libcamera: controls: Add support for float controls

Add support for float values in Control<> and ControlValue classes.

Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

include/libcamera/controls.h

@@ -24,6 +24,7 @@ enum ControlType {
 	ControlTypeBool,
 	ControlTypeInteger32,
 	ControlTypeInteger64,
+	ControlTypeFloat,
 };
 
 namespace details {
@@ -52,6 +53,11 @@ struct control_type<int64_t> {
 	static constexpr ControlType value = ControlTypeInteger64;
 };
 
+template<>
+struct control_type<float> {
+	static constexpr ControlType value = ControlTypeFloat;
+};
+
 template<typename T, std::size_t N>
 struct control_type<Span<T, N>> : public control_type<std::remove_cv_t<T>> {
 };

src/libcamera/control_serializer.cpp

@@ -165,6 +165,12 @@ void ControlSerializer::store(const ControlValue &value,
 		break;
 	}
 
+	case ControlTypeFloat: {
+		float data = value.get<float>();
+		buffer.write(&data);
+		break;
+	}
+
 	default:
 		break;
 	}
@@ -337,6 +343,12 @@ ControlValue ControlSerializer::load<ControlValue>(ControlType type,
 		return ControlValue(value);
 	}
 
+	case ControlTypeFloat: {
+		float value;
+		b.read(&value);
+		return ControlValue(value);
+	}
+
 	default:
 		return ControlValue();
 	}

src/libcamera/controls.cpp

@@ -55,6 +55,7 @@ static constexpr size_t ControlValueSize[] = {
 	[ControlTypeBool]		= sizeof(bool),
 	[ControlTypeInteger32]		= sizeof(int32_t),
 	[ControlTypeInteger64]		= sizeof(int64_t),
+	[ControlTypeFloat]		= sizeof(float),
 };
 
 } /* namespace */
@@ -70,6 +71,8 @@ static constexpr size_t ControlValueSize[] = {
  * The control stores a 32-bit integer value
  * \var ControlTypeInteger64
  * The control stores a 64-bit integer value
+ * \var ControlTypeFloat
+ * The control stores a 32-bit floating point value
  */
 
 /**
@@ -205,6 +208,11 @@ std::string ControlValue::toString() const
 			str += std::to_string(*value);
 			break;
 		}
+		case ControlTypeFloat: {
+			const float *value = reinterpret_cast<const float *>(data);
+			str += std::to_string(*value);
+			break;
+		}
 		case ControlTypeNone:
 			break;
 		}
@@ -374,9 +382,9 @@ void ControlValue::set(ControlType type, bool isArray, const void *data,
  * instead of Control.
  *
  * Controls of any type can be defined through template specialisation, but
- * libcamera only supports the bool, int32_t and int64_t types natively (this
+ * libcamera only supports the bool, int32_t, int64_t and float types natively
- * includes types that are equivalent to the supported types, such as int and
+ * (this includes types that are equivalent to the supported types, such as int
- * long int).
+ * and long int).
  *
  * Controls IDs shall be unique. While nothing prevents multiple instances of
  * the Control class to be created with the same ID for the same object, doing