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/****************************************************************************
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**
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** Implementation of asynchronous I/O classes
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**
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** Created : 970617
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**
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** Copyright (C) 1992-2008 Trolltech ASA. All rights reserved.
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**
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** This file is part of the kernel module of the TQt GUI Toolkit.
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**
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** This file may be used under the terms of the GNU General
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** Public License versions 2.0 or 3.0 as published by the Free
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** Software Foundation and appearing in the files LICENSE.GPL2
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** and LICENSE.GPL3 included in the packaging of this file.
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** Alternatively you may (at your option) use any later version
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** of the GNU General Public License if such license has been
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** publicly approved by Trolltech ASA (or its successors, if any)
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** and the KDE Free TQt Foundation.
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**
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** Please review the following information to ensure GNU General
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** Public Licensing retquirements will be met:
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** http://trolltech.com/products/qt/licenses/licensing/opensource/.
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** If you are unsure which license is appropriate for your use, please
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** review the following information:
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** http://trolltech.com/products/qt/licenses/licensing/licensingoverview
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** or contact the sales department at sales@trolltech.com.
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**
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** This file may be used under the terms of the Q Public License as
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** defined by Trolltech ASA and appearing in the file LICENSE.TQPL
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** included in the packaging of this file. Licensees holding valid TQt
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** Commercial licenses may use this file in accordance with the TQt
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** Commercial License Agreement provided with the Software.
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**
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** This file is provided "AS IS" with NO WARRANTY OF ANY KIND,
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** INCLUDING THE WARRANTIES OF DESIGN, MERCHANTABILITY AND FITNESS FOR
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** A PARTICULAR PURPOSE. Trolltech reserves all rights not granted
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** herein.
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**
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**********************************************************************/
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#include "qasyncio.h"
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#include "qiodevice.h"
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#include <stdlib.h>
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#ifndef QT_NO_ASYNC_IO
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/*!
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\class TQAsyncIO qasyncio.h
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\obsolete
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\brief The TQAsyncIO class encapsulates I/O asynchronicity.
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The TQt classes for asynchronous input/output provide a simple
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mechanism to allow large files or slow data sources to be processed
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without using large amounts of memory or blocking the user interface.
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This facility is used in TQt to drive animated images. See TQImageConsumer.
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*/
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/*!
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Destroys the async IO object.
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*/
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TQAsyncIO::~TQAsyncIO()
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{
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}
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/*!
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Ensures that only one object, \a obj and function, \a member, can
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respond to changes in readiness.
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*/
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void TQAsyncIO::connect(TQObject* obj, const char *member)
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{
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signal.disconnect(0, 0);
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signal.connect(obj, member);
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}
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/*!
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Derived classes should call this when they change from being
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unready to ready.
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*/
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void TQAsyncIO::ready()
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{
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signal.activate();
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}
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/*!
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\class TQDataSink qasyncio.h
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\obsolete
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\brief The TQDataSink class is an asynchronous consumer of data.
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A data sink is an object which receives data from some source in an
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asynchronous manner. This means that at some time not determined by
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the data sink, blocks of data are given to it from processing. The
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data sink is able to limit the maximum size of such blocks which it
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is currently able to process.
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\sa TQAsyncIO, TQDataSource, TQDataPump
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*/
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/*!
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\fn int TQDataSink::readyToReceive()
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The data sink should return a value indicating how much data it is ready
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to consume. This may be 0.
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*/
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/*!
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This should be called whenever readyToReceive() might have become non-zero.
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It is merely calls TQAsyncIO::ready() if readyToReceive() is non-zero.
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*/
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void TQDataSink::maybeReady()
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{
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if (readyToReceive()) ready();
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}
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/*!
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\fn void TQDataSink::receive(const uchar*, int count)
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This function is called to provide data for the data sink. The \a count
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will be no more than the amount indicated by the most recent call to
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readyToReceive(). The sink must use all the provided data.
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*/
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/*!
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\fn void TQDataSink::eof()
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This function will be called when no more data is available for
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processing.
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*/
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/*!
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\class TQDataSource qasyncio.h
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\obsolete
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\brief The TQDataSource class is an asynchronous producer of data.
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A data source is an object which provides data from some source in an
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asynchronous manner. This means that at some time not determined by
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the data source, blocks of data will be taken from it for processing.
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The data source is able to limit the maximum size of such blocks which
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it is currently able to provide.
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\sa TQAsyncIO, TQDataSink, TQDataPump
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*/
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/*!
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\fn int TQDataSource::readyToSend()
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The data source should return a value indicating how much data it is ready
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to provide. This may be 0. If the data source knows it will never be
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able to provide any more data (until after a rewind()), it may return -1.
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*/
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/*!
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This should be called whenever readyToSend() might have become non-zero.
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It is merely calls TQAsyncIO::ready() if readyToSend() is non-zero.
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*/
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void TQDataSource::maybeReady()
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{
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if (readyToSend()) ready();
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}
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/*!
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\fn void TQDataSource::sendTo(TQDataSink*, int count)
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This function is called to extract data from the source, by sending
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it to the given data sink. The \a count will be no more than the amount
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indicated by the most recent call to readyToSend(). The source must
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use all the provided data, and the sink will be prepared to accept at
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least this much data.
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*/
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/*!
