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# semaphores.cpp Example File
threads/semaphores/semaphores.cpp

     /****************************************************************************
     **
     ** Copyright (C) 2005-2006 Trolltech ASA. All rights reserved.
     **
     ** This file is part of the example classes of the Qt Toolkit.
     **
     ** This file may be used under the terms of the GNU General Public
     ** License version 2.0 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 GNU
     ** General Public Licensing requirements will be met:
     ** http://www.trolltech.com/products/qt/opensource.html
     **
     ** If you are unsure which license is appropriate for your use, please
     ** review the following information:
     ** http://www.trolltech.com/products/qt/licensing.html or contact the
     ** sales department at sales@trolltech.com.
     **
     ** This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
     ** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
     **
     ****************************************************************************/

     #include <QtCore>

     #include <stdio.h>
     #include <stdlib.h>

     const int DataSize = 100000;
     const int BufferSize = 8192;
     char buffer[BufferSize];

     QSemaphore freeBytes(BufferSize);
     QSemaphore usedBytes;

     class Producer : public QThread
     {
     public:
         void run();
     };

     void Producer::run()
     {
         qsrand(QTime(0,0,0).secsTo(QTime::currentTime()));
         for (int i = 0; i < DataSize; ++i) {
             freeBytes.acquire();
             buffer[i % BufferSize] = "ACGT"[(int)qrand() % 4];
             usedBytes.release();
         }
     }

     class Consumer : public QThread
     {
     public:
         void run();
     };

     void Consumer::run()
     {
         for (int i = 0; i < DataSize; ++i) {
             usedBytes.acquire();
             fprintf(stderr, "%c", buffer[i % BufferSize]);
             freeBytes.release();
         }
         fprintf(stderr, "\n");
     }

     int main(int argc, char *argv[])
     {
         QCoreApplication app(argc, argv);
         Producer producer;
         Consumer consumer;
         producer.start();
         consumer.start();
         producer.wait();
         consumer.wait();
         return 0;
     }