cobs.h

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/*
 * Copyright (c) 2024 Kelly Helmut Lord
 * Copyright (c) 2026 Basalte bv
 *
 * SPDX-License-Identifier: Apache-2.0
 */

 
#ifndef ZEPHYR_INCLUDE_DATA_COBS_H_
#define ZEPHYR_INCLUDE_DATA_COBS_H_
 
#include <stddef.h>
#include <sys/types.h>
#include <zephyr/sys/util.h>
 
#if defined(CONFIG_NET_BUF)
#include <zephyr/net_buf.h>
#endif
 
#ifdef __cplusplus
extern "C" {
#endif



#define COBS_DEFAULT_DELIMITER 0x00

#define COBS_FLAG_TRAILING_DELIMITER BIT(8)

#define COBS_FLAG_CUSTOM_DELIMITER(x) ((x) & 0xff)


static inline size_t cobs_max_encoded_len(size_t decoded_size, uint32_t flags)
{
        size_t len = decoded_size + decoded_size / 254U + 1U;
 
        if ((flags & COBS_FLAG_TRAILING_DELIMITER) != 0U) {
                len++;
        }
 
        return len;
}
 
#if defined(CONFIG_NET_BUF) || defined(__DOXYGEN__)

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

int cobs_decode(struct net_buf *src, struct net_buf *dst, uint32_t flags);
 
#endif /* defined(CONFIG_NET_BUF) || defined(__DOXYGEN__) */

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

struct cobs_encoder {
        cobs_stream_cb cb;
        void *cb_user_data;

        uint8_t fragment[255];
        uint32_t flags;
};

struct cobs_decoder {
        cobs_stream_cb cb;
        void *cb_user_data;

        uint8_t code;
        uint8_t code_index;
        uint32_t flags;
};

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

int cobs_encoder_close(struct cobs_encoder *enc);

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

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

int cobs_decoder_close(struct cobs_decoder *dec);

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

 
#ifdef __cplusplus
}
#endif
 
#endif /* ZEPHYR_INCLUDE_DATA_COBS_H_ */