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;   }