#include <io.h>
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include "system.h"

#define msleep(msec) usleep(1000*msec);

static void
gpu_write (unsigned int reg, unsigned int data)
{
  IOWR (GPU_0_BASE, reg << 2, data);
}

static int
find_intersection (int x, int y, int xd, int yd, int t)
{

  // super lazy - we should use the power of MATHS

  while (x != t)
    {
      x += xd;
      y += yd;

      if (y < 0)
        y = 0;
      if (y > 479)
        y = 479;
      if ((y == 479) || (y == 0))
        yd = -yd;

      if ((x == 639) || (x == 0))
        xd = -xd;
    }

  return y;
}

static int
dir (int a, int b)
{
  if (a > b)
    return 1;
  if (a < b)
    return -1;
  return 0;
}

static void
move_bat (int *b, int db)
{

  *b += dir (db, *b);
  if (*b < 20)
    *b = 20;
  if (*b > 459)
    *b = 459;

}

static void
load_sprite (void)
{
  //                      RRR GGG BBB
  // set the sprite color 111 010 000 - orange
  gpu_write (4, 0x01D0);

  // squirt the bromium logo into the sprite
  gpu_write (0x10, 0x00C0);
  gpu_write (0x11, 0x03E0);
  gpu_write (0x12, 0x0FF8);
  gpu_write (0x13, 0x1FFE);
  gpu_write (0x14, 0x3FC7);
  gpu_write (0x15, 0x3F83);
  gpu_write (0x16, 0x3933);
  gpu_write (0x17, 0x3987);
  gpu_write (0x18, 0x3D37);
  gpu_write (0x19, 0x3D37);
  gpu_write (0x1a, 0x3D87);
  gpu_write (0x1b, 0x3FFF);
  gpu_write (0x1c, 0x1FFE);
  gpu_write (0x1d, 0x07F8);
  gpu_write (0x1e, 0x01E0);
  gpu_write (0x1f, 0x00C0);
}

int
main (void)
{
  int x, y, xd, yd;
  int bat0, dbat0;
  int bat1, dbat1;
  int missed = 0;

  printf ("Working...\n");
  msleep (500);
  srand (12392184);

  bat0 = 100;
  bat1 = 200;

  load_sprite ();

  while (1)
    {
      x = 1;
      y = 1;
      xd = 1;
      yd = 1;

      dbat0 = find_intersection (x + xd, y + yd, xd, yd, 0);
      dbat1 = find_intersection (x + xd, y + yd, xd, yd, 639);

      while (!missed)
        {
          x += xd;
          y += yd;
          if (y < 0)
            y = 0;
          if (y > 479)
            y = 479;
          if ((y == 479) || (y == 0))
            yd = -yd;

          if ((x == 639) || (x == 0))
            {
              xd = -xd;
              yd = rand () % 7;
              yd -= 3;
              dbat0 = find_intersection (x + xd, y + yd, xd, yd, 0);
              dbat1 = find_intersection (x + xd, y + yd, xd, yd, 639);
            }

          move_bat (&bat0, dbat0);
          move_bat (&bat1, dbat1);


          gpu_write (0, x);
          gpu_write (1, y);

          gpu_write (2, bat0);
          gpu_write (3, bat1);

          msleep (2);
        }
    }
}

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