ControlGroup/Slider: Return state data by value

Makes it less error-prone to get state data from sliders (no need
to pass any locals), and also allows direct assignment, letting the
retrieved data be const.

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

@@ -115,9 +115,9 @@ void Guitar::GetState(u8* const data)
   // slider bar
   if (m_slider_bar->controls[0]->control_ref->BoundCount())
   {
-    ControlState slider_bar;
-    m_slider_bar->GetState(&slider_bar);
-    guitar_data.sb = s_slider_bar_control_codes.lower_bound(slider_bar)->second;
+    const ControllerEmu::Slider::StateData slider_data = m_slider_bar->GetState();
+
+    guitar_data.sb = s_slider_bar_control_codes.lower_bound(slider_data.value)->second;
   }
   else
   {

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

@@ -98,26 +98,22 @@ void Turntable::GetState(u8* const data)
 
   // left table
   {
-    ControlState tt;
-    m_left_table->GetState(&tt);
+    const ControllerEmu::Slider::StateData lt = m_left_table->GetState();
+    const s8 tt = static_cast<s8>(lt.value * 0x1F);
 
-    const s8 tt_ = static_cast<s8>(tt * 0x1F);
-
-    tt_data.ltable1 = tt_;
-    tt_data.ltable2 = tt_ >> 5;
+    tt_data.ltable1 = tt;
+    tt_data.ltable2 = tt >> 5;
   }
 
   // right table
   {
-    ControlState tt;
-    m_right_table->GetState(&tt);
+    const ControllerEmu::Slider::StateData rt = m_right_table->GetState();
+    const s8 tt = static_cast<s8>(rt.value * 0x1F);
 
-    const s8 tt_ = static_cast<s8>(tt * 0x1F);
-
-    tt_data.rtable1 = tt_;
-    tt_data.rtable2 = tt_ >> 1;
-    tt_data.rtable3 = tt_ >> 3;
-    tt_data.rtable4 = tt_ >> 5;
+    tt_data.rtable1 = tt;
+    tt_data.rtable2 = tt >> 1;
+    tt_data.rtable3 = tt >> 3;
+    tt_data.rtable4 = tt >> 5;
   }
 
   // effect dial
@@ -133,10 +129,9 @@ void Turntable::GetState(u8* const data)
 
   // crossfade slider
   {
-    ControlState cfs;
-    m_crossfade->GetState(&cfs);
+    const ControllerEmu::Slider::StateData cfs = m_crossfade->GetState();
 
-    tt_data.slider = static_cast<u8>((cfs * 0x07) + 0x08);
+    tt_data.slider = static_cast<u8>((cfs.value * 0x07) + 0x08);
   }
 
   // buttons

Source/Core/InputCommon/ControllerEmu/ControlGroup/Slider.cpp

@@ -30,14 +30,14 @@ Slider::Slider(const std::string& name_) : Slider(name_, name_)
 {
 }
 
-void Slider::GetState(ControlState* const slider)
+Slider::StateData Slider::GetState()
 {
   const ControlState deadzone = numeric_settings[0]->GetValue();
   const ControlState state = controls[1]->control_ref->State() - controls[0]->control_ref->State();
 
   if (fabs(state) > deadzone)
-    *slider = (state - (deadzone * sign(state))) / (1 - deadzone);
-  else
-    *slider = 0;
+    return {(state - (deadzone * sign(state))) / (1 - deadzone)};
+
+  return {0.0};
 }
 }  // namespace ControllerEmu

Source/Core/InputCommon/ControllerEmu/ControlGroup/Slider.h

@@ -13,9 +13,14 @@ namespace ControllerEmu
 class Slider : public ControlGroup
 {
 public:
+  struct StateData
+  {
+    ControlState value{};
+  };
+
   Slider(const std::string& name_, const std::string& ui_name_);
   explicit Slider(const std::string& name_);
 
-  void GetState(ControlState* slider);
+  StateData GetState();
 };
 }  // namespace ControllerEmu