shellmatta/src/shellmatta_transport.h

/*
 * Copyright (c) 2019 - 2024 Stefan Strobel <stefan.strobel@shimatta.net>
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at https://mozilla.org/MPL/2.0/.
 */

/**
 * @file    shellmatta_transport.h
 * @brief   transport layer functions of shellmatta
 * @authors Simon Fischer <dev@s-fischer.net> Stefan Strobel <stefan.strobel@shimatta.net>
 */

/**
 * @addtogroup shellmatta_transport
 * @{
 */

#ifndef _SHELLMATTA_TRANSPORT_H_
#define _SHELLMATTA_TRANSPORT_H_

#include "shellmatta.h"

/** @brief value of start-of-header character */
#define SHELLMATTA_TRANSPORT_START_OF_HEADER    0x01u
/** @brief currently supported protocol version */
#define SHELLMATTA_TRANSPORT_PROTOCOL_VERSION   0x01u
/** @brief broadcast address */
#define SHELLMATTA_TRANSPORT_BROADCAST_ADDRESS  0u
/** @brief master address */
#define SHELLMATTA_TRANSPORT_MASTER_ADDRESS     1u

/* header field length defines */
/** @brief length of header */
#define SHELLMATTA_TRANSPORT_LENGTH_HEADER      ((uint8_t)(8))
/** @brief maximum length of shellmatta internal packages (e.g. sequence counter packets) */
#define SHELLMATTA_TRANSPORT_LENGTH_PAYLOAD_INT ((uint8_t)(32))
/** @brief length of crc32 */
#define SHELLMATTA_TRANSPORT_LENGTH_CRC         ((uint8_t)(4))
/** @brief length of crc32 */
#define SHELLMATTA_TRANSPORT_LENGTH_STATIC      (SHELLMATTA_TRANSPORT_LENGTH_HEADER + SHELLMATTA_TRANSPORT_LENGTH_CRC)

/** @brief helper macro for CRC calculation */
#define SHELLMATTA_TRANSPORT_CALC_CRC(transporLayer, data, size)    NULL != (transportLayer)->customCrcFct ?         \
                                                                    (transportLayer)->customCrcFct((data), (size)) : \
                                                                    crc32Calc((data), (size));

/** @brief packet definition with reduced payload (for internal packets) */
typedef struct __attribute__((__packed__))
{
    shellmatta_transport_header_t   header;                 /**< header of the packet   */
    char payload[SHELLMATTA_TRANSPORT_LENGTH_PAYLOAD_INT];  /**< payload of the packet  */
    uint32_t                        crc;                    /**< checksum of the packet */
} shellmatta_transport_packet_int_t;


/**
 * @brief definitions of shellmatta transport layer packet types
 */

#define SHELLMATTA_TRANSPORT_PACKET_DATA                    0x00u   /**< packet type to send plain data                                  */
#define SHELLMATTA_TRANSPORT_PACKET_SEQ_CNT_REQUEST         0x01u   /**< packet type to request sequence counters                        */
#define SHELLMATTA_TRANSPORT_PACKET_SEQ_CNT_RESPOND         0x81u   /**< packet type to respond with sequence counters                   */
#define SHELLMATTA_TRANSPORT_PACKET_MAX_BUFFERSIZE_REQUEST  0x02u   /**< packet type to set and request max buffersize                   */
#define SHELLMATTA_TRANSPORT_PACKET_MAX_BUFFERSIZE_RESPOND  0x82u   /**< packet type to respond with max buffersize                      */
#define SHELLMATTA_TRANSPORT_PACKET_SEARCH_DEVICE_REQUEST   0x03u   /**< UNUSED: packet type to request search for a device by unique id */
#define SHELLMATTA_TRANSPORT_PACKET_SEARCH_DEVICE_RESPOND   0x83u   /**< UNUSED: packet type to respond with search results              */
#define SHELLMATTA_TRANSPORT_PACKET_SET_ADDRESS_REQUEST     0x04u   /**< UNUSED: packet type to set and request an address               */
#define SHELLMATTA_TRANSPORT_PACKET_SET_ADDRESS_RESPOND     0x84u   /**< UNUSED: packet type to respond with a set address               */


shellmatta_retCode_t shellmatta_transport_init( shellmatta_transport_layer_t    *transportLayer,
                                                shellmatta_write_t              writeFct);

shellmatta_retCode_t shellmatta_transport_process(shellmatta_transport_layer_t   *transportLayer,
                                                  char                           byte,
                                                  char                           **data,
                                                  uint32_t                       *length);

shellmatta_retCode_t shellmatta_transport_write(shellmatta_transport_layer_t *transportLayer,
                                                const char* data,
                                                uint32_t length);

#endif /* _SHELLMATTA_TRANSPORT_H_ */

/** @} */