ringbuf

ringbuf is a lock-free, single producer/single consumer (SPSC) ring buffer/circular buffer implementation using C11 atomics.

Its aim is to be as simple as possible, while being correct. So no fancy look ahead functions, memory reserving or similar.

ringbuf consists of 4 functions new, read, write, and free.

The backing buffer consists of an uint8_t array of user specified size. All read and write operations copy either from or to this buffer.

ringbuf is non-blocking for both read and write operations. read and write operations will return the number of bytes read/written.

ringbuf does partial read and write depending on how full/empty the ring buffer is and how big the user supplied buffers are.

ringbuf was originally developed for audio applications, aiding in the separation of audio decoding and PCM output.

Usage

To use the single file header library simply drop ringbuf.h into your source directory and include it.

#include "ringbuf.h"

Then create a ringbuf instance. The size will be rounded up to the next power of 2.

struct ringbuf * ringbuf_new(size_t capacity);

Now create your producer and consumer threads. The producer can now write to the buffer by calling ringbuf_write.

size_t ringbuf_write(struct ringbuf *rb, uint8_t *buf, size_t buf_size);

Make sure to check the returned size, as it might be smaller than buf_size depending on how full the ring buffer is.

On the consumer thread you can now read from the ring buffer by calling ringbuf_read.

size_t ringbuf_read(struct ringbuf *rb, uint8_t *buf, size_t buf_size);

This will read a maximum of buf_size bytes into the buffer buf, depending on how full the ring buffer is. Check the return value on how many bytes were actually copied.

Once all operations have completed make sure to free the ring buffer by calling:

void ringbuf_free(struct ringbuf *rb);

Dependencies

Runtime

• A C11 compatible compiler with C11 atomics support

Test

• Cmocka

License

ISC license, see the LICENSE file for more details.