WiimoteEmu: Update extensions from DesiredWiimoteState.

Source/Core/Core/CMakeLists.txt

@@ -287,6 +287,7 @@ add_library(core
   HW/WiimoteEmu/Encryption.h
   HW/WiimoteEmu/Extension/Classic.cpp
   HW/WiimoteEmu/Extension/Classic.h
+  HW/WiimoteEmu/Extension/DesiredExtensionState.h
   HW/WiimoteEmu/Extension/DrawsomeTablet.cpp
   HW/WiimoteEmu/Extension/DrawsomeTablet.h
   HW/WiimoteEmu/Extension/Drums.cpp

Source/Core/Core/HW/WiimoteEmu/DesiredWiimoteState.h

@@ -8,6 +8,7 @@
 
 #include "Core/HW/WiimoteCommon/WiimoteReport.h"
 #include "Core/HW/WiimoteEmu/Camera.h"
+#include "Core/HW/WiimoteEmu/Extension/DesiredExtensionState.h"
 #include "Core/HW/WiimoteEmu/MotionPlus.h"
 #include "Core/HW/WiimoteEmu/WiimoteEmu.h"
 
@@ -26,5 +27,6 @@ struct DesiredWiimoteState
   WiimoteCommon::AccelData acceleration = DEFAULT_ACCELERATION;
   std::array<CameraPoint, 2> camera_points = DEFAULT_CAMERA;
   std::optional<MotionPlus::DataFormat::Data> motion_plus = std::nullopt;
+  DesiredExtensionState extension;
 };
 }  // namespace WiimoteEmu

Source/Core/Core/HW/WiimoteEmu/Extension/Classic.cpp

@@ -10,6 +10,8 @@
 #include "Common/BitUtils.h"
 #include "Common/Common.h"
 #include "Common/CommonTypes.h"
+
+#include "Core/HW/WiimoteEmu/Extension/DesiredExtensionState.h"
 #include "Core/HW/WiimoteEmu/WiimoteEmu.h"
 
 #include "InputCommon/ControllerEmu/Control/Input.h"
@@ -105,7 +107,7 @@ Classic::Classic() : Extension1stParty("Classic", _trans("Classic Controller"))
   }
 }
 
-void Classic::Update()
+void Classic::BuildDesiredExtensionState(DesiredExtensionState* target_state)
 {
   DataFormat classic_data = {};
 
@@ -149,7 +151,12 @@ void Classic::Update()
 
   classic_data.SetButtons(buttons);
 
-  Common::BitCastPtr<DataFormat>(&m_reg.controller_data) = classic_data;
+  target_state->data = classic_data;
+}
+
+void Classic::Update(const DesiredExtensionState& target_state)
+{
+  DefaultExtensionUpdate<DataFormat>(&m_reg, target_state);
 }
 
 void Classic::Reset()

Source/Core/Core/HW/WiimoteEmu/Extension/Classic.h

@@ -178,7 +178,8 @@ public:
 
   Classic();
 
-  void Update() override;
+  void BuildDesiredExtensionState(DesiredExtensionState* target_state) override;
+  void Update(const DesiredExtensionState& target_state) override;
   void Reset() override;
 
   ControllerEmu::ControlGroup* GetGroup(ClassicGroup group);

