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Preparing for the Future of Embedded C Programming: An Overview of the Upcoming ISO/IEC 9899:2023 C Standard
Niall Cooling - Watch Now - Duration: 46:04
The ISO/IEC 9899:2023 C programming standard (C23) has been finalised and is set to release in the near future, and it is expected to bring several changes and improvements to the language. This talk is specifically aimed at embedded C programmers, who will benefit from understanding the changes in the upcoming standard.
The talk will begin by providing an overview of the significant changes and improvements that the new standard will introduce (with a quick review of C11 and C18) of interest to the embedded programmer. Many changes include an aim to “harmonize” with modern C++ and improve code interoperability. The presentation will also cover the potential challenges and issues that embedded C programmers may face when migrating to the new standard. This will include an overview of the potential compatibility issues and the need to update existing code and development practices.
The talk will conclude by highlighting the benefits that embedded C programmers can expect from adopting the new standard, including increased reliability, and reduced development time and costs.
The overall goal of the presentation is to provide embedded C programmers with a comprehensive understanding of the upcoming changes to the C programming language and how it will impact their work.
Unfortunately we don't have any guarantees as the standard works to a conceptual 'abstract machine'. There is no concept of Flash/RAM etc., only the lifetime and immutability concepts. It will depend on the allocation to the memory sections by the compiler/linker and then how we can map them to our actual memory implementation. Nevertheless, you would expect a compiler will map constexpr object to .rodata (or similar) which we can then place in Flash. So it's the same approach as current 'static const' data in C, but with better guarantees than simple 'const'. Hope that helps?
It does, thanks!
Nicely done, Niall; thank you very much for the talk. Question on 'attribute' syntax used in your slides: is the double bracket [[attrib]] syntax meant to be generic, or are the "[[" and "]]" required? (I'm thinking of gcc's __attribute__((attribute-list)) syntax--will gnu have to change?)
Hi, Thanks for the nice feedback.
The syntax (as per modern C++) is [[ attribute-list ]] where the list can be a comma separated list and is intended to be generic across all toolchains in an attempt to replace different compilers (e.g. GCC and __attribute__ etc.) and various pragma's being use for the same concept. The idea is the gnu syntax will be deprecated and replaced with the attribute specifier. The benefit of C23 adopting it is that C++ has been using it since C++11 and will help where we have mixed C and C++ (as per most embedded C++ applications). Cheers Niall.
Thanks for the talk, Niall! In discussing constexpr you mentioned a motivation being that embedded programmers would like to be able to ensure that some piece of data is stored in Flash but I didn't catch if constexpr actually guarantees that. Could you clarify that for me?