slip.h

/**
 * Copyright (c) 2015 - 2019, Nordic Semiconductor ASA
 *
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 * this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form, except as embedded into a Nordic
 *    Semiconductor ASA integrated circuit in a product or a software update for
 *    such product, must reproduce the above copyright notice, this list of
 *    conditions and the following disclaimer in the documentation and/or other
 *    materials provided with the distribution.
 *
 * 3. Neither the name of Nordic Semiconductor ASA nor the names of its
 *    contributors may be used to endorse or promote products derived from this
 *    software without specific prior written permission.
 *
 * 4. This software, with or without modification, must only be used with a
 *    Nordic Semiconductor ASA integrated circuit.
 *
 * 5. Any software provided in binary form under this license must not be
 * reverse engineered, decompiled, modified and/or disassembled.
 *
 * THIS SOFTWARE IS PROVIDED BY NORDIC SEMICONDUCTOR ASA "AS IS" AND ANY EXPRESS
 * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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 */
#ifndef SLIP_H__
#define SLIP_H__

#include <stdint.h>

#ifdef __cplusplus
extern "C" {
#endif

/** @file
 *
 * @defgroup slip SLIP encoding and decoding
 * @{
 * @ingroup app_common
 *
 * @brief  This module encodes and decodes SLIP packages.
 *
 * @details The SLIP protocol is described in @linkSLIP.
 */

/** @brief Status information that is used while receiving and decoding a
 * packet. */
typedef enum {
	SLIP_STATE_DECODING,	 //!< Ready to receive the next byte.
	SLIP_STATE_ESC_RECEIVED, //!< An ESC byte has been received and the next
							 //!< byte must be decoded differently.
	SLIP_STATE_CLEARING_INVALID_PACKET //!< The received data is invalid and
									   //!< transfer must be restarted.
} slip_read_state_t;

/** @brief Representation of a SLIP packet. */
typedef struct {
	slip_read_state_t
		state; //!< Current state of the packet (see @ref slip_read_state_t).

	uint8_t* p_buffer; //!< Decoded data.
	uint32_t
		current_index; //!< Current length of the packet that has been received.
	uint32_t buffer_len; //!< Size of the buffer that is available.
} slip_t;

/**@brief Function for encoding a SLIP packet.
 *
 * The maximum size of the output data is (2*input size + 1) bytes. Ensure that
 * the provided buffer is large enough.
 *
 * @param[in,out]   p_output                The buffer where the encoded SLIP
 * packet is stored. Ensure that it is large enough.
 * @param[in,out]   p_input                 The buffer to be encoded.
 * @param[in,out]   input_length            The length of the input buffer.
 * @param[out]      p_output_buffer_length  The length of the output buffer
 * after the input has been encoded.
 *
 * @retval  NRF_SUCCESS         If the input was successfully encoded into
 * output.
 * @retval  NRF_ERROR_NULL      If one of the provided parameters is NULL.
 */
int slip_encode(uint8_t* p_output, uint8_t* p_input, uint32_t input_length,
				uint32_t* p_output_buffer_length);

/**@brief Function for decoding a SLIP packet.
 *
 * The decoded packet is put into @p p_slip::p_buffer. The index and buffer
 * state is updated.
 *
 * Ensure that @p p_slip is properly initialized. The initial state must be set
 * to @ref SLIP_STATE_DECODING.
 *
 * @param[in,out]   p_slip  State of the decoding process.
 * @param[in]       c       Byte to decode.
 *
 * @retval NRF_SUCCESS              If a packet has been parsed. The received
 * packet can be retrieved from @p p_slip.
 * @retval NRF_ERROR_NULL           If @p p_slip is NULL.
 * @retval NRF_ERROR_NO_MEM         If there is no more room in the buffer
 * provided by @p p_slip.
 * @retval NRF_ERROR_BUSY           If the packet has not been parsed completely
 * yet.
 * @retval NRF_ERROR_INVALID_DATA   If the packet is encoded wrong. In this
 * case, @p p_slip::state is set to @ref SLIP_STATE_CLEARING_INVALID_PACKET, and
 * decoding will stay in this state until the END byte is received.
 */
int slip_decode_add_byte(slip_t* p_slip, uint8_t c);

#ifdef __cplusplus
}
#endif

#endif // SLIP_H__

/** @} */