#include "main.h"
unsigned int us_time,ms_time,s_time;
//1MHz
void timer0_init(void)
{
 TCCR0 = 0x00; 		  //stop
 OSCCAL=0xB9;		  //標定8M晶振
 TCNT0 = 0x38; 		  //set count;200us
 TCCR0 = 0x02; 		  //start timer
 MCUCR = 0x00;
 GICR  = 0x00;
 TIMSK = 0x01; 		  //timer interrupt sources
  	  		 		  
 us_time=0;
 ms_time=0;
 s_time=0;
 SEI();    			  //re-enable interrupts
}

#pragma interrupt_handler timer0_ovf_isr:10
void timer0_ovf_isr(void)
{
 TCNT0 = 0x38; 		          //時鐘節拍200us
 us_time++;
 if(us_time==5) 	     	  //1ms定時
   {
     us_time=0;
   	 ms_time++; 
     if(ms_time==1000)   	  //1s定時
       {
         ms_time=0; 
	     s_time++;    
	 if(s_time==60)           //1分鐘定時
	     s_time=0;
	} 
	}
}

void delay_s(unsigned char n)
{
 unsigned int time_now,time_set;
 time_now=s_time; 
 time_set=time_now+n;
 if(time_set>=60)
   time_set=time_set-60;
 while(time_now!=time_set)
 {
   time_now=s_time;
 }
}

void delay_ms(unsigned int n)
{
 unsigned int time_now,time_set;
 time_now=ms_time; 
 time_set=time_now+n;
 if(time_set>=1000)
   time_set=time_set-1000;
 while(time_now!=time_set)
 {
   time_now=ms_time;
 }
}

asm("_delay_us::	   		\n"	       
    "loop:       subi   R16,1		\n"//1
    "		 sbci   R17,0	        \n"//1		
    "		 breq	end		\n"//1~2
    "		 nop			\n"//1
    "		 nop			\n"//1
    "		 jmp	loop		\n"//3
    "		 end:   ret		\n");//4