1.2 KiB
Parts of an Embedded Program
[❗️Intro ]
Open the beginner/apps folder in VS Code.
$ # or use "File > Open Folder" in VS Code
$ code beginner/apps
Then open the src/bin/hello.rs file.
If you find it more convenient to open the repository at the root then please also add the beginner/apps folder to the VS Code workspace: right click the left side panel, select "Add folder to workspace" and add the beginner/apps folder.
[❗️No optional way of doing things here]
Note the differences between this embedded program and a desktop program:
[❗️Have a non embedded program up to compare]
The #![no_std] attribute indicates that the program will not make use of the standard library, std crate. Instead it will use the core library, a subset of the standard library that does depend not on a underlying operating system (OS).
The #![no_main] attribute indicates that the program will use a custom entry point instead of the default fn main() { .. } one.
The #[entry] attribute declares the custom entry point of the program. The entry point must be a divergent function; note that the return type is the never type !. The function is not allowed to return; therefore the program is not allowed to terminate.