libretro: Additional work

- Reliable resolution switching.
 - Hook up logging.
 - Memory cards and controller type settings.
 - Save state support.
 - Direct3D support.

src/duckstation-libretro/libretro_host_interface.h

@@ -9,7 +9,9 @@ public:
   LibretroHostInterface();
   ~LibretroHostInterface() override;
 
+  static void InitLogging();
   static bool SetCoreOptions();
+  static bool HasCoreVariablesChanged();
 
   bool Initialize() override;
   void Shutdown() override;
@@ -17,33 +19,49 @@ public:
   void ReportError(const char* message) override;
   void ReportMessage(const char* message) override;
   bool ConfirmMessage(const char* message) override;
+  void AddOSDMessage(std::string message, float duration = 2.0f) override;
 
-  const retro_hw_render_callback& GetHWRenderCallback() const { return m_hw_render_callback; }
+  void GetGameInfo(const char* path, CDImage* image, std::string* code, std::string* title) override;
+  std::string GetSharedMemoryCardPath(u32 slot) const override;
+  std::string GetGameMemoryCardPath(const char* game_code, u32 slot) const override;
 
   // Called by frontend
   void retro_get_system_av_info(struct retro_system_av_info* info);
   bool retro_load_game(const struct retro_game_info* game);
   void retro_run_frame();
   unsigned retro_get_region();
+  size_t retro_serialize_size();
+  bool retro_serialize(void* data, size_t size);
+  bool retro_unserialize(const void* data, size_t size);
 
 protected:
   bool AcquireHostDisplay() override;
   void ReleaseHostDisplay() override;
   std::unique_ptr<AudioStream> CreateAudioStream(AudioBackend backend) override;
+  void OnSystemDestroyed() override;
+  void CheckForSettingsChanges(const Settings& old_settings) override;
 
 private:
   void LoadSettings();
   void UpdateSettings();
   void UpdateControllers();
   void UpdateControllersDigitalController(u32 index);
+  void GetSystemAVInfo(struct retro_system_av_info* info, bool use_resolution_scale);
+  void UpdateSystemAVInfo(bool use_resolution_scale);
+  void UpdateGeometry();
+  void UpdateLogging();
 
   // Hardware renderer setup.
   bool RequestHardwareRendererContext();
+  void SwitchToHardwareRenderer();
+  void SwitchToSoftwareRenderer();
 
   static void HardwareRendererContextReset();
   static void HardwareRendererContextDestroy();
 
   retro_hw_render_callback m_hw_render_callback = {};
+  bool m_hw_render_callback_valid = false;
+  bool m_using_hardware_renderer = false;
 };
 
 extern LibretroHostInterface g_libretro_host_interface;