Talk

Modern C++ in Embedded Development: Expressive Compile-Time Computation

Amar Mahmutbegovic

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25:43

EOC 2024

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Amar Mahmutbegovic

Amar Mahmutbegovic is the co-founder and Head of Engineering at Semblie, where he leads the utilization of modern C++ for firmware development. He is passionate about demonstrating the advantages of C++ to the embedded community through his blog posts and LinkedIn activity. Amar's blog post series "Modern C++ in embedded development" can be accessed on Semblie's website at https://semblie.com/modern-cpp/.

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Topics Covered

C C++Microcontroller Software Design

Talk

Modern C++ in Embedded Development: Expressive Compile-Time Computation

Amar Mahmutbegovic

25:43 EOC 2024

Amar Mahmutbegovic

25:43

C++11 made a significant impact on C++, bringing in features such as auto, lambdas, and constexpr. These features modernized language, making it more expressive.

This talk guides embedded developers who dominantly use C for their daily tasks through compile-time evaluation of functions and expressions in C++. It demonstrates language capabilities to generate lookup tables and mathematical signals in compile time while providing expressive abstractions similar to Matlab.

The talk will help embedded developers to better understand modern C++ capabilities, and it will cover the following topics:

Constexpr variables,
Constexpr functions,
Operator overloading,
Lambdas,
Templates,
Abbreviated function template.

The talk aims to demonstrate C++’s compile-time computation capability through a practical example while gradually guiding the audience through the language features needed to build the example.

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Please log in or create an account to test your knowledge and see the answers.

What did Amar identify as the primary benefit of using constexpr for computations in embedded systems?

A It forces all constants to be stored in RAM so they’re quickly writable at runtime.

B It allows computations to be performed at compile time so runtime code and resources are freed for other tasks.

C It guarantees that no numerical errors can occur during floating-point math.

D It enables dynamic runtime initialization of global objects after boot.

E It replaces the need for any compiler optimizations to reduce binary size.

Which of the following is a requirement for a constexpr variable, as explained in the talk?

A It must be immediately initialized (have an initializer at the point of declaration).

B It may be of any non-literal type, such as std::unique_ptr.

C A constexpr function that returns a non-void type can omit a return statement with no error.

D It can be initialized later at runtime by assigning to it in main().

E Its initialization expression does not need to be a constant expression.

What portability limitation did Amar point out when using std::sin/std::cos in constexpr signal generation?

A std::sin and std::cos are guaranteed constexpr in all standard library implementations, so there is no portability issue.

B std::sin and std::cos are not constexpr in Clang’s headers but are in GCC’s, so code relying on them being constexpr may be non-portable across compilers.

C Using std::sin/std::cos in constexpr always produces incorrect results at compile time due to rounding.

D You must disable optimizations to make std::sin/std::cos constexpr-friendly.

E std::sin and std::cos cannot be used inside templates, making signal generation impossible.

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Upvotes Newest Oldest

JoeTrainor

Score: 0 | 2 years ago | 1 reply

When would someone use constexpr verse consteval?

amar_mahmutbegovicSpeaker

Score: 0 | 2 years ago | no reply

You would use consteval to enforce compile-time evaluation. Calling consteval function with run-time arguments would result in compile error.
Constexpr functions can be used both with const expressions and run-time arguments.

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