Source/Core/Core/HW/WiimoteEmu/Extension/DesiredExtensionState.h

@@ -0,0 +1,76 @@
+// Copyright 2022 Dolphin Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#pragma once
+
+#include <type_traits>
+#include <variant>
+
+#include "Common/BitUtils.h"
+
+#include "Core/HW/WiimoteEmu/Extension/Classic.h"
+#include "Core/HW/WiimoteEmu/Extension/DrawsomeTablet.h"
+#include "Core/HW/WiimoteEmu/Extension/Drums.h"
+#include "Core/HW/WiimoteEmu/Extension/Extension.h"
+#include "Core/HW/WiimoteEmu/Extension/Guitar.h"
+#include "Core/HW/WiimoteEmu/Extension/Nunchuk.h"
+#include "Core/HW/WiimoteEmu/Extension/Shinkansen.h"
+#include "Core/HW/WiimoteEmu/Extension/TaTaCon.h"
+#include "Core/HW/WiimoteEmu/Extension/Turntable.h"
+#include "Core/HW/WiimoteEmu/Extension/UDrawTablet.h"
+#include "Core/HW/WiimoteEmu/ExtensionPort.h"
+
+namespace WiimoteEmu
+{
+struct DesiredExtensionState
+{
+  using ExtensionData =
+      std::variant<std::monostate, Nunchuk::DataFormat, Classic::DataFormat, Guitar::DataFormat,
+                   Drums::DesiredState, Turntable::DataFormat, UDrawTablet::DataFormat,
+                   DrawsomeTablet::DataFormat, TaTaCon::DataFormat, Shinkansen::DesiredState>;
+  ExtensionData data = std::monostate();
+
+  static_assert(std::is_same_v<std::monostate,
+                               std::variant_alternative_t<ExtensionNumber::NONE, ExtensionData>>);
+  static_assert(
+      std::is_same_v<Nunchuk::DataFormat,
+                     std::variant_alternative_t<ExtensionNumber::NUNCHUK, ExtensionData>>);
+  static_assert(
+      std::is_same_v<Classic::DataFormat,
+                     std::variant_alternative_t<ExtensionNumber::CLASSIC, ExtensionData>>);
+  static_assert(std::is_same_v<Guitar::DataFormat,
+                               std::variant_alternative_t<ExtensionNumber::GUITAR, ExtensionData>>);
+  static_assert(std::is_same_v<Drums::DesiredState,
+                               std::variant_alternative_t<ExtensionNumber::DRUMS, ExtensionData>>);
+  static_assert(
+      std::is_same_v<Turntable::DataFormat,
+                     std::variant_alternative_t<ExtensionNumber::TURNTABLE, ExtensionData>>);
+  static_assert(
+      std::is_same_v<UDrawTablet::DataFormat,
+                     std::variant_alternative_t<ExtensionNumber::UDRAW_TABLET, ExtensionData>>);
+  static_assert(
+      std::is_same_v<DrawsomeTablet::DataFormat,
+                     std::variant_alternative_t<ExtensionNumber::DRAWSOME_TABLET, ExtensionData>>);
+  static_assert(
+      std::is_same_v<TaTaCon::DataFormat,
+                     std::variant_alternative_t<ExtensionNumber::TATACON, ExtensionData>>);
+  static_assert(
+      std::is_same_v<Shinkansen::DesiredState,
+                     std::variant_alternative_t<ExtensionNumber::SHINKANSEN, ExtensionData>>);
+  static_assert(std::variant_size_v<DesiredExtensionState::ExtensionData> == ExtensionNumber::MAX);
+};
+
+template <typename T>
+void DefaultExtensionUpdate(EncryptedExtension::Register* reg,
+                            const DesiredExtensionState& target_state)
+{
+  if (std::holds_alternative<T>(target_state.data))
+  {
+    Common::BitCastPtr<T>(&reg->controller_data) = std::get<T>(target_state.data);
+  }
+  else
+  {
+    Common::BitCastPtr<T>(&reg->controller_data) = T{};
+  }
+}
+}  // namespace WiimoteEmu

Source/Core/Core/HW/WiimoteEmu/Extension/DrawsomeTablet.cpp

@@ -9,6 +9,8 @@
 #include "Common/BitUtils.h"
 #include "Common/Common.h"
 #include "Common/CommonTypes.h"
+
+#include "Core/HW/WiimoteEmu/Extension/DesiredExtensionState.h"
 #include "Core/HW/WiimoteEmu/WiimoteEmu.h"
 
 #include "InputCommon/ControllerEmu/Control/Input.h"
@@ -31,9 +33,9 @@ DrawsomeTablet::DrawsomeTablet() : Extension3rdParty("Drawsome", _trans("Drawsom
   m_touch->AddInput(ControllerEmu::Translate, _trans("Pressure"));
 }
 
-void DrawsomeTablet::Update()
+void DrawsomeTablet::BuildDesiredExtensionState(DesiredExtensionState* target_state)
 {
-  DataFormat tablet_data = {};
+  DataFormat& tablet_data = target_state->data.emplace<DataFormat>();
 
   // Stylus X/Y (calibrated values):
   constexpr u16 MIN_X = 0x0000;
@@ -77,8 +79,11 @@ void DrawsomeTablet::Update()
 
   tablet_data.pressure1 = u8(pressure);
   tablet_data.pressure2 = u8(pressure >> 8);
+}
 
