.. _link_layer:

Link Layer
==========

.. _cv2xlinklayer:

CV2XLinkLayer
-------------

Overview
~~~~~~~~

`cv2xlinklayer` is a C++ library that provides an interface for Cellular Vehicle-to-Everything (C-V2X) communication. It interacts with a telematics SDK (`telux_cv2x`) to establish and manage transmission (Tx) and reception (Rx) flows. The library is exposed to Python using `pybind11`, allowing Python scripts to send and receive C-V2X messages.

Components
~~~~~~~~~~

`cv2x_link_layer.cpp`
^^^^^^^^^^^^^^^^^^^^
This file implements the main logic of the C-V2X communication layer, including:

- Initialization of the `Cv2xRadioManager`.
- Setup of transmission (Tx) and reception (Rx) flows.
- Callbacks for handling C-V2X status updates and data reception.
- A `send` method for transmitting data.
- A `receive` method for reading incoming messages.
- Integration with `pybind11` for Python compatibility.

`cv2x_link_layer.hpp`
^^^^^^^^^^^^^^^^^^^^
This header file declares the `CV2XLinkLayer` class and its methods.

`CMakeLists.txt`
^^^^^^^^^^^^^^^^
This file defines the build process, including:

- Minimum required CMake version (`3.12`).
- Setting the project name (`cv2xlinklayer`).
- Enforcing C++11 standard.
- Finding and linking `pybind11` and `telux_cv2x`.
- Generating a shared library (`cv2xlinklayer.so`).

Building the Library
~~~~~~~~~~~~~~~~~~~~

Prerequisites
^^^^^^^^^^^^^
Ensure the following dependencies are installed:

- CMake (`>= 3.12`)
- `pybind11`
- `telux_cv2x` SDK
- A C++11-compliant compiler

Build Steps
^^^^^^^^^^^

.. code-block:: sh

    mkdir build && cd build
    cmake ..
    make

The output shared library (`cv2xlinklayer.so`) will be placed in the `lib` directory.

Using the Library in Python
^^^^^^^^^^^^^^^^^^^^^^^^^^^

Importing the Module
^^^^^^^^^^^^^^^^^^^^

.. code-block:: python

    import cv2xlinklayer

Creating an Instance
^^^^^^^^^^^^^^^^^^^^

.. code-block:: python

    link_layer = cv2xlinklayer.CV2XLinkLayer()

Sending Data
^^^^^^^^^^^^
.. code-block:: python

    data = "Hello, C-V2X!"
    link_layer.send(data)

Receiving Data
^^^^^^^^^^^^^^

.. code-block:: python

    received_data = link_layer.receive()
    print(received_data)

Summary
~~~~~~~

This project enables C-V2X communication through a C++ library exposed to Python. By using `pybind11`, Python applications can seamlessly integrate with the underlying C++ logic for transmitting and receiving C-V2X messages.