Merge pull request #2 from dturner/master

Changing bool to std::atomic<bool>

Author: dturner

app/src/main/cpp/Oscillator.cpp

@@ -26,15 +26,18 @@ void Oscillator::setSampleRate(int32_t sampleRate) {
 }
 
 void Oscillator::setWaveOn(bool isWaveOn) {
-    isWaveOn_ = isWaveOn;
-    if (!isWaveOn) phase_ = 0;
+    isWaveOn_.store(isWaveOn);
 }
 
 void Oscillator::render(float *audioData, int32_t numFrames) {
 
+    // If the wave has been switched off then reset the phase to zero. Starting at a non-zero value
+    // could result in an unwanted audible 'click'
+    if (!isWaveOn_.load()) phase_ = 0;
+
     for (int i = 0; i < numFrames; i++) {
 
-        if (isWaveOn_) {
+        if (isWaveOn_.load()) {
 
             // Calculates the next sample value for the sine wave.
             audioData[i] = (float) (sin(phase_) * AMPLITUDE);

app/src/main/cpp/Oscillator.h

@@ -17,7 +17,7 @@
 #ifndef PART1_OSCILLATOR_H
 #define PART1_OSCILLATOR_H
 
-
+#include <atomic>
 #include <stdint.h>
 
 class Oscillator {
@@ -29,7 +29,8 @@ class Oscillator {
     void render(float *audioData, int32_t numFrames);
 
 private:
-    bool isWaveOn_ = false;
+    // We use an atomic bool to define isWaveOn_ because it is accessed from multiple threads.
+    std::atomic<bool> isWaveOn_{false};
     double phase_ = 0.0;
     double phaseIncrement_ = 0.0;
 };