ipa: libipa: Add Matrix class

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@ideasonboard.com>
Reviewed-by: Stefan Klug <stefan.klug@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

3 files changed, 355 insertions, 0 deletions

diff --git a/src/ipa/libipa/matrix.cpp b/src/ipa/libipa/matrix.cpp
new file mode 100644
index 00000000..7f000382
--- /dev/null
+++ b/src/ipa/libipa/matrix.cpp
@@ -0,0 +1,149 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2024, Paul Elder <paul.elder@ideasonboard.com>
+ *
+ * Matrix and related operations
+ */
+
+#include "matrix.h"
+
+#include <libcamera/base/log.h>
+
+/**
+ * \file matrix.h
+ * \brief Matrix class
+ */
+
+namespace libcamera {
+
+LOG_DEFINE_CATEGORY(Matrix)
+
+namespace ipa {
+
+/**
+ * \class Matrix
+ * \brief Matrix class
+ * \tparam T Type of numerical values to be stored in the matrix
+ * \tparam Rows Number of rows in the matrix
+ * \tparam Cols Number of columns in the matrix
+ */
+
+/**
+ * \fn Matrix::Matrix()
+ * \brief Construct a zero matrix
+ */
+
+/**
+ * \fn Matrix::Matrix(const std::vector<T> &data)
+ * \brief Construct a matrix from supplied data
+ * \param[in] data Data from which to construct a matrix
+ *
+ * \a data is a one-dimensional vector and will be turned into a matrix in
+ * row-major order. The size of \a data must be equal to the product of the
+ * number of rows and columns of the matrix (Rows x Cols).
+ */
+
+/**
+ * \fn Matrix::identity()
+ * \brief Construct an identity matrix
+ */
+
+/**
+ * \fn Matrix::toString()
+ * \brief Assemble and return a string describing the matrix
+ * \return A string describing the matrix
+ */
+
+/**
+ * \fn Span<const T, Cols> Matrix::operator[](size_t i) const
+ * \brief Index to a row in the matrix
+ * \param[in] i Index of row to retrieve
+ *
+ * This operator[] returns a Span, which can then be indexed into again with
+ * another operator[], allowing a convenient m[i][j] to access elements of the
+ * matrix. Note that the lifetime of the Span returned by this first-level
+ * operator[] is bound to that of the Matrix itself, so it is not recommended
+ * to save the Span that is the result of this operator[].
+ *
+ * \return Row \a i from the matrix, as a Span
+ */
+
+/**
+ * \fn Matrix::operator[](size_t i)
+ * \copydoc Matrix::operator[](size_t i) const
+ */
+
+/**
+ * \fn Matrix<T, Rows, Cols> &Matrix::operator*=(U d)
+ * \brief Multiply the matrix by a scalar in-place
+ * \tparam U Type of the numerical scalar value
+ * \param d The scalar multiplier
+ * \return Product of this matrix and scalar \a d
+ */
+
+/**
+ * \fn Matrix::Matrix<U, Rows, Cols> operator*(T d, const Matrix<U, Rows, Cols> &m)
+ * \brief Multiply the matrix by a scalar
+ * \tparam T Type of the numerical scalar value
+ * \tparam U Type of numerical values in the matrix
+ * \tparam Rows Number of rows in the matrix
+ * \tparam Cols Number of columns in the matrix
+ * \param d The scalar multiplier
+ * \param m The matrix
+ * \return Product of scalar \a d and matrix \a m
+ */
+
+/**
+ * \fn Matrix::Matrix<U, Rows, Cols> operator*(const Matrix<U, Rows, Cols> &m, T d)
+ * \copydoc operator*(T d, const Matrix<U, Rows, Cols> &m)
+ */
+
+/**
+ * \fn Matrix<T, R1, C2> operator*(const Matrix<T, R1, C1> &m1, const Matrix<T, R2, C2> &m2)
+ * \brief Matrix multiplication
+ * \tparam T Type of numerical values in the matrices
+ * \tparam R1 Number of rows in the first matrix
+ * \tparam C1 Number of columns in the first matrix
+ * \tparam R2 Number of rows in the second matrix
+ * \tparam C2 Number of columns in the second matrix
+ * \param m1 Multiplicand matrix
+ * \param m2 Multiplier matrix
+ * \return Matrix product of matrices \a m1 and \a m2
+ */
+
+/**
+ * \fn Matrix<T, Rows, Cols> operator+(const Matrix<T, Rows, Cols> &m1, const Matrix<T, Rows, Cols> &m2)
+ * \brief Matrix addition
+ * \tparam T Type of numerical values in the matrices
+ * \tparam Rows Number of rows in the matrices
+ * \tparam Cols Number of columns in the matrices
+ * \param m1 Summand matrix
+ * \param m2 Summand matrix
+ * \return Matrix sum of matrices \a m1 and \a m2
+ */
+
+} /* namespace ipa */
+
+#ifndef __DOXYGEN__
+/*
+ * The YAML data shall be a list of numerical values. Its size shall be equal
+ * to the product of the number of rows and columns of the matrix (Rows x
+ * Cols). The values shall be stored in row-major order.
