sbp.h

/*
 * Copyright (C) 2011-2014 Swift Navigation Inc.
 * Contact: Fergus Noble <fergus@swift-nav.com>
 *
 * This source is subject to the license found in the file 'LICENSE' which must
 * be be distributed together with this source. All other rights reserved.
 *
 * THIS CODE AND INFORMATION IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND,
 * EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND/OR FITNESS FOR A PARTICULAR PURPOSE.
 */
#ifdef __cplusplus
extern "C" {
#endif

#ifndef LIBSBP_SBP_H
    #define LIBSBP_SBP_H

    #include "common.h"

    /** \addtogroup sbp
 * \{ */

    /** Return value indicating success. */
    #define SBP_OK 0
    /** Return value indicating message decoded and callback executed by sbp_process. */
    #define SBP_OK_CALLBACK_EXECUTED 1
    /** Return value indicating message decoded with no associated callback in sbp_process. */
    #define SBP_OK_CALLBACK_UNDEFINED 2
    /** Return value indicating an error with the callback (function defined). */
    #define SBP_CALLBACK_ERROR -1
    /** Return value indicating a CRC error. */
    #define SBP_CRC_ERROR -2
    /** Return value indicating an error occured whilst sending an SBP message. */
    #define SBP_SEND_ERROR -3
    /** Return value indicating an error occured because an argument was NULL. */
    #define SBP_NULL_ERROR -4

    /** Default sender ID. Intended for messages sent from the host to the device. */
    #define SBP_SENDER_ID 0x42

/** SBP callback function prototype definition. */
typedef void (*sbp_msg_callback_t)(
    u16 sender_id,
    u8 len,
    u8 msg[],
    void* context
);

/** SBP callback node.
 * Forms a linked list of callbacks.
 * \note Must be statically allocated for use with sbp_register_callback().
 */
typedef struct sbp_msg_callbacks_node {
        u16 msg_type; /**< Message ID associated with callback. */
        sbp_msg_callback_t cb; /**< Pointer to callback function. */
        void* context; /**< Pointer to a context */
        struct sbp_msg_callbacks_node*
            next; /**< Pointer to next node in list. */
} sbp_msg_callbacks_node_t;

/** State structure for processing SBP messages. */
typedef struct {
        enum {
            WAITING = 0,
            GET_TYPE,
            GET_SENDER,
            GET_LEN,
            GET_MSG,
            GET_CRC
        } state;

        u16 msg_type;
        u16 sender_id;
        u16 crc;
        u8 msg_len;
        u8 n_read;
        u8 msg_buff[256];
        void* io_context;
        sbp_msg_callbacks_node_t* sbp_msg_callbacks_head;
} sbp_state_t;

/** \} */

s8 sbp_register_callback(
    sbp_state_t* s,
    u16 msg_type,
    sbp_msg_callback_t cb,
    void* context,
    sbp_msg_callbacks_node_t* node
);
s8 sbp_remove_callback(sbp_state_t* s, sbp_msg_callbacks_node_t* node);
void sbp_clear_callbacks(sbp_state_t* s);
void sbp_state_init(sbp_state_t* s);
void sbp_state_set_io_context(sbp_state_t* s, void* context);
s8 sbp_process(sbp_state_t* s, u32 (*read)(u8* buff, u32 n, void* context));
s8 sbp_process_payload(
    sbp_state_t* s,
    u16 sender_id,
    u16 msg_type,
    u8 msg_len,
    u8 payload[]
);
s8 sbp_send_message(
    sbp_state_t* s,
    u16 msg_type,
    u16 sender_id,
    u8 len,
    u8* payload,
    u32 (*write)(u8* buff, u32 n, void* context)
);

    #ifdef __cplusplus
}
    #endif

#endif /* LIBSBP_SBP_H */