新手初学DSP 希望大家多多帮助

#include "DSP2833x_Device.h"     // DSP2833x Headerfile Include File

#include "DSP2833x_Examples.h"   // DSP2833x Examples Include File

#define LED (*(unsigned short int *)0x180000)

#define DIP (*(unsigned short int *)0x180001)

//#define SRAM_Base_Adress 0x200000

//void Delay(unsigned int nTime); // 延时子程序

void main(void)

{

   //long i;

   InitSysCtrl();

   InitXintf16Gpio();

   DINT;

   InitPieCtrl();

   IER = 0x0000;

   IFR = 0x0000;

   while (1)

     {

      LED=DIP;

     }

}

谁能帮我解释一下这段程序，并且把它改成由高4位控制LED灯

scdfescszsafDECSSSSS