ipa: libipa: Introduce Algorithm class template

The algorithms are using the same function names with specialized
parameters. Instead of duplicating code, introduce a libipa Algorithm
class which implements a base class with template parameters in libipa,
and use it in each IPA.

As we now won't need an algorithm class for each IPA, move the
documentation to libipa, and make it agnostic of the IPA used. While at
it, fix the IPU3::Algorithm::Awb documentation.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Jean-Michel Hautbois <jeanmichel.hautbois@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Umang Jain <umang.jain@ideasonboard.com>

6 files changed, 67 insertions, 32 deletions

diff --git a/src/ipa/ipu3/algorithms/algorithm.h b/src/ipa/ipu3/algorithms/algorithm.h
index 16310ab1..d2eecc78 100644
--- a/src/ipa/ipu3/algorithms/algorithm.h
+++ b/src/ipa/ipu3/algorithms/algorithm.h
@@ -9,21 +9,15 @@
 
 #include <libcamera/ipa/ipu3_ipa_interface.h>
 
+#include <libipa/algorithm.h>
+
 #include "ipa_context.h"
 
 namespace libcamera {
 
 namespace ipa::ipu3 {
 
-class Algorithm
-{
-public:
-	virtual ~Algorithm() {}
-
-	virtual int configure(IPAContext &context, const IPAConfigInfo &configInfo);
-	virtual void prepare(IPAContext &context, ipu3_uapi_params *params);
-	virtual void process(IPAContext &context, const ipu3_uapi_stats_3a *stats);
-};
+using Algorithm = libcamera::ipa::Algorithm<IPAContext, IPAConfigInfo, ipu3_uapi_params, ipu3_uapi_stats_3a>;
 
 } /* namespace ipa::ipu3 */
 
diff --git a/src/ipa/ipu3/algorithms/awb.cpp b/src/ipa/ipu3/algorithms/awb.cpp
index c7bcb20e..1dc27fc9 100644
--- a/src/ipa/ipu3/algorithms/awb.cpp
+++ b/src/ipa/ipu3/algorithms/awb.cpp
@@ -193,6 +193,9 @@ Awb::Awb()
 
 Awb::~Awb() = default;
 
+/**
+ * \copydoc libcamera::ipa::Algorithm::configure
+ */
 int Awb::configure(IPAContext &context,
 		   [[maybe_unused]] const IPAConfigInfo &configInfo)
 {
@@ -373,6 +376,9 @@ void Awb::calculateWBGains(const ipu3_uapi_stats_3a *stats)
 	}
 }
 
+/**
+ * \copydoc libcamera::ipa::Algorithm::process
+ */
 void Awb::process(IPAContext &context, const ipu3_uapi_stats_3a *stats)
 {
 	calculateWBGains(stats);
@@ -394,6 +400,9 @@ constexpr uint16_t Awb::threshold(float value)
 	return value * 8191;
 }
 
+/**
+ * \copydoc libcamera::ipa::Algorithm::prepare
+ */
 void Awb::prepare(IPAContext &context, ipu3_uapi_params *params)
 {
 	/*
diff --git a/src/ipa/ipu3/algorithms/meson.build b/src/ipa/ipu3/algorithms/meson.build
index 3ec42f72..4db6ae1d 100644
--- a/src/ipa/ipu3/algorithms/meson.build
+++ b/src/ipa/ipu3/algorithms/meson.build
@@ -2,7 +2,6 @@
 
 ipu3_ipa_algorithms = files([
     'agc.cpp',
-    'algorithm.cpp',
     'awb.cpp',
     'blc.cpp',
     'tone_mapping.cpp',
diff --git a/src/ipa/ipu3/algorithms/algorithm.cpp b/src/ipa/libipa/algorithm.cpp
index 3e7e3018..398d5372 100644
--- a/src/ipa/ipu3/algorithms/algorithm.cpp
+++ b/src/ipa/libipa/algorithm.cpp
@@ -2,7 +2,7 @@
 /*
  * Copyright (C) 2021, Ideas On Board
  *
- * algorithm.cpp - IPU3 control algorithm interface
+ * algorithm.cpp - IPA control algorithm interface
  */
 
