#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)); //打印該寄存器地址的value  #if 1 // LINE IN   printf("%x /n", *(volatile unsigned int *)(map_base+0x30));    *(volatile unsigned int *)(map_base + 0x30) = 0x208121bc; //修改該寄存器地址的value   usleep(1000000);   *(volatile unsigned int *)(map_base + 0x30) &= ~(0x1<<16); //修改該寄存器地址的value   usleep(1000000);    printf("%x /n", *(volatile unsigned int *)(map_base+0x30)); #endif    if(dev_fd)     close(dev_fd);    munmap(map_base,MAP_SIZE);//解除映射關系    return 0; }