-  Common::BitCastPtr<DataFormat>(&m_reg.controller_data) = tablet_data;
+void DrawsomeTablet::Update(const DesiredExtensionState& target_state)
+{
+  DefaultExtensionUpdate<DataFormat>(&m_reg, target_state);
 }
 
 void DrawsomeTablet::Reset()

Source/Core/Core/HW/WiimoteEmu/Extension/DrawsomeTablet.h

@@ -27,7 +27,8 @@ class DrawsomeTablet : public Extension3rdParty
 public:
   DrawsomeTablet();
 
-  void Update() override;
+  void BuildDesiredExtensionState(DesiredExtensionState* target_state) override;
+  void Update(const DesiredExtensionState& target_state) override;
   void Reset() override;
 
   ControllerEmu::ControlGroup* GetGroup(DrawsomeTabletGroup group);

Source/Core/Core/HW/WiimoteEmu/Extension/Drums.cpp

@@ -9,6 +9,8 @@
 #include "Common/BitUtils.h"
 #include "Common/Common.h"
 #include "Common/CommonTypes.h"
+
+#include "Core/HW/WiimoteEmu/Extension/DesiredExtensionState.h"
 #include "Core/HW/WiimoteEmu/WiimoteEmu.h"
 
 #include "InputCommon/ControllerEmu/Control/Input.h"
@@ -77,8 +79,43 @@ Drums::Drums() : Extension1stParty("Drums", _trans("Drum Kit"))
   m_buttons->AddInput(ControllerEmu::DoNotTranslate, "+");
 }
 
-void Drums::Update()
+void Drums::BuildDesiredExtensionState(DesiredExtensionState* target_state)
 {
+  DesiredState& state = target_state->data.emplace<DesiredState>();
+
+  {
+    const ControllerEmu::AnalogStick::StateData stick_state = m_stick->GetState();
+
+    state.stick_x = MapFloat(stick_state.x, STICK_CENTER, STICK_MIN, STICK_MAX);
+    state.stick_y = MapFloat(stick_state.y, STICK_CENTER, STICK_MIN, STICK_MAX);
+  }
+
+  state.buttons = 0;
+  m_buttons->GetState(&state.buttons, drum_button_bitmasks.data());
+
+  state.drum_pads = 0;
+  m_pads->GetState(&state.drum_pads, drum_pad_bitmasks.data());
+
+  state.softness = u8(7 - std::lround(m_hit_strength_setting.GetValue() * 7 / 100));
+}
+
+void Drums::Update(const DesiredExtensionState& target_state)
+{
+  DesiredState desired_state;
+  if (std::holds_alternative<DesiredState>(target_state.data))
+  {
+    desired_state = std::get<DesiredState>(target_state.data);
+  }
+  else
+  {
+    // Set a sane default
+    desired_state.stick_x = STICK_CENTER;
+    desired_state.stick_y = STICK_CENTER;
+    desired_state.buttons = 0;
+    desired_state.drum_pads = 0;
+    desired_state.softness = 7;
+  }
+
   DataFormat drum_data = {};
 
   // The meaning of these bits are unknown but they are usually set.
@@ -94,20 +131,12 @@ void Drums::Update()
   drum_data.no_velocity_data_2 = 1;
   drum_data.softness = 7;
 
-  // Stick.
-  {
-    const ControllerEmu::AnalogStick::StateData stick_state = m_stick->GetState();
-
-    drum_data.stick_x = MapFloat(stick_state.x, STICK_CENTER, STICK_MIN, STICK_MAX);
-    drum_data.stick_y = MapFloat(stick_state.y, STICK_CENTER, STICK_MIN, STICK_MAX);
-  }
-
-  // Buttons.
-  m_buttons->GetState(&drum_data.buttons, drum_button_bitmasks.data());
+  drum_data.stick_x = desired_state.stick_x;
+  drum_data.stick_y = desired_state.stick_y;
+  drum_data.buttons = desired_state.buttons;
 
   // Drum pads.
-  u8 current_pad_input = 0;
-  m_pads->GetState(&current_pad_input, drum_pad_bitmasks.data());
+  u8 current_pad_input = desired_state.drum_pads;
   m_new_pad_hits |= ~m_prev_pad_input & current_pad_input;
   m_prev_pad_input = current_pad_input;
 