 #include "algorithm.h"
@@ -14,11 +14,15 @@
 
 namespace libcamera {
 
-namespace ipa::ipu3 {
+namespace ipa {
 
 /**
  * \class Algorithm
- * \brief The base class for all IPU3 algorithms
+ * \brief The base class for all IPA algorithms
+ * \tparam Context The type of shared IPA context
+ * \tparam Config The type of the IPA configuration data
+ * \tparam Params The type of the ISP specific parameters
+ * \tparam Stats The type of the IPA statistics and ISP results
  *
  * The Algorithm class defines a standard interface for IPA algorithms. By
  * abstracting algorithms, it makes possible the implementation of generic code
@@ -26,6 +30,7 @@ namespace ipa::ipu3 {
  */
 
 /**
+ * \fn Algorithm::configure()
  * \brief Configure the Algorithm given an IPAConfigInfo
  * \param[in] context The shared IPA context
  * \param[in] configInfo The IPA configuration data, received from the pipeline
@@ -39,37 +44,30 @@ namespace ipa::ipu3 {
  *
  * \return 0 if successful, an error code otherwise
  */
-int Algorithm::configure([[maybe_unused]] IPAContext &context,
-			 [[maybe_unused]] const IPAConfigInfo &configInfo)
-{
-	return 0;
-}
 
 /**
+ * \fn Algorithm::prepare()
  * \brief Fill the \a params buffer with ISP processing parameters for a frame
  * \param[in] context The shared IPA context
- * \param[out] params The IPU3 specific parameters.
+ * \param[out] params The ISP specific parameters.
  *
  * This function is called for every frame when the camera is running before it
- * is processed by the ImgU to prepare the ImgU processing parameters for that
+ * is processed by the ISP to prepare the ISP processing parameters for that
  * frame.
  *
  * Algorithms shall fill in the parameter structure fields appropriately to
- * configure the ImgU processing blocks that they are responsible for. This
+ * configure the ISP processing blocks that they are responsible for. This
  * includes setting fields and flags that enable those processing blocks.
  */
-void Algorithm::prepare([[maybe_unused]] IPAContext &context,
-			[[maybe_unused]] ipu3_uapi_params *params)
-{
-}
 
 /**
+ * \fn Algorithm::process()
  * \brief Process ISP statistics, and run algorithm operations
  * \param[in] context The shared IPA context
- * \param[in] stats The IPU3 statistics and ISP results
+ * \param[in] stats The IPA statistics and ISP results
  *
  * This function is called while camera is running for every frame processed by
- * the ImgU, to process statistics generated from that frame by the ImgU.
+ * the ISP, to process statistics generated from that frame by the ISP.
  * Algorithms shall use this data to run calculations and update their state
  * accordingly.
  *
@@ -91,11 +89,7 @@ void Algorithm::prepare([[maybe_unused]] IPAContext &context,
  * Care shall be taken to ensure the ordering of access to the information
  * such that the algorithms use up to date state as required.
  */
-void Algorithm::process([[maybe_unused]] IPAContext &context,
-			[[maybe_unused]] const ipu3_uapi_stats_3a *stats)
-{
-}
 
-} /* namespace ipa::ipu3 */
+} /* namespace ipa */
 
 } /* namespace libcamera */
diff --git a/src/ipa/libipa/algorithm.h b/src/ipa/libipa/algorithm.h
new file mode 100644
index 00000000..766aee5d
--- /dev/null
+++ b/src/ipa/libipa/algorithm.h
@@ -0,0 +1,38 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2021, Ideas On Board
+ *
+ * algorithm.h - ISP control algorithm interface
+ */
+#pragma once
+
+namespace libcamera {
+
+namespace ipa {
+
+template<typename Context, typename Config, typename Params, typename Stats>
+class Algorithm
+{
+public:
+	virtual ~Algorithm() {}
+
+	virtual int configure([[maybe_unused]] Context &context,
+			      [[maybe_unused]] const Config &configInfo)
+	{
+		return 0;
+	}
+
+	virtual void prepare([[maybe_unused]] Context &context,
+			     [[maybe_unused]] Params *params)
+	{
+	}
+
+	virtual void process([[maybe_unused]] Context &context,
+			     [[maybe_unused]] const Stats *stats)
+	{
+	}
+};
+
+} /* namespace ipa */
+
+} /* namespace libcamera */
diff --git a/src/ipa/libipa/meson.build b/src/ipa/libipa/meson.build
index 4d073a03..161cc5a1 100644
--- a/src/ipa/libipa/meson.build
+++ b/src/ipa/libipa/meson.build
@@ -1,6 +1,7 @@
 # SPDX-License-Identifier: CC0-1.0
 
 libipa_headers = files([
+    'algorithm.h',
     'camera_sensor_helper.h',
     'histogram.h'
 ])