aaudio: add tests for device switch detection and refactor

Add detection for device switch during capture and playback tests:
 write_sine, write_sine_callback, input_monitor, input_monitor_callback

Refactor tests and move simple player, simple recorder and utility
methods in separate header files and folder.

Bug: 33355262
Test: run write_sine and input_monitor tests
Change-Id: Iced66fa4344aecd8a2952e22a98e6e8454f38a5e
diff --git a/media/libaaudio/examples/utils/AAudioExampleUtils.h b/media/libaaudio/examples/utils/AAudioExampleUtils.h
new file mode 100644
index 0000000..66de25f
--- /dev/null
+++ b/media/libaaudio/examples/utils/AAudioExampleUtils.h
@@ -0,0 +1,62 @@
+/*
+ * Copyright (C) 2017 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef AAUDIO_EXAMPLE_UTILS_H
+#define AAUDIO_EXAMPLE_UTILS_H
+
+#include <unistd.h>
+#include <sched.h>
+#include <aaudio/AAudio.h>
+
+#define NANOS_PER_MICROSECOND ((int64_t)1000)
+#define NANOS_PER_MILLISECOND (NANOS_PER_MICROSECOND * 1000)
+#define NANOS_PER_SECOND      (NANOS_PER_MILLISECOND * 1000)
+
+static const char *getSharingModeText(aaudio_sharing_mode_t mode) {
+    const char *modeText = "unknown";
+    switch (mode) {
+    case AAUDIO_SHARING_MODE_EXCLUSIVE:
+        modeText = "EXCLUSIVE";
+        break;
+    case AAUDIO_SHARING_MODE_SHARED:
+        modeText = "SHARED";
+        break;
+    default:
+        break;
+    }
+    return modeText;
+}
+
+static int64_t getNanoseconds(clockid_t clockId = CLOCK_MONOTONIC) {
+    struct timespec time;
+    int result = clock_gettime(clockId, &time);
+    if (result < 0) {
+        return -errno;
+    }
+    return (time.tv_sec * NANOS_PER_SECOND) + time.tv_nsec;
+}
+
+void displayPeakLevel(float peakLevel) {
+    printf("%5.3f ", peakLevel);
+    const int maxStars = 50; // arbitrary, fits on one line
+    int numStars = (int) (peakLevel * maxStars);
+    for (int i = 0; i < numStars; i++) {
+        printf("*");
+    }
+    printf("\n");
+}
+
+#endif // AAUDIO_EXAMPLE_UTILS_H
diff --git a/media/libaaudio/examples/utils/AAudioSimplePlayer.h b/media/libaaudio/examples/utils/AAudioSimplePlayer.h
new file mode 100644
index 0000000..aaeb25f
--- /dev/null
+++ b/media/libaaudio/examples/utils/AAudioSimplePlayer.h
@@ -0,0 +1,253 @@
+/*
+ * Copyright (C) 2017 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+// Play sine waves using an AAudio callback.
+
+#ifndef AAUDIO_SIMPLE_PLAYER_H
+#define AAUDIO_SIMPLE_PLAYER_H
+
+#include <unistd.h>
+#include <sched.h>
+
+#include <aaudio/AAudio.h>
+#include "SineGenerator.h"
+
+//#define SHARING_MODE  AAUDIO_SHARING_MODE_EXCLUSIVE
+#define SHARING_MODE  AAUDIO_SHARING_MODE_SHARED
+#define PERFORMANCE_MODE AAUDIO_PERFORMANCE_MODE_NONE
+
+/**
+ * Simple wrapper for AAudio that opens an output stream either in callback or blocking write mode.
+ */
+class AAudioSimplePlayer {
+public:
+    AAudioSimplePlayer() {}
+    ~AAudioSimplePlayer() {
+        close();
+    };
+
+    /**
+     * Call this before calling open().
+     * @param requestedSharingMode
+     */
+    void setSharingMode(aaudio_sharing_mode_t requestedSharingMode) {
+        mRequestedSharingMode = requestedSharingMode;
+    }
+
+    /**
+     * Call this before calling open().
+     * @param requestedPerformanceMode
+     */
+    void setPerformanceMode(aaudio_performance_mode_t requestedPerformanceMode) {
+        mRequestedPerformanceMode = requestedPerformanceMode;
+    }
+
+    /**
+     * Also known as "sample rate"
+     * Only call this after open() has been called.
