Crate bbqueue

BBQueue

BBQueue, short for "BipBuffer Queue", is a Single Producer Single Consumer, lockless, no_std, thread safe, queue, based on BipBuffers. For more info on the design of the lock-free algorithm used by bbqueue, see this blog post.

BBQueue is designed (primarily) to be a First-In, First-Out queue for use with DMA on embedded systems.

While Circular/Ring Buffers allow you to send data between two threads (or from an interrupt to main code), you must push the data one piece at a time. With BBQueue, you instead are granted a block of contiguous memory, which can be filled (or emptied) by a DMA engine.

Local usage

// Create a buffer with six elements
let bb: BBBuffer<U6> = BBBuffer::new();
let (mut prod, mut cons) = bb.try_split().unwrap();

// Request space for one byte
let mut wgr = prod.grant_exact(1).unwrap();

// Set the data
wgr[0] = 123;

assert_eq!(wgr.len(), 1);

// Make the data ready for consuming
wgr.commit(1);

// Read all available bytes
let rgr = cons.read().unwrap();

assert_eq!(rgr[0], 123);

// Release the space for later writes
rgr.release(1);

Static usage

// Create a buffer with six elements
static BB: BBBuffer<U6> = BBBuffer( ConstBBBuffer::new() );

fn main() {
    // Split the bbqueue into producer and consumer halves.
    // These halves can be sent to different threads or to
    // an interrupt handler for thread safe SPSC usage
    let (mut prod, mut cons) = BB.try_split().unwrap();

    // Request space for one byte
    let mut wgr = prod.grant_exact(1).unwrap();

    // Set the data
    wgr[0] = 123;

    assert_eq!(wgr.len(), 1);

    // Make the data ready for consuming
    wgr.commit(1);

    // Read all available bytes
    let rgr = cons.read().unwrap();

    assert_eq!(rgr[0], 123);

    // Release the space for later writes
    rgr.release(1);

    // The buffer cannot be split twice
    assert!(BB.try_split().is_err());
}

Modules

atomic	A version of BBQueue built on Atomic CAS capabilities. This is recommended if your platform supports it.
cm_mutex	A version of BBQueue built on Cortex-M critical sections. This is useful on thumbv6 targets (Cortex-M0, Cortex-M0+) if your platform does not support atomic compare and swaps.

Enums

Error

Error type used by the BBQueue interfaces

Traits

ArrayLength

Trait making GenericArray work, marking types to be used as length of an array

Type Definitions

Result

Result type used by the BBQueue interfaces