前辈有个代码跑了rt，我不知道怎么用，自己定义了一个1ms延时的定时器，延时50ms，误差很大，跟rt有关吗

void delay_ms(uint32_t ms)
{
    uint32_t start_count = gs_count;
    while((gs_count - start_count) < ms);
}
void delay_us(uint32_t us)
{
   uint32_t start_counter = delay_counter;
    while ((delay_counter - start_counter) < us / 1000);
}

void timer2_init(void)
{
    timer_parameter_struct timer_init_struct;
    rcu_periph_clock_enable(RCU_TIMER2);
    timer_deinit(TIMER2);
    timer_init_struct.prescaler            = 12000-1;
    timer_init_struct.period            = 10-1;    
    timer_init_struct.alignedmode        = TIMER_COUNTER_EDGE;    
    timer_init_struct.counterdirection    = TIMER_COUNTER_UP;        
    timer_init_struct.clockdivision        = TIMER_CKDIV_DIV1;        
    timer_init_struct.repetitioncounter = 0;                    
    timer_init(TIMER2, &timer_init_struct);
    nvic_irq_enable(TIMER2_IRQn, 1, 1);
    timer_interrupt_enable(TIMER2, TIMER_INT_UP);
    timer_enable(TIMER2);
}