#include<stdio.h>
#include<stdlib.h> 
#include<fcntl.h> 			
#include<sys/mman.h> 		
#include<unistd.h> 		

#define DEV_NAME 	"/dev/mem"
#define BaseAddress 	0x11000000	
#define GPX0CON_OFFSET 	0x0C00		
#define GPX0DAT_OFFSET 	0x0C04		
#define GPX0_WR_CON 	0x11111111	

volatile void *Addr_start = NULL; 
volatile unsigned *GPX0_DAT = NULL; 

/************************ 内存映射+寄存器地址确定 ***************************/
int port_write( unsigned n, unsigned fd) 
{
	
	Addr_start = (volatile void *)mmap(NULL, 1024*n, PROT_READ | PROT_WRITE, MAP_SHARED, fd, BaseAddress);

	if (Addr_start == NULL) 
	{
		printf("内存映射出错！\n");
		return -1;
	}
	
	*(volatile unsigned *)(Addr_start+GPX0CON_OFFSET) = GPX0_WR_CON;
	
	GPX0_DAT = (volatile unsigned *)(Addr_start+GPX0DAT_OFFSET);
	return 0;
}

/********************* 打开一个设备文件，标志符为fd ***************************/
int port_open()
{
	int fd;
	fd = open(DEV_NAME, O_RDWR);
	if ( fd < 0 ) 
	{
		exit(1);
	}
	return fd;
}

/************************ 关闭标志符为fd的设备文件 ***************************/
int port_close(int n, int fd)
{
	munmap( (void *)Addr_start, 1024*n ); 
	close(fd);
	return 0;
}