CppCon 2020

Most, if not all, modern CPUs communicate with external devices via memory-mapped device registers. A memory-mapped register is circuitry that connects to a CPU’s bus structure and responds to bus signals almost as if it were ordinary memory. Almost, but not quite.

C++ programs can use C features such as pointers and casts to access memory-mapped registers. This is still widespread practice. However, traditional C techniques tend to treat memory-mapped registers more as raw storage than as objects with constrained behaviors. C idioms for accessing memory-mapped devices leave too many opportunities for programming errors and late nights with a debugger.

This session explains various C++ techniques for placing objects into memory-mapped locations and for guaranteeing proper initialization and destruction. It shows how you can use base classes and templates to capture commonalities among different devices that use similar register layouts. By applying these techniques, you’ll be able to package memory-mapped devices as lightweight class objects that are easy to use correctly and hard to use incorrectly.