FrontendCommon: Add XAudio2 audio backend

src/frontend-common/xaudio2_audio_stream.h

@@ -0,0 +1,61 @@
+#pragma once
+#include "common/audio_stream.h"
+#include "common/windows_headers.h"
+#include <array>
+#include <cstdint>
+#include <memory>
+#include <wrl/client.h>
+
+// We need to use the Windows 10 headers otherwise this won't compile.
+#undef _WIN32_WINNT
+#define _WIN32_WINNT _WIN32_WINNT_WIN10
+#include <xaudio2.h>
+
+class XAudio2AudioStream final : public AudioStream, private IXAudio2VoiceCallback
+{
+public:
+  XAudio2AudioStream();
+  ~XAudio2AudioStream();
+
+  bool Initialize();
+
+  void SetOutputVolume(u32 volume) override;
+
+protected:
+  enum : u32
+  {
+    NUM_BUFFERS = 2
+  };
+
+  ALWAYS_INLINE bool IsOpen() const { return static_cast<bool>(m_xaudio); }
+
+  bool OpenDevice() override;
+  void PauseDevice(bool paused) override;
+  void CloseDevice() override;
+  void FramesAvailable() override;
+
+  // Inherited via IXAudio2VoiceCallback
+  virtual void __stdcall OnVoiceProcessingPassStart(UINT32 BytesRequired) override;
+  virtual void __stdcall OnVoiceProcessingPassEnd(void) override;
+  virtual void __stdcall OnStreamEnd(void) override;
+  virtual void __stdcall OnBufferStart(void* pBufferContext) override;
+  virtual void __stdcall OnBufferEnd(void* pBufferContext) override;
+  virtual void __stdcall OnLoopEnd(void* pBufferContext) override;
+  virtual void __stdcall OnVoiceError(void* pBufferContext, HRESULT Error) override;
+
+  void EnqueueBuffer();
+
+  Microsoft::WRL::ComPtr<IXAudio2> m_xaudio;
+  IXAudio2MasteringVoice* m_mastering_voice = nullptr;
+  IXAudio2SourceVoice* m_source_voice = nullptr;
+
+  std::array<std::unique_ptr<SampleType[]>, NUM_BUFFERS> m_buffers;
+  u32 m_current_buffer = 0;
+  bool m_buffer_enqueued = false;
+  bool m_paused = true;
+
+#if WINAPI_FAMILY_PARTITION(WINAPI_PARTITION_DESKTOP)
+  HMODULE m_xaudio2_library = {};
+  bool m_com_initialized_by_us = false;
+#endif
+};