+     */
+    int32_t getFramesPerSecond() {
+        if (mStream == nullptr) {
+            return AAUDIO_ERROR_INVALID_STATE;
+        }
+        return AAudioStream_getSampleRate(mStream);;
+    }
+
+    /**
+     * Only call this after open() has been called.
+     */
+    int32_t getChannelCount() {
+        if (mStream == nullptr) {
+            return AAUDIO_ERROR_INVALID_STATE;
+        }
+        return AAudioStream_getChannelCount(mStream);;
+    }
+
+    /**
+     * Open a stream
+     */
+    aaudio_result_t open(int channelCount, int sampSampleRate, aaudio_format_t format,
+                         AAudioStream_dataCallback dataProc, AAudioStream_errorCallback errorProc,
+                         void *userContext) {
+        aaudio_result_t result = AAUDIO_OK;
+
+        // Use an AAudioStreamBuilder to contain requested parameters.
+        result = AAudio_createStreamBuilder(&mBuilder);
+        if (result != AAUDIO_OK) return result;
+
+        //AAudioStreamBuilder_setSampleRate(mBuilder, 44100);
+        AAudioStreamBuilder_setPerformanceMode(mBuilder, mRequestedPerformanceMode);
+        AAudioStreamBuilder_setSharingMode(mBuilder, mRequestedSharingMode);
+        if (dataProc != nullptr) {
+            AAudioStreamBuilder_setDataCallback(mBuilder, dataProc, userContext);
+        }
+        if (errorProc != nullptr) {
+            AAudioStreamBuilder_setErrorCallback(mBuilder, errorProc, userContext);
+        }
+        AAudioStreamBuilder_setChannelCount(mBuilder, channelCount);
+        AAudioStreamBuilder_setSampleRate(mBuilder, sampSampleRate);
+        AAudioStreamBuilder_setFormat(mBuilder, format);
+        //AAudioStreamBuilder_setFramesPerDataCallback(mBuilder, CALLBACK_SIZE_FRAMES);
+        AAudioStreamBuilder_setBufferCapacityInFrames(mBuilder, 48 * 8);
+
+        //aaudio_performance_mode_t perfMode = AAUDIO_PERFORMANCE_MODE_NONE;
+        aaudio_performance_mode_t perfMode = AAUDIO_PERFORMANCE_MODE_LOW_LATENCY;
+        //aaudio_performance_mode_t perfMode = AAUDIO_PERFORMANCE_MODE_POWER_SAVING;
+        AAudioStreamBuilder_setPerformanceMode(mBuilder, perfMode);
+
+        // Open an AAudioStream using the Builder.
+        result = AAudioStreamBuilder_openStream(mBuilder, &mStream);
+        if (result != AAUDIO_OK) goto finish1;
+
+        printf("AAudioStream_getFramesPerBurst() = %d\n",
+               AAudioStream_getFramesPerBurst(mStream));
+        printf("AAudioStream_getBufferSizeInFrames() = %d\n",
+               AAudioStream_getBufferSizeInFrames(mStream));
+        printf("AAudioStream_getBufferCapacityInFrames() = %d\n",
+               AAudioStream_getBufferCapacityInFrames(mStream));
+        printf("AAudioStream_getPerformanceMode() = %d, requested %d\n",
+               AAudioStream_getPerformanceMode(mStream), perfMode);
+
+     finish1:
+        AAudioStreamBuilder_delete(mBuilder);
+        mBuilder = nullptr;
+        return result;
+    }
+
+    aaudio_result_t close() {
+        if (mStream != nullptr) {
+            printf("call AAudioStream_close(%p)\n", mStream);  fflush(stdout);
+            AAudioStream_close(mStream);
+            mStream = nullptr;
+            AAudioStreamBuilder_delete(mBuilder);
+            mBuilder = nullptr;
+        }
+        return AAUDIO_OK;
+    }
+
+    // Write zero data to fill up the buffer and prevent underruns.
+    aaudio_result_t prime() {
+        int32_t samplesPerFrame = AAudioStream_getChannelCount(mStream);
+        const int numFrames = 32;
+        float zeros[numFrames * samplesPerFrame];
+        memset(zeros, 0, sizeof(zeros));
+        aaudio_result_t result = numFrames;
+        while (result == numFrames) {
+            result = AAudioStream_write(mStream, zeros, numFrames, 0);
+        }
+        return result;
+    }
+
+    // Start the stream. AAudio will start calling your callback function.
