP messages, individual
messages should be no more than a few bytes in length (QCOP
messages are generated by the client applications and not Qt for
Embedded Linux).
\list
\o Modify \c qwssocket_qws.cpp
\endlist
\section1 Screen Management
When rendering, the default behavior in \l{Qt for Embedded Linux} is
for each client to render its widgets into memory while the server is
responsible for putting the contents of the memory onto the screen
using the screen driver.
When porting, a new screen driver must be implemented, providing a
byte pointer to a memory-mapped framebuffer and information about
width, height and bit depth (the latter information can most
likely be hard-coded).
\list
\o Reimplement \c qscreen_qws.cpp
\endlist
\section1 Sound Management
To implement sound, \l{Qt for Embedded Linux} uses a Linux style device (\c
/dev/dsp). If you want to use the \l{Qt for Embedded Linux} sound server on
another platform you must reimplement it.
\list
\o Reimplement \c qsoundqss_qws.cpp
\endlist
\section1 Event Dispatching
\l{Qt for Embedded Linux} uses an event dispatcher to pass events to and
from the \l{Qt for Embedded Linux} server application. Reimplement the \c
select() function to enable \l{Qt for Embedded Linux} to dispatch events on
your platform.
\list
\o Modify \c qeventdispatcher_qws.cpp
\endlist
*/
/*!
\page qt-embedded-porting-device.html
\title Porting Qt for Embedded Linux to a New Architecture
\ingroup qt-embedded-linux
When porting \l{Qt for Embedded Linux} to a new architecture there are
several issues to be aware of: You must provide suitable hardware
drivers, and you must ensure to implement platform dependent
atomic operations to enable multithreading on the new
architecture.
\section1 Hardware Drivers
When running a \l{Qt for Embedded Linux} application, it either runs as a
server or connects to an existing server. All system generated
events, including keyboard and mouse events, are passed to the
server application which then propagates the event to the
appropriate client. When rendering, the default behavior is for
each client to render its widgets into memory while the server is
responsible for putting the contents of the memory onto the
screen.
The various hardware drivers are loaded by the server
application when it starts running, using Qt's \l {How to Create
Qt Plugins}{plugin system}.
Derive from the QWSMouseHandler, QWSKeyboardHandler and QScreen
classes to create a custom mouse, keyboard and screen driver
respectively. To load the drivers into the server application at
runtime, you must also create corresponding plugins. See the
following documentation for more details:
\list
\o \l{Qt for Embedded Linux Pointer Handling}{Pointer Handling}
\o \l{Qt for Embedded Linux Character Input}{Character Input}
\o \l{Qt for Embedded Linux Display Management}{Display Management}
\endlist
\section1 Atomic Operations
Qt uses an optimization called \l {Implicitly Shared Classes}{implicit sharing}
for many of its value classes; implicitly shared classes can safely be
copied across threads. This technology is implemented using atomic
operations; i.e., \l{Qt for Embedded Linux} requires that platform-specific
atomic operations are implemented to support Linux.
When porting \l{Qt for Embedded Linux} to a new architecture, it is
important to ensure that the platform-specific atomic operations
are implemented in a corresponding header file, and that this file
is located in Qt's \c src/corelib/arch directory.
See the \l {Implementing Atomic Operations}{atomic operations}
documentation for more details.
*/
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