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

[Barnabás Pőcze]

Hi


2024. május 7., kedd 8:10 keltezéssel, Paul Elder <paul.elder at ideasonboard.com> írta:

> 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()
	: data_(R * C, static_cast<T>(false))
{
	for (std::size_t i = 0; i < std::min(R, C); i++)
		(*this)[i][i] = static_cast<T>(true); // see below for indexing
}


> +	};

`;` not needed.


> +
> +	Matrix(const std::vector<T> &data)

Any reason why `Span<const T, R * C>` (or just `Span<const T>`) is not acceptable?


> +	{
> +		ASSERT(data.size() == R * C);
> +
> +		data_.clear();
> +		for (const T &x : data)
> +			data_.push_back(x);
> +	}
> +
> +	~Matrix(){};

`= default;` or just omit it completely please.


> [...]
> +
> +	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; }

Maybe

  const T& operator()(std::size_t i, std::size_t j) const { return data[i * C + ]; }
  T& operator()(std::size_t i, std::size_t j) { return data[i * C + ]; }

?

I believe this is a pretty standard way to implement n-dimensional indexing in C++
since operator[] cannot have multiple arguments until C++23.

Or I think the following also works, which might be "better":

  Span<const T, C> operator[](std::size_t i) const { return { &data[i * C], C }; }
  Span<T, C> operator[](std::size_t i) { return { &data[i * C], C }; }


> +
> +private:
> +	std::vector<T> data_;
> +};
> [...]


Regards,
Barnabás Pőcze