+     aaudio_result_t start() {
+        aaudio_result_t result = AAudioStream_requestStart(mStream);
+        if (result != AAUDIO_OK) {
+            printf("ERROR - AAudioStream_requestStart() returned %d %s\n",
+                    result, AAudio_convertResultToText(result));
+        }
+        return result;
+    }
+
+    // Stop the stream. AAudio will stop calling your callback function.
+    aaudio_result_t stop() {
+        aaudio_result_t result = AAudioStream_requestStop(mStream);
+        if (result != AAUDIO_OK) {
+            printf("ERROR - AAudioStream_requestStop() returned %d %s\n",
+                    result, AAudio_convertResultToText(result));
+        }
+        int32_t xRunCount = AAudioStream_getXRunCount(mStream);
+        printf("AAudioStream_getXRunCount %d\n", xRunCount);
+        return result;
+    }
+
+    AAudioStream *getStream() const {
+        return mStream;
+    }
+
+private:
+    AAudioStreamBuilder      *mBuilder = nullptr;
+    AAudioStream             *mStream = nullptr;
+    aaudio_sharing_mode_t     mRequestedSharingMode = SHARING_MODE;
+    aaudio_performance_mode_t mRequestedPerformanceMode = PERFORMANCE_MODE;
+};
+
+typedef struct SineThreadedData_s {
+    SineGenerator  sineOsc1;
+    SineGenerator  sineOsc2;
+    int            scheduler;
+    bool           schedulerChecked;
+} SineThreadedData_t;
+
+// Callback function that fills the audio output buffer.
+aaudio_data_callback_result_t SimplePlayerDataCallbackProc(
+        AAudioStream *stream,
+        void *userData,
+        void *audioData,
+        int32_t numFrames
+        ) {
+
+    // should not happen but just in case...
+    if (userData == nullptr) {
+        fprintf(stderr, "ERROR - SimplePlayerDataCallbackProc needs userData\n");
+        return AAUDIO_CALLBACK_RESULT_STOP;
+    }
+    SineThreadedData_t *sineData = (SineThreadedData_t *) userData;
+
+    if (!sineData->schedulerChecked) {
+        sineData->scheduler = sched_getscheduler(gettid());
+        sineData->schedulerChecked = true;
+    }
+
+    int32_t samplesPerFrame = AAudioStream_getChannelCount(stream);
+    // This code only plays on the first one or two channels.
+    // TODO Support arbitrary number of channels.
+    switch (AAudioStream_getFormat(stream)) {
+        case AAUDIO_FORMAT_PCM_I16: {
+            int16_t *audioBuffer = (int16_t *) audioData;
+            // Render sine waves as shorts to first channel.
+            sineData->sineOsc1.render(&audioBuffer[0], samplesPerFrame, numFrames);
+            // Render sine waves to second channel if there is one.
+            if (samplesPerFrame > 1) {
+                sineData->sineOsc2.render(&audioBuffer[1], samplesPerFrame, numFrames);
+            }
+        }
+        break;
+        case AAUDIO_FORMAT_PCM_FLOAT: {
+            float *audioBuffer = (float *) audioData;
+            // Render sine waves as floats to first channel.
+            sineData->sineOsc1.render(&audioBuffer[0], samplesPerFrame, numFrames);
+            // Render sine waves to second channel if there is one.
+            if (samplesPerFrame > 1) {
+                sineData->sineOsc2.render(&audioBuffer[1], samplesPerFrame, numFrames);
+            }
+        }
+        break;
+        default:
+            return AAUDIO_CALLBACK_RESULT_STOP;
+    }
+
+    return AAUDIO_CALLBACK_RESULT_CONTINUE;
+}
+
+void SimplePlayerErrorCallbackProc(
+        AAudioStream *stream __unused,
+        void *userData __unused,
+        aaudio_result_t error)
+{
+    printf("Error Callback, error: %d\n",(int)error);
+}
+
+#endif //AAUDIO_SIMPLE_PLAYER_H
diff --git a/media/libaaudio/examples/utils/AAudioSimpleRecorder.h b/media/libaaudio/examples/utils/AAudioSimpleRecorder.h
new file mode 100644
index 0000000..9e7c463
--- /dev/null
+++ b/media/libaaudio/examples/utils/AAudioSimpleRecorder.h
@@ -0,0 +1,260 @@
+/*
+ * Copyright (C) 2017 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+// Record input using AAudio and display the peak amplitudes.
