RaspberrPi project source code
Guo Wenxue
6 days ago f7889e2ceddbc3e15ea4b5377d831f4432169f76
project/socketd/booster/packet.c
@@ -40,42 +40,42 @@
        return -1;
    }
    time_t now = time(NULL);
    localtime_r(&now, ptm);
    return 0;
}
int packet_segmented_pack(pack_info_t *pack_info, char *pack_buf, int size)
int packet_segmented_pack(pack_info_t *pack_info, uint8_t *pack_buf, int size)
{
    char              strtime[TIME_LEN] = {'\0'};
    struct tm        *ptm;
    char             *buf = (char *)pack_buf;
    if( !pack_info || !pack_buf || size<=0 )
    if( !pack_info || !buf || size<=0 )
    {
        log_error("Invalid input arguments\n");
        return -1;
    }
    ptm = &pack_info->sample_time;
    snprintf(strtime, sizeof(strtime), "%04d-%02d-%2d %02d:%02d:%02d",
    snprintf(strtime, sizeof(strtime), "%04d-%02d-%02d %02d:%02d:%02d",
            ptm->tm_year+1900, ptm->tm_mon+1, ptm->tm_mday,
            ptm->tm_hour, ptm->tm_min, ptm->tm_sec);
    memset(buf, 0, size);
    snprintf(buf, size, "%s|%s|%.3f", pack_info->devid, strtime, pack_info->temper);
    memset(pack_buf, 0, size);
    snprintf(pack_buf, size, "%s|%s|%.3f", pack_info->devid, strtime, pack_info->temper);
    return strlen(pack_buf);
    return strlen(buf);
}
int packet_json_pack(pack_info_t *pack_info, char *pack_buf, int size)
int packet_json_pack(pack_info_t *pack_info, uint8_t *pack_buf, int size)
{
    char              strtime[TIME_LEN] = {'\0'};
    struct tm        *ptm;
    char             *buf = (char *)pack_buf;
    if( !pack_info || !pack_buf || size<=0 )
    if( !pack_info || !buf || size<=0 )
    {
        log_error("Invalid input arguments\n");
        return -1;
@@ -86,10 +86,122 @@
            ptm->tm_year+1900, ptm->tm_mon+1, ptm->tm_mday,
            ptm->tm_hour, ptm->tm_min, ptm->tm_sec);
    memset(pack_buf, 0, size);
    snprintf(pack_buf, size, "{\"devid\":\"%s\", \"time\":\"%s\",\"temperature\":\"%.3f\"}",
    memset(buf, 0, size);
    snprintf(buf, size, "{\"devid\":\"%s\", \"time\":\"%s\",\"temperature\":\"%.3f\"}",
            pack_info->devid, strtime, pack_info->temper);
    return strlen(pack_buf);
    return strlen(buf);
}
/*
 * The CRC-ITU-T, also known as CRC-16-ITU-T or CRC-16-V.41, uses the polynomial:
 *     0x1021:  x^16 + x^12 + x^5 + 1
 */
#define CRC16_ITU_T_POLY 0x1021   /* Define the CRC-ITU-T polynomial */
static uint16_t crc_itu_t(const uint8_t *data, size_t length)
{
    uint16_t          crc = 0xFFFF;
    size_t            i, j;
    for (i=0; i<length; i++)
    {
        crc ^= ((uint16_t)data[i] << 8);
        for(j=0; j<8; j++)
        {
            if (crc & 0x8000)
            {
                crc = (crc << 1) ^ CRC16_ITU_T_POLY;
            }
            else
            {
                crc <<= 1;
            }
        }
    }
    return crc;
}
uint16_t to_big_endian(uint16_t num)
{
    return (num << 8) | (num >> 8);
}
/* TLV(Tag Length Value) PDU(Protocal Data Unit) format:
 *
 * +-----------+-----------+------------+-------------+-------------+
 * | Header(2B)|  Tag(1B)  | Length(2B) |  Value(nB)  |  CRC16(2B)  |
 * +-----------+-----------+------------+-------------+-------------+
 *
 * Header(2B): 0xFE 0xFD
 *    Tag(1B): 0x01->temperature 0x02->Humidity 0x03->Noisy ...
 * Length(2B): Data value length
 *  Value(nB): Data value
 *  CRC16(2B): CRC from Header to Value
 */
int packet_tlv_pack(pack_info_t *pack_info, uint8_t *pack_buf, int size)
{
    struct tm          *ptm;
    int                 ofset = 0;
    uint16_t            crc;
    if( !pack_info || !pack_buf || size<TLV_MINSIZE )
    {
        log_error("Invalid input arguments\n");
        return -1;
    }
    /*+----------------------+
     *|    TLV Header(2B)    |
     *+----------------------+*/
    *(uint16_t *)pack_buf = to_big_endian(TLV_HEADER);
    ofset += 2;
    /*+----------------------+
     *|      TLV Tag(1B)     |
     *+----------------------+*/
    pack_buf[ofset++] = TAG_TEMPERATURE;
    /* Skip data length here, we will calculate it later */
    ofset += 2;
    /*+----------------------+
     *|  payload data value  |
     *+----------------------+*/
    /* 6 bytes sample time */
    ptm = &pack_info->sample_time;
    pack_buf[ofset++] = (uint8_t)(ptm->tm_year+1900-2000);
    pack_buf[ofset++] = (uint8_t)(ptm->tm_mon+1);
    pack_buf[ofset++] = (uint8_t)(ptm->tm_mday);
    pack_buf[ofset++] = (uint8_t)(ptm->tm_hour);
    pack_buf[ofset++] = (uint8_t)(ptm->tm_min);
    pack_buf[ofset++] = (uint8_t)(ptm->tm_sec);
    /* 8 bytes device SN */
    strncpy((char *)(pack_buf+ofset), pack_info->devid, DEVID_LEN);
    ofset += DEVID_LEN;
    /* 2 bytes temperature value */
    pack_buf[ofset++] = (int)pack_info->temper;  /* integer part */
    pack_buf[ofset++] = (((int)(pack_info->temper*100))%100); /* fractional part */
    /*+----------------------+
     *|    TLV Length(2B)    |
     *+----------------------+*/
    *(uint16_t *)(pack_buf+3) = (ofset-5);
    /*+----------------------+
     *|      TLV CRC(2B)     |
     *+----------------------+*/
    crc = crc_itu_t(pack_buf, ofset);
    *(uint16_t *)(pack_buf+ofset) = crc;
    ofset += 2;
    return ofset;
}