ipa: libipa: algorithm: Add an algorithm registration mechanism

In order to allow dynamic instantiation of algorithms based on tuning
data files, add a mechanism to register algorithms with the IPA module.
The implementation relies on an AlgorithmFactory class and a
registration macro, similar to the pipeline handler registration
mechanism. The main difference is that the algorithm registration and
instantiation are implemented in the Module class instead of the
AlgorithmFactory class, making the factory an internal implementation
detail.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Paul Elder <paul.elder@ideasonboard.com>

src/ipa/libipa/algorithm.h

@@ -6,14 +6,19 @@
  */
 #pragma once
 
+#include <memory>
+#include <string>
+
 namespace libcamera {
 
 namespace ipa {
 
-template<typename Module>
+template<typename _Module>
 class Algorithm
 {
 public:
+	using Module = _Module;
+
 	virtual ~Algorithm() {}
 
 	virtual int configure([[maybe_unused]] typename Module::Context &context,
@@ -34,6 +39,46 @@ public:
 	}
 };
 
+template<typename _Module>
+class AlgorithmFactoryBase
+{
+public:
+	AlgorithmFactoryBase(const char *name)
+		: name_(name)
+	{
+		_Module::registerAlgorithm(this);
+	}
+
+	virtual ~AlgorithmFactoryBase() = default;
+
+	const std::string &name() const { return name_; }
+
+	virtual std::unique_ptr<Algorithm<_Module>> create() const = 0;
+
+private:
+	std::string name_;
+};
+
+template<typename _Algorithm>
+class AlgorithmFactory : public AlgorithmFactoryBase<typename _Algorithm::Module>
+{
+public:
+	AlgorithmFactory(const char *name)
+		: AlgorithmFactoryBase<typename _Algorithm::Module>(name)
+	{
+	}
+
+	~AlgorithmFactory() = default;
+
+	std::unique_ptr<Algorithm<typename _Algorithm::Module>> create() const override
+	{
+		return std::make_unique<_Algorithm>();
+	}
+};
+
+#define REGISTER_IPA_ALGORITHM(algorithm, name) \
+static AlgorithmFactory<algorithm> global_##algorithm##Factory(name);
+
 } /* namespace ipa */
 
 } /* namespace libcamera */