/*
 *  This program can be used and distributed without restrictions.
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <signal.h>

#include <fcntl.h>        /* low-level i/o */
#include <unistd.h>
#include <errno.h>
#include <malloc.h>
#include <sys/types.h>
#include <sys/mman.h>
#include <sys/ioctl.h>

#include <linux/fb.h>


#define TPASS 0
#define TFAIL -1

int fd_fb = 0;
unsigned short * fb;
int g_fb_size;
unsigned char *megabuff = NULL;

//-----------------------------------------------------------------------------

void showFrame(const void *p, size_t length)
{

    //printf (".");

    int screenwidth=1024;
    int screenheight = 768;

    memcpy ( fb, p, screenwidth*screenheight*3 );

    return ;

}


//-----------------------------------------------------------------------------

int InitFrameBuffer(struct fb_var_screeninfo *screen_info, u_int32_t *screensize)
{
    u_int32_t retval;

    *screensize = 0;

    if ((fd_fb = open("/dev/fb0", O_RDWR, 0)) < 0)
    {
        printf("Unable to open /dev/fb0\n");
        return TFAIL;
    }

    retval = ioctl(fd_fb, FBIOGET_VSCREENINFO, screen_info);
    if (retval < 0)
    {
        return TFAIL;
    }
    printf("Set the background to 16-bpp\n");
    screen_info->bits_per_pixel = 16;
    screen_info->yoffset = 0;
    retval = ioctl(fd_fb, FBIOPUT_VSCREENINFO, screen_info);
    if (retval < 0)
    {
        return TFAIL;
    }
    printf ("screen info xres=%d, yres=%d, bits per pixel =%d\n", screen_info->xres , screen_info->yres , screen_info->bits_per_pixel );
    *screensize = screen_info->xres * screen_info->yres * screen_info->bits_per_pixel / 8;
    g_fb_size = screen_info->xres * screen_info->yres_virtual * screen_info->bits_per_pixel / 8;

    //printf("\n Screen size = %u \n", *screensize);

    /* Map the device to memory*/
    fb = (unsigned short *)mmap(0, g_fb_size,PROT_READ | PROT_WRITE, MAP_SHARED, fd_fb, 0);
    if ((int)fb <= 0)
    {
        printf("\nError: failed to map framebuffer device 0 to memory.\n");
        return TFAIL;
    }

    retval = ioctl(fd_fb, FBIOGET_VSCREENINFO, screen_info);
    if (retval < 0)
    {
        printf ("FBIOGET_VSCREENINFO failed\n");
        return TFAIL;
    }

    printf("Set the BG to 24-bpp\n");
    screen_info->bits_per_pixel = 24;
    retval = ioctl(fd_fb, FBIOPUT_VSCREENINFO, screen_info);
    if (retval < 0)
    {
        return TFAIL;
    }
    printf("fb_test: xres_virtual = %d\n", screen_info->xres_virtual);
    *screensize = screen_info->xres * screen_info->yres * screen_info->bits_per_pixel / 8;


    return TPASS;
}

//-----------------------------------------------------------------------------

void my_handler(int s){
    if (megabuff) free(megabuff);
  munmap(fb,g_fb_size);
  close(fd_fb);
    printf("exit\n");
  exit(EXIT_SUCCESS);
}

//-----------------------------------------------------------------------------

int main(int argc, char **argv) {

    struct fb_var_screeninfo screen_info;
    u_int32_t screensize;
    struct sigaction sigIntHandler;

  if (InitFrameBuffer(&screen_info,&screensize))
    {
        printf ("Error. Failed\n");
        return;
    }
    printf("\n At last screen size = %u \n", screensize);

  megabuff = malloc ( screensize );

  sigIntHandler.sa_handler = my_handler;
  sigemptyset(&sigIntHandler.sa_mask);
  sigIntHandler.sa_flags = 0;

  sigaction(SIGINT, &sigIntHandler, NULL);


  int i=0,val;

  u_int32_t hAct_high,vAct_high = 0;
  u_int32_t vcounter=0,retval;

    #if 0
    while (vAct_high == 0)
    {
        retval = ioctl(fd_fb, FBIOGET_VSCREENINFO, &screen_info);
        if (retval < 0)
        {
            printf ("FBIOGET_VSCREENINFO failed\n");
            break;
        }
        hAct_high = (screen_info.sync & FB_SYNC_HOR_HIGH_ACT) != 0;
        vAct_high = (screen_info.sync & FB_SYNC_VERT_HIGH_ACT) != 0;
        vcounter++;

    }
  printf("hsync %d vsync %d\n",hAct_high,vAct_high);
  #endif

    while (1)
    {

        if ( i == 0 ) val = 0x00;
        if ( i == 1 ) val = 0x80;
        if ( i == 2 ) val = 0xff;
        memset(megabuff,val,screensize);
        printf("val %d\n",val);
        showFrame (megabuff, screensize);
        usleep(40);

        i++;
        if ( i>2 ) i = 0;
    }

  return 0;
}