请给解析一下什么意思

void GetLogNum(rtc_time_t *time)
{
uint8_t data[256];
uint32_t read_addr = LOGIN_NUM_START_ADDR;
uint16_t i,j;

osMutexWait(spi_flash_mutex_id, osWaitForever);
    
while(read_addr < LOGIN_NUM_END_ADDR)
{
    W25QXX_Read(data,read_addr,sizeof(data));
    for(i=0;i<sizeof(data);i+=8) //时间+lognum总共8个字节
    {
        if(data[i]==0xff)
        {
            for(j=0;j<8;j++) //时间+lognum总共8个字节
            {
                if(data[i+j]!=0xff)
                {
                    break;
                }
            }
            
            if(j==8)
            {    
                time->year = 0xff;
                time->month = 0xff;
                time->date = 0xff;
                time->hour = 0xff;
                time->minute = 0xff;
                time->second = 0xff;                    
                break;
            }
        }
        else
        {
            time->year = data[i];
            time->month = data[i+1];
            time->date = data[i+2];
            time->hour = data[i+3];
            time->minute = data[i+4];
            time->second = data[i+5];
        }
    }
    
    if(i!=sizeof(data))
    {
        break;
    }        
    read_addr += sizeof(data);
}
osMutexRelease(spi_flash_mutex_id);

}丰铭12:00

osMutexWait(spi_flash_mutex_id, osWaitForever); 上锁

W25QXX_Read(data,read_addr,sizeof(data));从flash read_addr（开始时LOGIN_NUM_START_ADDR，后面循环递增） 这个地址读取数据，每次大小256字节，

寻找第一个不是0xff开头的数字，找到就解析日期，如果都是0xff说明书结尾，退出大循环

osMutexRelease(spi_flash_mutex_id);释放锁