Circular Buffers

A circular buffer that will automatically increase in size as necessary as data is pushed to the front or back.

Deprecated since version 30.1: Replaced by Double-Ended Queue

#include <util/circlebuf.h>

Circular Buffer Structure (struct circlebuf)

struct circlebuf
void *circlebuf.data
size_t circlebuf.size
size_t circlebuf.start_pos
size_t circlebuf.end_pos
size_t circlebuf.capacity

Circular Buffer Inline Functions

void circlebuf_init(struct circlebuf *cb)

Initializes a circular buffer (just zeroes out the entire structure).

Parameters:

  • cb – The circular buffer

void circlebuf_free(struct circlebuf *cb)

Frees a circular buffer.

Parameters:

  • cb – The circular buffer

void circlebuf_reserve(struct circlebuf *cb, size_t capacity)

Reserves a specific amount of buffer space to ensure minimum upsizing.

Parameters:

  • cb – The circular buffer

  • capacity – The new capacity, in bytes

void circlebuf_upsize(struct circlebuf *cb, size_t size)

Sets the current active (not just reserved) size. Any new data is zeroed.

Parameters:

  • cb – The circular buffer

  • size – The new size, in bytes

void circlebuf_place(struct circlebuf *cb, size_t position, const void *data, size_t size)

Places data at a specific positional index (relative to the starting point) within the circular buffer.

Parameters:

  • cb – The circular buffer

  • position – Positional index relative to starting point

  • data – Data to insert

  • size – Size of data to insert

void circlebuf_push_back(struct circlebuf *cb, const void *data, size_t size)

Pushes data to the end of the circular buffer.

Parameters:

  • cb – The circular buffer

  • data – Data

  • size – Size of data

void circlebuf_push_front(struct circlebuf *cb, const void *data, size_t size)

Pushes data to the front of the circular buffer.

Parameters:

  • cb – The circular buffer

  • data – Data

  • size – Size of data

void circlebuf_push_back_zero(struct circlebuf *cb, size_t size)

Pushes zeroed data to the end of the circular buffer.

Parameters:

  • cb – The circular buffer

  • size – Size

void circlebuf_push_front_zero(struct circlebuf *cb, size_t size)

Pushes zeroed data to the front of the circular buffer.

Parameters:

  • cb – The circular buffer

  • size – Size

void circlebuf_peek_front(struct circlebuf *cb, void *data, size_t size)

Peeks data at the front of the circular buffer.

Parameters:

  • cb – The circular buffer

  • data – Buffer to store data in

  • size – Size of data to retrieve

void circlebuf_peek_back(struct circlebuf *cb, void *data, size_t size)

Peeks data at the back of the circular buffer.

Parameters:

  • cb – The circular buffer

  • data – Buffer to store data in

  • size – Size of data to retrieve

void circlebuf_pop_front(struct circlebuf *cb, void *data, size_t size)

Pops data from the front of the circular buffer.

Parameters:

  • cb – The circular buffer

  • data – Buffer to store data in, or NULL

  • size – Size of data to retrieve

void circlebuf_pop_back(struct circlebuf *cb, void *data, size_t size)

Pops data from the back of the circular buffer.

Parameters:

  • cb – The circular buffer

  • data – Buffer to store data in, or NULL

  • size – Size of data to retrieve

void *circlebuf_data(struct circlebuf *cb, size_t idx)

Gets a direct pointer to data at a specific positional index within the circular buffer, relative to the starting point.

Parameters:

  • cb – The circular buffer

  • idx – Byte index relative to the starting point