Gain insights into using Modern C++ for embedded programming. Learn about safety-critical systems, optimize performance, manage limited resources, and handle parallel execution effectively.

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C++11

C++ 17

Embedded Programming with Modern C++  is highly valuable for each professional programmer.

In the past, embedded and system programming have had their pitfalls, but modern C++ has been designed to be a better language for this type of development, addressing the previous pitfalls/requirements explicitly. What are these requirements? Embedded systems deal with safety-critical systems, meaning they must guarantee high performance combined with limited resources, while also working in parallel.

The scope of this course goes beyond just embedded programming. Developers who write servers, games, or trading systems may especially benefit from this course because they also have to deal with safety-critical systems, high performance, reduced resources, and parallel execution in their jobs.

To get the most out of the course, you only need a basic understanding of C++. Building off this understanding, this course goes over all the essentials of embedded programming with Modern C++.

Let's get started!

Embedded Programming with Modern C++


# MISRA C++
The current MISRA C++:2008 guidelines were published by the [**M**otor **I**ndustry **S**oftware **R**eliability **A**ssociation](https://www.misra.org.uk/Activities/tabid/56/Default.aspx). They are based on the [MISRA C](https://en.wikipedia.org/wiki/MISRA-C) guidelines from 1998. Originally designed for the automotive industry, MISRA C++ became the standard for the implementation of critical software in the aviation, military, and medical sector. Just like MISRA C, MISRA C++ also describes guidelines for a safe subset of C++.

This subset consists of more than 200 rules classified as a document, required, or advisory.

* Document:
  * Mandatory requirements on the developer
  * Derivations are not permitted
* Required:
  * Mandatory requirements for the developer
  * Formal derivation must be raised
* Advisory:
  * Should be followed as closely as possible
  * Formal derivation is not necessary but may be considered

## MISRA C++ Rules
Lets's look at some of the important rules regarding the C++ core language and libraries. To make it clearer, we will present a few rules from [MISRA C++](https://www.misra.org.uk/misra-cpp/Activities/MISRAC/tabid/171/Default.aspx).

* Unnecessary construct
  * The project shall not contain unreachable code. (required)
  * The project shall not contain unused variables. (required) 
* Assembler
  * All usage of assembler shall be documented. (document)
* Arithmetic
  * Use of floating-point arithmetic shall be documented. (document)
* Language
  * The code shall conform to the C++03 standard (Remark: Small addition to C++98). (required)
* Comments
  * No C comments shall be used to "comment out" code. (required)
  * No C++ comments shall be used to "comment out" code. (advisory)
* Pointer conversions
  * NULL shall not be used as an integer value. (required)
* Multiple base classes
  * Classes should not be derived from virtual bases. (advisory)
* Virtual functions
  * Each overriding virtual function shall be declared with the virtual keyword. (required)
* Exception handling
  * Exceptions shall only be used for error handling. (document)
* Templates
  * All partial and explicit specializations for a template shall be declared in the same file as the declarations of their primary template. (required)
* Macro replacements
  * The # and ## operators should not be used. (advisory)
* Library
   * The C library shall not be used. (required)
  * All library code shall conform to MISRA C++.(document)

You can verify these and all the other MISRA C++ rules with static code analysis tools.

## Conclusion
Which conclusions can we draw from the MISRA C++ rules for the usage of C++ in critical systems? Neither one feature nor the whole language is excluded by MISRA C++.

MISRA C++ also emphasizes why C++ in critical systems becomes more important. (1.1 The use of C++ in critical systems):

* C++ offers support for high-speed, low-level, input/output operations, which are essential to many embedded systems.
* The increased complexity of applications makes the use of a high-level language more appropriate than assembly language.
* C++ compilers generate code with similar size and RAM requirements to those of C.

One small issue remains, however. MISRA C++ is based on classical C++, while Modern C++ has more to offer for embedded systems. Sadly, MISRA C++ cannot keep in lockstep with the C++ standardization but there are efforts being made to fill the gap.






Here are some facts regarding embedded programming with C++, as well as MISRA C++ and AUTOSAR C++14 guidelines. 


Introduction

Safety-Critical Systems

High Performance

Reduced Resources

Several Tasks Simultaneously

Conclusion

Facts

MISRA C++