#include <stdio.h>
#include <fcntl.h>
#include <errno.h>
#include <linux/fb.h>

int main(int argc, char** argv) {
    int h,r;
    struct fb_fix_screeninfo fix;
    struct fb_var_screeninfo var;
    
    h = open("/dev/fb0",O_RDONLY);
    if (h==-1) {
        printf("could not open /dev/fb0; are you root?\n");
        exit(0);
    }
    r = ioctl(h,FBIOGET_FSCREENINFO,&fix);
    if (r==0) {
        printf("frame buffer:  %s\n",fix.id);
        printf("video memory:  %p\n",fix.smem_start);
        printf("video length:  %p\n",fix.smem_len);
        printf("io registers:  %p\n",fix.mmio_start);
        printf("scan line:     %d bytes\n",fix.line_length);
    } else {
        printf("ioctl failed with %d, errno %d\n",r, errno);
    }

    r = ioctl(h,FBIOGET_VSCREENINFO,&var);
    if (r==0) {
        printf("resolution:    %d by %d\n",var.xres,var.yres);
        printf("virtual res:   %d by %d\n",var.xres_virtual,var.yres_virtual);
        printf("screen shift:  %d, %d\n",var.xoffset,var.yoffset);
        printf("bits per pixel: %d\n",var.bits_per_pixel);
    } else {
        printf("ioctl failed with %d, errno %d\n",r,errno);
    }
    close(h);
}