Ring buffer

Lockless byte-based ring buffer using C11 atomic operations. More...

Data Structures
struct	ringbuf_t
	Ring buffer descriptor. More...

Macros
#define	RINGBUF_VAR_INIT(bufp, buf_len)
	Static initializer for a ring buffer descriptor. More...

Functions
void	ringbuf_init (ringbuf_t *rb, void *bufp, size_t buf_len)
	Runtime initializer for a ring buffer descriptor. More...
int	ringbuf_get (ringbuf_t *rb)
	Extract a byte from the ring buffer. More...
bool	ringbuf_empty (ringbuf_t *rb)
	Test whether the ring buffer contains any data. More...
bool	ringbuf_put (ringbuf_t *rb, uint8_t d)
	Insert a byte into the ring buffer. More...
void	ringbuf_putchar (void *rb, char c)
	Insert a character into the ring buffer. More...

Detailed Description

Lockless byte-based ring buffer using C11 atomic operations.

The message queue is thread safe (and SMP safe) only for one-to-one messaging. It cannot be used with multiple sender threads nor multiple receiver threads without additional locking.

Macro Definition Documentation

#define RINGBUF_VAR_INIT	(		bufp,
			buf_len
	)

Value:

{ \
                (uint8_t *) (bufp), \
                (buf_len), \
                ATOMIC_VAR_INIT(0), \
                ATOMIC_VAR_INIT(0) \
        }

Static initializer for a ring buffer descriptor.

Definition at line 48 of file ringbuf.h.

Function Documentation

bool ringbuf_empty

(

ringbuf_t *

rb

)

Test whether the ring buffer contains any data.

Returns

true if data is present, otherwise false.

Definition at line 52 of file ringbuf.c.

int ringbuf_get

(

ringbuf_t *

rb

)

Extract a byte from the ring buffer.

Returns

Unsigned byte on success, otherwise -1.

Definition at line 31 of file ringbuf.c.

void ringbuf_init	(	ringbuf_t *	rb,
		void *	bufp,
		size_t	buf_len
	)

Runtime initializer for a ring buffer descriptor.

Definition at line 22 of file ringbuf.c.

bool ringbuf_put	(	ringbuf_t *	rb,
		uint8_t	d
	)

Insert a byte into the ring buffer.

Definition at line 58 of file ringbuf.c.

void ringbuf_putchar	(	void *	rb,
		char	c
	)

Insert a character into the ring buffer.

This function is intended to be use from callback functions. For this reason the ringbuffer is passed as a void pointer (i.e. user data) and there is no return value.

Warning

This function busy waits until there is space in the ring buffer. This leaves the system at risk of deadlock if this function is called from a calling context that can pre-empt the consumer. For example if the data is consumed by an interrupt handler then this function should not be called only from higher (or equal) priority interrupt handler.

Definition at line 75 of file ringbuf.c.