+
+#ifndef AAUDIO_SIMPLE_RECORDER_H
+#define AAUDIO_SIMPLE_RECORDER_H
+
+#include <aaudio/AAudio.h>
+
+//#define SHARING_MODE  AAUDIO_SHARING_MODE_EXCLUSIVE
+#define SHARING_MODE  AAUDIO_SHARING_MODE_SHARED
+#define PERFORMANCE_MODE AAUDIO_PERFORMANCE_MODE_NONE
+/**
+ * Simple wrapper for AAudio that opens an input stream either in callback or blocking read mode.
+ */
+class AAudioSimpleRecorder {
+public:
+    AAudioSimpleRecorder() {}
+    ~AAudioSimpleRecorder() {
+        close();
+    };
+
+    /**
+     * Call this before calling open().
+     * @param requestedSharingMode
+     */
+    void setSharingMode(aaudio_sharing_mode_t requestedSharingMode) {
+        mRequestedSharingMode = requestedSharingMode;
+    }
+
+    /**
+     * Call this before calling open().
+     * @param requestedPerformanceMode
+     */
+    void setPerformanceMode(aaudio_performance_mode_t requestedPerformanceMode) {
+        mRequestedPerformanceMode = requestedPerformanceMode;
+    }
+
+    /**
+     * Also known as "sample rate"
+     * Only call this after open() has been called.
+     */
+    int32_t getFramesPerSecond() {
+        if (mStream == nullptr) {
+            return AAUDIO_ERROR_INVALID_STATE;
+        }
+        return AAudioStream_getSampleRate(mStream);;
+    }
+
+    /**
+     * Only call this after open() has been called.
+     */
+    int32_t getSamplesPerFrame() {
+        if (mStream == nullptr) {
+            return AAUDIO_ERROR_INVALID_STATE;
+        }
+        return AAudioStream_getSamplesPerFrame(mStream);;
+    }
+    /**
+     * Only call this after open() has been called.
+     */
+    int64_t getFramesRead() {
+        if (mStream == nullptr) {
+            return AAUDIO_ERROR_INVALID_STATE;
+        }
+        return AAudioStream_getFramesRead(mStream);;
+    }
+
+    /**
+     * Open a stream
+     */
+    aaudio_result_t open(int channelCount, int sampSampleRate, aaudio_format_t format,
+                         AAudioStream_dataCallback dataProc, AAudioStream_errorCallback errorProc,
+                         void *userContext) {
+        aaudio_result_t result = AAUDIO_OK;
+
+        // Use an AAudioStreamBuilder to contain requested parameters.
+        result = AAudio_createStreamBuilder(&mBuilder);
+        if (result != AAUDIO_OK) return result;
+
+        AAudioStreamBuilder_setDirection(mBuilder, AAUDIO_DIRECTION_INPUT);
+        AAudioStreamBuilder_setPerformanceMode(mBuilder, mRequestedPerformanceMode);
+        AAudioStreamBuilder_setSharingMode(mBuilder, mRequestedSharingMode);
+        if (dataProc != nullptr) {
+            AAudioStreamBuilder_setDataCallback(mBuilder, dataProc, userContext);
+        }
+        if (errorProc != nullptr) {
+            AAudioStreamBuilder_setErrorCallback(mBuilder, errorProc, userContext);
+        }
+        AAudioStreamBuilder_setChannelCount(mBuilder, channelCount);
+        AAudioStreamBuilder_setSampleRate(mBuilder, sampSampleRate);
+        AAudioStreamBuilder_setFormat(mBuilder, format);
+
+        // Open an AAudioStream using the Builder.
