libcamera: controls: Expose raw data in ControlValue

Add a data() function to the ControlValue class to expose the raw data
stored by the class as a Span<const uint8_t>. This will be useful to
simplify the serialization of ControlValue instances.

The size computation for the raw data is moved from the
ControlSerializer, which is updated accordingly to use the data()
function in order to access the size. Simplification of the
ControlSerializer will happen in a subsequent change.

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

3 files changed, 27 insertions, 12 deletions

diff --git a/include/libcamera/controls.h b/include/libcamera/controls.h
index 6f0ebf4f..4538be06 100644
--- a/include/libcamera/controls.h
+++ b/include/libcamera/controls.h
@@ -12,6 +12,8 @@
 #include <string>
 #include <unordered_map>
 
+#include <libcamera/span.h>
+
 namespace libcamera {
 
 class ControlValidator;
@@ -65,6 +67,7 @@ public:
 
 	ControlType type() const { return type_; }
 	bool isNone() const { return type_ == ControlTypeNone; }
+	Span<const uint8_t> data() const;
 
 	std::string toString() const;
 
diff --git a/src/libcamera/control_serializer.cpp b/src/libcamera/control_serializer.cpp
index 803ac16c..2b66ab97 100644
--- a/src/libcamera/control_serializer.cpp
+++ b/src/libcamera/control_serializer.cpp
@@ -27,17 +27,6 @@ namespace libcamera {
 
 LOG_DEFINE_CATEGORY(Serializer)
 
-namespace {
-
-static constexpr size_t ControlValueSize[] = {
-	[ControlTypeNone]	= 1,
-	[ControlTypeBool]	= sizeof(bool),
-	[ControlTypeInteger32]	= sizeof(int32_t),
-	[ControlTypeInteger64]	= sizeof(int64_t),
-};
-
-} /* namespace */
-
 /**
  * \class ControlSerializer
  * \brief Serializer and deserializer for control-related classes
@@ -106,7 +95,7 @@ void ControlSerializer::reset()
 
 size_t ControlSerializer::binarySize(const ControlValue &value)
 {
-	return ControlValueSize[value.type()];
+	return value.data().size_bytes();
 }
 
 size_t ControlSerializer::binarySize(const ControlRange &range)
diff --git a/src/libcamera/controls.cpp b/src/libcamera/controls.cpp
index 76230a05..e5131880 100644
--- a/src/libcamera/controls.cpp
+++ b/src/libcamera/controls.cpp
@@ -47,6 +47,17 @@ namespace libcamera {
 
 LOG_DEFINE_CATEGORY(Controls)
 
+namespace {
+
+static constexpr size_t ControlValueSize[] = {
+	[ControlTypeNone]		= 1,
+	[ControlTypeBool]		= sizeof(bool),
+	[ControlTypeInteger32]		= sizeof(int32_t),
+	[ControlTypeInteger64]		= sizeof(int64_t),
+};
+
+} /* namespace */
+
 /**
  * \enum ControlType
  * \brief Define the data type of a Control
@@ -92,6 +103,18 @@ ControlValue::ControlValue()
  */
 
 /**
+ * \brief Retrieve the raw data of a control value
+ * \return The raw data of the control value as a span of uint8_t
+ */
+Span<const uint8_t> ControlValue::data() const
+{
+	return {
+		reinterpret_cast<const uint8_t *>(&bool_),
+		ControlValueSize[type_]
+	};
+}
+
+/**
  * \brief Assemble and return a string describing the value
  * \return A string describing the ControlValue
  */