#include "st_sys.h"

//1秒换算成1us的倍数
#define US_PER_SECOND   1000000

//当前的时间
static volatile int cur_second = 0;
static volatile int cur_ms = 0;
static int reload_valve = 0;
unsigned long dwTickCount = 0;
static volatile int system_core_clock = 400; //系统时钟
void SysTick_Handler(void)
{
    dwTickCount++;
    
    if (++cur_ms >= 1000) {
		cur_ms = 0;
		cur_second++;
     }
}


/**
 * 初始化定时器
 * 
 * @author lxz 
 * 
 * @param void 
 */
void sw_timer_init(int clk)
{
    //clk = clk * 1000000;
    /*
    SysTick->CTRL &= ~(1 << 2);                    //SYSTICK 时钟跟系统同步
    SysTick->CTRL |= 1 << 1;                    //中断使能
    SysTick->LOAD = (clk / 8000) - 1; //1ms中断
    SysTick->CTRL |= 1 << 0;                    //使能systick
    Sys_NVIC_Init(1,1,SysTick_IRQn,1);
  */
    reload_valve = clk * 1000 - 1;
    SysTick_Config(clk * 1000);
    
    //__NVIC_EnableIRQ(SysTick_IRQn);
}


/**
 * 获取当前的定时器时间
 * 
 * @author lxz 
 * 
 * @param timer 
 */
void sw_timer_now(sw_timer_t *timer)
{
    int second;
    int us;
    int ms;

    do
    {
        ms = cur_ms;
        second = cur_second;
        us = SysTick->VAL;
    }while (ms != cur_ms);

    timer->second = second;
    timer->usec = (ms * 1000) + (reload_valve - us) * 1000 / reload_valve;
}




/**
 * 初始化一个定时器实体用于时间比较
 * 
 * @author lxz 
 * 
 * @param timer object 定时实体
 * @param second   要延时的秒单位
 * @param usec    要延时的毫秒单位 
 */
void sw_timer_start(sw_timer_t *timer, int sec, int usec)
{
    sw_timer_now(timer);
    sw_timer_delay(timer, sec, usec);
}
/**
 * 返回定时器是否已经计时到了
 * 
 * @author lxz 
 * 
 * @param timer 定时器实体
 * 
 * @return int 
 */
int sw_timer_expire(sw_timer_t *timer)
{
    sw_timer_t now;
    sw_timer_now(&now);
    if (timer->second < now.second || 
        (timer->second == now.second && timer->usec <= now.usec)) return 1;
    return 0;
}
/**
 * 对当关定时器进行时间延后
 * 
 * @author lxz 
 * 
 * @param timer 定时器实体
 * @param sec  要延后的秒数
 * @param usec  要延后的微秒数
 * 
 * @return int 
 */
void sw_timer_delay(sw_timer_t *timer, int sec, int usec)
{

    timer->usec += usec;
    timer->second += sec + timer->usec / US_PER_SECOND;
    timer->usec %= US_PER_SECOND;
}