circular_buffer.h File Reference

Fast circular buffer. More...

#include <stdint.h>
#include <stdbool.h>

Go to the source code of this file.

Data Structures
struct	_circular_buffer
	Implementation of a circular buffer. More...

Typedefs
typedef _circular_buffer *	circular_buffer
	The public interface type is a pointer to the implementation.

Functions
static uint32_t	_circular_buffer_next (circular_buffer buffer, uint32_t current)
	Get the index of the next position in the buffer from the given value.
static bool	_circular_buffer_not_empty (circular_buffer buffer)
	Get whether the buffer is not empty.
static bool	_circular_buffer_not_full (circular_buffer buffer, uint32_t next)
	Get whether the buffer is able to accept more values.
circular_buffer	circular_buffer_initialize (uint32_t size)
	Create a new FIFO circular buffer of at least the given size. For efficiency, the buffer can be bigger than requested.
static bool	circular_buffer_add (circular_buffer buffer, uint32_t item)
	Add an item to an existing buffer.
static bool	circular_buffer_get_next (circular_buffer buffer, uint32_t *item)
	Get the next item from an existing buffer.
static bool	circular_buffer_advance_if_next_equals (circular_buffer buffer, uint32_t item)
	Advance the buffer if the next item is equal to the given value.
static uint32_t	circular_buffer_size (circular_buffer buffer)
	Get the size of the buffer.
static uint32_t	circular_buffer_get_n_buffer_overflows (circular_buffer buffer)
	Get the number of overflows that have occurred when adding to the buffer.
static void	circular_buffer_clear (circular_buffer buffer)
	Clear the circular buffer.
void	circular_buffer_print_buffer (circular_buffer buffer)
	Print the contents of the buffer.
static uint32_t	circular_buffer_input (circular_buffer buffer)
	Get the input index.
static uint32_t	circular_buffer_output (circular_buffer buffer)
	Get the output index.
static uint32_t	circular_buffer_real_size (circular_buffer buffer)
	Get the buffer size.
static uint32_t	circular_buffer_value_at_index (circular_buffer buffer, uint32_t index)
	Get the buffer contents at a particular index.

Detailed Description

Fast circular buffer.

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Data Structure Documentation

_circular_buffer

struct _circular_buffer

Implementation of a circular buffer.

Data Fields
uint32_t	buffer_size	The size of the buffer. One less than a power of two.
uint32_t	output	The index of the next position in the buffer to read from.
uint32_t	input	The index of the next position in the buffer to write to.
uint32_t	overflows	The number of times an insertion has failed due to the buffer being full.
uint32_t	buffer[]	The buffer itself.

Function Documentation

_circular_buffer_next()

static uint32_t _circular_buffer_next ( circular_buffer  buffer, uint32_t  current  )

inlinestatic

Get the index of the next position in the buffer from the given value.

Parameters

[in]	buffer	The buffer.
[in]	current	The index to get the next one after.

Returns

The next index after the given one.

_circular_buffer_not_empty()

static bool _circular_buffer_not_empty ( circular_buffer  buffer )

inlinestatic

Get whether the buffer is not empty.

Parameters

[in]

buffer

The buffer.

Returns

Whether the buffer has anything in it.

_circular_buffer_not_full()

static bool _circular_buffer_not_full ( circular_buffer  buffer, uint32_t  next  )

inlinestatic

Get whether the buffer is able to accept more values.

Parameters

[in]	buffer	The buffer.
[in]	next	The next position in the buffer

Returns

Whether the buffer has room to take another value.

circular_buffer_initialize()

circular_buffer circular_buffer_initialize

(

uint32_t

size

)

Create a new FIFO circular buffer of at least the given size. For efficiency, the buffer can be bigger than requested.

Parameters

[in]

size

The minimum number of elements in the buffer to be created

Returns

A reference to the created buffer.

circular_buffer_add()

static bool circular_buffer_add ( circular_buffer  buffer, uint32_t  item  )

inlinestatic

Add an item to an existing buffer.

Parameters

[in]	buffer	The buffer struct to add to
[in]	item	The item to add.

Returns

Whether the item was added (it fails if the buffer is full).

circular_buffer_get_next()

static bool circular_buffer_get_next ( circular_buffer  buffer, uint32_t *  item  )

inlinestatic

Get the next item from an existing buffer.

Parameters

[in]	buffer	The buffer to get the next item from.
[out]	item	The retrieved item.

Returns

Whether an item was retrieved.

circular_buffer_advance_if_next_equals()

static bool circular_buffer_advance_if_next_equals ( circular_buffer  buffer, uint32_t  item  )

inlinestatic

Advance the buffer if the next item is equal to the given value.

Parameters

[in]	buffer	The buffer to advance
[in]	item	The item to check

Returns

Whether the buffer was advanced.

circular_buffer_size()

static uint32_t circular_buffer_size ( circular_buffer  buffer )

inlinestatic

Get the size of the buffer.

Parameters

[in]

buffer

The buffer to get the size of

Returns

The number of elements currently in the buffer

circular_buffer_get_n_buffer_overflows()

static uint32_t circular_buffer_get_n_buffer_overflows ( circular_buffer  buffer )

inlinestatic

Get the number of overflows that have occurred when adding to the buffer.

Parameters

[in]

buffer

The buffer to check for overflows

Returns

The number of times add was called and returned False

circular_buffer_clear()

static void circular_buffer_clear ( circular_buffer  buffer )

inlinestatic

Clear the circular buffer.

Parameters

[in]

buffer

The buffer to clear

circular_buffer_print_buffer()

void circular_buffer_print_buffer

(

circular_buffer

buffer

)

Print the contents of the buffer.

Do not use if the sark IO_BUF is being used for binary data.

Parameters

[in]

buffer

The buffer to print

circular_buffer_input()

static uint32_t circular_buffer_input ( circular_buffer  buffer )

inlinestatic

Get the input index.

Parameters

[in]

buffer

The buffer.

Returns

The index that the next value to be put into the buffer will be placed at.

circular_buffer_output()

static uint32_t circular_buffer_output ( circular_buffer  buffer )

inlinestatic

Get the output index.

Parameters

[in]

buffer

The buffer.

Returns

The index that the next value to be removed from the buffer is/will be at.

circular_buffer_real_size()

static uint32_t circular_buffer_real_size ( circular_buffer  buffer )

inlinestatic

Get the buffer size.

Parameters

[in]

buffer

The buffer.

Returns

The real size of the buffer.

circular_buffer_value_at_index()

static uint32_t circular_buffer_value_at_index ( circular_buffer  buffer, uint32_t  index  )

inlinestatic

Get the buffer contents at a particular index.

Parameters

[in]	buffer	The buffer.
[in]	index	The index to use. Note that the index is not limited to the size of the buffer.

Returns

The contents of the buffer at a particular index.