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This function should return TRUE if the data source can be rewound.
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The default returns FALSE.
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*/
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bool TQDataSource::rewindable() const
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{
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return FALSE;
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}
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/*!
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If this function is called with \a on set to TRUE, and rewindable()
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is TRUE, then the data source must take measures to allow the rewind()
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function to subsequently operate as described. If rewindable() is FALSE,
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the function should call TQDataSource::enableRewind(), which aborts with
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a qFatal() error.
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For example, a network connection may choose to use a disk cache
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of input only if rewinding is enabled before the first buffer-full of
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data is discarded, returning FALSE in rewindable() if that first buffer
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is discarded.
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*/
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void TQDataSource::enableRewind( bool /* on */ )
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{
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qFatal( "Attempted to make unrewindable TQDataSource rewindable" );
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}
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/*!
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This function rewinds the data source. This may only be called if
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enableRewind(TRUE) has been previously called.
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*/
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void TQDataSource::rewind()
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{
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qFatal("Attempted to rewind unrewindable TQDataSource");
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}
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/*!
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\class TQIODeviceSource qasyncio.h
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\obsolete
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\brief The TQIODeviceSource class is a TQDataSource that draws data from a TQIODevice.
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This class encapsulates retrieving data from a TQIODevice (such as a TQFile).
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*/
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/*!
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Constructs a TQIODeviceSource from the TQIODevice \a device. The TQIODevice
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\e must be dynamically allocated, becomes owned by the TQIODeviceSource,
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and will be deleted when the TQIODeviceSource is destroyed. \a buffer_size
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determines the size of buffering to use between asynchronous operations.
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The higher the \a buffer_size, the more efficient, but the less interleaved
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the operation will be with other processing.
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*/
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TQIODeviceSource::TQIODeviceSource(TQIODevice* device, int buffer_size) :
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buf_size(buffer_size),
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buffer(new uchar[buf_size]),
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iod(device),
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rew(FALSE)
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{
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}
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/*!
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Destroys the TQIODeviceSource, deleting the TQIODevice from which it was
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constructed.
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*/
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TQIODeviceSource::~TQIODeviceSource()
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{
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delete iod;
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delete [] buffer;
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}
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/*!
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Ready until end-of-file.
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*/
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int TQIODeviceSource::readyToSend()
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{
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if ( iod->status() != IO_Ok || !(iod->state() & IO_Open) )
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return -1;
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int n = TQMIN((uint)buf_size, iod->size()-iod->at()); // ### not 64-bit safe
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// ### not large file safe
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return n ? n : -1;
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}
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/*!
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Reads a block of data and sends up to \a n bytes to the \a sink.
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*/
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void TQIODeviceSource::sendTo(TQDataSink* sink, int n)
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{
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iod->readBlock((char*)buffer, n);
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sink->receive(buffer, n);
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}
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/*!
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All TQIODeviceSource's are rewindable.
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*/
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bool TQIODeviceSource::rewindable() const
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{
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return TRUE;
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}
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/*!
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If \a on is set to TRUE then rewinding is enabled.
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No special action is taken. If \a on is set to
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FALSE then rewinding is disabled.
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*/
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void TQIODeviceSource::enableRewind(bool on)
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{
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rew = on;
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}
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/*!
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Calls reset() on the TQIODevice.
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*/
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void TQIODeviceSource::rewind()
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{
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if (!rew) {
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TQDataSource::rewind();
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} else {
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iod->reset();
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ready();
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}
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}
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/*!
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\class TQDataPump qasyncio.h
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\obsolete
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\brief The TQDataPump class moves data from a TQDataSource to a TQDataSink during event processing.
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For a TQDataSource to provide data to a TQDataSink, a controller must exist
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to examine the TQDataSource::readyToSend() and TQDataSink::readyToReceive()
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methods and respond to the TQASyncIO::activate() signal of the source and
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sink. One very useful way to do this is interleaved with other event
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processing. TQDataPump provides this - create a pipe between a source
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and a sink, and data will be moved during subsequent event processing.
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Note that each source can only provide data to one sink and each sink
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can only receive data from one source (although it is quite possible
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to write a multiplexing sink that is multiple sources).
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*/
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/*!
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Constructs a TQDataPump to move data from a given \a data_source
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to a given \a data_sink.
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*/
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TQDataPump::TQDataPump(TQDataSource* data_source, TQDataSink* data_sink) :
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source(data_source), sink(data_sink)
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{
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source->connect(this, SLOT(kickStart()));
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sink->connect(this, SLOT(kickStart()));
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connect(&timer, SIGNAL(timeout()), this, SLOT(tryToPump()));
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timer.start(0, TRUE);
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}
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void TQDataPump::kickStart()
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{
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if (!timer.isActive()) {
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interval = 0;
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timer.start(0, TRUE);
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}
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}
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void TQDataPump::tryToPump()
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{
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int supply, demand;
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supply = source->readyToSend();
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demand = sink->readyToReceive();
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if (demand <= 0) {
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return;
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}
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interval = 0;
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if (supply < 0) {
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// All done (until source signals change in readiness)
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sink->eof();
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return;
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}
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if (!supply)
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return;
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source->sendTo(sink, TQMIN(supply, demand));
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timer.start(0, TRUE);
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}
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#endif // QT_NO_ASYNC_IO
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