Implemented very basic tone generator

basetonegenerator.cpp

@@ -0,0 +1,87 @@
+#include "basetonegenerator.h"
+
+// Qt includes
+#include <QAudioOutput>
+
+namespace
+{
+//! private helper to allow QAudioOutput to read from a io device
+class BaseToneGeneratorHelper : public QIODevice
+{
+public:
+    BaseToneGeneratorHelper(BaseToneGenerator &generator, QObject *parent = nullptr);
+
+    qint64 readData(char *data, qint64 maxlen) override;
+    qint64 writeData(const char *data, qint64 len) override;
+
+private:
+    BaseToneGenerator &m_generator;
+};
+
+class BaseToneGeneratorPrivate
+{
+public:
+    BaseToneGeneratorPrivate(BaseToneGenerator &generator, const QAudioDeviceInfo &audioDeviceInfo, const QAudioFormat &format);
+    ~BaseToneGeneratorPrivate() { output.stop(); }
+
+    BaseToneGeneratorHelper helper;
+    QAudioOutput output;
+};
+
+}
+
+BaseToneGenerator::BaseToneGenerator() = default;
+
+BaseToneGenerator::~BaseToneGenerator() = default;
+
+void BaseToneGenerator::start()
+{
+    Q_ASSERT(!running());
+
+    QAudioFormat format;
+    format.setSampleRate(m_samplerate);
+    format.setChannelCount(2);
+    format.setSampleSize(sizeof(SamplePair::Type) * 8);
+    format.setSampleType(QAudioFormat::SignedInt);
+    format.setCodec("audio/pcm");
+    format.setByteOrder(QAudioFormat::LittleEndian);
+
+    m_private = std::make_unique<BaseToneGeneratorPrivate>(*this, m_device, format);
+    m_private->output.start(&m_private->helper);
+
+}
+
+void BaseToneGenerator::stop()
+{
+    Q_ASSERT(running());
+
+    m_private = nullptr;
+}
+
+namespace {
+BaseToneGeneratorHelper::BaseToneGeneratorHelper(BaseToneGenerator &generator, QObject *parent) :
+    QIODevice{parent}, m_generator{generator}
+{
+    setOpenMode(QIODevice::ReadOnly);
+}
+
+qint64 BaseToneGeneratorHelper::readData(char *data, qint64 maxlen)
+{
+    Q_ASSERT(maxlen % sizeof(SamplePair) == 0);
+
+    return m_generator.fill(reinterpret_cast<SamplePair*>(data),
+                            reinterpret_cast<SamplePair*>(data) + (maxlen/sizeof(SamplePair))) * sizeof(SamplePair);
+}
+
+qint64 BaseToneGeneratorHelper::writeData(const char *data, qint64 len)
+{
+    Q_UNUSED(data)
+    Q_UNUSED(len)
+    qFatal("writing is not allowed!");
+}
+
+BaseToneGeneratorPrivate::BaseToneGeneratorPrivate(BaseToneGenerator &generator, const QAudioDeviceInfo &audioDeviceInfo, const QAudioFormat &format) :
+    helper{generator}, output{audioDeviceInfo, format}
+{
+}
+}