[PATCH v8 1/4] ipa: libipa: Add Vector class

[Paul Elder]

Add a vector class to libipa. The original purpose of this is to replace
the floating-point Point class that Raspberry Pi used in their Pwl, as
that implementation of Point seemed more akin to a Vector than a Point.

This is added to libipa instead of to geometry.h to avoid public API
issues, plus this is not expected to be needed by applications.

Signed-off-by: Paul Elder <paul.elder at ideasonboard.com>
Reviewed-by: Stefan Klug <stefan.klug at ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham at ideasonboard.com>

---
Changes in v8:
- s/D/Rows/ in Vector class
- add z accessor function
- move SFINAE for x() and y() (and z()) to the functions instead of the
  class
- add vector to meson

Changes in v7:
- fix documentation
- fix license and copyright
- remove toString()

No change in v6

New in v5
---
 src/ipa/libipa/meson.build |   2 +
 src/ipa/libipa/vector.cpp  | 150 +++++++++++++++++++++++++++
 src/ipa/libipa/vector.h    | 203 +++++++++++++++++++++++++++++++++++++
 3 files changed, 355 insertions(+)
 create mode 100644 src/ipa/libipa/vector.cpp
 create mode 100644 src/ipa/libipa/vector.h

diff --git a/src/ipa/libipa/meson.build b/src/ipa/libipa/meson.build
index 7ce885da7b99..8b0c8fff901b 100644
--- a/src/ipa/libipa/meson.build
+++ b/src/ipa/libipa/meson.build
@@ -8,6 +8,7 @@ libipa_headers = files([
     'fc_queue.h',
     'histogram.h',
     'module.h',
+    'vector.h',
 ])
 
 libipa_sources = files([
@@ -18,6 +19,7 @@ libipa_sources = files([
     'fc_queue.cpp',
     'histogram.cpp',
     'module.cpp',
+    'vector.cpp',
 ])
 
