[PATCH v3 1/3] ipa: libipa: Add Matrix class

[Stefan Klug]

Hi Paul,

thanks for the patch.

On Tue, May 07, 2024 at 03:10:14PM +0900, Paul Elder wrote:
> 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 v3:
> - fix template parameters of operator* to allow different types for the
>   scalar multiplier and the matrix's number type
> - clear data in constructors
> - fix assert in constructor
> 
> Changes v2:
> - make rows and columns into template arguments
> - initialize to identity matrix on construction
> - add getter and setter
> - change from struct to class
> - fix matrix multiplication
> - clean up unused includes
> - avoid dereferencing an absent std::optional
> ---
>  src/ipa/libipa/matrix.cpp  |  17 +++++
>  src/ipa/libipa/matrix.h    | 146 +++++++++++++++++++++++++++++++++++++
>  src/ipa/libipa/meson.build |   2 +
>  3 files changed, 165 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..bbdb838b
> --- /dev/null
> +++ b/src/ipa/libipa/matrix.h
> @@ -0,0 +1,146 @@
> +/* 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 <algorithm>
> +#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, unsigned int R, unsigned int C,
> +	 std::enable_if_t<std::is_arithmetic_v<T>> * = nullptr>
> +class Matrix
> +{
> +public:
> +	Matrix()
> +	{
> +		data_.clear();
> +		for (unsigned int i = 0; i < R; i++)
> +			for (unsigned int j = 0; j < C; j++)
> +				data_.push_back(static_cast<T>(i == j));
> +	};
> +
> +	Matrix(const std::vector<T> &data)
> +	{
> +		ASSERT(data.size() == R * C);
> +
> +		data_.clear();
> +		for (const T &x : data)
> +			data_.push_back(x);
> +	}
> +
> +	~Matrix(){};
> +
> +	int readYaml(const libcamera::YamlObject &yaml)
> +	{
> +		if (yaml.size() != R * C) {
> +			LOG(Matrix, Error)
> +				<< "Wrong number of values in matrix: expected "
> +				<< R * C << ", got " << yaml.size();
> +			return -EINVAL;
> +		}
> +
> +		unsigned int i = 0;
> +		for (const auto &x : yaml.asList()) {
> +			auto value = x.get<T>();
> +			if (!value) {
> +				LOG(Matrix, Error) << "Failed to read matrix value";
> +				return -EINVAL;
> +			}
> +
> +			data_[i++] = *value;
> +		}
> +
> +		return 0;
> +	}
> +
> +	const std::string toString() const

I don't recall if I mentioned that. For consistency you could move this
into a ostream& operator<<(...).  

Aside from that I think we should get this in. We'll later see what else
is needed.

Reviewed-by: Stefan Klug <stefan.klug at ideasonboard.com> 

Cheers,
Stefan

> +	{
> +		std::stringstream ss;
> +		ss << "Matrix { ";
> +		for (unsigned int i = 0; i < R; i++) {
> +			ss << "[ ";
> +			for (unsigned int j = 0; j < C; j++) {
> +				ss << get(i, j);
> +				ss << ((j + 1 < C) ? ", " : " ");
> +			}
> +			ss << ((i + 1 < R) ? "], " : "]");
> +		}
> +		ss << " }";
> +
> +		return ss.str();
> +	}
> +
> +	const T &get(unsigned int i, unsigned int j) const { return data_.at(i * C + j); }
> +	void set(unsigned int i, unsigned int j, T value) { data_[i * C + j] = value; }
> +
> +private:
> +	std::vector<T> data_;
> +};
> +
> +template<typename T, typename U, unsigned int R, unsigned int C,
> +	 std::enable_if_t<std::is_arithmetic_v<T> && std::is_arithmetic_v<U>> * = nullptr>
> +Matrix<U, R, C> operator*(T d, const Matrix<U, R, C> &m)
> +{
> +	Matrix<U, R, C> result;
> +
> +	for (unsigned int i = 0; i < R; i++)
> +		for (unsigned int j = 0; j < C; j++)
> +			result.set(i, j, d * m.get(i, j));
> +
> +	return result;
> +}
> +
> +template<typename T,
> +	 unsigned int R1, unsigned int C1,
> +	 unsigned int R2, unsigned int C2,
> +	 std::enable_if_t<std::is_arithmetic_v<T> && C1 == R2> * = nullptr>
> +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.get(i, k) * m2.get(k, j);
> +
> +			result.set(i, j, sum);
> +		}
> +	}
> +
> +	return result;
> +}
> +
> +template<typename T, unsigned int R, unsigned int C,
> +	 std::enable_if_t<std::is_arithmetic_v<T>> * = nullptr>
> +Matrix<T, R, C> operator+(const Matrix<T, R, C> &m1, const Matrix<T, R, C> &m2)
> +{
> +	Matrix<T, R, C> result;
> +
> +	for (unsigned int i = 0; i < R; i++)
> +		for (unsigned int j = 0; j < C; j++)
> +			result.set(i, j, m1.get(i, j) + m2.get(i, j));
> +
> +	return result;
> +}
> +
> +} /* namespace ipa */
> +
> +} /* namespace libcamera */
> diff --git a/src/ipa/libipa/meson.build b/src/ipa/libipa/meson.build
> index 1b3faf8d..1e34355f 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',
>  ])
> @@ -18,6 +19,7 @@ libipa_sources = files([
>      'exposure_mode_helper.cpp',
>      'fc_queue.cpp',
>      'histogram.cpp',
> +    'matrix.cpp',
>      'module.cpp',
>      'pwl.cpp'
>  ])
> -- 
> 2.39.2
>