[libcamera-devel] [PATCH 2/6] ipu3: Add a class AiqResultsRingBuffer to reserve AiqResults history

[Han-Lin Chen]

The AIQ algorithm expects the statstistics comes with the effective AiqResults
applied on the sensor, which may not always be the latest AiqResults,
since pipeline handler may delay setting the controls based on SOF.
Add a class to reserve the history of the AiqResults generated for previous
frames, so IPA can have a chance to look for the suitable one backwards.
---
 aiq/aiq_results.cpp | 85 ++++++++++++++++++++++++++++++++++++++++-----
 aiq/aiq_results.h   | 38 +++++++++++++++-----
 2 files changed, 107 insertions(+), 16 deletions(-)

diff --git a/aiq/aiq_results.cpp b/aiq/aiq_results.cpp
index f727f36..deda4be 100644
--- a/aiq/aiq_results.cpp
+++ b/aiq/aiq_results.cpp
@@ -63,7 +63,34 @@ AiqResults::AiqResults()
 	sa_.channel_b = channelB_.data();
 }
 
-void AiqResults::setAe(ia_aiq_ae_results *ae)
+AiqResults::AiqResults(const AiqResults &other)
+	:AiqResults()
+{
+	setAe(&other.ae_);
+	setAf(&other.af_);
+	setAfBracket(&other.afBracket_);
+	setAwb(&other.awb_);
+	setGbce(&other.gbce_);
+	setDetectedSceneMode(other.detectedSceneMode_);
+	setPa(&other.pa_);
+	setSa(&other.sa_);
+}
+
+AiqResults& AiqResults::operator=(const AiqResults &other)
+{
+	setAe(&other.ae_);
+	setAf(&other.af_);
+	setAfBracket(&other.afBracket_);
+	setAwb(&other.awb_);
+	setGbce(&other.gbce_);
+	setDetectedSceneMode(other.detectedSceneMode_);
+	setPa(&other.pa_);
+	setSa(&other.sa_);
+
+	return *this;
+}
+
+void AiqResults::setAe(const ia_aiq_ae_results *ae)
 {
 	/* Todo: Potentially Requires copying
 	 *   ia_aiq_aperture_control *aperture_control;
@@ -121,7 +148,7 @@ void AiqResults::setAe(ia_aiq_ae_results *ae)
 	}
 }
 
-void AiqResults::setAf(ia_aiq_af_results *af)
+void AiqResults::setAf(const ia_aiq_af_results *af)
 {
 	ASSERT(af);
 
@@ -133,7 +160,7 @@ void AiqResults::setAf(ia_aiq_af_results *af)
 	af_.final_lens_position_reached = af->final_lens_position_reached;
 }
 
-void AiqResults::setAfBracket(ia_aiq_af_bracket_results *afBracket)
+void AiqResults::setAfBracket(const ia_aiq_af_bracket_results *afBracket)
 {
 	ASSERT(afBracket);
 
@@ -145,7 +172,7 @@ void AiqResults::setAfBracket(ia_aiq_af_bracket_results *afBracket)
 	afBracket_.lens_positions_bracketing = afBracket->lens_positions_bracketing;
 }
 
-void AiqResults::setAwb(ia_aiq_awb_results *awb)
+void AiqResults::setAwb(const ia_aiq_awb_results *awb)
 {
 	ASSERT(awb);
 
@@ -157,7 +184,7 @@ void AiqResults::setAwb(ia_aiq_awb_results *awb)
 	awb_.distance_from_convergence = awb->distance_from_convergence;
 }
 
-void AiqResults::setGbce(ia_aiq_gbce_results *gbce)
+void AiqResults::setGbce(const ia_aiq_gbce_results *gbce)
 {
 	ASSERT(gbce);
 
@@ -181,12 +208,12 @@ void AiqResults::setGbce(ia_aiq_gbce_results *gbce)
 	}
 }
 
-void AiqResults::setDetectedSceneMode(ia_aiq_scene_mode dsm)
+void AiqResults::setDetectedSceneMode(const ia_aiq_scene_mode dsm)
 {
 	detectedSceneMode_ = dsm;
 }
 
-void AiqResults::setPa(ia_aiq_pa_results *pa)
+void AiqResults::setPa(const ia_aiq_pa_results *pa)
 {
 	ASSERT(pa);
 
@@ -234,7 +261,7 @@ void AiqResults::setPa(ia_aiq_pa_results *pa)
 	pa_.brightness_level = pa->brightness_level;
 }
 
