--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/demos/spectrum/app/tonegenerator.cpp	Fri Jun 11 14:24:45 2010 +0300
@@ -0,0 +1,92 @@
+/****************************************************************************
+**
+** Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).
+** All rights reserved.
+** Contact: Nokia Corporation (qt-info@nokia.com)
+**
+** This file is part of the examples 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 Technology Preview License Agreement accompanying
+** this package.
+**
+** 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 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** If you have questions regarding the use of this file, please contact
+** Nokia at qt-info@nokia.com.
+**
+**
+**
+**
+**
+**
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "spectrum.h"
+#include "utils.h"
+#include <QByteArray>
+#include <QtMultimedia/QAudioFormat>
+#include <QtCore/qmath.h>
+#include <QtCore/qendian.h>
+
+void generateTone(const SweptTone &tone, const QAudioFormat &format, QByteArray &buffer)
+{
+    Q_ASSERT(isPCMS16LE(format));
+
+    const int channelBytes = format.sampleSize() / 8;
+    const int sampleBytes = format.channels() * channelBytes;
+    int length = buffer.size();
+    const int numSamples = buffer.size() / sampleBytes;
+
+    Q_ASSERT(length % sampleBytes == 0);
+    Q_UNUSED(sampleBytes) // suppress warning in release builds
+
+    unsigned char *ptr = reinterpret_cast<unsigned char *>(buffer.data());
+
+    qreal phase = 0.0;
+
+    const qreal d = 2 * M_PI / format.frequency();
+
+    // We can't generate a zero-frequency sine wave
+    const qreal startFreq = tone.startFreq ? tone.startFreq : 1.0;
+
+    // Amount by which phase increases on each sample
+    qreal phaseStep = d * startFreq;
+
+    // Amount by which phaseStep increases on each sample
+    // If this is non-zero, the output is a frequency-swept tone
+    const qreal phaseStepStep = d * (tone.endFreq - startFreq) / numSamples;
+
+    while (length) {
+        const qreal x = tone.amplitude * qSin(phase);
+        const qint16 value = realToPcm(x);
+        for (int i=0; i<format.channels(); ++i) {
+            qToLittleEndian<qint16>(value, ptr);
+            ptr += channelBytes;
+            length -= channelBytes;
+        }
+
+        phase += phaseStep;
+        while (phase > 2 * M_PI)
+            phase -= 2 * M_PI;
+        phaseStep += phaseStepStep;
+    }
+}
+