Inefficient, but pumping audio.

src/xenia/apu/audio_system.cc

@@ -23,7 +23,7 @@ using namespace xe::cpu;
 AudioSystem::AudioSystem(Emulator* emulator) :
     emulator_(emulator), memory_(emulator->memory()),
     thread_(0), running_(false), driver_(0),
-    client_({ 0 }) {
+    client_({ 0 }), can_submit_(false) {
   // Create the run loop used for any windows/etc.
   // This must be done on the thread we create the driver.
   run_loop_ = xe_run_loop_create();
@@ -87,11 +87,13 @@ void AudioSystem::ThreadStart() {
     }
 
     // Pump worker.
+    Pump();
+
     xe_mutex_lock(lock_);
     uint32_t client_callback = client_.callback;
     uint32_t client_callback_arg = client_.wrapped_callback_arg;
     xe_mutex_unlock(lock_);
-    if (client_callback) {
+    if (client_callback && can_submit_) {
       processor->Execute(
         thread_state_, client_callback, client_callback_arg, 0);
     } else {

src/xenia/apu/audio_system.h

@@ -84,6 +84,7 @@ protected:
     uint32_t callback_arg;
     uint32_t wrapped_callback_arg;
   } client_;
+  bool              can_submit_;
 
   AudioDriver*      driver_;
 };

src/xenia/apu/xaudio2/xaudio2_audio_system.cc

@@ -67,7 +67,14 @@ void XAudio2AudioSystem::Initialize() {
 }
 
 void XAudio2AudioSystem::Pump() {
-  //
+  XAUDIO2_VOICE_STATE state;
+  pcm_voice_->GetState(&state);
+  auto n = state.BuffersQueued;
+  if (n > 30) {
+    can_submit_ = false;
+  } else {
+    can_submit_ = true;
+  }
 }
 
 void XAudio2AudioSystem::SubmitFrame(uint32_t samples_ptr) {