-void AiqResults::setSa(ia_aiq_sa_results *sa)
+void AiqResults::setSa(const ia_aiq_sa_results *sa)
 {
 	ASSERT(sa && sa->channel_r && sa->channel_gr &&
 	       sa->channel_gb && sa->channel_b);
@@ -275,6 +302,48 @@ void AiqResults::setSa(ia_aiq_sa_results *sa)
 	sa_.frame_params = sa->frame_params;
 }
 
+AiqResults& AiqResultsRingBuffer::operator[](unsigned int index)
+{
+	return std::array<AiqResults, bufferSize>::operator[](index % bufferSize);
+}
+
+const AiqResults& AiqResultsRingBuffer::operator[](unsigned int index) const
+{
+	return std::array<AiqResults, bufferSize>::operator[](index % bufferSize);
+}
+
+void AiqResultsRingBuffer::Reset()
+{
+	start_ = end_ = size_ = 0;
+}
+
+void AiqResultsRingBuffer::Push(const AiqResults& result)
+{
+	operator[](end_) = result;
+	end_ = (end_ + 1) % bufferSize;
+	size_ = std::min(size_ + 1, bufferSize);
+	if (size_ == bufferSize) {
+		start_ = end_;
+	}
+}
+
+AiqResults& AiqResultsRingBuffer::searchBackward(
+		const std::function<bool(AiqResults&)> pred, AiqResults& def)
+{
+	if (size_ == 0)
+		return def;
+
+	unsigned int i = (end_ - 1) % bufferSize;
+	while (i != start_) {
+		if (pred(operator[](i))) {
+			return operator[](i);
+		}
+		i = --i % bufferSize;
+	}
+
+	return def;
+}
+
 } /* namespace ipa::ipu3::aiq */
 
 } /* namespace libcamera */
diff --git a/aiq/aiq_results.h b/aiq/aiq_results.h
index ae19a6c..7005a47 100644
--- a/aiq/aiq_results.h
+++ b/aiq/aiq_results.h
@@ -8,6 +8,8 @@
  * of the aiq result structures.
  */
 
+#include <array>
+#include <functional>
 #include <vector>
 
 #include <ia_imaging/ia_aiq.h>
@@ -37,6 +39,8 @@ class AiqResults
 {
 public:
 	AiqResults();
+	AiqResults(const AiqResults &other);
+	AiqResults &operator=(const AiqResults &other);
 
 	const ia_aiq_ae_results *ae() { return &ae_; }
 	ia_aiq_af_results *af() { return &af_; }
@@ -46,14 +50,14 @@ public:
 	const ia_aiq_pa_results *pa() { return &pa_; }
 	const ia_aiq_sa_results *sa() { return &sa_; }
 
-	void setAe(ia_aiq_ae_results *ae);
-	void setAf(ia_aiq_af_results *af);
-	void setAfBracket(ia_aiq_af_bracket_results *afBracket);
-	void setAwb(ia_aiq_awb_results *awb);
-	void setGbce(ia_aiq_gbce_results *gbce);
-	void setDetectedSceneMode(ia_aiq_scene_mode dsm);
-	void setPa(ia_aiq_pa_results *pa);
-	void setSa(ia_aiq_sa_results *sa);
+	void setAe(const ia_aiq_ae_results *ae);
+	void setAf(const ia_aiq_af_results *af);
+	void setAfBracket(const ia_aiq_af_bracket_results *afBracket);
+	void setAwb(const ia_aiq_awb_results *awb);
+	void setGbce(const ia_aiq_gbce_results *gbce);
+	void setDetectedSceneMode(const ia_aiq_scene_mode dsm);
+	void setPa(const ia_aiq_pa_results *pa);
+	void setSa(const ia_aiq_sa_results *sa);
 
 private:
 	ia_aiq_ae_results ae_;
@@ -109,6 +113,24 @@ private:
 	std::vector<float> channelGb_;
 };
 
+static constexpr unsigned int bufferSize = 16;
+class AiqResultsRingBuffer: public std::array<AiqResults, bufferSize>
+{
+public:
+	AiqResults &operator[](unsigned int index);
+	const AiqResults &operator[](unsigned int index) const;
+	void Reset();
+	void Push(const AiqResults& result);
+	unsigned int size() { return size_; }
+	AiqResults& searchBackward(const std::function<bool(AiqResults&)> pred,
+														 AiqResults& def);
+
+private:
+	unsigned int start_ = 0;
+	unsigned int end_ = 0;
+	unsigned int size_ = 0;
+};
+
 } /* namespace libcamera::ipa::ipu3::aiq */
 
 #endif /* IPA_IPU3_AIQ_RESULTS_H */
-- 
2.33.1.1089.g2158813163f-goog