COBS (Consistent Overhead Byte Stuffing)

COBS encoding and decoding functions with custom delimiter support. More...

Data Structures
struct	cobs_encoder
	COBS streaming encoder state. More...
struct	cobs_decoder
	COBS streaming decoder state. More...

Typedefs
typedef int(*	cobs_stream_cb) (const uint8_t *buf, size_t len, void *user_data)
	Callback function type for streaming COBS encoder/decoder.

Functions
static size_t	cobs_max_encoded_len (size_t decoded_size, uint32_t flags)
	Calculate maximum encoded buffer size.
int	cobs_encode (struct net_buf *src, struct net_buf *dst, uint32_t flags)
	COBS encoding.
int	cobs_decode (struct net_buf *src, struct net_buf *dst, uint32_t flags)
	COBS decoding.
int	cobs_encoder_init (struct cobs_encoder *enc, cobs_stream_cb cb, void *user_data, uint32_t flags)
	Initialize COBS streaming encoder.
int	cobs_encoder_close (struct cobs_encoder *enc)
	Finalize COBS streaming encoder.
int	cobs_encoder_write (struct cobs_encoder *enc, const uint8_t *buf, size_t len)
	Write data to COBS streaming encoder.
int	cobs_decoder_init (struct cobs_decoder *dec, cobs_stream_cb cb, void *user_data, uint32_t flags)
	Initialize COBS streaming decoder.
int	cobs_decoder_close (struct cobs_decoder *dec)
	Finalize COBS streaming decoder.
int	cobs_decoder_write (struct cobs_decoder *dec, const uint8_t *buf, size_t len)
	Write data to COBS streaming decoder.

Detailed Description

COBS encoding and decoding functions with custom delimiter support.

Provides functions for COBS encoding/decoding with configurable delimiters. The implementation handles both standard zero-delimited COBS and custom delimiter variants.

Typedef Documentation

cobs_stream_cb

typedef int(* cobs_stream_cb) (const uint8_t *buf, size_t len, void *user_data)

#include <zephyr/data/cobs.h>

Callback function type for streaming COBS encoder/decoder.

This callback is invoked by the streaming encoder/decoder to output processed data chunks. A decoder that allows trailing delimiters and encounters one will invoke this callback with a NULL pointer and zero length indicating a completed frame.

When this callback function returns a negative error value, the encoder or decoder stream is aborted and the error will be propagated.

Parameters

buf	Buffer containing processed data
len	Length of data in buffer
user_data	User-provided context pointer

Returns

0 on success, negative errno code on failure

Function Documentation

cobs_decode()

int cobs_decode	(	struct net_buf *	src,
		struct net_buf *	dst,
		uint32_t	flags )

#include <zephyr/data/cobs.h>

COBS decoding.

Decodes COBS-encoded data from source buffer to destination buffer.

Parameters

src	Source buffer to decode
dst	Destination buffer for decoded data
flags	Decoding flags COBS_FLAGS

Return values

0	Success
-ENOMEM	Insufficient destination space
-EINVAL	Invalid COBS structure or parameters

cobs_decoder_close()

int cobs_decoder_close

(

struct cobs_decoder *

dec

)

#include <zephyr/data/cobs.h>

Finalize COBS streaming decoder.

Completes the decoding process and verifies that the stream ended properly. Should be called after all data has been written to the decoder.

The decoder state will be reset.

Parameters

dec	Pointer to decoder structure

Return values

0	Success
-EINVAL	More data was expected before closing

cobs_decoder_init()

int cobs_decoder_init	(	struct cobs_decoder *	dec,
		cobs_stream_cb	cb,
		void *	user_data,
		uint32_t	flags )

#include <zephyr/data/cobs.h>

Initialize COBS streaming decoder.

Initializes a COBS decoder for streaming operation. The decoder will call the provided callback function to output decoded data chunks as they become available.

Parameters

dec	Pointer to decoder structure to initialize
cb	Callback function for output data
user_data	User data pointer passed to callback
flags	Decoding flags COBS_FLAGS

Returns

0 on success, negative errno code on failure

cobs_decoder_write()

int cobs_decoder_write	(	struct cobs_decoder *	dec,
		const uint8_t *	buf,
		size_t	len )

#include <zephyr/data/cobs.h>

Write data to COBS streaming decoder.

Decodes the provided encoded data and outputs decoded chunks via the registered callback function. This function can be called multiple times to decode data incrementally.

In case an error is returned, the decoder state will be reset.

Note

If a delimiter is encountered, and the COBS_FLAG_TRAILING_DELIMITER flag is set, the registered callback function will be called with a NULL pointer indicating a frame end.

Parameters

dec	Pointer to decoder structure
buf	Buffer containing encoded data
len	Length of data in buffer

Returns

Number of bytes used from buf on success, negative errno code on failure

cobs_encode()

int cobs_encode	(	struct net_buf *	src,
		struct net_buf *	dst,
		uint32_t	flags )

#include <zephyr/data/cobs.h>

COBS encoding.

Encodes data from source buffer to destination buffer using COBS encoding.

Parameters

src	Source buffer to encode
dst	Destination buffer for encoded data
flags	Encoding flags COBS_FLAGS

Return values

0	Success
-ENOMEM	Insufficient destination space
-EINVAL	Invalid COBS structure or parameters

cobs_encoder_close()

int cobs_encoder_close

(

struct cobs_encoder *

enc

)

#include <zephyr/data/cobs.h>

Finalize COBS streaming encoder.

Flushes any remaining data and optionally writes trailing delimiter if COBS_FLAG_TRAILING_DELIMITER was set during initialization.

The encoder state will be reset.

Parameters

enc	Pointer to encoder structure

Returns

0 on success, negative errno code on failure

cobs_encoder_init()

int cobs_encoder_init	(	struct cobs_encoder *	enc,
		cobs_stream_cb	cb,
		void *	user_data,
		uint32_t	flags )

#include <zephyr/data/cobs.h>

Initialize COBS streaming encoder.

Initializes a COBS encoder for streaming operation. The encoder will call the provided callback function to output encoded data chunks as they become available.

Parameters

enc	Pointer to encoder structure to initialize
cb	Callback function for output data
user_data	User data pointer passed to callback
flags	Encoding flags COBS_FLAGS

Returns

0 on success, negative errno code on failure

cobs_encoder_write()

int cobs_encoder_write	(	struct cobs_encoder *	enc,
		const uint8_t *	buf,
		size_t	len )

#include <zephyr/data/cobs.h>

Write data to COBS streaming encoder.

Encodes the provided data and outputs encoded chunks via the registered callback function. This function can be called multiple times to encode data incrementally.

In case an error is returned, the encoder state will be reset.

Parameters

enc	Pointer to encoder structure
buf	Buffer containing data to encode
len	Length of data in buffer

Returns

Number of bytes used from buf on success, negative errno code on failure

cobs_max_encoded_len()

size_t cobs_max_encoded_len ( size_t decoded_size, uint32_t flags )

inlinestatic

#include <zephyr/data/cobs.h>

Calculate maximum encoded buffer size.

Parameters

decoded_size	Size of input data to be encoded
flags	Encoding flags COBS_FLAGS

Returns

Required buffer size for worst-case encoding scenario