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https://github.com/cbiffle/lilos

A wee async RTOS for Cortex-M
https://github.com/cbiffle/lilos

Last synced: 4 days ago
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A wee async RTOS for Cortex-M

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README

        

# `lilos`: A minimal async RTOS

![crates.io published version badge](https://img.shields.io/crates/v/lilos.svg)
![docs.rs badge link](https://img.shields.io/docsrs/lilos.svg)
![CI status badge](https://github.com/cbiffle/lilos/actions/workflows/ci.yml/badge.svg)

- [Intro guide](doc/intro.adoc)
- [API Docs](https://docs.rs/lilos)
- [crates.io](https://crates.io/crates/lilos)

This is a wee operating system written to support the `async` style of
programming in Rust on microcontrollers. It fits in about 2 kiB of Flash and
uses about 40 bytes of RAM (before your tasks are added). In that space, you get
a full `async` runtime with multiple tasks, support for complex concurrency via
`join` and `select`, and a lot of convenient but simple APIs. (If you want to
see what a `lilos` program looks like, look in the `examples` directory, or read
the intro guide.)

`lilos` has been deployed in real embedded systems since 2019, running
continuously. I've built about a dozen systems around it of varying complexity,
on half a dozen varieties of microcontroller. It works pretty okay! Perhaps you
will find it useful too.

## Repo layout

This repo contains crates in subdirectories, and the subdirectories use
`.cargo/config.toml` files to change settings that Cargo has so far declined to
allow in `Cargo.toml`, such as the target triple. This means you will need to
`cd` into subdirectories to build things, rather than using `cargo build
--all`. Here is a map:

- `os` contains the operating system crate.
- `testsuite` contains a test suite for the operating system, which can run on a
Cortex-M0 or better. See [its
README](https://github.com/cbiffle/lilos/blob/main/testsuite/README.mkdn) for
instructions.
- `examples` contains example programs for various microcontrollers.
- `extra` contains a few "non-core" crates providing features that don't need to
be in the OS proper:
- `handoff` provides a synchronous rendezvous for transferring data from one
task to another with minimal copies.
- `semaphore` provides a counting semaphore implementation.
- `rwlock` provides a read-write lock implementation.

## Building

These instructions are mostly for building the examples or working on the
operating system itself. If you're trying to use `lilos` in a program, the usual
way is to just `cargo add lilos` to your application.

To build in the repo, you will need a Rust toolchain installed through `rustup`,
because we use a `rustup`-style `rust-toolchain.toml` file to pin the toolchain
version to ensure that you get the right results. `rustup` will automatically
ensure you've got the appropriate toolchain version available, including support
for the right target architecture for whatever program you're building.

1. Enter the directory you're interested in, for example, `cd os`.
2. Build: `cargo build` (or, for smaller binaries, `cargo build --release`).
3. To try an example on a microcontroller eval board, see the README in the
individual example. (In most cases `cargo run` in the directory will
suffice.)

To build everything in the repo, run `./build-all.sh`.

## Contact and License

If you have questions, or you use it for something, I'd love to find out! Send
me an email.

All the code in this repo is MPL-2 licensed.