基于DE2-115开发板，采用控制波动开关 SW[2:0]实现图像±45°，±90°旋转及VGA显示-Implementing the rotation of image based on DE2-115 board. Used switch SW[2:0] to control the orientation of rotating image(±45°&±90°).

The first iteration rotates the vectors the second or third quadrant to the first or fourth, respectively. The shift sequence is 0,0,1, and 2. The rotation angle of the first four steps becomes: arctan(∞) = 90◦ , arctan(20) = 45◦ , arctan(2