#include <unistd.h>

#include <stdlib.h>

#include <stdio.h>

#include <fcntl.h>

#include <linux/fb.h>

#include <sys/mman.h>

int main()

{

    int fbfd = ;

    struct fb_var_screeninfo vinfo;

    struct fb_fix_screeninfo finfo;

    long int screensize = ;

    char *fbp = NULL;

    int x,y,r = ,g = , b = ;

    unsigned int rgb;

    /*打开设备文件*/

    fbfd = open("/dev/fb0", O_RDWR);

    /*取得屏幕相关参数*/

    ioctl(fbfd, FBIOGET_FSCREENINFO, &finfo);

    ioctl(fbfd, FBIOGET_VSCREENINFO, &vinfo);

    /*计算屏幕缓冲区大小*/

    screensize = vinfo.xres * vinfo.yres * vinfo.bits_per_pixel / ;

    /*映射屏幕缓冲区到用户地址空间*/

    fbp=(char*)mmap(,screensize,PROT_READ | PROT_WRITE,MAP_SHARED, fbfd, );

    if((int)fbp == -)

    {

        printf("Error: failed to map framebuffer device to memory .\n");

        return -;

    }

    /*下面可通过fbp指针操作缓冲区:显示红 */

    for(y = ;y<(vinfo.yres);y++)//vinfo.yres = 272

    {

        for(x = ;x < vinfo.xres;x++)//vinfo.xres=480

        {

            long location = x* + y * vinfo.xres * ;//用户缓冲区地址移动,一个像素3字节(24位真彩色)

            r = ;

            g = ;

            b = ;

            rgb = (r << ) | (g << ) | b;    //分别获得相应颜色

            *((unsigned short *)(fbp + location)) = rgb;

        }

    }

    /*释放缓冲区，关闭设备*/

    munmap(fbp, screensize);

    close(fbfd);

}