ipa: raspberrypi: Generalise statistics

At present, the controller algorithms access the bcm2835_isp_stats structure,
which is hardware specific. It would be desirable to abstract out the statistics
structure to remove hardware specific headers from the algorithms source files.

Define a new templated RegionStats class that encompasses region based
statistics generated by the ISP. For the VC4 ISP, this can be used to hold
RGB sums and focus FoM values.

Define a new Statistics structure that holds all the VC4 ISP statistics output.
This includes AGC histograms, AGC/AWB region sums and focus FoM regions.

Signed-off-by: Naushir Patuck <naush@raspberrypi.com>
Reviewed-by: David Plowman <david.plowman@raspberrypi.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

src/ipa/raspberrypi/controller/region_stats.h

@@ -0,0 +1,123 @@
+/* SPDX-License-Identifier: BSD-2-Clause */
+/*
+ * Copyright (C) 2022, Raspberry Pi Ltd
+ *
+ * region_stats.h - Raspberry Pi region based statistics container
+ */
+#pragma once
+
+#include <array>
+#include <stdint.h>
+#include <vector>
+
+#include <libcamera/geometry.h>
+
+namespace RPiController {
+
+template<typename T>
+class RegionStats
+{
+public:
+	struct Region {
+		T val;
+		uint32_t counted;
+		uint32_t uncounted;
+	};
+
+	RegionStats()
+		: size_({}), numFloating_(0), default_({})
+	{
+	}
+
+	void init(const libcamera::Size &size, unsigned int numFloating = 0)
+	{
+		size_ = size;
+		numFloating_ = numFloating;
+		regions_.clear();
+		regions_.resize(size_.width * size_.height + numFloating_);
+	}
+
+	void init(unsigned int num)
+	{
+		size_ = libcamera::Size(num, 1);
+		numFloating_ = 0;
+		regions_.clear();
+		regions_.resize(num);
+	}
+
+	unsigned int numRegions() const
+	{
+		return size_.width * size_.height;
+	}
+
+	unsigned int numFloatingRegions() const
+	{
+		return numFloating_;
+	}
+
+	libcamera::Size size() const
+	{
+		return size_;
+	}
+
+	void set(unsigned int index, const Region &region)
+	{
+		if (index >= numRegions())
+			return;
+		set_(index, region);
+	}
+
+	void set(const libcamera::Point &pos, const Region &region)
+	{
+		set(pos.y * size_.width + pos.x, region);
+	}
+
+	void setFloating(unsigned int index, const Region &region)
+	{
+		if (index >= numFloatingRegions())
+			return;
+		set(numRegions() + index, region);
+	}
+
+	const Region &get(unsigned int index) const
+	{
+		if (index >= numRegions())
+			return default_;
+		return get_(index);
+	}
+
+	const T &get(const libcamera::Point &pos) const
+	{
+		return get(pos.y * size_.width + pos.x);
+	}
+
+	const T &getFloating(unsigned int index) const
+	{
+		if (index >= numFloatingRegions())
+			return default_;
+		return get_(numRegions() + index);
+	}
+
+	typename std::vector<Region>::iterator begin() { return regions_.begin(); }
+	typename std::vector<Region>::iterator end() { return regions_.end(); }
+	typename std::vector<Region>::const_iterator begin() const { return regions_.begin(); }
+	typename std::vector<Region>::const_iterator end() const { return regions_.end(); }
+
+private:
+	void set_(unsigned int index, const Region &region)
+	{
+		regions_[index] = region;
+	}
+
+	const Region &get_(unsigned int index) const
+	{
+		return regions_[index];
+	}
+
+	libcamera::Size size_;
+	unsigned int numFloating_;
+	std::vector<Region> regions_;
+	Region default_;
+};
+
+} /* namespace RPiController */

src/ipa/raspberrypi/statistics.h

@@ -0,0 +1,76 @@
+/* SPDX-License-Identifier: BSD-2-Clause */
+/*
+ * Copyright (C) 2022, Raspberry Pi Ltd
+ *
+ * statistics.h - Raspberry Pi generic statistics structure
+ */
+#pragma once
+
+#include <memory>
+#include <stdint.h>
+#include <vector>
+
+#include "histogram.h"
+#include "region_stats.h"
+
+namespace RPiController {
+
+struct RgbySums {
+	RgbySums(uint64_t _rSum = 0, uint64_t _gSum = 0, uint64_t _bSum = 0, uint64_t _ySum = 0)
+		: rSum(_rSum), gSum(_gSum), bSum(_bSum), ySum(_ySum)
+	{
+	}
+	uint64_t rSum;
+	uint64_t gSum;
+	uint64_t bSum;
+	uint64_t ySum;
+};
+
+using RgbyRegions = RegionStats<RgbySums>;
+using FocusRegions = RegionStats<uint64_t>;
+
+struct Statistics {
+	/*
+	 * All region based statistics are normalised to 16-bits, giving a
+	 * maximum value of (1 << NormalisationFactorPow2) - 1.
+	 */
+	static constexpr unsigned int NormalisationFactorPow2 = 16;
+
+	/*
+	 * Positioning of the AGC statistics gathering in the pipeline:
+	 * Pre-WB correction or post-WB correction.
+	 * Assume this is post-LSC.
+	 */
+	enum class AgcStatsPos { PreWb, PostWb };
+	const AgcStatsPos agcStatsPos;
+
+	/*
+	 * Positioning of the AWB/ALSC statistics gathering in the pipeline:
+	 * Pre-LSC or post-LSC.
+	 */
+	enum class ColourStatsPos { PreLsc, PostLsc };
+	const ColourStatsPos colourStatsPos;
+
+	Statistics(AgcStatsPos a, ColourStatsPos c)
+		: agcStatsPos(a), colourStatsPos(c)
+	{
+	}
+
+	/* Histogram statistics. Not all histograms may be populated! */
+	Histogram rHist;
+	Histogram gHist;
+	Histogram bHist;
+	Histogram yHist;
+
+	/* Row sums for flicker avoidance. */
+	std::vector<RgbySums> rowSums;
+
+	/* Region based colour sums. */
+	RgbyRegions agcRegions;
+	RgbyRegions awbRegions;
+
+	/* Region based focus FoM. */
+	FocusRegions focusRegions;
+};
+
+} /* namespace RPiController */