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/*
* Copyright (C) 2014 Tomasz Kramkowski <tk@the-tk.com>
*
* This program is free software. It is licensed under version 3 of the
* GNU General Public License.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see [http://www.gnu.org/licenses/].
*/
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <linux/fb.h>
#include <sys/mman.h>
int main()
{
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;
int count ;
/* Open the file for reading and writing */
fbfd = open("/dev/fb0", O_RDWR);
if (!fbfd) {
printf("Error: cannot open framebuffer device.\n");
exit(1);
}
printf("The framebuffer device was opened successfully.\n");
/* Get fixed screen information */
if (ioctl(fbfd, FBIOGET_FSCREENINFO, &finfo)) {
printf("Error reading fixed information.\n");
exit(2);
}
/* Get variable screen information */
if (ioctl(fbfd, FBIOGET_VSCREENINFO, &vinfo)) {
printf("Error reading variable information.\n");
exit(3);
}
/* Figure out the size of the screen in bytes */
screensize = vinfo.xres * vinfo.yres * vinfo.bits_per_pixel / 8;
printf("\nScreen size is %d",screensize);
printf("\nVinfo.bpp = %d",vinfo.bits_per_pixel);
/* Map the device to memory */
fbp = (char *)mmap(0, screensize, PROT_READ | PROT_WRITE, MAP_SHARED,fbfd, 0);
if ((int)fbp == -1) {
printf("Error: failed to map framebuffer device to memory.\n");
exit(4);
}
printf("The framebuffer device was mapped to memory successfully.\n");
x = 100; y = 100; /* Where we are going to put the pixel */
/* Figure out where in memory to put the pixel */
location = (x+vinfo.xoffset) * (vinfo.bits_per_pixel/8) + (y+vinfo.yoffset) * finfo.line_length;
for(count = 1 ;count < 100 ;count++)
{
*(fbp + location) = 255; /* Some blue */
*(fbp + location + count) = 0; /* A little green */
*(fbp + location + count + 1) = 0; /* A lot of red */
*(fbp + location + count + 2) = 0; /* No transparency */
}
munmap(fbp, screensize);
close(fbfd);
return 0;
}
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