 libipa_includes = include_directories('..')
diff --git a/src/ipa/libipa/vector.cpp b/src/ipa/libipa/vector.cpp
new file mode 100644
index 000000000000..b9fad90386a1
--- /dev/null
+++ b/src/ipa/libipa/vector.cpp
@@ -0,0 +1,150 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2024, Paul Elder <paul.elder at ideasonboard.com>
+ *
+ * Vector and related operations
+ */
+
+#include "vector.h"
+
+#include <libcamera/base/log.h>
+
+/**
+ * \file vector.h
+ * \brief Vector class
+ */
+
+namespace libcamera {
+
+LOG_DEFINE_CATEGORY(Vector)
+
+namespace ipa {
+
+/**
+ * \class Vector
+ * \brief Vector class
+ * \tparam T Type of numerical values to be stored in the vector
+ * \tparam Rows Number of dimension of the vector (= number of elements)
+ */
+
+/**
+ * \fn Vector::Vector()
+ * \brief Construct a zero vector
+ */
+
+/**
+ * \fn Vector::Vector(const std::array<T, Rows> &data)
+ * \brief Construct vector from supplied data
+ * \param data Data from which to construct a vector
+ *
+ * The size of \a data must be equal to the dimension size Rows of the vector.
+ */
+
+/**
+ * \fn Vector::readYaml
+ * \brief Populate the vector with yaml data
+ * \param yaml Yaml data to populate the vector with
+ *
+ * Any existing data in the vector will be overwritten. The size of the data
+ * read from \a yaml must be equal to the dimension size Rows of the vector.
+ *
+ * The yaml data is expected to be a list with elements of type T.
+ *
+ * \return 0 on success, negative error code otherwise
+ */
+
+/**
+ * \fn T Vector::operator[](size_t i) const
+ * \brief Index to an element in the vector
+ * \param i Index of element to retrieve
+ * \return Element at index \a i from the vector
+ */
+
+/**
+ * \fn T &Vector::operator[](size_t i)
+ * \copydoc Vector::operator[](size_t i) const
+ */
+
+/**
+ * \fn Vector::x()
+ * \brief Convenience function to access the first element of the vector
+ */
+
+/**
+ * \fn Vector::y()
+ * \brief Convenience function to access the second element of the vector
+ */
+
+/**
+ * \fn Vector::z()
+ * \brief Convenience function to access the third element of the vector
+ */
+
+/**
+ * \fn Vector::operator-() const
+ * \brief Negate a Vector by negating both all of its coordinates
+ * \return The negated vector
+ */
+
+/**
+ * \fn Vector::operator-(Vector const &other) const
+ * \brief Subtract one vector from another
+ * \param[in] other The other vector
+ * \return The difference of \a other from this vector
+ */
+
+/**
+ * \fn Vector::operator+()
+ * \brief Add two vectors together
+ * \param[in] other The other vector
+ * \return The sum of the two vectors
+ */
+
+/**
+ * \fn Vector::operator*(const Vector<T, Rows> &other) const
+ * \brief Compute the dot product
+ * \param[in] other The other vector
+ * \return The dot product of the two vectors
+ */
+
+/**
+ * \fn Vector::operator*(T factor) const
+ * \brief Multiply the vector by a scalar
+ * \param[in] factor The factor
+ * \return The vector multiplied by \a factor
+ */
+
+/**
+ * \fn Vector::operator/()
+ * \brief Divide the vector by a scalar
+ * \param[in] factor The factor
+ * \return The vector divided by \a factor
+ */
+
+/**
+ * \fn Vector::length2()
+ * \brief Get the squared length of the vector
+ * \return The squared length of the vector
+ */
+
+/**
+ * \fn Vector::length()
+ * \brief Get the length of the vector
+ * \return The length of the vector
+ */
+
+/**
+ * \fn bool operator==(const Vector<T, Rows> &lhs, const Vector<T, Rows> &rhs)
+ * \brief Compare vectors for equality
+ * \return True if the two vectors are equal, false otherwise
+ */
+
+/**
+ * \fn bool operator!=(const Vector<T, Rows> &lhs, const Vector<T, Rows> &rhs)
+ * \brief Compare vectors for inequality
+ * \return True if the two vectors are not equal, false otherwise
+ */
+
+} /* namespace ipa */
+
+} /* namespace libcamera */
diff --git a/src/ipa/libipa/vector.h b/src/ipa/libipa/vector.h
new file mode 100644
index 000000000000..b281f079365a
--- /dev/null
+++ b/src/ipa/libipa/vector.h
@@ -0,0 +1,203 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2024, Paul Elder <paul.elder at ideasonboard.com>
+ *
