Add mixed comments to input code, make some tooltip clearer

Source/Core/InputCommon/ControlReference/ExpressionParser.cpp

@@ -371,6 +371,7 @@ public:
     }
     case TOK_ASSIGN:
     {
+      // Use this carefully as it's extremely powerful and can end up in unforeseen situations
       lhs->SetValue(rhs->GetValue());
       return lhs->GetValue();
     }
@@ -565,6 +566,9 @@ private:
 
 // This class proxies all methods to its either left-hand child if it has bound controls, or its
 // right-hand child. Its intended use is for supporting old-style barewords expressions.
+// Note that if you have a keyboard device as default device and the expression is a single digit
+// number, this will usually resolve in a numerical key instead of a numerical value.
+// Though if this expression belongs to NumericSetting, it will likely be simplifed back to a value.
 class CoalesceExpression : public Expression
 {
 public:
@@ -945,6 +949,7 @@ static std::unique_ptr<Expression> ParseBarewordExpression(const std::string& st
   qualifier.control_name = str;
   qualifier.has_device = false;
 
+  // This control expression will only work (find the specified control) with the default device.
   return std::make_unique<ControlExpression>(qualifier);
 }
 

Source/Core/InputCommon/ControlReference/ExpressionParser.h

@@ -63,7 +63,9 @@ public:
 enum class ParseStatus
 {
   Successful,
+  // Note that the expression could still work in this case (be valid and return a value)
   SyntaxError,
+  // Will return the default value
   EmptyExpression,
 };
 
@@ -107,6 +109,7 @@ class ControlQualifier
 public:
   bool has_device;
   Core::DeviceQualifier device_qualifier;
+  // Makes no distinction between input and output
   std::string control_name;
 
   ControlQualifier() : has_device(false) {}

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

@@ -44,7 +44,7 @@ void ControlGroup::AddDeadzoneSetting(SettingValue<double>* value, double maximu
               // i18n: The percent symbol.
               _trans("%"),
               // i18n: Refers to the dead-zone setting of gamepad inputs.
-              _trans("Input strength to ignore.")},
+              _trans("Input strength to ignore and remap.")},
              0, 0, maximum_deadzone);
 }
 

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

@@ -40,7 +40,7 @@ IMUGyroscope::IMUGyroscope(std::string name_, std::string ui_name_)
               // i18n: "°/s" is the symbol for degrees (angular measurement) divided by seconds.
               _trans("°/s"),
               // i18n: Refers to the dead-zone setting of gyroscope input.
-              _trans("Angular velocity to ignore.")},
+              _trans("Angular velocity to ignore and remap.")},
              2, 0, 180);
 
   AddSetting(&m_calibration_period_setting,

Source/Core/InputCommon/ControllerEmu/StickGate.cpp

@@ -128,6 +128,7 @@ std::optional<u32> SquareStickGate::GetIdealCalibrationSampleCount() const
 ReshapableInput::ReshapableInput(std::string name_, std::string ui_name_, GroupType type_)
     : ControlGroup(std::move(name_), std::move(ui_name_), type_)
 {
+  // 50 is not always enough but users can set it to more with an expression
   AddDeadzoneSetting(&m_deadzone_setting, 50);
 }
 
@@ -285,6 +286,10 @@ ReshapableInput::ReshapeData ReshapableInput::Reshape(ControlState x, ControlSta
   x -= m_center.x;
   y -= m_center.y;
 
+  // We run this even if both x and y will be zero.
+  // In that case, std::atan2(0, 0) returns a valid non-NaN value, but the exact value
+  // (which depends on the signs of x and y) does not matter here as dist is zero
+
   // TODO: make the AtAngle functions work with negative angles:
   ControlState angle = std::atan2(y, x) + MathUtil::TAU;
 

Source/Core/InputCommon/InputConfig.cpp

@@ -133,7 +133,6 @@ bool InputConfig::LoadConfig(bool isGC)
       }
 #endif
       controller->LoadConfig(&config);
-      // Update refs
       controller->UpdateReferences(g_controller_interface);
       controller_names.push_back(controller->GetName());