/* life1
   The first simple version of Conway's Life on Mefisto 8x8 chess board.
   Copyright (C) 2005, Antti Karttunen, Antti.Karttunen@iki.fi
 */

module life1(CLK,PB_IN,SW_IN,BCOL_IN,BCOL_OUT,BROW,LED_OUT);
input CLK;
input [3:0] PB_IN;
input [7:0] SW_IN;
input [7:0] BCOL_IN;
output [7:0] BCOL_OUT;
output [7:0] BROW;
output [7:0] LED_OUT;


// wire RST = PB_IN[3];


reg [7:0] BOARD_ROW [7:0];

wire [7:0] PIECES_ROW [7:0];


function fredkin;
  input n;
  input s;
  input w;
  input e;
  fredkin = (n^s^w^e);
endfunction


// The cell will be alife if it has either 3 neighbours
// or if it has 2 neighbours and it itself is alive.
function life;
  input c;
  input n;
  input ne;
  input s;
  input se;
  input w;
  input sw;
  input e;
  input nw;
//life = (4'b0011 == ((n+ne+e+se+s+sw+w+nw)|c));
  life = (4'b0011 == (({3'b000,n}+{3'b000,ne}+{3'b000,s}+{3'b000,se}+{3'b000,w}+{3'b000,sw}+{3'b000,e}+{3'b000,nw})|{3'b000,c}));
endfunction


mefi8x8a BOARD_IO(.CLK(CLK),
                  .BCOL_IN(BCOL_IN),
                  .BCOL_OUT(BCOL_OUT),
                  .BROW(BROW),
                  .LEDS2LIT0(BOARD_ROW[0]),
                  .LEDS2LIT1(BOARD_ROW[1]),
                  .LEDS2LIT2(BOARD_ROW[2]),
                  .LEDS2LIT3(BOARD_ROW[3]),
                  .LEDS2LIT4(BOARD_ROW[4]),
                  .LEDS2LIT5(BOARD_ROW[5]),
                  .LEDS2LIT6(BOARD_ROW[6]),
                  .LEDS2LIT7(BOARD_ROW[7]),
                  .PIECES0(PIECES_ROW[0]),
                  .PIECES1(PIECES_ROW[1]),
                  .PIECES2(PIECES_ROW[2]),
                  .PIECES3(PIECES_ROW[3]),
                  .PIECES4(PIECES_ROW[4]),
                  .PIECES5(PIECES_ROW[5]),
                  .PIECES6(PIECES_ROW[6]),
                  .PIECES7(PIECES_ROW[7])
                 );


wire [2:0] shrow = {SW_IN[2],SW_IN[1],SW_IN[0]};

wire input_mode = SW_IN[7];


wire PB_NEXT; // State of the debounced push button for incrementing.
reg pb_next_prev = 0; // is saved here also.

wire next_gen = (PB_NEXT && ~pb_next_prev);

debounced_button DBB0(CLK,PB_IN[0],PB_NEXT);

assign LED_OUT = {PIECES_ROW[shrow][0],PIECES_ROW[shrow][1],PIECES_ROW[shrow][2],PIECES_ROW[shrow][3],PIECES_ROW[shrow][4],PIECES_ROW[shrow][5],PIECES_ROW[shrow][6],PIECES_ROW[shrow][7]};

integer i; // A "compile-time" index to board rows. (for the for loop).
integer j;

always @(posedge CLK)
  begin
// if(RST)
//  begin
//  end
// else
    begin
      pb_next_prev <= PB_NEXT;

      if(input_mode)
        begin
          for(i=0; i<8; i=i+1) BOARD_ROW[i] <= PIECES_ROW[i];
        end
      else if(next_gen)
        begin
          for(i=0; i<8; i=i+1)
            for(j=0; j<8; j=j+1)
              BOARD_ROW[i][j] <= life(BOARD_ROW[i][j], // The cell itself.
                                      BOARD_ROW[i][(7==j ? 0 : j+1)], // n
                                      BOARD_ROW[(7==i ? 0 : i+1)][(7==j ? 0 : j+1)], // ne
                                      BOARD_ROW[(7==i ? 0 : i+1)][j], // e
                                      BOARD_ROW[(7==i ? 0 : i+1)][(0==j ? 7 : j-1)], // se
                                      BOARD_ROW[i][(0==j ? 7 : j-1)], // s
                                      BOARD_ROW[(0==i ? 7 : i-1)][(0==j ? 7 : j-1)], // sw
                                      BOARD_ROW[(0==i ? 7 : i-1)][j], // w
                                      BOARD_ROW[(0==i ? 7 : i-1)][(7==j ? 0 : j+1)] // nw
                                     );
        end
    end
  end

endmodule