1 files changed, 90 insertions, 0 deletions
diff --git a/examples/multimedia/spectrum/app/tonegenerator.cpp b/examples/multimedia/spectrum/app/tonegenerator.cpp
new file mode 100644
index 000000000..51a1de357
--- /dev/null
+++ b/examples/multimedia/spectrum/app/tonegenerator.cpp
@@ -0,0 +1,90 @@
+/****************************************************************************
+**
+** Copyright (C) 2012 Digia Plc and/or its subsidiary(-ies).
+** Contact: http://www.qt-project.org/legal
+**
+** This file is part of the examples of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:BSD$
+** You may use this file under the terms of the BSD license as follows:
+**
+** "Redistribution and use in source and binary forms, with or without
+** modification, are permitted provided that the following conditions are
+** met:
+**   * Redistributions of source code must retain the above copyright
+**     notice, this list of conditions and the following disclaimer.
+**   * Redistributions in binary form must reproduce the above copyright
+**     notice, this list of conditions and the following disclaimer in
+**     the documentation and/or other materials provided with the
+**     distribution.
+**   * Neither the name of Digia Plc and its Subsidiary(-ies) nor the names
+**     of its contributors may be used to endorse or promote products derived
+**     from this software without specific prior written permission.
+**
+**
+** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "spectrum.h"
+#include "utils.h"
+#include <QByteArray>
+#include <QAudioFormat>
+#include <qmath.h>
+#include <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.channelCount() * 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.sampleRate();
+
+    // 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.channelCount(); ++i) {
+            qToLittleEndian<qint16>(value, ptr);
+            ptr += channelBytes;
+            length -= channelBytes;
+        }
+
+        phase += phaseStep;
+        while (phase > 2 * M_PI)
+            phase -= 2 * M_PI;
+        phaseStep += phaseStepStep;
+    }
+}