9 releases
0.2.2 | Dec 21, 2021 |
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0.2.1 | Dec 21, 2021 |
0.1.5 | Dec 19, 2021 |
#1756 in Embedded development
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Used in 2 crates
44KB
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Byte Slab
Byte Slab is a crate that provides a pool or slab of bytes, which can be granted in
fixed-size chunks. It is similar to heapless::Pool, however it also allows conversion
of the allocations (SlabBox
es) into shared, reference counted objects (SlabArc
s).
Currently, it maintains its free list as an MPMC queue, though that is an implementation detail that may change. This implementation is convenient, but not particularly memory-dense.
The slab is statically allocated, and the size of each Box, as well as the total number of
Boxes available is selected through compile time const
values.
Byte Slab is intended to provide boxes suitable for using as DMA buffers on bare metal embedded systems without a general purpose allocator. All allocations are failable.
Main components
The byte slab crate is made up of the following primary elements:
BSlab
- a Byte Slab. This struct represents the storage of all boxes and their related metadata.SlabBox
- An owned allocation from the BSlab, which may be read or written to (exclusively) by the owner. ASlabBox
may be converted into aSlabArc
. The underlying memory is freed for reuse automatically when the Box has been dropped.SlabArc
- A reference counted allocation from the BSlab, obtained by consuming aSlabBox
. As the underlying allocation may be shared, aSlabArc
does not allow for the contents to be modified.SlabArc
s may be cloned (which increases the reference count), allowing for multiple (immutable) access to the same data. The underlying memory is freed for reuse automatically when the reference count reaches zero.SlabSliceArc
- a reference counted view of aSlabArc
. This is used to provide a view onto a portion of aSlabArc
, without sharing the entire allocation. It shares the same reference count as the underlyingSlabArc
, meaning the underlyingSlabArc
will not be freed if there are onlySlabSliceArc
s remaining. The underlying memory is freed for reuse automatically when the reference count reaches zero.ManagedArcSlab
- a convenience type that may contain EITHER a borrowed&[u8]
slice, or aSlabSliceArc
.
Dependencies
~1.2–1.9MB
~40K SLoC