ringbuffer.h File Reference

A utility for storing and retrieving byte data using a ring buffer. More...

Detailed Description

A utility for storing and retrieving byte data using a ring buffer.

Author

Kaspar Schleiser kaspa.nosp@m.r@sc.nosp@m.hleis.nosp@m.er.d.nosp@m.e

René Kijewski rene..nosp@m.kije.nosp@m.wski@.nosp@m.fu-b.nosp@m.erlin.nosp@m..de

The ringbuffer is useful for buffering data in the same thread context but it is not thread-safe. For a thread-safe ring buffer, see Thread safe ringbuffer in the System library.

Definition in file ringbuffer.h.

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Data Structures
struct	ringbuffer_t
	Ringbuffer. More...

Macros
#define	RINGBUFFER_INIT(BUF)   { (BUF), sizeof(BUF), 0, 0 }
	Initialize a ringbuffer.

Functions
static void	ringbuffer_init (ringbuffer_t *__restrict rb, char *buffer, unsigned bufsize)
	Initialize a ringbuffer.
int	ringbuffer_add_one (ringbuffer_t *__restrict rb, char c)
	Add an element to the ringbuffer.
unsigned	ringbuffer_add (ringbuffer_t *__restrict rb, const char *buf, unsigned n)
	Add a number of elements to the ringbuffer.
int	ringbuffer_get_one (ringbuffer_t *__restrict rb)
	Peek and remove oldest element from the ringbuffer.
unsigned	ringbuffer_get (ringbuffer_t *__restrict rb, char *buf, unsigned n)
	Read and remove a number of elements from the ringbuffer.
unsigned	ringbuffer_remove (ringbuffer_t *__restrict rb, unsigned n)
	Remove a number of elements from the ringbuffer.
static int	ringbuffer_empty (const ringbuffer_t *__restrict rb)
	Test if the ringbuffer is empty.
static int	ringbuffer_full (const ringbuffer_t *__restrict rb)
	Test if the ringbuffer is full.
static unsigned int	ringbuffer_get_free (const ringbuffer_t *__restrict rb)
	Return available space in ringbuffer.
int	ringbuffer_peek_one (const ringbuffer_t *__restrict rb)
	Read, but don't remove, the oldest element in the buffer.
unsigned	ringbuffer_peek (const ringbuffer_t *__restrict rb, char *buf, unsigned n)
	Read, but don't remove, the a number of element of the buffer.

Macro Definition Documentation

RINGBUFFER_INIT

#define RINGBUFFER_INIT

(

BUF

)

{ (BUF), sizeof(BUF), 0, 0 }

Initialize a ringbuffer.

This macro is meant for static ringbuffers.

Parameters

[in]

BUF

Buffer to use for the ringbuffer. The size is deduced through sizeof (BUF).

Returns

The static initializer.

Definition at line 50 of file ringbuffer.h.

Function Documentation

ringbuffer_add()

unsigned ringbuffer_add	(	ringbuffer_t *__restrict	rb,
		const char *	buf,
		unsigned	n
	)

Add a number of elements to the ringbuffer.

Only so many elements are added as fit in the ringbuffer. No elements get overwritten. If this is not the intended behavior, then use ringbuffer_add_one() in a loop instead.

Parameters

[in,out]	rb	Ringbuffer to operate on.
[in]	buf	Buffer to add elements from.
[in]	n	Maximum number of elements to add.

Returns

Number of elements actually added. 0 if rb is full.

ringbuffer_add_one()

int ringbuffer_add_one	(	ringbuffer_t *__restrict	rb,
		char	c
	)

Add an element to the ringbuffer.

If rb is full, then the oldest element gets overwritten. Test ringbuffer_full() first if overwriting is not intended.

Parameters

[in,out]	rb	Ringbuffer to operate on.
[in]	c	Element to add.

Returns

The element that was dropped, iff the buffer was full. -1 iff the buffer was not full.

ringbuffer_empty()

static int ringbuffer_empty ( const ringbuffer_t *__restrict  rb )

inlinestatic

Test if the ringbuffer is empty.

Parameters

[in,out]

rb

Ringbuffer to operate on.

Returns

0 iff not empty

Definition at line 120 of file ringbuffer.h.

ringbuffer_full()

static int ringbuffer_full ( const ringbuffer_t *__restrict  rb )

inlinestatic

Test if the ringbuffer is full.

Parameters

[in,out]

rb

Ringbuffer to operate on.

Returns

0 iff not full

Definition at line 130 of file ringbuffer.h.

ringbuffer_get()

unsigned ringbuffer_get	(	ringbuffer_t *__restrict	rb,
		char *	buf,
		unsigned	n
	)

Read and remove a number of elements from the ringbuffer.

Parameters

[in,out]	rb	Ringbuffer to operate on.
[out]	buf	Buffer to write into.
[in]	n	Read at most n elements.

Returns

Number of elements actually read.

ringbuffer_get_free()

static unsigned int ringbuffer_get_free ( const ringbuffer_t *__restrict  rb )

inlinestatic

Return available space in ringbuffer.

Parameters

[in,out]

rb

Ringbuffer to query.

Returns

number of available bytes

Definition at line 140 of file ringbuffer.h.

ringbuffer_get_one()

int ringbuffer_get_one

(

ringbuffer_t *__restrict

rb

)

Peek and remove oldest element from the ringbuffer.

Parameters

[in,out]

rb

Ringbuffer to operate on.

Returns

The oldest element that was added, or -1 if rb is empty.

ringbuffer_init()

static void ringbuffer_init ( ringbuffer_t *__restrict  rb, char *  buffer, unsigned  bufsize  )

inlinestatic

Initialize a ringbuffer.

Parameters

[out]	rb	Datum to initialize.
[in]	buffer	Buffer to use by rb.
[in]	bufsize	sizeof (buffer)

Definition at line 58 of file ringbuffer.h.

ringbuffer_peek()

unsigned ringbuffer_peek	(	const ringbuffer_t *__restrict	rb,
		char *	buf,
		unsigned	n
	)

Read, but don't remove, the a number of element of the buffer.

Parameters

[in]	rb	Ringbuffer to operate on.
[out]	buf	Buffer to write into.
[in]	n	Read at most n elements.

Returns

Same as ringbuffer_get()

ringbuffer_peek_one()

int ringbuffer_peek_one

(

const ringbuffer_t *__restrict

rb

)

Read, but don't remove, the oldest element in the buffer.

Parameters

[in]

rb

Ringbuffer to operate on.

Returns

Same as ringbuffer_get_one()

ringbuffer_remove()

unsigned ringbuffer_remove	(	ringbuffer_t *__restrict	rb,
		unsigned	n
	)

Remove a number of elements from the ringbuffer.

Parameters

[in,out]	rb	Ringbuffer to operate on.
[in]	n	Read at most n elements.

Returns

Number of elements actually removed.