/*
 * 聲明：本范例源于書籍‘NiosII軟件架構解析’
 * 作者：蔡偉綱
 * 博客地址： http://NiosII.cublog.cn 
 *
 * 一、功能: 中斷演示代碼.
 * 
 * 二、相關說明：
 *    由于NiosII IDE的ISS(Instruction Set Simulation)支持JTAG_UART和
 *    定時器的仿真功能,所以該源碼可以運行于ISS模式,無須任何硬件開發板的支持.
 * 
 * 三、運行前提:
 *    1. 定時器必須具有周期中斷功能;
 *    2. 定時器命名為: SYS_CLK_TIMER
*/

#include <stdio.h>
#include "system.h"
#include <sys/alt_irq.h>
#include "altera_avalon_timer_regs.h"

static volatile int Time_Counter = 0;

static void Timer_ISR(void* Base_Address, alt_u32 Interrupt_Level)
{  
  //清除中斷標志位
  IOWR_ALTERA_AVALON_TIMER_STATUS((alt_u32)Base_Address, 0);
  //累計定時器中斷發生次數
  Time_Counter++;
}


int main()
{
  printf("\nISR Demo!\n");

  //設置定時器為自由運行模式
  IOWR_ALTERA_AVALON_TIMER_CONTROL(SYS_CLK_TIMER_BASE, 
            ALTERA_AVALON_TIMER_CONTROL_ITO_MSK  |
            ALTERA_AVALON_TIMER_CONTROL_CONT_MSK |
            ALTERA_AVALON_TIMER_CONTROL_START_MSK);
  //開始中斷注冊操作          
  alt_irq_register(SYS_CLK_TIMER_IRQ, SYS_CLK_TIMER_BASE, Timer_ISR);

  printf("Timer interrupt has occurred for: %d times\n", Time_Counter);
  int Old_Value = Time_Counter;
  for(;;)
  {
    if(Old_Value != Time_Counter)
    {
      Old_Value = Time_Counter;
      printf("Timer interrupt has occurred for: %d times\n", Old_Value);
    }
  }  
}