+ * Vector and related operations
+ */
+#pragma once
+
+#include <algorithm>
+#include <array>
+#include <cmath>
+#include <sstream>
+
+#include <libcamera/base/log.h>
+#include <libcamera/base/span.h>
+
+#include "libcamera/internal/yaml_parser.h"
+
+namespace libcamera {
+
+LOG_DECLARE_CATEGORY(Vector)
+
+namespace ipa {
+
+#ifndef __DOXYGEN__
+template<typename T, unsigned int Rows,
+	 std::enable_if_t<std::is_arithmetic_v<T>> * = nullptr>
+#else
+template<typename T, unsigned int Rows>
+#endif /* __DOXYGEN__ */
+class Vector
+{
+public:
+	constexpr Vector() = default;
+
+	constexpr Vector(const std::array<T, Rows> &data)
+	{
+		for (unsigned int i = 0; i < Rows; i++)
+			data_[i] = data[i];
+	}
+
+	int readYaml(const libcamera::YamlObject &yaml)
+	{
+		if (yaml.size() != Rows) {
+			LOG(Vector, Error)
+				<< "Wrong number of values in vector: expected "
+				<< Rows << ", got " << yaml.size();
+			return -EINVAL;
+		}
+
+		unsigned int i = 0;
+		for (const auto &x : yaml.asList()) {
+			auto value = x.get<T>();
+			if (!value) {
+				LOG(Vector, Error) << "Failed to read vector value";
+				return -EINVAL;
+			}
+
+			data_[i++] = *value;
+		}
+
+		return 0;
+	}
+
+	const T &operator[](size_t i) const
+	{
+		ASSERT(i < data_.size());
+		return data_[i];
+	}
+
+	T &operator[](size_t i)
+	{
+		ASSERT(i < data_.size());
+		return data_[i];
+	}
+
+#ifndef __DOXYGEN__
+	template<bool Dependent = false, typename = std::enable_if_t<Dependent || Rows >= 1>>
+#endif /* __DOXYGEN__ */
+	constexpr T x() const
+	{
+		return data_[0];
+	}
+
+#ifndef __DOXYGEN__
+	template<bool Dependent = false, typename = std::enable_if_t<Dependent || Rows >= 2>>
+#endif /* __DOXYGEN__ */
+	constexpr T y() const
+	{
+		return data_[1];
+	}
+
+#ifndef __DOXYGEN__
+	template<bool Dependent = false, typename = std::enable_if_t<Dependent || Rows >= 3>>
+#endif /* __DOXYGEN__ */
+	constexpr T z() const
+	{
+		return data_[2];
+	}
+
+	constexpr Vector<T, Rows> operator-() const
+	{
+		Vector<T, Rows> ret;
+		for (unsigned int i = 0; i < Rows; i++)
+			ret[i] = -data_[i];
+		return ret;
+	}
+
+	constexpr Vector<T, Rows> operator-(const Vector<T, Rows> &other) const
+	{
+		Vector<T, Rows> ret;
+		for (unsigned int i = 0; i < Rows; i++)
+			ret[i] = data_[i] - other[i];
+		return ret;
+	}
+
+	constexpr Vector<T, Rows> operator+(const Vector<T, Rows> &other) const
+	{
+		Vector<T, Rows> ret;
+		for (unsigned int i = 0; i < Rows; i++)
+			ret[i] = data_[i] + other[i];
+		return ret;
+	}
+
+	constexpr T operator*(const Vector<T, Rows> &other) const
+	{
+		T ret = 0;
+		for (unsigned int i = 0; i < Rows; i++)
+			ret += data_[i] * other[i];
+		return ret;
+	}
+
+	constexpr Vector<T, Rows> operator*(T factor) const
+	{
+		Vector<T, Rows> ret;
+		for (unsigned int i = 0; i < Rows; i++)
+			ret[i] = data_[i] * factor;
+		return ret;
+	}
+
+	constexpr Vector<T, Rows> operator/(T factor) const
+	{
+		Vector<T, Rows> ret;
+		for (unsigned int i = 0; i < Rows; i++)
+			ret[i] = data_[i] / factor;
+		return ret;
+	}
+
+	constexpr double length2() const
+	{
+		double ret = 0;
+		for (unsigned int i = 0; i < Rows; i++)
+			ret += data_[i] * data_[i];
+		return ret;
+	}
+
+	constexpr double length() const
+	{
+		return std::sqrt(length2());
+	}
+
+private:
+	std::array<T, Rows> data_;
+};
+
+template<typename T, unsigned int Rows>
+bool operator==(const Vector<T, Rows> &lhs, const Vector<T, Rows> &rhs)
+{
+	for (unsigned int i = 0; i < Rows; i++)
+		if (lhs[i] != rhs[i])
+			return false;
+
+	return true;
+}
+
+template<typename T, unsigned int Rows>
+bool operator!=(const Vector<T, Rows> &lhs, const Vector<T, Rows> &rhs)
+{
+	for (unsigned int i = 0; i < Rows; i++)
+		if (lhs[i] != rhs[i])
+			return true;
+
+	return false;
+}
+
+} /* namespace ipa */
+
+#ifndef __DOXYGEN__
+template<typename T, unsigned int Rows>
+std::ostream &operator<<(std::ostream &out, const ipa::Vector<T, Rows> &v)
+{
+	out << "Vector { ";
+	for (unsigned int i = 0; i < Rows; i++) {
+		out << v[i];
+		out << ((i + 1 < Rows) ? ", " : " ");
+	}
+	out << " }";
+
+	return out;
+}
+#endif /* __DOXYGEN__ */
+
+} /* namespace libcamera */
-- 
2.39.2