nios定时器

#include "altera_avalon_pio_regs.h"
#include "altera_avalon_timer_regs.h"
#include "system.h"
#include <stdio.h>


unsigned int timerVal = 0;
static void ISR_timer1(void *context, alt_u32 id)
{
    timerVal++;
    IOWR_ALTERA_AVALON_TIMER_STATUS(TIMER_BASE, 0x00);
    IOWR_ALTERA_AVALON_TIMER_CONTROL(TIMER_BASE, 0x05);
}


int main()
{
    printf("Hello from Nios II!\n");


    IOWR_ALTERA_AVALON_TIMER_STATUS(TIMER_BASE, 0x00);
    IOWR_ALTERA_AVALON_TIMER_PERIODH(TIMER_BASE, (TIMER_FREQ / TIMER_TICKS_PER_SEC) >>16);
    IOWR_ALTERA_AVALON_TIMER_PERIODL(TIMER_BASE, (TIMER_FREQ / TIMER_TICKS_PER_SEC) & 0xffff);
    alt_irq_register(TIMER_IRQ,NULL,ISR_timer1);
    IOWR_ALTERA_AVALON_TIMER_CONTROL(TIMER_BASE, 0x05);

      while(1)
      {
          if(( (timerVal+1 )% 1000)==0)
          {
            printf("timerVal=%d\n",timerVal);
          }
      }
  return 0;
}