# Slice Ring Buffer
[][documentation]
[](https://crates.io/crates/slice_ring_buf)
[](https://github.com/BillyDM/slice_ring_buf/blob/master/LICENSE)
A ring buffer implementation optimized for working with slices. Note this pretty much does the same thing as [`VecDeque`], but with the added ability to index using negative values, as well as working with buffers allocated on the stack. This crate can also be used without the standard library (`#![no_std]`).
This crate has no consumer/producer logic, and is meant to be used for DSP or as a base for other data structures.
This data type is optimized for manipulating data in chunks with slices. Indexing one element at a time is slow. If your algorithm indexes elements one at a time and only uses buffers that have a size equal to a power of two, then consider my crate [`bit_mask_ring_buf`].
## Example
```rust
use core::num::NonZeroUsize;
use slice_ring_buf::{SliceRB, SliceRbRefMut};
// Create a ring buffer with type u32. The data will be
// initialized with the value of `0`.
let mut rb = SliceRB::<u32>::new(NonZeroUsize::new(4).unwrap(), 0);
// Memcpy data from a slice into the ring buffer at arbitrary
// `isize` indexes. Earlier data will not be copied if it will
// be overwritten by newer data, avoiding unecessary memcpy's.
// The correct placement of the newer data will still be preserved.
rb.write_latest(&[0, 2, 3, 4, 1], 0);
assert_eq!(rb[0], 1);
assert_eq!(rb[1], 2);
assert_eq!(rb[2], 3);
assert_eq!(rb[3], 4);
// Memcpy into slices at arbitrary `isize` indexes and length.
let mut read_buffer = [0u32; 7];
rb.read_into(&mut read_buffer, 2);
assert_eq!(read_buffer, [3, 4, 1, 2, 3, 4, 1]);
// Read/write by retrieving slices directly.
let (s1, s2) = rb.as_slices_len(1, 4);
assert_eq!(s1, &[2, 3, 4]);
assert_eq!(s2, &[1]);
// Read/write to buffer by indexing. (Note that indexing
// one element at a time is slow.)
rb[0] = 0;
rb[1] = 1;
rb[2] = 2;
rb[3] = 3;
// Wrap when reading/writing outside of bounds.
assert_eq!(rb[-1], 3);
assert_eq!(rb[10], 2);
// Aligned/stack data may also be used.
let mut stack_data = [0u32, 1, 2, 3];
let mut rb_ref = SliceRbRefMut::new(&mut stack_data);
rb_ref[-4] = 5;
let (s1, s2) = rb_ref.as_slices_len(0, 3);
assert_eq!(s1, &[5, 1, 2]);
assert_eq!(s2, &[]);
```
[documentation]: https://docs.rs/slice_ring_buf/
[`VecDeque`]: https://doc.rust-lang.org/std/collections/struct.VecDeque.html
[`bit_mask_ring_buf`]: https://crates.io/crates/bit_mask_ring_buf/