@@ -130,8 +159,7 @@ void Drums::Update()
       drum_data.no_velocity_data_1 = 0;
       drum_data.no_velocity_data_2 = 0;
 
-      // Set softness from user-configured hit strength setting.
-      drum_data.softness = u8(7 - std::lround(m_hit_strength_setting.GetValue() * 7 / 100));
+      drum_data.softness = desired_state.softness;
 
       // A drum-pad hit causes the relevent bit to be triggered for the next 10 frames.
       constexpr u8 HIT_FRAME_COUNT = 10;

Source/Core/Core/HW/WiimoteEmu/Extension/Drums.h

@@ -28,6 +28,15 @@ enum class DrumsGroup
 class Drums : public Extension1stParty
 {
 public:
+  struct DesiredState
+  {
+    u8 stick_x;    // 6 bits
+    u8 stick_y;    // 6 bits
+    u8 buttons;    // 2 bits
+    u8 drum_pads;  // 6 bits
+    u8 softness;   // 3 bits
+  };
+
   struct DataFormat
   {
     u8 stick_x : 6;
@@ -77,7 +86,8 @@ public:
 
   Drums();
 
-  void Update() override;
+  void BuildDesiredExtensionState(DesiredExtensionState* target_state) override;
+  void Update(const DesiredExtensionState& target_state) override;
   void Reset() override;
 
   ControllerEmu::ControlGroup* GetGroup(DrumsGroup group);

Source/Core/Core/HW/WiimoteEmu/Extension/Extension.cpp

@@ -9,6 +9,8 @@
 
 #include "Common/CommonTypes.h"
 #include "Common/Inline.h"
+
+#include "Core/HW/WiimoteEmu/Extension/DesiredExtensionState.h"
 #include "Core/HW/WiimoteEmu/WiimoteEmu.h"
 
 #include "Common/Logging/Log.h"
@@ -43,7 +45,12 @@ bool None::ReadDeviceDetectPin() const
   return false;
 }
 
-void None::Update()
+void None::BuildDesiredExtensionState(DesiredExtensionState* target_state)
+{
+  target_state->data.emplace<std::monostate>();
+}
+
+void None::Update(const DesiredExtensionState& target_state)
 {
   // Nothing needed.
 }

Source/Core/Core/HW/WiimoteEmu/Extension/Extension.h

@@ -16,6 +16,8 @@
 
 namespace WiimoteEmu
 {
+struct DesiredExtensionState;
+
 class Extension : public ControllerEmu::EmulatedController, public I2CSlave
 {
 public:
@@ -32,7 +34,8 @@ public:
 
   virtual void Reset() = 0;
   virtual void DoState(PointerWrap& p) = 0;
-  virtual void Update() = 0;
+  virtual void BuildDesiredExtensionState(DesiredExtensionState* target_state) = 0;
+  virtual void Update(const DesiredExtensionState& target_state) = 0;
 
 private:
   const char* const m_config_name;
@@ -46,7 +49,8 @@ public:
 
 private:
   bool ReadDeviceDetectPin() const override;
-  void Update() override;
+  void BuildDesiredExtensionState(DesiredExtensionState* target_state) override;
+  void Update(const DesiredExtensionState& target_state) override;
   void Reset() override;
   void DoState(PointerWrap& p) override;
 
@@ -67,7 +71,6 @@ public:
   // TODO: TAS handles encryption poorly.
   EncryptionKey ext_key;
 
-protected:
   static constexpr int CALIBRATION_CHECKSUM_BYTES = 2;
 
 #pragma pack(push, 1)
@@ -97,6 +100,7 @@ protected:
 
   static_assert(0x100 == sizeof(Register));
 
+protected:
   Register m_reg = {};
 
   void Reset() override;

Source/Core/Core/HW/WiimoteEmu/Extension/Guitar.cpp

@@ -11,6 +11,8 @@
 #include "Common/BitUtils.h"
 #include "Common/Common.h"
 #include "Common/CommonTypes.h"
+
+#include "Core/HW/WiimoteEmu/Extension/DesiredExtensionState.h"
 #include "Core/HW/WiimoteEmu/WiimoteEmu.h"
 
 #include "InputCommon/ControllerEmu/Control/Input.h"
@@ -93,7 +95,7 @@ Guitar::Guitar() : Extension1stParty(_trans("Guitar"))
   groups.emplace_back(m_slider_bar = new ControllerEmu::Slider(_trans("Slider Bar")));
 }
 
