Struct SpscFrameRing 

pub struct SpscFrameRing<const N: usize, const BYTES: usize> { /* private fields */ }

A fixed-capacity SPSC FIFO of BYTES-sized frames for the ISR-to-pipeline capture hand-off. N slots live inline (no alloc); usable capacity is N - 1 (one slot separates a full ring from an empty one), so N >= 2, and N >= 3 gives a double-buffer plus one frame in flight.

Implementations

impl<const N: usize, const BYTES: usize> SpscFrameRing<N, BYTES>

pub const fn new() -> Self

Build an empty ring. const, so it lives in a static (the DMA-ring idiom) shared between the producer ISR and the consumer. N >= 2.

pub const fn capacity(&self) -> usize

Slot count (the const N); usable capacity is N - 1.

pub fn overruns(&self) -> u32

Full-ring events: produce calls that found no free slot. For the canonical ISR producer (one attempt per frame, no retry) this is the count of frames dropped to back-pressure.

pub fn is_empty(&self) -> bool

True if the ring currently holds no published frames.

pub fn produce( &self, fill: impl FnOnce(&mut [u8; BYTES]), ) -> Result<(), Overrun>

PRODUCER side (call from exactly one context, e.g. a DMA-completion ISR): fill the next free slot via fill and publish it to the consumer.

Returns Err(Overrun) if the ring is full (the consumer is behind): the frame is dropped and counted, never blocked on, because a producer in an interrupt cannot wait.

pub fn borrow(&self) -> Option<SystemSlice>

CONSUMER side: borrow the oldest published frame zero-copy as a SystemSlice, or None if the ring is empty. The borrow aliases the ring slot (no copy); it stays valid until release advances past it.

Contract: borrow at most one frame at a time and [release] it before the next borrow, after the frame (and its slice) is dropped, the single-frame- in-flight discipline the static runners already follow (each frame is dropped before the next next()). Releasing a still-referenced slice would let the producer reuse the slot under the reader.

Not built under --cfg loom: the lend hands out a raw pointer that outlives any scoped cell access, which loom’s UnsafeCell cannot model. The loom consumer reads through [Self::loom_peek0] instead.

pub fn release(&self)

CONSUMER side: reclaim the slot last returned by [borrow], freeing it for the producer to refill. Call once per consumed frame, after the frame is dropped. A release with nothing borrowed is a no-op.

Trait Implementations

impl<const N: usize, const BYTES: usize> Debug for SpscFrameRing<N, BYTES>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<const N: usize, const BYTES: usize> Default for SpscFrameRing<N, BYTES>

fn default() -> Self

Returns the “default value” for a type.

impl<const N: usize, const BYTES: usize> Sync for SpscFrameRing<N, BYTES>