mmap函数使用

#include <sys/types.h>
 #include <stdio.h>
 #include <sys/ioctl.h>
 #include <sys/mman.h>
#include <fcntl.h>
 #include <memory.h>
 void * map_base;FILE *f;int n,fd;
 int main(int argc,char *argv[])
 {
 if((fd=open("/dev/mem",O_RDWR|O_SYNC))==-1)     { return(-1); }
 map_base=mmap(0,0xff,PROT_READ|PROT_WRITE,MAP_SHARED,fd,GPIO_BASE);
 PEDR = (volatile unsigned int *) (map_base+rPEDR);
 PEDDR = (volatile unsigned int *) (map_base+rPEDDR);
 PEDR = 0x03; //E0 E1配成输出
 while(1)
{
PEDR = (1<<0);//E0置高
 sleep(1);
 PEDR &= !(1<<0);//E0口置低
sleep(1);
}
 close(fd);
munmap(map_base,0xff);//解除映射关系
 }