#include "includes.h"

volatile u32 Systick_TickCount = 0;

void SysTick_Handler(void)
{
	Systick_TickCount++;
//	if(Systick_TickCount % 10 == 0)
//		printf("#");
}

u32 GetDelayTick(u32 ms)
{
	return GetTickCount() + ms;
}
	
// 考虑了u32溢出翻转的情况
u8 IsTickOut(u32 OutTick)
{
    u32 tick = GetTickCount();

    if(tick > OutTick)
    {
        if(tick - OutTick > 0x80000000UL)
            return 0;
        return 1;
    }
    if(OutTick - tick > 0x80000000UL)
        return 1;
    return 0;
}

// 考虑了u32溢出翻转的情况
u32 GetTickElapse(u32 start_tick, u32 end_tick)
{
    if(end_tick >= start_tick)
        return (end_tick - start_tick);
    return (0xFFFFFFFFUL - start_tick + end_tick);
}

// 这个函数必须在初始化完成，中断开启以后才有效
void delay_ms(u32 ms)
{
	u32 tick = GetDelayTick(ms);

	do
	{
	} while(!IsTickOut(tick));
}

// 通过TMR2来产生1ms中断
void Clock_Init()
{
  u32 us = CyclesPerUs * 1000; // 1ms
	
  if ((us - 1UL) > SysTick_LOAD_RELOAD_Msk)
    return;                                                   /* Reload value impossible */

  SysTick->LOAD  = (uint32_t)(us - 1UL);                      /* set reload register */
  NVIC_SetPriority (SysTick_IRQn, 0); 						  /* set Priority for Systick Interrupt */
  SysTick->VAL   = 0UL;                                       /* Load the SysTick Counter Value */
  SysTick->CTRL  |= (SysTick_CTRL_CLKSOURCE_Msk |
                   SysTick_CTRL_TICKINT_Msk   |
                   SysTick_CTRL_ENABLE_Msk);                   /* Enable SysTick IRQ and SysTick Timer */
}

void delay_us(uint16_t us)
{
	uint32_t j;
	
	while(us--)
	{
		j = SystemCoreClock / 1000000;
		while(j--);
	}
}