Keep the colleague's microbu-esp32c5 tree in this repository

obu-firmware builds against vanetza-idf from microbu-esp32c5/external, but
that tree was gitignored, so a clone of this repository could not build the
firmware it ships. It is now committed here as ordinary files in its own
folder, microbu-esp32c5/: the colleague's commit cf4b99f plus the V2X2MAP
bridge's signature verification (--trust) used on the bench. Nothing is
fetched from or pushed to the colleague's repository; this repository and
its remotes carry everything. The folder's own .gitignore keeps build output,
downloaded components and private key material out, as it did there; the
committed file set is identical to that repository's tracked files.

The ESP32-C5 is still flashed from obu-firmware/, which only takes
vanetza-idf from microbu-esp32c5/, so the two stay separate folders.
FLASHING.md says how to take a newer version of the colleague's tree (copy
it over the folder, rebuild, test, commit).

microbu-esp32c5/external/vanetza-idf/vanetza/geonet/areas.cpp

@@ -0,0 +1,115 @@
+#include "areas.hpp"
+#include <boost/math/constants/constants.hpp>
+#include <boost/units/cmath.hpp>
+#include <algorithm>
+#include <cassert>
+#include <limits>
+
+namespace vanetza
+{
+namespace geonet
+{
+
+double geometric_function(const Circle& c, const CartesianPosition& p)
+{
+    if (c.r.value() != 0.0) {
+        const double x_over_r = p.x / c.r;
+        const double y_over_r = p.y / c.r;
+        return 1.0 - (x_over_r * x_over_r) - (y_over_r * y_over_r);
+    } else {
+        return -std::numeric_limits<double>::infinity();
+    };
+}
+
+double geometric_function(const Rectangle& r, const CartesianPosition& p)
+{
+    if (r.a.value() != 0.0 && r.b.value() != 0.0) {
+        const double x_over_a = p.x / r.a;
+        const double y_over_b = p.y / r.b;
+        return std::min(1.0 - x_over_a * x_over_a, 1.0 - y_over_b * y_over_b);
+    } else {
+        return -std::numeric_limits<double>::infinity();
+    }
+}
+
+double geometric_function(const Ellipse& e, const CartesianPosition& p)
+{
+    if (e.a.value() != 0.0 && e.b.value() != 0.0) {
+        const double x_over_a = p.x / e.a;
+        const double y_over_b = p.y / e.b;
+        return 1.0 - (x_over_a * x_over_a) - (y_over_b * y_over_b);
+    } else {
+        return -std::numeric_limits<double>::infinity();
+    }
+}
+
+struct geometric_function_visitor : public boost::static_visitor<double>
+{
+    geometric_function_visitor(const CartesianPosition& p) : point(p) {}
+
+    template<class SHAPE>
+    double operator()(const SHAPE& s) const
+    {
+        return geometric_function(s, point);
+    }
+
+    const CartesianPosition& point;
+};
+
+double geometric_function(const decltype(Area::shape)& shape, const CartesianPosition& p)
+{
+    geometric_function_visitor visitor(p);
+    return boost::apply_visitor(visitor, shape);
+}
+
+CartesianPosition canonicalize(const CartesianPosition& point, units::Angle azimuth)
+{
+    using namespace boost::math::double_constants;
+    // area.angle is azimuth angle of EN 302 931 V1.1.1
+    const units::Angle zenith = half_pi * units::si::radian - azimuth;
+    const double sin_z = sin(zenith);
+    const double cos_z = cos(zenith);
+    // rotate canonical point around origin clockwise: zenith = 90 deg - azimuth
+    // other interpretation: rotate shape's long side onto abscissa
+    CartesianPosition canonical;
+    canonical.x = cos_z * point.x + sin_z * point.y;
+    canonical.y = -sin_z * point.x + cos_z * point.y;
+    return canonical;
+}
+
+struct area_size_visitor : public boost::static_visitor<units::Area>
+{
+    units::Area operator()(const Circle& circle) const
+    {
+        using namespace boost::math::double_constants;
+        return pi * circle.r * circle.r;
+    }
+
+    units::Area operator()(const Rectangle& rectangle) const
+    {
+        using namespace boost::math::double_constants;
+        return 4.0 * rectangle.a * rectangle.b;
+    }
+
+    units::Area operator()(const Ellipse& ellipse) const
+    {
+        using namespace boost::math::double_constants;
+        return pi * ellipse.a * ellipse.b;
+    }
+};
+
+units::Area area_size(const Area& area)
+{
+    return boost::apply_visitor(area_size_visitor(), area.shape);
+}
+
+bool inside_or_at_border(const Area& area, const GeodeticPosition& geo_position)
+{
+    const CartesianPosition local = local_cartesian(area.position, geo_position);
+    const CartesianPosition canonical = canonicalize(local, area.angle);
+    return !outside_shape(area.shape, canonical);
+}
+
+} // namespace geonet
+} // namespace vanetza
+