-void Guitar::Update()
+void Guitar::BuildDesiredExtensionState(DesiredExtensionState* target_state)
 {
   DataFormat guitar_data = {};
 
@@ -135,7 +137,12 @@ void Guitar::Update()
   // flip button bits
   guitar_data.bt ^= 0xFFFF;
 
-  Common::BitCastPtr<DataFormat>(&m_reg.controller_data) = guitar_data;
+  target_state->data = guitar_data;
+}
+
+void Guitar::Update(const DesiredExtensionState& target_state)
+{
+  DefaultExtensionUpdate<DataFormat>(&m_reg, target_state);
 }
 
 void Guitar::Reset()

Source/Core/Core/HW/WiimoteEmu/Extension/Guitar.h

@@ -50,7 +50,8 @@ public:
 
   Guitar();
 
-  void Update() override;
+  void BuildDesiredExtensionState(DesiredExtensionState* target_state) override;
+  void Update(const DesiredExtensionState& target_state) override;
   void Reset() override;
 
   ControllerEmu::ControlGroup* GetGroup(GuitarGroup group);

Source/Core/Core/HW/WiimoteEmu/Extension/Nunchuk.cpp

@@ -12,7 +12,9 @@
 #include "Common/Common.h"
 #include "Common/CommonTypes.h"
 #include "Common/MathUtil.h"
+
 #include "Core/HW/Wiimote.h"
+#include "Core/HW/WiimoteEmu/Extension/DesiredExtensionState.h"
 #include "Core/HW/WiimoteEmu/WiimoteEmu.h"
 
 #include "InputCommon/ControllerEmu/Control/Input.h"
@@ -60,7 +62,7 @@ Nunchuk::Nunchuk() : Extension1stParty(_trans("Nunchuk"))
                           "IMUAccelerometer", _trans("Accelerometer")));
 }
 
-void Nunchuk::Update()
+void Nunchuk::BuildDesiredExtensionState(DesiredExtensionState* target_state)
 {
   DataFormat nc_data = {};
 
@@ -110,7 +112,12 @@ void Nunchuk::Update()
   const auto acc = ConvertAccelData(accel, ACCEL_ZERO_G << 2, ACCEL_ONE_G << 2);
   nc_data.SetAccel(acc.value);
 
-  Common::BitCastPtr<DataFormat>(&m_reg.controller_data) = nc_data;
+  target_state->data = nc_data;
+}
+
+void Nunchuk::Update(const DesiredExtensionState& target_state)
+{
+  DefaultExtensionUpdate<DataFormat>(&m_reg, target_state);
 }
 
 void Nunchuk::Reset()

Source/Core/Core/HW/WiimoteEmu/Extension/Nunchuk.h

@@ -149,7 +149,8 @@ public:
 
   Nunchuk();
 
-  void Update() override;
+  void BuildDesiredExtensionState(DesiredExtensionState* target_state) override;
+  void Update(const DesiredExtensionState& target_state) override;
   void Reset() override;
   void DoState(PointerWrap& p) override;
 

Source/Core/Core/HW/WiimoteEmu/Extension/Shinkansen.cpp

@@ -8,6 +8,8 @@
 #include "Common/Assert.h"
 #include "Common/Common.h"
 #include "Common/CommonTypes.h"
+
+#include "Core/HW/WiimoteEmu/Extension/DesiredExtensionState.h"
 #include "Core/HW/WiimoteEmu/WiimoteEmu.h"
 
 #include "InputCommon/ControllerEmu/ControlGroup/Buttons.h"
@@ -50,9 +52,9 @@ Shinkansen::Shinkansen() : Extension3rdParty("Shinkansen", _trans("Shinkansen Co
   m_led->AddOutput(ControllerEmu::Translate, _trans("Doors Locked"));
 }
 