+ */
+bool matrixValidateYaml(const YamlObject &obj, unsigned int size)
+{
+	if (!obj.isList())
+		return false;
+
+	if (obj.size() != size) {
+		LOG(Matrix, Error)
+			<< "Wrong number of values in matrix: expected "
+			<< size << ", got " << obj.size();
+		return false;
+	}
+
+	return true;
+}
+#endif /* __DOXYGEN__ */
+
+} /* namespace libcamera */
diff --git a/src/ipa/libipa/matrix.h b/src/ipa/libipa/matrix.h
new file mode 100644
index 00000000..8aa8f343
--- /dev/null
+++ b/src/ipa/libipa/matrix.h
@@ -0,0 +1,204 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2024, Paul Elder <paul.elder@ideasonboard.com>
+ *
+ * Matrix and related operations
+ */
+#pragma once
+
+#include <algorithm>
+#include <cmath>
+#include <sstream>
+#include <vector>
+
+#include <libcamera/base/log.h>
+#include <libcamera/base/span.h>
+
+#include "libcamera/internal/yaml_parser.h"
+
+namespace libcamera {
+
+LOG_DECLARE_CATEGORY(Matrix)
+
+namespace ipa {
+
+#ifndef __DOXYGEN__
+template<typename T, unsigned int Rows, unsigned int Cols,
+	 std::enable_if_t<std::is_arithmetic_v<T>> * = nullptr>
+#else
+template<typename T, unsigned int Rows, unsigned int Cols>
+#endif /* __DOXYGEN__ */
+class Matrix
+{
+public:
+	Matrix()
+	{
+		data_.fill(static_cast<T>(0));
+	}
+
+	Matrix(const std::vector<T> &data)
+	{
+		std::copy(data.begin(), data.end(), data_.begin());
+	}
+
+	static Matrix identity()
+	{
+		Matrix ret;
+		for (size_t i = 0; i < std::min(Rows, Cols); i++)
+			ret[i][i] = static_cast<T>(1);
+		return ret;
+	}
+
+	~Matrix() = default;
+
+	const std::string toString() const
+	{
+		std::stringstream out;
+
+		out << "Matrix { ";
+		for (unsigned int i = 0; i < Rows; i++) {
+			out << "[ ";
+			for (unsigned int j = 0; j < Cols; j++) {
+				out << (*this)[i][j];
+				out << ((j + 1 < Cols) ? ", " : " ");
+			}
+			out << ((i + 1 < Rows) ? "], " : "]");
+		}
+		out << " }";
+
+		return out.str();
+	}
+
+	Span<const T, Cols> operator[](size_t i) const
+	{
+		return Span<const T, Cols>{ &data_.data()[i * Cols], Cols };
+	}
+
+	Span<T, Cols> operator[](size_t i)
+	{
+		return Span<T, Cols>{ &data_.data()[i * Cols], Cols };
+	}
+
+#ifndef __DOXYGEN__
+	template<typename U, std::enable_if_t<std::is_arithmetic_v<U>>>
+#else
+	template<typename U>
+#endif /* __DOXYGEN__ */
+	Matrix<T, Rows, Cols> &operator*=(U d)
+	{
+		for (unsigned int i = 0; i < Rows * Cols; i++)
+			data_[i] *= d;
+		return *this;
+	}
+
+private:
+	std::array<T, Rows * Cols> data_;
+};
+
+#ifndef __DOXYGEN__
+template<typename T, typename U, unsigned int Rows, unsigned int Cols,
+	 std::enable_if_t<std::is_arithmetic_v<T>> * = nullptr>
+#else
+template<typename T, typename U, unsigned int Rows, unsigned int Cols>
+#endif /* __DOXYGEN__ */
+Matrix<U, Rows, Cols> operator*(T d, const Matrix<U, Rows, Cols> &m)
+{
+	Matrix<U, Rows, Cols> result;
+
+	for (unsigned int i = 0; i < Rows; i++) {
+		for (unsigned int j = 0; j < Cols; j++)
