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Implementing Your Own C++ Atomics - Ben Saks - CppCon 2025
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Atomic objects are extremely useful for concurrent programming. Unfortunately, some embedded toolchains like AVR-GCC omit portions of the C++ Standard Library, including headers like ＜atomic＞ .This makes it much harder to program concurrent software on these platforms, since many tutorials and open-source libraries assume Standard Library support. For example, these talks from past CppCons present lock-free data structures and algorithms that rely strongly on lock-free instantiations of std::atomic＜T＞: 
 
 -  Single Producer Single Consumer Lock-free FIFO From the Ground Up – Charles Frasch – CppCon 2023 
-  Introduction to Wait-free Algorithms in C++ Programming – Daniel Anderson – CppCon 2024 
-  User API & C++ Implementation of a Multi Producer, Multi Consumer, Lock Free, Atomic Queue – Erez Strauss – CppCon 2024
 
This session will show you how to implement your own atomic types in the absence of library support. These atomic types can greatly expand the number of tutorials and open-source libraries available for you to use. A clear understanding of how atomic types are implemented will also help you use objects of those types more effectively on platforms that do provide native support. 
 
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Slides: https://github.com/CppCon/CppCon2025/blob/main/Presentations/Implementing_Your_Own_Atomics.pdf

Work at Hudson River Trading (HRT): https://tinyurl.com/safxfctf
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Ben Saks
 
Ben Saks is the chief engineer of Saks & Associates, which offers training and consulting in C and C++ and their use in developing embedded systems. Ben has represented Saks & Associates on the ISO C++ Standards committee as well as two of the committee’s study groups: SG14 (low-latency) and SG20 (education). He has spoken at industry conferences, including the C++ and System Software Summit, the Embedded Systems Conference, NDC Techtown, and CppCon, where he’s also chair of the Embedded Track and a member of the program committee. Ben previously worked as a software engineer for Vorne Industries, where he used C++ and JavaScript to develop embedded systems that help improve manufacturing productivity in factories all over the world. He’s also a contributing author on multiple Vorne patents.
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#cpp #cplusplus #programming #coding #softwareengineering

ISO C++ is the official website for the C++ programming language standardization committee, providing information, resources, and updates on the evolution of the C++ language. With a focus on language features, library enhancements, and standardization efforts, ISO C++ keeps developers informed about the latest developments in C++ programming. Developers can learn about upcoming language features, review proposals for language changes, and contribute to the evolution of the C++ language through active participation in the standardization process.

A CppCon 2025 talk by Ben Saks on implementing a custom C++ atomic class template from scratch, motivated by the Arduino Mega 2560 lacking a C++23 atomic header. The talk covers what makes an operation atomic (non-preemptability and synchronizability), demonstrates a lock-free single-producer single-consumer ring buffer using custom atomic head/tail indices, and explains three implementation strategies: disabling hardware interrupts via RAII wrappers, inline assembly with memory clobbers to establish memory barriers, and compiler intrinsic functions like GCC's __atomic_load_n/__atomic_store_n. Memory ordering concepts (acquire/release semantics) and platform-specific considerations for 8-bit vs multi-core systems are also discussed.