File syn_cobs.h¶

FileList > proto > syn_cobs.h

COBS (Consistent Overhead Byte Stuffing) packet framing. More...

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

Classes¶

Type	Name
struct	SYN_COBS_Decoder Streaming COBS frame decoder.

Public Types¶

Type	Name
typedef void(*	SYN_COBS_PacketCallback Callback invoked when a complete packet is decoded.

Public Functions¶

Type	Name
size_t	syn_cobs_decode (const void * src, size_t src_len, void * dst) Decode a COBS-encoded packet.
void	syn_cobs_decoder_feed (SYN_COBS_Decoder * dec, uint8_t byte) Feed a byte to the streaming decoder.
void	syn_cobs_decoder_init (SYN_COBS_Decoder * dec, uint8_t * buf, size_t buf_size, SYN_COBS_PacketCallback callback, void * ctx) Initialize streaming COBS decoder.
void	syn_cobs_decoder_reset (SYN_COBS_Decoder * dec) Reset the streaming decoder state.
size_t	syn_cobs_encode (const void * src, size_t src_len, void * dst) Encode data using COBS.

Detailed Description¶

Turns an arbitrary byte stream into framed packets separated by 0x00 delimiters, with zero bytes inside replaced by run-length codes. Overhead is exactly 1 byte per 254 data bytes.

Use this over UART, RS-485, or any byte-oriented link where you need reliable packet boundaries.

** **

// Encode a packet
uint8_t encoded[256];
size_t enc_len = syn_cobs_encode(data, data_len, encoded);

// Decode a packet
uint8_t decoded[256];
size_t dec_len = syn_cobs_decode(encoded, enc_len, decoded);

// Streaming decoder (byte-at-a-time from UART RX)
SYN_COBS_Decoder dec;
syn_cobs_decoder_init(&dec, rx_buf, sizeof(rx_buf), on_packet, NULL);
syn_cobs_decoder_feed(&dec, byte);

Public Types Documentation¶

typedef SYN_COBS_PacketCallback¶

Callback invoked when a complete packet is decoded.

typedef void(* SYN_COBS_PacketCallback) (const uint8_t *data, size_t len, void *ctx);

Parameters:

data Decoded packet data.
len Decoded packet length.
ctx User context.

Public Functions Documentation¶

function syn_cobs_decode¶

Decode a COBS-encoded packet.

size_t syn_cobs_decode (
    const void * src,
    size_t src_len,
    void * dst
)

Parameters:

src COBS-encoded data (without the 0x00 delimiter).
src_len Encoded length.
dst Output buffer (must be at least src_len).

Returns:

Number of decoded bytes, or 0 on error.

function syn_cobs_decoder_feed¶

Feed a byte to the streaming decoder.

void syn_cobs_decoder_feed (
    SYN_COBS_Decoder * dec,
    uint8_t byte
)

When a 0x00 delimiter is received, the accumulated bytes are decoded and the callback is invoked with the decoded packet.

Parameters:

dec Decoder.
byte Received byte.

function syn_cobs_decoder_init¶

Initialize streaming COBS decoder.

void syn_cobs_decoder_init (
    SYN_COBS_Decoder * dec,
    uint8_t * buf,
    size_t buf_size,
    SYN_COBS_PacketCallback callback,
    void * ctx
)

Parameters:

dec Decoder instance.
buf Receive buffer for accumulating encoded bytes.
buf_size Buffer capacity.
callback Called when a complete packet is decoded.
ctx User context for callback.

function syn_cobs_decoder_reset¶

Reset the streaming decoder state.

void syn_cobs_decoder_reset (
    SYN_COBS_Decoder * dec
)

Parameters:

dec Decoder.

function syn_cobs_encode¶

Encode data using COBS.

size_t syn_cobs_encode (
    const void * src,
    size_t src_len,
    void * dst
)

Parameters:

src Input data.
src_len Input length.
dst Output buffer (must be at least src_len + src_len/254 + 1).

Returns:

Number of bytes written to dst (excluding the trailing 0x00 delimiter).

The documentation for this class was generated from the following file src/syntropic/proto/syn_cobs.h