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/agc.hpp

@@ -0,0 +1,123 @@
+/* SPDX-License-Identifier: BSD-2-Clause */
+/*
+ * Copyright (C) 2019, Raspberry Pi (Trading) Limited
+ *
+ * agc.hpp - AGC/AEC control algorithm
+ */
+#pragma once
+
+#include <vector>
+#include <mutex>
+
+#include "../agc_algorithm.hpp"
+#include "../agc_status.h"
+#include "../pwl.hpp"
+
+// This is our implementation of AGC.
+
+// This is the number actually set up by the firmware, not the maximum possible
+// number (which is 16).
+
+#define AGC_STATS_SIZE 15
+
+namespace RPi {
+
+struct AgcMeteringMode {
+	double weights[AGC_STATS_SIZE];
+	void Read(boost::property_tree::ptree const &params);
+};
+
+struct AgcExposureMode {
+	std::vector<double> shutter;
+	std::vector<double> gain;
+	void Read(boost::property_tree::ptree const &params);
+};
+
+struct AgcConstraint {
+	enum class Bound { LOWER = 0, UPPER = 1 };
+	Bound bound;
+	double q_lo;
+	double q_hi;
+	Pwl Y_target;
+	void Read(boost::property_tree::ptree const &params);
+};
+
+typedef std::vector<AgcConstraint> AgcConstraintMode;
+
+struct AgcConfig {
+	void Read(boost::property_tree::ptree const &params);
+	std::map<std::string, AgcMeteringMode> metering_modes;
+	std::map<std::string, AgcExposureMode> exposure_modes;
+	std::map<std::string, AgcConstraintMode> constraint_modes;
+	Pwl Y_target;
+	double speed;
+	uint16_t startup_frames;
+	double max_change;
+	double min_change;
+	double fast_reduce_threshold;
+	double speed_up_threshold;
+	std::string default_metering_mode;
+	std::string default_exposure_mode;
+	std::string default_constraint_mode;
+	double base_ev;
+};
+
+class Agc : public AgcAlgorithm
+{
+public:
+	Agc(Controller *controller);
+	char const *Name() const override;
+	void Read(boost::property_tree::ptree const &params) override;
+	void SetEv(double ev) override;
+	void SetFlickerPeriod(double flicker_period) override;
+	void SetFixedShutter(double fixed_shutter) override; // microseconds
+	void SetFixedAnalogueGain(double fixed_analogue_gain) override;
+	void SetMeteringMode(std::string const &metering_mode_name) override;
+	void SetExposureMode(std::string const &exposure_mode_name) override;
+	void SetConstraintMode(std::string const &contraint_mode_name) override;
+	void Prepare(Metadata *image_metadata) override;
+	void Process(StatisticsPtr &stats, Metadata *image_metadata) override;
+
+private:
+	AgcConfig config_;
+	void housekeepConfig();
+	void fetchCurrentExposure(Metadata *image_metadata);
+	void computeGain(bcm2835_isp_stats *statistics, Metadata *image_metadata,
+			 double &gain, double &target_Y);
+	void computeTargetExposure(double gain);
+	bool applyDigitalGain(Metadata *image_metadata, double gain,
+			      double target_Y);
+	void filterExposure(bool desaturate);
+	void divvyupExposure();
+	void writeAndFinish(Metadata *image_metadata, bool desaturate);
+	AgcMeteringMode *metering_mode_;
+	AgcExposureMode *exposure_mode_;
+	AgcConstraintMode *constraint_mode_;
+	uint64_t frame_count_;
+	struct ExposureValues {
+		ExposureValues() : shutter(0), analogue_gain(0),
+				   total_exposure(0), total_exposure_no_dg(0) {}
+		double shutter;
+		double analogue_gain;
+		double total_exposure;
+		double total_exposure_no_dg; // without digital gain
+	};
+	ExposureValues current_;  // values for the current frame
+	ExposureValues target_;   // calculate the values we want here
+	ExposureValues filtered_; // these values are filtered towards target
+	AgcStatus status_;        // to "latch" settings so they can't change
+	AgcStatus output_status_; // the status we will write out
+	std::mutex output_mutex_;
+	int lock_count_;
+	// Below here the "settings" that applications can change.
+	std::mutex settings_mutex_;
+	std::string metering_mode_name_;
+	std::string exposure_mode_name_;
+	std::string constraint_mode_name_;
+	double ev_;
+	double flicker_period_;
+	double fixed_shutter_;
+	double fixed_analogue_gain_;
+};
+
+} // namespace RPi