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# libfringe

  libfringe is a low-level green threading library for Rust.
  It's usable in freestanding environments (like kernels),
  but it can also provide an easy-to-use stack allocator using
  your operating system's memory mapping facility.

## Performance

  libfringe does context switches in 3.5ns flat on x86_64!
```
test swap ... bench:         7 ns/iter (+/- 0)
```

  …and on x86, a mere 2.5ns!

```
test swap ... bench:         5 ns/iter (+/- 1)
```

## Limitations

  libfringe currently doesn't work on anything but x86 and x86_64,
  and is untested on anything but Linux.

## Installation

  libfringe is a [Cargo](https://crates.io) package.
  It's not stable software yet, so you'll have to use it as a git dependency.
  Add this to your `Cargo.toml`:
```toml
[dependencies.fringe]
git = "https://github.com/edef1c/libfringe.git"
```

### Feature flags

  [Cargo's feature flags]: http://doc.crates.io/manifest.html#the-[features]-section
  libfringe provides several optional features through [Cargo's feature flags].
  Currently, all of them are enabled by default.

#### `valgrind`

  [Valgrind]: http://valgrind.org
  [Valgrind] integration. libfringe will register context stacks with Valgrind.

#### `os`

  [Built-in stack allocator]: https://edef1c.github.io/libfringe/fringe/struct.OsStack.html
  [Built-in stack allocator] using your your operating system's anonymous memory mapping facility.
  Currently only available for Unix.