sgEncodeDataReq.c

/**
 * @copyright Copyright (c) 2021 Sagetech, Inc. All rights reserved.
 *
 * @file sgEncodeDataReq.c
 * @author Jacob.Garrison
 *
 * @date Feb 23, 2021
 *
 * This file receives a populated data request struct and
 * converts it into a data request message buffer.
 */

#include <stdbool.h>
#include <stdlib.h>

#include "sg.h"
#include "sgUtil.h"

#define SG_PAYLOAD_LEN_DATAREQ SG_MSG_LEN_DATAREQ - 5 /// the payload length.

#define PBASE 4 /// the payload offset.

#define OFFSET_REQ_TYPE 0 /// the requested response message type
#define OFFSET_RSVD_1 1   /// a reserved field
#define OFFSET_RSVD_2 2   /// a reserved field
#define OFFSET_RSVD_3 3   /// a reserved field

/*
 * Documented in the header file.
 */
bool sgEncodeDataReq(uint8_t *buffer, sg_datareq_t *data, uint8_t msgId)
{
    // populate header
    buffer[0] = SG_MSG_START_BYTE;
    buffer[1] = SG_MSG_TYPE_HOST_DATAREQ;
    buffer[2] = msgId;
    buffer[3] = SG_PAYLOAD_LEN_DATAREQ;

    // populate Request Type
    buffer[PBASE + OFFSET_REQ_TYPE] = data->reqType;

    // populate Reserved fields
    buffer[PBASE + OFFSET_RSVD_1] = 0;
    buffer[PBASE + OFFSET_RSVD_2] = 0;
    buffer[PBASE + OFFSET_RSVD_3] = 0;

    // populate checksum
    appendChecksum(buffer, SG_MSG_LEN_DATAREQ);

    return true;
}