Struct DmaRxStreamBuf 

pub struct DmaRxStreamBuf { /* private fields */ }

Available on crate feature unstable only.

DMA Streaming Receive Buffer.

This is a contiguous buffer linked together by DMA descriptors, and the buffer is evenly distributed between each descriptor provided.

It is used for continuously streaming data from a peripheral’s FIFO.

It maintains a sliding window of descriptors that progresses when DmaRxStreamBufView::consume is called.

The list starts out like so A (empty) -> B (empty) -> C (empty) -> D (empty) -> NULL.

As the DMA writes to the buffers the list progresses like so:

• A (empty) -> B (empty) -> C (empty) -> D (empty) -> NULL
• A (full) -> B (empty) -> C (empty) -> D (empty) -> NULL
• A (full) -> B (full) -> C (empty) -> D (empty) -> NULL
• A (full) -> B (full) -> C (full) -> D (empty) -> NULL

As DmaRxStreamBufView::consume is called, the list (approximately) progresses like so:

• A (full) -> B (full) -> C (full) -> D (empty) -> NULL
• B (full) -> C (full) -> D (empty) -> A (empty) -> NULL
• C (full) -> D (empty) -> A (empty) -> B (empty) -> NULL
• D (empty) -> A (empty) -> B (empty) -> C (empty) -> NULL

If all the descriptors fill up, the DmaRxInterrupt::DescriptorEmpty interrupt fires and the DMA stops writing. The transfer must then be resumed or restarted.

This buffer does not indicate when this condition occurs. Check with the driver to see if the DMA has stopped.

When constructing this buffer, tune the ratio between the chunk size and buffer size appropriately. Smaller chunk sizes mean data is received more frequently, but the DMA interrupts (DmaRxInterrupt::Done) also fire more frequently when they are used.

See DmaRxStreamBufView for APIs available while a transfer is in progress.

Implementations

impl DmaRxStreamBuf

pub fn new( descriptors: DmaAlignedMut<'static, [DmaDescriptor]>, buffer: DmaAlignedMut<'static, [u8]>, ) -> Result<Self, DmaBufError>

Creates a new DmaRxStreamBuf evenly distributing the buffer between the provided descriptors.

pub fn split( self, ) -> (DmaAlignedMut<'static, [DmaDescriptor]>, DmaAlignedMut<'static, [u8]>)

Consumes the buf, returning the descriptors and buffer.

Trait Implementations

impl Debug for DmaRxStreamBuf

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

Formats the value using the given formatter.

impl DmaRxBuffer for DmaRxStreamBuf

type View = DmaRxStreamBufView

A type providing operations that are safe to perform on the buffer while the DMA is actively using it.

type Final = DmaRxStreamBuf

The type returned when a transfer finishes.

fn prepare(&mut self) -> Preparation

Prepares the buffer for an imminent transfer and returns information required to use this buffer.

fn into_view(self) -> DmaRxStreamBufView

This is called before the DMA starts using the buffer.

fn from_view(view: Self::View) -> Self

This is called after the DMA is done using the buffer.