LwRB

group LWRB

Lightweight ring buffer manager.

Defines

LWRB_VOLATILE

Enable buffer structure pointer parameters as volatile To use this feature, uncomment keyword below, or define in global compiler settings.

LWRB_USE_MAGIC

Adds 2 magic words to make sure if memory is corrupted application can detect wrong data pointer and maximum size.

Typedefs

typedef void (*lwrb_evt_fn)(struct lwrb *buff, lwrb_evt_type_t evt, size_t bp)

Event callback function type.

Parameters

  • buff – [in] Buffer handle for event

  • evt – [in] Event type

  • bp – [in] Number of bytes written or read (when used), depends on event type

Enums

enum lwrb_evt_type_t

Event type for buffer operations.

Values:

enumerator LWRB_EVT_READ

Read event

enumerator LWRB_EVT_WRITE

Write event

enumerator LWRB_EVT_RESET

Reset event

Functions

uint8_t lwrb_init(lwrb_t *buff, void *buffdata, size_t size)

Initialize buffer handle to default values with size and buffer data array.

Parameters

  • buff – [in] Buffer handle

  • buffdata – [in] Pointer to memory to use as buffer data

  • size – [in] Size of buffdata in units of bytes Maximum number of bytes buffer can hold is size - 1

Returns

1 on success, 0 otherwise

uint8_t lwrb_is_ready(lwrb_t *buff)

Check if buff is initialized and ready to use.

Parameters

buff – [in] Buffer handle

Returns

1 if ready, 0 otherwise

void lwrb_free(lwrb_t *buff)

Free buffer memory.

Note

Since implementation does not use dynamic allocation, it just sets buffer handle to NULL

Parameters

buff – [in] Buffer handle

void lwrb_reset(lwrb_t *buff)

Resets buffer to default values. Buffer size is not modified.

Note

This function is not thread safe. When used, application must ensure there is no active read/write operation

Parameters

buff – [in] Buffer handle

void lwrb_set_evt_fn(lwrb_t *buff, lwrb_evt_fn fn)

Set event function callback for different buffer operations.

Parameters

  • buff – [in] Buffer handle

  • evt_fn – [in] Callback function

size_t lwrb_write(lwrb_t *buff, const void *data, size_t btw)

Write data to buffer. Copies data from data array to buffer and marks buffer as full for maximum btw number of bytes.

Parameters

  • buff – [in] Buffer handle

  • data – [in] Pointer to data to write into buffer

  • btw – [in] Number of bytes to write

Returns

Number of bytes written to buffer. When returned value is less than btw, there was no enough memory available to copy full data array

size_t lwrb_read(lwrb_t *buff, void *data, size_t btr)

Read data from buffer. Copies data from buffer to data array and marks buffer as free for maximum btr number of bytes.

Parameters

  • buff – [in] Buffer handle

  • data – [out] Pointer to output memory to copy buffer data to

  • btr – [in] Number of bytes to read

Returns

Number of bytes read and copied to data array

size_t lwrb_peek(lwrb_t *buff, size_t skip_count, void *data, size_t btp)

Read from buffer without changing read pointer (peek only)

Parameters

  • buff – [in] Buffer handle

  • skip_count – [in] Number of bytes to skip before reading data

  • data – [out] Pointer to output memory to copy buffer data to

  • btp – [in] Number of bytes to peek

Returns

Number of bytes peeked and written to output array

size_t lwrb_get_free(lwrb_t *buff)

Get available size in buffer for write operation.

Parameters

buff – [in] Buffer handle

Returns

Number of free bytes in memory

size_t lwrb_get_full(lwrb_t *buff)

Get number of bytes currently available in buffer.

Parameters

buff – [in] Buffer handle

Returns

Number of bytes ready to be read

void *lwrb_get_linear_block_read_address(lwrb_t *buff)

Get linear address for buffer for fast read.

Parameters

buff – [in] Buffer handle

Returns

Linear buffer start address

size_t lwrb_get_linear_block_read_length(lwrb_t *buff)

Get length of linear block address before it overflows for read operation.

Parameters

buff – [in] Buffer handle

Returns

Linear buffer size in units of bytes for read operation

size_t lwrb_skip(lwrb_t *buff, size_t len)

Skip (ignore; advance read pointer) buffer data Marks data as read in the buffer and increases free memory for up to len bytes.

Note

Useful at the end of streaming transfer such as DMA

Parameters

  • buff – [in] Buffer handle

  • len – [in] Number of bytes to skip and mark as read

Returns

Number of bytes skipped

void *lwrb_get_linear_block_write_address(lwrb_t *buff)

Get linear address for buffer for fast read.

Parameters

buff – [in] Buffer handle

Returns

Linear buffer start address

size_t lwrb_get_linear_block_write_length(lwrb_t *buff)

Get length of linear block address before it overflows for write operation.

Parameters

buff – [in] Buffer handle

Returns

Linear buffer size in units of bytes for write operation

size_t lwrb_advance(lwrb_t *buff, size_t len)

Advance write pointer in the buffer. Similar to skip function but modifies write pointer instead of read.

Note

Useful when hardware is writing to buffer and application needs to increase number of bytes written to buffer by hardware

Parameters

  • buff – [in] Buffer handle

  • len – [in] Number of bytes to advance

Returns

Number of bytes advanced for write operation

struct lwrb_t
#include <lwrb.h>

Buffer structure.

Public Members

uint32_t magic1

Magic 1 word

uint8_t *buff

Pointer to buffer data. Buffer is considered initialized when buff != NULL and size > 0

LWRB_VOLATILE size_t size

Size of buffer data. Size of actual buffer is 1 byte less than value holds

LWRB_VOLATILE size_t r

Next read pointer. Buffer is considered empty when r == w and full when w == r - 1

LWRB_VOLATILE size_t w

Next write pointer. Buffer is considered empty when r == w and full when w == r - 1

lwrb_evt_fn evt_fn

Pointer to event callback function

uint32_t magic2

Magic 2 word