Framebuffer-yresvirtual

#include <stdio.h>
#include <stdint.h>
#include <sys/ioctl.h>
#include <sys/mman.h>
#include <unistd.h>
#include <fcntl.h>
#include "frameutils.h"

int mainloop(FrameBuffer *fb) {
    int active = 1;
    while(active) {
        active = 0;
    }
    return 0;
}

int main() {
    FrameBuffer fb; //Framebuffer properties

    fb.fd = open("/dev/fb0", O_RDWR); //Framebuffer device

    ioctl(fb.fd, FBIOGET_VSCREENINFO, &fb.vinfo); //Get variable screen info
    fb.vinfo.grayscale = 0;
    fb.vinfo.bits_per_pixel = 32;
    fb.vinfo.yres_virtual = fb.vinfo.yres * 2;

    if(ioctl(fb.fd, FBIOPUT_VSCREENINFO, &fb.vinfo) == -1) { //Set variable screen info
        perror("App ioctl FBIOPUT_VSCREENINFO");
        return -1;
    }

    ioctl(fb.fd, FBIOGET_VSCREENINFO, &fb.vinfo); //Get variable screen info

    ioctl(fb.fd, FBIOGET_FSCREENINFO, &fb.finfo);

    long screensize = fb.vinfo.yres_virtual * fb.finfo.line_length; //Size needed for allocation.

    fb.fbp = mmap(0, screensize, PROT_READ | PROT_WRITE, MAP_SHARED, fb.fd, (off_t)0); //Map fb to memory.

    fill_box(10, 10, 500, 500, &fb, pixel_color(0xff, 0xff, 0x00, &fb));

    printf("Allocated: %d MB (%d bytes).\nReal resolution: %ix%i.\nVirtual resolution: %ix%i.\n", screensize / 1000000, screensize, fb.vinfo.xres, fb.vinfo.yres, fb.vinfo.xres_virtual, fb.vinfo.yres_virtual);

    close(fb.fd);

    return 0;
}