-void Shinkansen::Update()
+void Shinkansen::BuildDesiredExtensionState(DesiredExtensionState* target_state)
 {
-  DataFormat ext_data = {};
+  DesiredState& state = target_state->data.emplace<DesiredState>();
 
   u16 digital = 0;
   const u16 lever_bitmasks[2] = {};
@@ -62,8 +64,8 @@ void Shinkansen::Update()
   // guesses).
   const u8 brake_values[] = {0, 53, 79, 105, 132, 159, 187, 217, 250};
   const u8 power_values[] = {255, 229, 208, 189, 170, 153, 135, 118, 101, 85, 68, 51, 35, 17};
-  ext_data.brake = brake_values[size_t(analog[0] * (sizeof(brake_values) - 1))];
-  ext_data.power = power_values[size_t(analog[1] * (sizeof(power_values) - 1))];
+  state.brake = brake_values[size_t(analog[0] * (sizeof(brake_values) - 1))];
+  state.power = power_values[size_t(analog[1] * (sizeof(power_values) - 1))];
 
   // Note: This currently assumes a little-endian host.
   const u16 button_bitmasks[] = {
@@ -78,8 +80,27 @@ void Shinkansen::Update()
       0x0010,  // Select
       0x0004,  // Start
   };
-  m_buttons->GetState(&ext_data.buttons, button_bitmasks);
-  ext_data.buttons ^= 0xFFFF;
+  m_buttons->GetState(&state.buttons, button_bitmasks);
+}
+
+void Shinkansen::Update(const DesiredExtensionState& target_state)
+{
+  DesiredState desired_state;
+  if (std::holds_alternative<DesiredState>(target_state.data))
+  {
+    desired_state = std::get<DesiredState>(target_state.data);
+  }
+  else
+  {
+    desired_state.brake = 0;
+    desired_state.power = 255;
+    desired_state.buttons = 0;
+  }
+
+  DataFormat ext_data = {};
+  ext_data.brake = desired_state.brake;
+  ext_data.power = desired_state.power;
+  ext_data.buttons = desired_state.buttons ^ 0xFFFF;
   Common::BitCastPtr<DataFormat>(&m_reg.controller_data) = ext_data;
 
   const auto lock = GetStateLock();

Source/Core/Core/HW/WiimoteEmu/Extension/Shinkansen.h

@@ -24,9 +24,17 @@ enum class ShinkansenGroup
 class Shinkansen : public Extension3rdParty
 {
 public:
+  struct DesiredState
+  {
+    u8 brake;
+    u8 power;
+    u16 buttons;
+  };
+
   Shinkansen();
 
-  void Update() override;
+  void BuildDesiredExtensionState(DesiredExtensionState* target_state) override;
+  void Update(const DesiredExtensionState& target_state) override;
   void Reset() override;
   ControllerEmu::ControlGroup* GetGroup(ShinkansenGroup group);
 

Source/Core/Core/HW/WiimoteEmu/Extension/TaTaCon.cpp

@@ -10,6 +10,8 @@
 #include "Common/BitUtils.h"
 #include "Common/Common.h"
 #include "Common/CommonTypes.h"
+
+#include "Core/HW/WiimoteEmu/Extension/DesiredExtensionState.h"
 #include "Core/HW/WiimoteEmu/WiimoteEmu.h"
 
 #include "InputCommon/ControllerEmu/Control/Input.h"
@@ -48,7 +50,7 @@ TaTaCon::TaTaCon() : Extension3rdParty("TaTaCon", _trans("Taiko Drum"))
     m_rim->AddInput(ControllerEmu::Translate, name);
 }
 
-void TaTaCon::Update()
+void TaTaCon::BuildDesiredExtensionState(DesiredExtensionState* target_state)
 {
   DataFormat tatacon_data = {};
 
@@ -58,7 +60,12 @@ void TaTaCon::Update()
   // Flip button bits.
   tatacon_data.state ^= 0xff;
 
-  Common::BitCastPtr<DataFormat>(&m_reg.controller_data) = tatacon_data;
+  target_state->data = tatacon_data;
+}
+
+void TaTaCon::Update(const DesiredExtensionState& target_state)
+{
+  DefaultExtensionUpdate<DataFormat>(&m_reg, target_state);
 }
 
 void TaTaCon::Reset()

Source/Core/Core/HW/WiimoteEmu/Extension/TaTaCon.h

@@ -31,7 +31,8 @@ public:
 
   TaTaCon();
 
-  void Update() override;
+  void BuildDesiredExtensionState(DesiredExtensionState* target_state) override;
+  void Update(const DesiredExtensionState& target_state) override;
   void Reset() override;
 
   ControllerEmu::ControlGroup* GetGroup(TaTaConGroup group);

