# xalloc

[<img src="https://docs.rs/xalloc/badge.svg" alt="docs.rs">](https://docs.rs/xalloc/)

Dynamic suballocators for external memory (e.g., Vulkan device memory).

## Provided Algorithms

### Generic

|               Name              | Time Complexity |  Space Complexity |
| ------------------------------- | --------------- | ----------------- |
| TLSF (Two-Level Segregated Fit) | `O(1)`          | `O(N + log size)` |
| Free space bitmap               | `O(size)`       | `O(size)`         |

### Specialized

|               Name              | Time Complexity |  Space Complexity |
| ------------------------------- | --------------- | ----------------- |
| Ring buffer                     | `O(1)`          | `O(N)`            |

(`size`: heap size measured by the number of allocation units, `N`: number of allocations)

## Examples

```rust
use xalloc::{SysTlsf, SysTlsfRegion};
let mut tlsf = xalloc::SysTlsf::new(8u32);

// Allocate regions
let alloc1: (SysTlsfRegion, u32) = tlsf.alloc(4).unwrap();
let alloc2: (SysTlsfRegion, u32) = tlsf.alloc(4).unwrap();
let (region1, offset1) = alloc1;
let (region2, offset2) = alloc2;
println!("allocated #1: {:?}", (&region1, offset1));
println!("allocated #2: {:?}", (&region2, offset2));

// Deallocate a region
tlsf.dealloc(region1).unwrap();

// Now we can allocate again
tlsf.alloc(2).unwrap();
tlsf.alloc(2).unwrap();
```

## Feature Flags

- `nightly` — Enables optimizations which currently require a Nightly Rust
  compiler. This flag is now unused due to the [stabilization] of `NonNull`
  in Rust 1.25.

[stabilization]: https://blog.rust-lang.org/2018/03/29/Rust-1.25.html


License: MIT