+        result = AAudioStreamBuilder_openStream(mBuilder, &mStream);
+        if (result != AAUDIO_OK) {
+            fprintf(stderr, "ERROR - AAudioStreamBuilder_openStream() returned %d %s\n",
+                    result, AAudio_convertResultToText(result));
+            goto finish1;
+        }
+
+        printf("AAudioStream_getFramesPerBurst() = %d\n",
+               AAudioStream_getFramesPerBurst(mStream));
+        printf("AAudioStream_getBufferSizeInFrames() = %d\n",
+               AAudioStream_getBufferSizeInFrames(mStream));
+        printf("AAudioStream_getBufferCapacityInFrames() = %d\n",
+               AAudioStream_getBufferCapacityInFrames(mStream));
+        return result;
+
+     finish1:
+        AAudioStreamBuilder_delete(mBuilder);
+        mBuilder = nullptr;
+        return result;
+    }
+
+    aaudio_result_t close() {
+        if (mStream != nullptr) {
+            printf("call AAudioStream_close(%p)\n", mStream);  fflush(stdout);
+            AAudioStream_close(mStream);
+            mStream = nullptr;
+            AAudioStreamBuilder_delete(mBuilder);
+            mBuilder = nullptr;
+        }
+        return AAUDIO_OK;
+    }
+
+    // Write zero data to fill up the buffer and prevent underruns.
+    aaudio_result_t prime() {
+        int32_t samplesPerFrame = AAudioStream_getSamplesPerFrame(mStream);
+        const int numFrames = 32; // arbitrary
+        float zeros[numFrames * samplesPerFrame];
+        memset(zeros, 0, sizeof(zeros));
+        aaudio_result_t result = numFrames;
+        while (result == numFrames) {
+            result = AAudioStream_write(mStream, zeros, numFrames, 0);
+        }
+        return result;
+    }
+
+    // Start the stream. AAudio will start calling your callback function.
+     aaudio_result_t start() {
+        aaudio_result_t result = AAudioStream_requestStart(mStream);
+        if (result != AAUDIO_OK) {
+            fprintf(stderr, "ERROR - AAudioStream_requestStart() returned %d %s\n",
+                    result, AAudio_convertResultToText(result));
+        }
+        return result;
+    }
+
+    // Stop the stream. AAudio will stop calling your callback function.
+    aaudio_result_t stop() {
+        aaudio_result_t result = AAudioStream_requestStop(mStream);
+        if (result != AAUDIO_OK) {
+            fprintf(stderr, "ERROR - AAudioStream_requestStop() returned %d %s\n",
+                    result, AAudio_convertResultToText(result));
+        }
+        return result;
+    }
+
+    // Pause the stream. AAudio will stop calling your callback function.
+    aaudio_result_t pause() {
+        aaudio_result_t result = AAudioStream_requestPause(mStream);
+        if (result != AAUDIO_OK) {
+            fprintf(stderr, "ERROR - AAudioStream_requestPause() returned %d %s\n",
+                    result, AAudio_convertResultToText(result));
+        }
+        return result;
+    }
+
+    AAudioStream *getStream() const {
+        return mStream;
+    }
+
+private:
+    AAudioStreamBuilder      *mBuilder = nullptr;
+    AAudioStream             *mStream = nullptr;
+    aaudio_sharing_mode_t     mRequestedSharingMode = SHARING_MODE;
+    aaudio_performance_mode_t mRequestedPerformanceMode = PERFORMANCE_MODE;
+};
+
+// Application data that gets passed to the callback.
+typedef struct PeakTrackerData {
+    float peakLevel;
+} PeakTrackerData_t;
+
+#define DECAY_FACTOR   0.999
+
+// Callback function that fills the audio output buffer.
+aaudio_data_callback_result_t SimpleRecorderDataCallbackProc(
+        AAudioStream *stream,
+        void *userData,
+        void *audioData,
+        int32_t numFrames
+        ) {
+
+    // should not happen but just in case...
+    if (userData == nullptr) {
+        fprintf(stderr, "ERROR - SimpleRecorderDataCallbackProc needs userData\n");
+        return AAUDIO_CALLBACK_RESULT_STOP;
+    }
+    PeakTrackerData_t *data = (PeakTrackerData_t *) userData;
+    // printf("MyCallbackProc(): frameCount = %d\n", numFrames);
+    int32_t samplesPerFrame = AAudioStream_getSamplesPerFrame(stream);
+    float sample;
+    // This code assume mono or stereo.
