Tag: C

When writing a freestanding application, it’s generally necessary for the firmware engineer to handle runtime initialization. Even when a library like newlib includes a rudimentary implementation of crt0.o, initialization is a very application-specific process owing to the need to initialize hardware, memory, and other loading tasks.

In this essay, we examine the current and historical implementation of executable initialization, finishing with a minimal implementation usable with firmware applications.

Note: Most firmware applications need to address the initialization of .data and .bss from nonvolatile memory. That is not addressed in this essay.

Inline functions are a notable feature of both C and C++. By exposing the source file to the implementation of a function, they allow a variety of optimization techniques that wouldn’t be possible if it had to call out to a subroutine in a different file (at least without link-time optimization).

However, despite the common syntax, the C and C++ languages implement them in very different ways. While C++ takes a “user friendly” approach and automatically manages the manipulation of multiple implementations, C requires a more manual approach. As a result, inline functions are less common in C and mixed language code, generally using the nuclear option of declaring them static.