[PATCH v2 1/3] ipa: libipa: Add Matrix class

[Paul Elder]

Add a class to represent a Matrix object and operations for adding
matrices, multipling a matrix by a scalar, and multiplying two matrices.

Signed-off-by: Paul Elder <paul.elder at ideasonboard.com>
---
Changes in v2:
- clean up unused includes
- avoid dereferencing an absent std::optional
---
 src/ipa/libipa/matrix.cpp  |  17 +++++
 src/ipa/libipa/matrix.h    | 136 +++++++++++++++++++++++++++++++++++++
 src/ipa/libipa/meson.build |   2 +
 3 files changed, 155 insertions(+)
 create mode 100644 src/ipa/libipa/matrix.cpp
 create mode 100644 src/ipa/libipa/matrix.h

diff --git a/src/ipa/libipa/matrix.cpp b/src/ipa/libipa/matrix.cpp
new file mode 100644
index 00000000..c222c3f0
--- /dev/null
+++ b/src/ipa/libipa/matrix.cpp
@@ -0,0 +1,17 @@
+/* SPDX-License-Identifier: BSD-2-Clause */
+/*
+ * Copyright (C) 2019, Raspberry Pi Ltd
+ * Copyright (C) 2024, Paul Elder <paul.elder at ideasonboard.com>
+ *
+ * matrix.cpp - Matrix and related operations
+ */
+
+#include "matrix.h"
+
+#include <libcamera/base/log.h>
+
+namespace libcamera {
+
+LOG_DEFINE_CATEGORY(Matrix)
+
+} /* namespace libcamera */
diff --git a/src/ipa/libipa/matrix.h b/src/ipa/libipa/matrix.h
new file mode 100644
index 00000000..f5520260
--- /dev/null
+++ b/src/ipa/libipa/matrix.h
@@ -0,0 +1,136 @@
+/* SPDX-License-Identifier: BSD-2-Clause */
+/*
+ * Copyright (C) 2019, Raspberry Pi Ltd
+ * Copyright (C) 2024, Paul Elder <paul.elder at ideasonboard.com>
+ *
+ * matrix.cpp - Matrix and related operations
+ */
+#pragma once
+
+#include <cmath>
+#include <sstream>
+#include <vector>
+
+#include <libcamera/base/log.h>
+
+#include "libcamera/internal/yaml_parser.h"
+
+namespace libcamera {
+
+LOG_DECLARE_CATEGORY(Matrix)
+
+namespace ipa {
+
+template<typename T>
+struct Matrix {
+public:
+	Matrix(){};
+	~Matrix(){};
+
+	Matrix(const unsigned int &_rows, const unsigned int &_cols,
+	       const std::vector<T> &_data)
+		: rows(_rows), cols(_cols)
+	{
+		for (const T &x : _data)
+			data.push_back(x);
+
+		while (rows * cols < data.size())
+			data.push_back(0);
+	}
+
+	int readYaml(unsigned int _rows, unsigned int _cols,
+		     const libcamera::YamlObject &yaml)
+	{
+		rows = _rows;
+		cols = _cols;
+
+		if (yaml.size() != rows * cols) {
+			LOG(Matrix, Error)
+				<< "Wrong number of values in matrix: expected "
+				<< rows * cols << ", got " << yaml.size();
+			return -EINVAL;
+		}
+
+		for (const auto &x : yaml.asList()) {
+			auto value = x.get<T>();
+			if (!value) {
+				LOG(Matrix, Error) << "Failed to read matrix value";
+				return -EINVAL;
+			}
+			data.push_back(*value);
+		}
+
+		return 0;
+	}
+
+	const std::string toString() const
+	{
+		std::stringstream ss;
+		ss << "Matrix { ";
+		for (unsigned int i = 0; i < rows; i++) {
+			ss << "[ ";
+			for (unsigned int j = 0; j < cols; j++) {
+				ss << data[i * cols + j];
+				ss << ((j + 1 < cols) ? ", " : " ");
+			}
+			ss << ((i + 1 < rows) ? "], " : "]");
+		}
+		ss << " }";
+
+		return ss.str();
+	}
+
+	const T &operator[](unsigned int i) const { return data.at(i); }
+
+	unsigned int rows;
+	unsigned int cols;
+	std::vector<T> data;
+};
+
+template<typename T>
+Matrix<T> operator*(T d, const Matrix<T> &m)
+{
+	std::vector<T> result(m.data.size());
+
+	for (const T &x : m.data)
+		result.push_back(d * x);
+
+	return Matrix(m.rows, m.cols, result);
+}
+
+template<typename T>
+Matrix<T> operator*(const Matrix<T> &m1, const Matrix<T> &m2)
+{
+	ASSERT(m1.cols == m2.rows);
+
+	std::vector<T> result(m1.rows * m2.cols);
+
+	for (unsigned int i = 0; i < m1.rows; i++) {
+		T sum = 0;
+
+		for (unsigned int j = 0; j < m2.cols; j++)
+			sum += m1[i * m1.cols + j] * m2[j * m2.cols + i];
+
+		result.push_back(sum);
+	}
+
+	return Matrix<T>(m1.rows, m2.cols, result);
+}
+
+template<typename T>
+Matrix<T> operator+(const Matrix<T> &m1, const Matrix<T> &m2)
+{
+	ASSERT(m1.cols == m2.cols && m1.rows == m2.rows);
+
+	unsigned int len = m1.rows * m1.cols;
+	std::vector<T> result(len);
+
+	for (unsigned int i = 0; i < len; i++)
+		result[i] = m1[i] + m2[i];
+
+	return Matrix<T>(m1.rows, m1.cols, result);
+}
+
+} /* namespace ipa */
+
+} /* namespace libcamera */
diff --git a/src/ipa/libipa/meson.build b/src/ipa/libipa/meson.build
index 817a09cf..5d5ba5e5 100644
--- a/src/ipa/libipa/meson.build
+++ b/src/ipa/libipa/meson.build
@@ -6,6 +6,7 @@ libipa_headers = files([
     'exposure_mode_helper.h',
     'fc_queue.h',
     'histogram.h',
+    'matrix.h',
     'module.h',
     'pwl.h',
 ])
@@ -16,6 +17,7 @@ libipa_sources = files([
     'exposure_mode_helper.cpp',
     'fc_queue.cpp',
     'histogram.cpp',
+    'matrix.cpp',
     'module.cpp',
     'pwl.cpp'
 ])
-- 
2.39.2