libcamera: ipa: Raspberry Pi IPA

Initial implementation of the Raspberry Pi (BCM2835) libcamera IPA and
associated libraries.

All code is licensed under the BSD-2-Clause terms.
Copyright (c) 2019-2020 Raspberry Pi Trading Ltd.

Signed-off-by: Naushir Patuck <naush@raspberrypi.com>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

src/ipa/raspberrypi/controller/rpi/alsc.hpp

@@ -0,0 +1,104 @@
+/* SPDX-License-Identifier: BSD-2-Clause */
+/*
+ * Copyright (C) 2019, Raspberry Pi (Trading) Limited
+ *
+ * alsc.hpp - ALSC (auto lens shading correction) control algorithm
+ */
+#pragma once
+
+#include <mutex>
+#include <condition_variable>
+#include <thread>
+
+#include "../algorithm.hpp"
+#include "../alsc_status.h"
+
+namespace RPi {
+
+// Algorithm to generate automagic LSC (Lens Shading Correction) tables.
+
+struct AlscCalibration {
+	double ct;
+	double table[ALSC_CELLS_X * ALSC_CELLS_Y];
+};
+
+struct AlscConfig {
+	// Only repeat the ALSC calculation every "this many" frames
+	uint16_t frame_period;
+	// number of initial frames for which speed taken as 1.0 (maximum)
+	uint16_t startup_frames;
+	// IIR filter speed applied to algorithm results
+	double speed;
+	double sigma_Cr;
+	double sigma_Cb;
+	double min_count;
+	uint16_t min_G;
+	double omega;
+	uint32_t n_iter;
+	double luminance_lut[ALSC_CELLS_X * ALSC_CELLS_Y];
+	double luminance_strength;
+	std::vector<AlscCalibration> calibrations_Cr;
+	std::vector<AlscCalibration> calibrations_Cb;
+	double default_ct; // colour temperature if no metadata found
+	double threshold; // iteration termination threshold
+};
+
+class Alsc : public Algorithm
+{
+public:
+	Alsc(Controller *controller = NULL);
+	~Alsc();
+	char const *Name() const override;
+	void Initialise() override;
+	void SwitchMode(CameraMode const &camera_mode) override;
+	void Read(boost::property_tree::ptree const &params) override;
+	void Prepare(Metadata *image_metadata) override;
+	void Process(StatisticsPtr &stats, Metadata *image_metadata) override;
+
+private:
+	// configuration is read-only, and available to both threads
+	AlscConfig config_;
+	bool first_time_;
+	std::atomic<CameraMode> camera_mode_;
+	std::thread async_thread_;
+	void asyncFunc(); // asynchronous thread function
+	std::mutex mutex_;
+	CameraMode async_camera_mode_;
+	// condvar for async thread to wait on
+	std::condition_variable async_signal_;
+	// condvar for synchronous thread to wait on
+	std::condition_variable sync_signal_;
+	// for sync thread to check  if async thread finished (requires mutex)
+	bool async_finished_;
+	// for async thread to check if it's been told to run (requires mutex)
+	bool async_start_;
+	// for async thread to check if it's been told to quit (requires mutex)
+	bool async_abort_;
+
+	// The following are only for the synchronous thread to use:
+	// for sync thread to note its has asked async thread to run
+	bool async_started_;
+	// counts up to frame_period before restarting the async thread
+	int frame_phase_;
+	// counts up to startup_frames
+	int frame_count_;
+	// counts up to startup_frames for Process method
+	int frame_count2_;
+	double sync_results_[3][ALSC_CELLS_Y][ALSC_CELLS_X];
+	double prev_sync_results_[3][ALSC_CELLS_Y][ALSC_CELLS_X];
+	// The following are for the asynchronous thread to use, though the main
+	// thread can set/reset them if the async thread is known to be idle:
+	void restartAsync(StatisticsPtr &stats, Metadata *image_metadata);
+	// copy out the results from the async thread so that it can be restarted
+	void fetchAsyncResults();
+	double ct_;
+	bcm2835_isp_stats_region statistics_[ALSC_CELLS_Y * ALSC_CELLS_X];
+	double async_results_[3][ALSC_CELLS_Y][ALSC_CELLS_X];
+	double async_lambda_r_[ALSC_CELLS_X * ALSC_CELLS_Y];
+	double async_lambda_b_[ALSC_CELLS_X * ALSC_CELLS_Y];
+	void doAlsc();
+	double lambda_r_[ALSC_CELLS_X * ALSC_CELLS_Y];
+	double lambda_b_[ALSC_CELLS_X * ALSC_CELLS_Y];
+};
+
+} // namespace RPi