+    switch (AAudioStream_getFormat(stream)) {
+        case AAUDIO_FORMAT_PCM_I16: {
+            int16_t *audioBuffer = (int16_t *) audioData;
+            // Peak follower
+            for (int frameIndex = 0; frameIndex < numFrames; frameIndex++) {
+                sample = audioBuffer[frameIndex * samplesPerFrame] * (1.0/32768);
+                data->peakLevel *= DECAY_FACTOR;
+                if (sample > data->peakLevel) {
+                    data->peakLevel = sample;
+                }
+            }
+        }
+        break;
+        case AAUDIO_FORMAT_PCM_FLOAT: {
+            float *audioBuffer = (float *) audioData;
+            // Peak follower
+            for (int frameIndex = 0; frameIndex < numFrames; frameIndex++) {
+                sample = audioBuffer[frameIndex * samplesPerFrame];
+                data->peakLevel *= DECAY_FACTOR;
+                if (sample > data->peakLevel) {
+                    data->peakLevel = sample;
+                }
+            }
+        }
+        break;
+        default:
+            return AAUDIO_CALLBACK_RESULT_STOP;
+    }
+
+    return AAUDIO_CALLBACK_RESULT_CONTINUE;
+}
+
+void SimpleRecorderErrorCallbackProc(
+        AAudioStream *stream __unused,
+        void *userData __unused,
+        aaudio_result_t error)
+{
+    printf("Error Callback, error: %d\n",(int)error);
+}
+
+#endif //AAUDIO_SIMPLE_RECORDER_H
diff --git a/media/libaaudio/examples/utils/SineGenerator.h b/media/libaaudio/examples/utils/SineGenerator.h
new file mode 100644
index 0000000..64b772d
--- /dev/null
+++ b/media/libaaudio/examples/utils/SineGenerator.h
@@ -0,0 +1,95 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef SINE_GENERATOR_H
+#define SINE_GENERATOR_H
+
+#include <math.h>
+
+class SineGenerator
+{
+public:
+    SineGenerator() {}
+    virtual ~SineGenerator() = default;
+
+    void setup(double frequency, double frameRate) {
+        mFrameRate = frameRate;
+        mPhaseIncrement = frequency * M_PI * 2 / frameRate;
+    }
+
+    void setSweep(double frequencyLow, double frequencyHigh, double seconds) {
+        mPhaseIncrementLow = frequencyLow * M_PI * 2 / mFrameRate;
+        mPhaseIncrementHigh = frequencyHigh * M_PI * 2 / mFrameRate;
+
+        double numFrames = seconds * mFrameRate;
+        mUpScaler = pow((frequencyHigh / frequencyLow), (1.0 / numFrames));
+        mDownScaler = 1.0 / mUpScaler;
+        mGoingUp = true;
+        mSweeping = true;
+    }
+
+    void render(int16_t *buffer, int32_t channelStride, int32_t numFrames) {
+        int sampleIndex = 0;
+        for (int i = 0; i < numFrames; i++) {
+            buffer[sampleIndex] = (int16_t) (32767 * sin(mPhase) * mAmplitude);
+            sampleIndex += channelStride;
+            advancePhase();
+        }
+    }
+    void render(float *buffer, int32_t channelStride, int32_t numFrames) {
+        int sampleIndex = 0;
+        for (int i = 0; i < numFrames; i++) {
+            buffer[sampleIndex] = sin(mPhase) * mAmplitude;
+            sampleIndex += channelStride;
+            advancePhase();
+        }
+    }
+
+private:
+    void advancePhase() {
+        mPhase += mPhaseIncrement;
+        if (mPhase > M_PI * 2) {
+            mPhase -= M_PI * 2;
+        }
+        if (mSweeping) {
+            if (mGoingUp) {
+                mPhaseIncrement *= mUpScaler;
+                if (mPhaseIncrement > mPhaseIncrementHigh) {
+                    mGoingUp = false;
+                }
+            } else {
+                mPhaseIncrement *= mDownScaler;
+                if (mPhaseIncrement < mPhaseIncrementLow) {
+                    mGoingUp = true;
+                }
+            }
+        }
+    }
+
+    double mAmplitude = 0.05;  // unitless scaler
+    double mPhase = 0.0;
+    double mPhaseIncrement = 440 * M_PI * 2 / 48000;
+    double mFrameRate = 48000;
+    double mPhaseIncrementLow;
+    double mPhaseIncrementHigh;
+    double mUpScaler = 1.0;
+    double mDownScaler = 1.0;
+    bool   mGoingUp = false;
+    bool   mSweeping = false;
+};
+
+#endif /* SINE_GENERATOR_H */
+