This directory contains BSV source for several versions of a 
pong game implemented for a Xilinx FPGA. The generated hardware 
processes input to control (and play) the game and generates the 
VGA output to display the ball, paddles, etc. To simplify the 
example, the support files required to load the game on an FPGA 
have not been provided, but you can compile (and generate Verilog RTL) 
for the example by running:

bsc -u -verilog TopLevel.bsv

ISLANDS ETC.

This directory contains versions 0, 1 and 2 of some files.

Ball.bsv --     versions 0, 1 and 2
Island.bsv --   versions 0, 1 and 2
TopLevel.bsv -- versions 0, 1 and 2

Version 0 corresponds to no island, version 1 to a stationary island, and
version 2 to the elliptically moving island.

The unadorned versions should be set to copies of the version you want to
compile.

To do a manual conversion of Version 0 to Version 1, you have to do the
following:
1. Adapt the definition of Paddle to make an Island.
2. Get the TopLevel to instantiate it, to add it to its list of shapes, and to
pass it as a parameter to Ball (so that the ball can bounce off it).
3. Edit Ball, to incorporate the island into its calculations about bouncing.
Proceed as follows.

1.
Copy the file Paddle.bsv to make Island.bsv.  Globally replace all occurrences
of "paddle" therein to "island" (preserving case differences).

2a.
In Island.bsv, amend the size and position information, by replacing
------------
XSize islandWidthC;
islandWidthC = fromInteger(islandWidth);
					
YSize islandHeightC;
islandHeightC = fromInteger(islandHeight);
					  
YCoord islandLowC;
islandLowC = fromInteger(islandEdgeDist);
					 
YCoord islandHighC;
islandHighC = fromInteger(vSize - islandHeight - islandEdgeDist);
								 
YCoord islandStartC;
islandStartC = fromInteger(div((vSize- islandHeight), 2));
------------
with
------------
XSize islandWidthC;     islandWidthC = 100;
YSize islandHeightC;    islandHeightC = 60;

XCoord islandLeftC;     islandLeftC = 590;
YCoord islandLowC;      islandLowC = 210;
------------

2b.
Delete the unneeded methods
------------
    method YCoord center;
    method Action inc_dec(Bool x1);
------------
from the Island interface definition.

2c.
Delete the various instantiations before and after that of islandRect, and
amend islandRect itself, leaving just
------------
  Shape islandRect();
  mkRectangle#(islandLeftC,
	       islandWidthC,
	       islandLowC,
	       islandHeightC,
	       cRed) the_islandRect(islandRect);
------------

2d.
Amend the innards of function inside1 to read
------------
  return (x > islandLeftC &&
	  x < islandLeftC + islandWidthC &&
	  y > islandLowC &&
	  y < islandLowC + islandHeightC);
------------

2e.
Delete the rule rule1island (corresponding to moving the paddle), and the
method definitions for  center  and  inc_dec.

2f.
In method inside, replace the line
------------
                   ((y0 - yposr.get) - ((islandHeightC- dy)>> 1))
------------
with 0

3a.
In TopLevel.bsv, add
------------
  import Island::*;
------------

3b.
Add (e.g. after the second mkPaddle)
------------
  Island island();
  mkIsland the_island(island);
------------

3c.
Supply the island as an extra parameter to the ball, by adding "island," after
"paddleR" in the parameter list for mkBall.

3d.
Increase the size of the array shapes by 1, and add the line
------------
  shapes[6] = island.shape;
------------

4a.
In Ball.bsv, add "import Island::*;"

4b.
Add
------------
	       Island island,
------------
to the parameter list of mkBall.

4c.
In tickActions[0], duplicate the lines
------------
               // Right Paddle
	       rpd <= paddleR.inside(ball_x, ball_x_r, ball_y, ball_y_b, ballHeightC);
------------
and change the second copy to
------------
               // Island
	       ipd <= island.inside(ball_x, ball_x_r, ball_y, ball_y_b, ballHeightC);
------------

4d.
In the definition of diry, duplicate the lines
------------
                      bounce( (tpl_1(lpd) || tpl_3(lpd)),
                              (tpl_2(lpd) || tpl_4(lpd)), 
------------
and change the occurrences of "lpd" in the second copy to "ipd".  Add an extra
closing paren to the line ");".  Treat the definition of dirx similarly.