U128, Ordering};

let foo = AtomicU128::new(23);
assert_eq!(foo.fetch_min(42, Ordering::Relaxed), 23);
assert_eq!(foo.load(Ordering::Relaxed), 23);
assert_eq!(foo.fetch_min(22, Ordering::Relaxed), 23);
assert_eq!(foo.load(Ordering::Relaxed), 22);
```

If you want to obtain the minimum value in one step, you can use the following:

```
use portable_atomic::{AtomicU128, Ordering};

let foo = AtomicU128::new(23);
let bar = 12;
let min_foo = foo.fetch_min(bar, Ordering::SeqCst).min(bar);
assert_eq!(min_foo, 12);
```