# lv_circle_buf_private.h (/api/private/misc/lv_circle_buf_private_h) Functions [#functions] lv_circle_buf_create [#lv_circle_buf_create] Create a circle buffer ```c title=" " lineNumbers=1 lv_circle_buf_t * lv_circle_buf_create(uint32_t capacity, uint32_t element_size) ``` Parameters | Name | Type | Description | | -------------- | ---------- | -------------------------------------------- | | `capacity` | `uint32_t` | the maximum number of elements in the buffer | | `element_size` | `uint32_t` | the size of an element in bytes | **Returns:** — pointer to the created buffer lv_circle_buf_create_from_buf [#lv_circle_buf_create_from_buf] Create a circle buffer from an existing buffer ```c title=" " lineNumbers=1 lv_circle_buf_t * lv_circle_buf_create_from_buf(void *buf, uint32_t capacity, uint32_t element_size) ``` Parameters | Name | Type | Description | | -------------- | ---------- | -------------------------------------------- | | `buf` | `void *` | pointer to a buffer | | `capacity` | `uint32_t` | the maximum number of elements in the buffer | | `element_size` | `uint32_t` | the size of an element in bytes | **Returns:** — pointer to the created buffer lv_circle_buf_create_from_array [#lv_circle_buf_create_from_array] Create a circle buffer from an existing array ```c title=" " lineNumbers=1 lv_circle_buf_t * lv_circle_buf_create_from_array(const lv_array_t *array) ``` Parameters | Name | Type | Description | | ------- | ---------------------------------------------------------- | ------------------- | | `array` | | pointer to an array | **Returns:** — pointer to the created buffer lv_circle_buf_resize [#lv_circle_buf_resize] Resize the buffer ```c title=" " lineNumbers=1 lv_result_t lv_circle_buf_resize(lv_circle_buf_t *circle_buf, uint32_t capacity) ``` Parameters | Name | Type | Description | | ------------ | -------------------------------------------------------------- | ------------------------------ | | `circle_buf` | | pointer to a buffer | | `capacity` | `uint32_t` | the new capacity of the buffer | **Returns:** — LV\_RESULT\_OK: the buffer is resized; LV\_RESULT\_INVALID: the buffer is not resized lv_circle_buf_destroy [#lv_circle_buf_destroy] Destroy a circle buffer ```c title=" " lineNumbers=1 void lv_circle_buf_destroy(lv_circle_buf_t *circle_buf) ``` Parameters | Name | Type | Description | | ------------ | -------------------------------------------------------------- | ----------------- | | `circle_buf` | | pointer to buffer | lv_circle_buf_size [#lv_circle_buf_size] Get the size of the buffer ```c title=" " lineNumbers=1 uint32_t lv_circle_buf_size(const lv_circle_buf_t *circle_buf) ``` Parameters | Name | Type | Description | | ------------ | -------------------------------------------------------------------- | ----------------- | | `circle_buf` | | pointer to buffer | **Returns:** `uint32_t` — the number of elements in the buffer lv_circle_buf_capacity [#lv_circle_buf_capacity] Get the capacity of the buffer ```c title=" " lineNumbers=1 uint32_t lv_circle_buf_capacity(const lv_circle_buf_t *circle_buf) ``` Parameters | Name | Type | Description | | ------------ | -------------------------------------------------------------------- | ----------------- | | `circle_buf` | | pointer to buffer | **Returns:** `uint32_t` — the maximum number of elements in the buffer lv_circle_buf_remain [#lv_circle_buf_remain] Get the remaining space in the buffer ```c title=" " lineNumbers=1 uint32_t lv_circle_buf_remain(const lv_circle_buf_t *circle_buf) ``` Parameters | Name | Type | Description | | ------------ | -------------------------------------------------------------------- | ----------------- | | `circle_buf` | | pointer to buffer | **Returns:** `uint32_t` — the number of elements that can be written to the buffer lv_circle_buf_is_empty [#lv_circle_buf_is_empty] Check if the buffer is empty ```c title=" " lineNumbers=1 bool lv_circle_buf_is_empty(const lv_circle_buf_t *circle_buf) ``` Parameters | Name | Type | Description | | ------------ | -------------------------------------------------------------------- | ----------------- | | `circle_buf` | | pointer to buffer | **Returns:** `bool` — true: the buffer is empty; false: the buffer is not empty lv_circle_buf_is_full [#lv_circle_buf_is_full] Check if the buffer is full ```c title=" " lineNumbers=1 bool lv_circle_buf_is_full(const lv_circle_buf_t *circle_buf) ``` Parameters | Name | Type | Description | | ------------ | -------------------------------------------------------------------- | ----------------- | | `circle_buf` | | pointer to buffer | **Returns:** `bool` — true: the buffer is full; false: the buffer is not full lv_circle_buf_reset [#lv_circle_buf_reset] Reset the buffer ```c title=" " lineNumbers=1 void lv_circle_buf_reset(lv_circle_buf_t *circle_buf) ``` Parameters | Name | Type | Description | | ------------ | -------------------------------------------------------------- | ----------------- | | `circle_buf` | | pointer to buffer | lv_circle_buf_head [#lv_circle_buf_head] Get the head of the buffer ```c title=" " lineNumbers=1 void * lv_circle_buf_head(const lv_circle_buf_t *circle_buf) ``` Parameters | Name | Type | Description | | ------------ | -------------------------------------------------------------------- | ----------------- | | `circle_buf` | | pointer to buffer | **Returns:** `void *` — pointer to the head of the buffer The capacity of the buffer must be greater than 0. lv_circle_buf_tail [#lv_circle_buf_tail] Get the tail of the buffer ```c title=" " lineNumbers=1 void * lv_circle_buf_tail(const lv_circle_buf_t *circle_buf) ``` Parameters | Name | Type | Description | | ------------ | -------------------------------------------------------------------- | ----------------- | | `circle_buf` | | pointer to buffer | **Returns:** `void *` — pointer to the tail of the buffer The capacity of the buffer must be greater than 0. lv_circle_buf_read [#lv_circle_buf_read] Read a value ```c title=" " lineNumbers=1 lv_result_t lv_circle_buf_read(lv_circle_buf_t *circle_buf, void *data) ``` Parameters | Name | Type | Description | | ------------ | -------------------------------------------------------------- | --------------------------------------------- | | `circle_buf` | | pointer to buffer | | `data` | `void *` | pointer to a variable to store the read value | **Returns:** — LV\_RESULT\_OK: the value is read; LV\_RESULT\_INVALID: the value is not read lv_circle_buf_write [#lv_circle_buf_write] Write a value ```c title=" " lineNumbers=1 lv_result_t lv_circle_buf_write(lv_circle_buf_t *circle_buf, const void *data) ``` Parameters | Name | Type | Description | | ------------ | -------------------------------------------------------------- | ----------------------------- | | `circle_buf` | | pointer to buffer | | `data` | `const void *` | pointer to the value to write | **Returns:** — LV\_RESULT\_OK: the value is written; LV\_RESULT\_INVALID: the value is not written lv_circle_buf_fill [#lv_circle_buf_fill] Fill the buffer with values ```c title=" " lineNumbers=1 uint32_t lv_circle_buf_fill(lv_circle_buf_t *circle_buf, uint32_t count, lv_circle_buf_fill_cb_t fill_cb, void *user_data) ``` Parameters | Name | Type | Description | | ------------ | -------------------------------------------------------------- | ---------------------------------------- | | `circle_buf` | | pointer to buffer | | `count` | `uint32_t` | the number of values to fill | | `fill_cb` | | the callback function to fill the buffer | | `user_data` | `void *` | | **Returns:** `uint32_t` — the number of values filled lv_circle_buf_skip [#lv_circle_buf_skip] Skip a value ```c title=" " lineNumbers=1 lv_result_t lv_circle_buf_skip(lv_circle_buf_t *circle_buf) ``` Parameters | Name | Type | Description | | ------------ | -------------------------------------------------------------- | ----------------- | | `circle_buf` | | pointer to buffer | **Returns:** — LV\_RESULT\_OK: the value is skipped; LV\_RESULT\_INVALID: the value is not skipped lv_circle_buf_peek [#lv_circle_buf_peek] Peek a value ```c title=" " lineNumbers=1 lv_result_t lv_circle_buf_peek(const lv_circle_buf_t *circle_buf, void *data) ``` Parameters | Name | Type | Description | | ------------ | -------------------------------------------------------------------- | ----------------------------------------------- | | `circle_buf` | | pointer to buffer | | `data` | `void *` | pointer to a variable to store the peeked value | **Returns:** — LV\_RESULT\_OK: the value is peeked; LV\_RESULT\_INVALID: the value is not peeked lv_circle_buf_peek_at [#lv_circle_buf_peek_at] Peek a value at an index ```c title=" " lineNumbers=1 lv_result_t lv_circle_buf_peek_at(const lv_circle_buf_t *circle_buf, uint32_t index, void *data) ``` Parameters | Name | Type | Description | | ------------ | -------------------------------------------------------------------- | ----------------------------------------------------------------------------------------------------------- | | `circle_buf` | | pointer to buffer | | `index` | `uint32_t` | the index of the value to peek, if the index is greater than the size of the buffer, it will return looply. | | `data` | `void *` | pointer to a variable to store the peeked value | **Returns:** — LV\_RESULT\_OK: the value is peeked; LV\_RESULT\_INVALID: the value is not peeked The size of the buffer must be greater than 0. Typedefs [#typedefs] lv_circle_buf_t [#lv_circle_buf_t] ```c title=" " lineNumbers=1 typedef struct _lv_circle_buf_t lv_circle_buf_t ``` * `lv_circle_buf_resize` — param `circle_buf` * `lv_circle_buf_destroy` — param `circle_buf` * `lv_circle_buf_size` — param `circle_buf` * `lv_circle_buf_capacity` — param `circle_buf` * `lv_circle_buf_remain` — param `circle_buf` * `lv_circle_buf_is_empty` — param `circle_buf` * `lv_circle_buf_is_full` — param `circle_buf` * `lv_circle_buf_reset` — param `circle_buf` * `lv_circle_buf_head` — param `circle_buf` * `lv_circle_buf_tail` — param `circle_buf` * `lv_circle_buf_read` — param `circle_buf` * `lv_circle_buf_write` — param `circle_buf` * `lv_circle_buf_fill` — param `circle_buf` * `lv_circle_buf_skip` — param `circle_buf` * `lv_circle_buf_peek` — param `circle_buf` * `lv_circle_buf_peek_at` — param `circle_buf` lv_circle_buf_fill_cb_t [#lv_circle_buf_fill_cb_t] ```c title=" " lineNumbers=1 typedef bool(* lv_circle_buf_fill_cb_t) (void *buf, uint32_t buff_len, int32_t index, void *user_data) ``` * `lv_circle_buf_fill` — param `fill_cb` Dependencies [#dependencies]