[PATCH 05/10] ipa: ipu3: Parse and store Agc stats

[Daniel Scally]

In preparation for switching to a derivation of MeanLuminanceAgc, add
a function to parse and store the statistics for easy retrieval in an
overriding estimateLuminance() function.

Signed-off-by: Daniel Scally <dan.scally at ideasonboard.com>
---
 src/ipa/ipu3/algorithms/agc.cpp | 33 +++++++++++++++++++++++++++++++++
 src/ipa/ipu3/algorithms/agc.h   |  8 ++++++++
 2 files changed, 41 insertions(+)

diff --git a/src/ipa/ipu3/algorithms/agc.cpp b/src/ipa/ipu3/algorithms/agc.cpp
index 606a237a..ee9a42cf 100644
--- a/src/ipa/ipu3/algorithms/agc.cpp
+++ b/src/ipa/ipu3/algorithms/agc.cpp
@@ -142,6 +142,39 @@ double Agc::measureBrightness(const ipu3_uapi_stats_3a *stats,
 	return Histogram(Span<uint32_t>(hist)).interQuantileMean(0.98, 1.0);
 }
 
+void Agc::parseStatistics(const ipu3_uapi_stats_3a *stats,
+			  const ipu3_uapi_grid_config &grid)
+{
+	uint32_t hist[knumHistogramBins] = { 0 };
+
+	reds_.clear();
+	greens_.clear();
+	blues_.clear();
+
+	for (unsigned int cellY = 0; cellY < grid.height; cellY++) {
+		for (unsigned int cellX = 0; cellX < grid.width; cellX++) {
+			uint32_t cellPosition = cellY * stride_ + cellX;
+
+			const ipu3_uapi_awb_set_item *cell =
+				reinterpret_cast<const ipu3_uapi_awb_set_item *>(
+					&stats->awb_raw_buffer.meta_data[cellPosition]);
+
+			reds_.push_back(cell->R_avg);
+			greens_.push_back((cell->Gr_avg + cell->Gb_avg) / 2);
+			blues_.push_back(cell->B_avg);
+
+			/*
+			 * Store the average green value to estimate the
+			 * brightness. Even the overexposed pixels are
+			 * taken into account.
+			 */
+			hist[(cell->Gr_avg + cell->Gb_avg) / 2]++;
+		}
+	}
+
+	hist_ = Histogram(Span<uint32_t>(hist));
+}
+
 /**
  * \brief Apply a filter on the exposure value to limit the speed of changes
  * \param[in] exposureValue The target exposure from the AGC algorithm
diff --git a/src/ipa/ipu3/algorithms/agc.h b/src/ipa/ipu3/algorithms/agc.h
index 9d6e3ff1..7ed0ef7a 100644
--- a/src/ipa/ipu3/algorithms/agc.h
+++ b/src/ipa/ipu3/algorithms/agc.h
@@ -13,6 +13,8 @@
 
 #include <libcamera/geometry.h>
 
+#include "libipa/histogram.h"
+
 #include "algorithm.h"
 
 namespace libcamera {
@@ -43,6 +45,8 @@ private:
 				 const ipu3_uapi_grid_config &grid,
 				 const ipu3_uapi_stats_3a *stats,
 				 double gain);
+	void parseStatistics(const ipu3_uapi_stats_3a *stats,
+			     const ipu3_uapi_grid_config &grid);
 
 	uint64_t frameCount_;
 
@@ -55,6 +59,10 @@ private:
 	utils::Duration filteredExposure_;
 
 	uint32_t stride_;
+	std::vector<uint8_t> reds_;
+	std::vector<uint8_t> blues_;
+	std::vector<uint8_t> greens_;
+	Histogram hist_;
 };
 
 } /* namespace ipa::ipu3::algorithms */
-- 
2.34.1