callback for new audio data

src/sound.cpp

@@ -85,3 +85,15 @@ void Sound::stop() {
 void Sound::end() {
   i2s_driver_uninstall(i2s_num); //stop & destroy i2s driver
 }
+
+/* callback(?) for new audio data */
+int Sound::render_sample_block(uint16_t *sample_buf_left, uint16_t *sample_buf_right, int num_samples) {
+  int num_pushed_samples = 0;
+  for (int i=0; i < num_samples; i++) {
+    unsigned int sample = ((unsigned short) sample_buf_left[i] << 16 & 0xffff0000) | ((unsigned short) sample_buf_right[i]);
+    int num_pushed_bytes = i2s_push_sample(i2s_num, (char *)&sample, portMAX_DELAY);
+    if (num_pushed_bytes > 0) num_pushed_samples += num_pushed_bytes;
+    else break;
+  }
+  return num_pushed_samples;
+}

src/sound.h

@@ -25,6 +25,7 @@ class Sound {
     void play();
 //    void pause();
     void stop();
+    int render_sample_block(uint16_t *sample_buf_left, uint16_t *sample_buf_right, int num_samples);
   private:
     i2sbuffer_t buffer;
     const i2s_port_t i2s_num = (i2s_port_t)I2S_NUM;