[ext] added eigen linear algebra submodule and example

Author: hshose

.gitmodules

@@ -52,3 +52,6 @@
 [submodule "ext/segger/rtt"]
 	path = ext/segger/rtt
 	url = https://github.com/modm-ext/segger-rtt.git
+[submodule "ext/eigen/eigen"]
+	path = ext/eigen/eigen
+	url = https://gitlab.com/libeigen/eigen

examples/nucleo_g474re/eigen/main.cpp

@@ -0,0 +1,41 @@
+/*
+ * Copyright (c) 2025, Henrik Hose
+ *
+ * This file is part of the modm project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+#include <eigen_conf.h>
+
+#include <Eigen/Dense>
+#include <modm/board.hpp>
+
+using namespace Board;
+
+int
+main()
+{
+	Board::initialize();
+	LedD13::setOutput();
+
+	while (1)
+	{
+		Eigen::Matrix2f mat{{1, 2}, {3, 4}};
+		Eigen::Vector2f u{-1, 1}, v{2, 0};
+		MODM_LOG_INFO << "Here is mat*mat:\n" << mat * mat << modm::endl;
+		MODM_LOG_INFO << "Here is mat*u:\n" << mat * u << modm::endl;
+		MODM_LOG_INFO << "Here is u^T*mat:\n" << u.transpose() * mat << modm::endl;
+		MODM_LOG_INFO << "Here is u^T*v:\n" << u.transpose() * v << modm::endl;
+		MODM_LOG_INFO << "Here is u*v^T:\n" << u * v.transpose() << modm::endl;
+		MODM_LOG_INFO << "Let's multiply mat by itself" << modm::endl;
+		mat = mat * mat;
+		MODM_LOG_INFO << "Now mat is mat:\n" << mat << modm::endl;
+
+		modm::delay(std::chrono::seconds(1));
+	}
+
+	return 0;
+}

examples/nucleo_g474re/eigen/project.xml

@@ -0,0 +1,10 @@
+<library>
+  <extends>modm:nucleo-g474re</extends>
+  <options>
+    <option name="modm:build:build.path">../../../build/nucleo_g474re/eigen</option>
+  </options>
+  <modules>
+    <module>modm:build:scons</module>
+    <module>modm:eigen</module>
+  </modules>
+</library>

ext/eigen/eigen

@@ -0,0 +1,41 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+#
+# Copyright (c) 2025, Henrik Hose
+#
+# This file is part of the modm project.
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+# -----------------------------------------------------------------------------
+
+def init(module):
+    module.name = ":eigen"
+    module.description = """\
+# Eigen Linear Algebra Library
+"""
+
+def prepare(module, options):
+    if options[":target"].identifier.platform != "hosted":
+        module.depends(":platform:heap")
+
+    module.add_option(
+        BooleanOption(
+            name="eigen_no_malloc",
+            description="if defined, any request from inside the Eigen to allocate memory from the heap results in an assertion failure.",
+            default=True))
+    return True
+
+def build(env):
+    env.outbasepath = "modm/ext/eigen"
+    env.copy("eigen/Eigen", "Eigen")
+    env.copy("eigen/COPYING.APACHE", "COPYING.APACHE")
+    env.copy("eigen/COPYING.BSD", "COPYING.BSD")
+    env.copy("eigen/COPYING.MINPACK", "COPYING.MINPACK")
+    env.copy("eigen/COPYING.MPL2", "COPYING.MPL2")
+    env.copy("eigen/COPYING.README", "COPYING.README")
+    env.copy("eigen/LICENSE", "LICENSE")
+    env.collect(":build:path.include", "modm/ext/eigen")
+    env.substitutions = {"eigen_no_malloc": env.get("eigen_no_malloc", True)}
+    env.template("eigen_conf.h.in")

ext/eigen/eigen.lb

@@ -0,0 +1,36 @@
+#ifndef EIGEN_CONF_H
+#define EIGEN_CONF_H
+
+#if __has_include(<eigen_conf_local.h>)
+#  include <eigen_conf_local.h>
+#endif
+
+#define EIGEN_DONT_VECTORIZE
+#define EIGEN_DISABLE_UNALIGNED_ARRAY_ASSERT
+
+{% if eigen_no_malloc %}
+#define EIGEN_NO_MALLOC
+{% endif %}
+
+
+#include <Eigen/Dense>
+#include <modm/io/iostream.hpp>
+
+namespace modm {
+
+template<typename Derived>
+modm::IOStream& operator<<(modm::IOStream& s, const Eigen::MatrixBase<Derived>& m)
+{
+    for (Eigen::Index r = 0; r < m.rows(); ++r) {
+        for (Eigen::Index c = 0; c < m.cols(); ++c) {
+            s << m(r, c);
+            if (c + 1 < m.cols()) s << ", ";
+        }
+        if (r + 1 < m.rows()) s << "\n";
+    }
+    return s;
+}
+
+} // namespace modm
+
+#endif // EIGEN_CONF_H