EfErrCode ef_log_read(size_t index, uint32_t *log, size_t size) {
    EfErrCode result = EF_NO_ERR;
    size_t cur_using_size = ef_log_get_used_size();
    size_t read_size_temp = 0;
    size_t header_total_num = 0;
    if (!size) {
        return result;
    }
    EF_ASSERT(size % 4 == 0);
    EF_ASSERT(index < cur_using_size);
    if (index + size > cur_using_size) {
        EF_DEBUG("Warning: Log read size out of bound. Cut read size.\n");
        size = cur_using_size - index;
    }
    /* must be call this function after initialize OK */
    if (!init_ok) {
        return EF_ENV_INIT_FAILED;
    }
    if (log_start_addr < log_end_addr) {
        log_seq_read(log_index2addr(index), log, size);
    } else {
        if (log_index2addr(index) + size <= log_area_start_addr + LOG_AREA_SIZE) {
            /*                          Flash log area
             *                         |--------------|
             * log_area_start_addr --> |##############|
             *                         |##############|
             *                         |##############|
             *                         |--------------|
             *                         |##############|
             *                         |##############|
             *                         |##############| <-- log_end_addr
             *                         |--------------|
             *      log_start_addr --> |##############|
             *          read start --> |**************| <-- read end
             *                         |##############|
             *                         |--------------|
             *
             * read from (log_start_addr + log_index2addr(index)) to (log_start_addr + index + log_index2addr(index))
             */
            result = log_seq_read(log_index2addr(index), log, size);
        } else if (log_index2addr(index) < log_area_start_addr + LOG_AREA_SIZE) {