Source/Core/Core/HW/WiimoteEmu/Extension/Turntable.cpp

@@ -10,6 +10,8 @@
 #include "Common/BitUtils.h"
 #include "Common/Common.h"
 #include "Common/CommonTypes.h"
+
+#include "Core/HW/WiimoteEmu/Extension/DesiredExtensionState.h"
 #include "Core/HW/WiimoteEmu/WiimoteEmu.h"
 
 #include "InputCommon/ControllerEmu/Control/Input.h"
@@ -78,7 +80,7 @@ Turntable::Turntable() : Extension1stParty("Turntable", _trans("DJ Turntable"))
   groups.emplace_back(m_crossfade = new ControllerEmu::Slider(_trans("Crossfade")));
 }
 
-void Turntable::Update()
+void Turntable::BuildDesiredExtensionState(DesiredExtensionState* target_state)
 {
   DataFormat tt_data = {};
 
@@ -133,7 +135,12 @@ void Turntable::Update()
   tt_data.bt ^= (BUTTON_L_GREEN | BUTTON_L_RED | BUTTON_L_BLUE | BUTTON_R_GREEN | BUTTON_R_RED |
                  BUTTON_R_BLUE | BUTTON_MINUS | BUTTON_PLUS | BUTTON_EUPHORIA);
 
-  Common::BitCastPtr<DataFormat>(&m_reg.controller_data) = tt_data;
+  target_state->data = tt_data;
+}
+
+void Turntable::Update(const DesiredExtensionState& target_state)
+{
+  DefaultExtensionUpdate<DataFormat>(&m_reg, target_state);
 }
 
 void Turntable::Reset()

Source/Core/Core/HW/WiimoteEmu/Extension/Turntable.h

@@ -56,7 +56,8 @@ public:
 
   Turntable();
 
-  void Update() override;
+  void BuildDesiredExtensionState(DesiredExtensionState* target_state) override;
+  void Update(const DesiredExtensionState& target_state) override;
   void Reset() override;
 
   ControllerEmu::ControlGroup* GetGroup(TurntableGroup group);

Source/Core/Core/HW/WiimoteEmu/Extension/UDrawTablet.cpp

@@ -9,6 +9,8 @@
 #include "Common/BitUtils.h"
 #include "Common/Common.h"
 #include "Common/CommonTypes.h"
+
+#include "Core/HW/WiimoteEmu/Extension/DesiredExtensionState.h"
 #include "Core/HW/WiimoteEmu/WiimoteEmu.h"
 
 #include "InputCommon/ControllerEmu/Control/Input.h"
@@ -48,7 +50,7 @@ UDrawTablet::UDrawTablet() : Extension3rdParty("uDraw", _trans("uDraw GameTablet
   m_touch->AddInput(ControllerEmu::Translate, _trans("Pressure"));
 }
 
-void UDrawTablet::Update()
+void UDrawTablet::BuildDesiredExtensionState(DesiredExtensionState* target_state)
 {
   DataFormat tablet_data = {};
 
@@ -105,7 +107,12 @@ void UDrawTablet::Update()
   // Always 0xff
   tablet_data.unk = 0xff;
 
-  Common::BitCastPtr<DataFormat>(&m_reg.controller_data) = tablet_data;
+  target_state->data = tablet_data;
+}
+
+void UDrawTablet::Update(const DesiredExtensionState& target_state)
+{
+  DefaultExtensionUpdate<DataFormat>(&m_reg, target_state);
 }
 
 void UDrawTablet::Reset()

Source/Core/Core/HW/WiimoteEmu/Extension/UDrawTablet.h

@@ -27,7 +27,8 @@ class UDrawTablet : public Extension3rdParty
 public:
   UDrawTablet();
 
-  void Update() override;
+  void BuildDesiredExtensionState(DesiredExtensionState* target_state) override;
+  void Update(const DesiredExtensionState& target_state) override;
   void Reset() override;
 
   ControllerEmu::ControlGroup* GetGroup(UDrawTabletGroup group);

Source/Core/Core/HW/WiimoteEmu/MotionPlus.cpp

@@ -18,6 +18,7 @@
 
 #include "Core/HW/Wiimote.h"
 #include "Core/HW/WiimoteEmu/Dynamics.h"
+#include "Core/HW/WiimoteEmu/Extension/DesiredExtensionState.h"
 
 namespace
 {
@@ -387,7 +388,12 @@ bool MotionPlus::ReadDeviceDetectPin() const
   }
 }
 
