Linux在应用层读写寄存器的方法及实现实例

#include <stdio.h> 
#include <stdlib.h> 
#include <time.h> 
#include <unistd.h> 
#include <fcntl.h> 
#include <unistd.h>  
#include <sys/mman.h> 
#define AUDIO_REG_BASE  (0xB800E000) 
#define MAP_SIZE    0xFF 
 
static int dev_fd; 
int main(int argc, char **argv) 
{ 
 
  dev_fd = open("/dev/mem", O_RDWR | O_NDELAY);    
 
  if (dev_fd < 0)  
  { 
    printf("open(/dev/mem) failed.");   
    return 0; 
  }  
 
  unsigned char *map_base=(unsigned char * )mmap(NULL, MAP_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, dev_fd, AUDIO_REG_BASE ); 
 
  printf("%x \n", *(volatile unsigned int *)(map_base+0x38)); //打印该寄存器地址的value 
 
#if 1 // LINE IN 
  printf("%x \n", *(volatile unsigned int *)(map_base+0x30)); 
 
  *(volatile unsigned int *)(map_base + 0x30) = 0x208121bc; //修改该寄存器地址的value 
  usleep(1000000); 
  *(volatile unsigned int *)(map_base + 0x30) &= ~(0x1<<16); //修改该寄存器地址的value 
  usleep(1000000); 
 
  printf("%x \n", *(volatile unsigned int *)(map_base+0x30)); 
#endif 
 
  if(dev_fd) 
    close(dev_fd); 
 
  munmap(map_base,MAP_SIZE);//解除映射关系 
 
  return 0; 
}