Запускаю раз:
#include <stdlib.h>
#include <unistd.h>
#include <stdio.h>
#include <fcntl.h>
#include <linux/fb.h>
#include <sys/mman.h>
#include <sys/ioctl.h>
int main()
{
usleep(2 * 1000 * 1000);
int fbfd = 0;
struct fb_var_screeninfo vinfo;
struct fb_fix_screeninfo finfo;
long int screensize = 0;
char *fbp = 0;
int x = 0, y = 0;
long int location = 0;
// Open the file for reading and writing
fbfd = open("/dev/fb0", O_RDWR);
if (fbfd == -1) {
perror("Error: cannot open framebuffer device");
exit(1);
}
printf("The framebuffer device was opened successfully.\n");
// Get fixed screen information
if (ioctl(fbfd, FBIOGET_FSCREENINFO, &finfo) == -1) {
perror("Error reading fixed information");
exit(2);
}
// Get variable screen information
if (ioctl(fbfd, FBIOGET_VSCREENINFO, &vinfo) == -1) {
perror("Error reading variable information");
exit(3);
}
printf("%dx%d, %dbpp\nVirt: %dx%d\n", vinfo.xres, vinfo.yres, vinfo.bits_per_pixel, vinfo.xres_virtual, vinfo.yres_virtual);
// Figure out the size of the screen in bytes
screensize = vinfo.xres * vinfo.yres * vinfo.bits_per_pixel / 8;
// Map the device to memory
fbp = (char *)mmap(0, screensize, PROT_READ | PROT_WRITE, MAP_SHARED,
fbfd, 0);
if ((int)fbp == -1) {
perror("Error: failed to map framebuffer device to memory");
exit(4);
}
printf("The framebuffer device was mapped to memory successfully.\n");
// Figure out where in memory to put the pixel
while (1)
for (y = 0; y < 300; y++)
for (x = 0; x < 300; x++)
{
location = (x+vinfo.xoffset) * (vinfo.bits_per_pixel/8) +
(y+vinfo.yoffset) * finfo.line_length;
if (vinfo.bits_per_pixel == 32)
{
*(fbp + location + vinfo .red.offset / 8) = 0xFF;
*(fbp + location + vinfo .green.offset / 8) = 0x00;
*(fbp + location + vinfo .blue.offset / 8) = 0xFF;
*(fbp + location + vinfo.transp.offset / 8) = 0x0;
}
}
munmap(fbp, screensize);
close(fbfd);
return 0;
}
The framebuffer device was opened successfully.
640x480, 32bpp
Virt: 640x480
The framebuffer device was mapped to memory successfully.