+			result[i][j] = d * m[i][j];
+	}
+
+	return result;
+}
+
+#ifndef __DOXYGEN__
+template<typename T, typename U, unsigned int Rows, unsigned int Cols,
+	 std::enable_if_t<std::is_arithmetic_v<T>> * = nullptr>
+#else
+template<typename T, typename U, unsigned int Rows, unsigned int Cols>
+#endif /* __DOXYGEN__ */
+Matrix<U, Rows, Cols> operator*(const Matrix<U, Rows, Cols> &m, T d)
+{
+	return d * m;
+}
+
+#ifndef __DOXYGEN__
+template<typename T,
+	 unsigned int R1, unsigned int C1,
+	 unsigned int R2, unsigned int C2,
+	 std::enable_if_t<C1 == R2> * = nullptr>
+#else
+template<typename T, unsigned int R1, unsigned int C1, unsigned int R2, unsigned in C2>
+#endif /* __DOXYGEN__ */
+Matrix<T, R1, C2> operator*(const Matrix<T, R1, C1> &m1, const Matrix<T, R2, C2> &m2)
+{
+	Matrix<T, R1, C2> result;
+
+	for (unsigned int i = 0; i < R1; i++) {
+		for (unsigned int j = 0; j < C2; j++) {
+			T sum = 0;
+
+			for (unsigned int k = 0; k < C1; k++)
+				sum += m1[i][k] * m2[k][j];
+
+			result[i][j] = sum;
+		}
+	}
+
+	return result;
+}
+
+template<typename T, unsigned int Rows, unsigned int Cols>
+Matrix<T, Rows, Cols> operator+(const Matrix<T, Rows, Cols> &m1, const Matrix<T, Rows, Cols> &m2)
+{
+	Matrix<T, Rows, Cols> result;
+
+	for (unsigned int i = 0; i < Rows; i++) {
+		for (unsigned int j = 0; j < Cols; j++)
+			result[i][j] = m1[i][j] + m2[i][j];
+	}
+
+	return result;
+}
+
+#ifndef __DOXYGEN__
+bool matrixValidateYaml(const YamlObject &obj, unsigned int size);
+#endif /* __DOXYGEN__ */
+
+} /* namespace ipa */
+
+#ifndef __DOXYGEN__
+template<typename T, unsigned int Rows, unsigned int Cols>
+std::ostream &operator<<(std::ostream &out, const ipa::Matrix<T, Rows, Cols> &m)
+{
+	out << m.toString();
+	return out;
+}
+
+template<typename T, unsigned int Rows, unsigned int Cols>
+struct YamlObject::Getter<ipa::Matrix<T, Rows, Cols>> {
+	std::optional<ipa::Matrix<T, Rows, Cols>> get(const YamlObject &obj) const
+	{
+		if (!ipa::matrixValidateYaml(obj, Rows * Cols))
+			return std::nullopt;
+
+		ipa::Matrix<T, Rows, Cols> matrix;
+		T *data = &matrix[0][0];
+
+		unsigned int i = 0;
+		for (const YamlObject &entry : obj.asList()) {
+			const auto value = entry.get<T>();
+			if (!value)
+				return std::nullopt;
+
+			data[i++] = *value;
+		}
+
+		return matrix;
+	}
+};
+#endif /* __DOXYGEN__ */
+
+} /* namespace libcamera */
diff --git a/src/ipa/libipa/meson.build b/src/ipa/libipa/meson.build
index 49608423..1952dccf 100644
--- a/src/ipa/libipa/meson.build
+++ b/src/ipa/libipa/meson.build
@@ -7,6 +7,7 @@ libipa_headers = files([
     'exposure_mode_helper.h',
     'fc_queue.h',
     'histogram.h',
+    'matrix.h',
     'module.h',
     'pwl.h',
     'vector.h',
@@ -19,6 +20,7 @@ libipa_sources = files([
     'exposure_mode_helper.cpp',
     'fc_queue.cpp',
     'histogram.cpp',
+    'matrix.cpp',
     'module.cpp',
     'pwl.cpp',
     'vector.cpp',