Struct FrameAllocator 

pub struct FrameAllocator<const ORDER: usize = 33> { /* private fields */ }

A frame allocator that uses buddy system, requiring a global allocator.

The max order of the allocator is determined by the const generic parameter ORDER (MAX_ORDER = ORDER - 1). The frame allocator will only be able to allocate ranges of size up to 2^MAX_ORDER, out of a total range of size at most 2^{MAX_ORDER + 1} - 1.

Usage

Create a frame allocator and add some frames to it:

use buddy_system_allocator::*;
// Notice that the max order is `ORDER - 1`.
let mut frame = FrameAllocator::<33>::new();
assert!(frame.alloc(1).is_none());

frame.add_frame(0, 3);
let num = frame.alloc(1);
assert_eq!(num, Some(2));
let num = frame.alloc(2);
assert_eq!(num, Some(0));

Implementations

impl<const ORDER: usize> FrameAllocator<ORDER>

pub const fn new() -> Self

Create an empty frame allocator

pub fn add_frame(&mut self, start: usize, end: usize)

Add a range of frame number [start, end) to the allocator

pub fn insert(&mut self, range: Range<usize>)

Add a range of frames to the allocator.

pub fn alloc(&mut self, count: usize) -> Option<usize>

Allocate a range of frames from the allocator, returning the first frame of the allocated range.

pub fn alloc_aligned(&mut self, layout: Layout) -> Option<usize>

Allocate a range of frames with the given size and alignment from the allocator, returning the first frame of the allocated range. The allocated size is the maximum of the next power of two of the given size and the alignment.

pub fn dealloc(&mut self, start_frame: usize, count: usize)

Deallocate a range of frames [frame, frame+count) from the frame allocator.

The range should be exactly the same when it was allocated, as in heap allocator

pub fn dealloc_aligned(&mut self, start_frame: usize, layout: Layout)

Deallocate a range of frames which was previously allocated by [alloc_aligned].

The layout must be exactly the same as when it was allocated.

Trait Implementations

impl<const ORDER: usize> Default for FrameAllocator<ORDER>

fn default() -> Self

Returns the “default value” for a type.