-void MotionPlus::Update()
+void MotionPlus::BuildDesiredExtensionState(DesiredExtensionState* target_state)
+{
+  // MotionPlus is handled separately, nothing to do here.
+}
+
+void MotionPlus::Update(const DesiredExtensionState& target_state)
 {
   if (m_progress_timer)
     --m_progress_timer;

Source/Core/Core/HW/WiimoteEmu/MotionPlus.h

@@ -118,7 +118,8 @@ public:
 
   MotionPlus();
 
-  void Update() override;
+  void BuildDesiredExtensionState(DesiredExtensionState* target_state) override;
+  void Update(const DesiredExtensionState& target_state) override;
   void Reset() override;
   void DoState(PointerWrap& p) override;
 

Source/Core/Core/HW/WiimoteEmu/WiimoteEmu.cpp

@@ -27,6 +27,7 @@
 #include "Core/HW/WiimoteCommon/WiimoteHid.h"
 #include "Core/HW/WiimoteEmu/DesiredWiimoteState.h"
 #include "Core/HW/WiimoteEmu/Extension/Classic.h"
+#include "Core/HW/WiimoteEmu/Extension/DesiredExtensionState.h"
 #include "Core/HW/WiimoteEmu/Extension/DrawsomeTablet.h"
 #include "Core/HW/WiimoteEmu/Extension/Drums.h"
 #include "Core/HW/WiimoteEmu/Extension/Guitar.h"
@@ -465,6 +466,13 @@ DesiredWiimoteState Wiimote::BuildDesiredWiimoteState()
   if (m_motion_plus_setting.GetValue())
     wiimote_state.motion_plus = MotionPlus::GetGyroscopeData(GetTotalAngularVelocity());
 
+  // Build Extension state.
+  // This also allows the extension to perform any regular duties it may need.
+  // (e.g. Nunchuk motion simulation step)
+  static_cast<Extension*>(
+      m_attachments->GetAttachmentList()[m_attachments->GetSelectedAttachment()].get())
+      ->BuildDesiredExtensionState(&wiimote_state.extension);
+
   return wiimote_state;
 }
 
@@ -480,19 +488,16 @@ void Wiimote::Update()
   UpdateButtonsStatus(target_state);
 
   // If a new extension is requested in the GUI the change will happen here.
-  HandleExtensionSwap(static_cast<ExtensionNumber>(m_attachments->GetSelectedAttachment()),
+  HandleExtensionSwap(static_cast<ExtensionNumber>(target_state.extension.data.index()),
                       target_state.motion_plus.has_value());
 
-  // Allow extension to perform any regular duties it may need.
-  // (e.g. Nunchuk motion simulation step)
-  // Input is prepared here too.
-  // TODO: Separate input preparation from Update.
-  GetActiveExtension()->Update();
+  // Prepare input data of the extension for reading.
+  GetActiveExtension()->Update(target_state.extension);
 
   if (m_is_motion_plus_attached)
   {
     // M+ has some internal state that must processed.
-    m_motion_plus.Update();
+    m_motion_plus.Update(target_state.extension);
   }
 
   // Returns true if a report was sent.

Source/Core/Core/HW/WiimoteEmu/WiimoteEmu.h

@@ -38,6 +38,7 @@ class Tilt;
 namespace WiimoteEmu
 {
 struct DesiredWiimoteState;
+struct DesiredExtensionState;
 
 enum class WiimoteGroup
 {

Source/Core/DolphinLib.props

@@ -318,6 +318,7 @@
     <ClInclude Include="Core\HW\WiimoteEmu\DesiredWiimoteState.h" />
     <ClInclude Include="Core\HW\WiimoteEmu\Encryption.h" />
     <ClInclude Include="Core\HW\WiimoteEmu\Extension\Classic.h" />
+    <ClInclude Include="Core\HW\WiimoteEmu\Extension\DesiredExtensionState.h" />
     <ClInclude Include="Core\HW\WiimoteEmu\Extension\DrawsomeTablet.h" />
     <ClInclude Include="Core\HW\WiimoteEmu\Extension\Drums.h" />
     <ClInclude Include="Core\HW\WiimoteEmu\Extension\Extension.h" />