[AFV] Finalize blocking tone

Blocking tone is emitted if more than one station is received
in parallel.

src/blacksound/sampleprovider/sinusgenerator.cpp

@@ -0,0 +1,41 @@
+/* Copyright (C) 2019
+ * swift project Community / Contributors
+ *
+ * This file is part of swift project. It is subject to the license terms in the LICENSE file found in the top-level
+ * directory of this distribution. No part of swift project, including this file, may be copied, modified, propagated,
+ * or distributed except according to the terms contained in the LICENSE file.
+ */
+
+#include "sinusgenerator.h"
+#include <cmath>
+
+namespace BlackSound
+{
+    namespace SampleProvider
+    {
+        CSinusGenerator::CSinusGenerator(double frequency, QObject *parent) :
+            ISampleProvider(parent),
+            m_frequency(frequency)
+        {}
+
+        int CSinusGenerator::readSamples(QVector<float> &samples, qint64 count)
+        {
+            samples.clear();
+            samples.fill(0, static_cast<int>(count));
+
+            for (int sampleCount = 0; sampleCount < count; sampleCount++)
+            {
+                double multiple = m_twoPi * m_frequency / m_sampleRate;
+                double sampleValue = m_gain * qSin(m_nSample * multiple);
+                samples[sampleCount] = static_cast<float>(sampleValue);
+                m_nSample++;
+            }
+            return static_cast<int>(count);
+        }
+
+        void CSinusGenerator::setFrequency(double frequency)
+        {
+            m_frequency = frequency;
+        }
+    } // ns
+} // ns

src/blacksound/sampleprovider/sinusgenerator.h

@@ -0,0 +1,51 @@
+/* Copyright (C) 2019
+ * swift project Community / Contributors
+ *
+ * This file is part of swift project. It is subject to the license terms in the LICENSE file found in the top-level
+ * directory of this distribution. No part of swift project, including this file, may be copied, modified, propagated,
+ * or distributed except according to the terms contained in the LICENSE file.
+ */
+
+//! \file
+
+#ifndef BLACKSOUND_SAMPLEPROVIDER_SINUSGENERATOR_H
+#define BLACKSOUND_SAMPLEPROVIDER_SINUSGENERATOR_H
+
+#include "blacksound/blacksoundexport.h"
+#include "blacksound/sampleprovider/sampleprovider.h"
+
+#include <QtMath>
+
+namespace BlackSound
+{
+    namespace SampleProvider
+    {
+        //! Saw tooth generator
+        class BLACKSOUND_EXPORT CSinusGenerator : public ISampleProvider
+        {
+            Q_OBJECT
+
+        public:
+            //! Ctor
+            CSinusGenerator(double frequency, QObject *parent = nullptr);
+
+            //! \copydoc ISampleProvider::readSamples
+            virtual int readSamples(QVector<float> &samples, qint64 count) override;
+
+            //! Set the gain
+            void setGain(double gain) { m_gain = gain; }
+
+            //! Set frequency in Hz
+            void setFrequency(double frequency);
+
+        private:
+            double m_gain = 0.0;
+            double m_frequency = 0.0;
+            double m_sampleRate = 48000;
+            int m_nSample = 0;
+            const double m_twoPi = 2 * M_PI;
+        };
+    } // ns
+} // ns
+
+#endif // guard