[Linux-fbdev-devel] The promised code for my newbie question

[Hihn J. <Jas...@DA...>]

> Whoops, I hit send accidentally.
> 
> #include <unistd.h>
> #include <stdio.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;
> 	struct fb_var_cursorinfo  vcinfo;
> 	struct fb_fix_cursorinfo  fcinfo;
> 	struct fb_cursorstate cstate;
> 
>         long int screensize = 0;
>         char *fbp = 0;
>         int x = 0, y = 0, bit, pow,c;
>         long int location = 0;         /* 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");
>         } else {
> 	    printf("fixed screen
> info(%s):\n\ttype=%d\n\tvis=%d\n\tll=%d\n\taccel=%d\n",
>                    finfo.id, finfo.type, finfo.visual, finfo.line_length,
> finfo.accel);
>         }
>         
>         /* Get variable screen information */
>         if (ioctl(fbfd, FBIOGET_VSCREENINFO, &vinfo)) {
>                 printf("Error reading variable information.\n");
>         } else {
>           printf("variable screen
> info:\n\txres=%d\n\tyres=%d\n\tbpp=%d\n\tgrey=%d\n\tnonstd=%d\n\taccel_fla
> gs
> =%d\n",
>                  vinfo.xres, vinfo.yres, vinfo.bits_per_pixel,
> vinfo.grayscale, vinfo.nonstd, vinfo.accel_flags);	
> 
>          /* Figure out the size of the screen in bytes */
>         screensize = vinfo.xres * vinfo.yres * vinfo.bits_per_pixel / 8;
>         }       
>         if (ioctl(fbfd, FBIOGET_FCURSORINFO, &fcinfo)) {
>                 printf("Error reading Fixed Cursor information.\n");
>         } else {
> 	printf("fcinfo:\tw=%d\n\th=%d\n\txs=%d\n\tys=%d\n\tc1=%dc2=%d\n",
>                 fcinfo.crsr_width,
>                 fcinfo.crsr_height,
>                 fcinfo.crsr_xsize,
>                 fcinfo.crsr_ysize,
>                 fcinfo.crsr_color1,
>                 fcinfo.crsr_color2);
> 	}
>         if (ioctl(fbfd, FBIOGET_VCURSORINFO, &vcinfo)) {
>                 printf("Error reading Variable Cursor information.\n");
>         } else {
> 	printf("vcinfo:\tx=%d\n\ty=%d\n", vcinfo.xspot, vcinfo.yspot);
> 	}
> 
>         if (ioctl(fbfd, FBIOGET_CURSORSTATE, &cstate)) {
>                 printf("Error reading Cursor State information.\n");
>         }else {   
> 	printf("vcinfo:\tx=%d\n\ty=%d\n\ts=%d\n", cstate.xoffset, 
>                cstate.yoffset, cstate.mode);
> 	}
> 
>         /* 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");
> 
> 
>         /* Set variable screen information */
> vinfo.xres=320; vinfo.yres=240;
> vinfo.xres_virtual=320; vinfo.yres_virtual=240;
> vinfo.xoffset=0; vinfo.yoffset=0;
> vinfo.bits_per_pixel=1;
> 
>         if (ioctl(fbfd, FBIOPUT_VSCREENINFO, &vinfo)) {
>                 printf("Error setting variable information.\n");
>         }       
>    
>         /* Get variable screen information */
>         if (ioctl(fbfd, FBIOGET_VSCREENINFO, &vinfo)) {
>                 printf("Error reading variable information.\n");
>         } else {
>           printf("variable screen
> info:\n\txres=%d\n\tyres=%d\n\tbpp=%d\n\tgrey=%d\n\tnonstd=%d\n\taccel_fla
> gs
> =%d\n",
>                  vinfo.xres, vinfo.yres, vinfo.bits_per_pixel,
> vinfo.grayscale, vinfo.nonstd, vinfo.accel_flags);	
> 
>          /* Figure out the size of the screen in bytes */
>         screensize = vinfo.xres * vinfo.yres * vinfo.bits_per_pixel / 8;
>         }       
> 
> 
> 
> 	memset(fbp, time(NULL)%256, screensize);
>   
> 
> 
> 	munmap(fbp, screensize);
>         close(fbfd);
>         return 0;
> }
>