//
//  Display for Verilog version of RDP
//
//
//  9/16/94  RJM
//

`define MAX_X		320
`define MAX_Y		240

`define DISP_Y_DELAY	y_d27
`define DISP_X_DELAY	x_d27


module display(gclk, span_r, span_g, span_b, span_a, span_clr_we, st_span, start_x, new_prim, y_h);
  //
  //  Inputs
  //
  input				gclk;
  input		[7:0]		span_r;
  input		[7:0]		span_g;
  input		[7:0]		span_b;
  input		[2:0]		span_a;
  input		     		span_clr_we;
  input		     		st_span;
  input		[11:0]		start_x;
  input				new_prim;
  input		[63:0]		y_h;

  //
  //  Delay x/y
  //
  reg				left;

  reg		[11:0]		y_d1;
  reg		[11:0]		y_d2;
  reg		[11:0]		y_d3;
  reg		[11:0]		y_d4;
  reg		[11:0]		y_d5;
  reg		[11:0]		y_d6;
  reg		[11:0]		y_d7;
  reg		[11:0]		y_d8;
  reg		[11:0]		y_d9;
  reg		[11:0]		y_d10;
  reg		[11:0]		y_d11;
  reg		[11:0]		y_d12;
  reg		[11:0]		y_d13;
  reg		[11:0]		y_d14;
  reg		[11:0]		y_d15;
  reg		[11:0]		y_d16;
  reg		[11:0]		y_d17;
  reg		[11:0]		y_d18;
  reg		[11:0]		y_d19;
  reg		[11:0]		y_d20;
  reg		[11:0]		y_d21;
  reg		[11:0]		y_d22;
  reg		[11:0]		y_d23;
  reg		[11:0]		y_d24;
  reg		[11:0]		y_d25;
  reg		[11:0]		y_d26;
  reg		[11:0]		y_d27;

  reg		[11:0]		x_d1;
  reg		[11:0]		x_d2;
  reg		[11:0]		x_d3;
  reg		[11:0]		x_d4;
  reg		[11:0]		x_d5;
  reg		[11:0]		x_d6;
  reg		[11:0]		x_d7;
  reg		[11:0]		x_d8;
  reg		[11:0]		x_d9;
  reg		[11:0]		x_d10;
  reg		[11:0]		x_d11;
  reg		[11:0]		x_d12;
  reg		[11:0]		x_d13;
  reg		[11:0]		x_d14;
  reg		[11:0]		x_d15;
  reg		[11:0]		x_d16;
  reg		[11:0]		x_d17;
  reg		[11:0]		x_d18;
  reg		[11:0]		x_d19;
  reg		[11:0]		x_d20;
  reg		[11:0]		x_d21;
  reg		[11:0]		x_d22;
  reg		[11:0]		x_d23;
  reg		[11:0]		x_d24;
  reg		[11:0]		x_d25;
  reg		[11:0]		x_d26;
  reg		[11:0]		x_d27;

  integer			x;
  integer			y;
  integer			r;
  integer			g;
  integer			b;
  integer			a;
  reg		[1:256*8]	filename;
  integer			ret_val;

  //
  //  Initialize frame buffer
  //
  initial
  begin
    if ($open_frame_buffer(`MAX_X, `MAX_Y) == -1)
    begin
        $write("Cannot open frame buffer\n");
        $finish();
    end
  end

  //
  //  Grab start x
  //
  always @(posedge gclk) 
  begin
    if(st_span)
      x_d1 <= start_x;
    else
    begin
      if(left)
        x_d1 <= x_d1 + 1; /* 1 cycle for now */
      else // right major
        x_d1 <= x_d1 - 1; /* 1 cycle for now */
    end
  end

  //
  //  Grab start y
  //    make a named event so we can test for it in an if statement
  //
  always @(posedge new_prim) 
  begin
    y_d1 <= y_h[12:2]; /* load */
    left <= y_h[55];
  end

  //
  //  Increment y every span
  //
  always @(posedge gclk) 
  begin
    if(st_span)
      y_d1 <= y_d1 + 1;  /* increment */
    else
      y_d1 <= y_d1;  /* hold */
  end


  //
  //  Delay start x, y
  //
  always @(posedge gclk)
  begin
    x_d2  <= x_d1;
    x_d3  <= x_d2;
    x_d4  <= x_d3;
    x_d5  <= x_d4;
    x_d6  <= x_d5;
    x_d7  <= x_d6;
    x_d8  <= x_d7;
    x_d9  <= x_d8;
    x_d10 <= x_d9;
    x_d11 <= x_d10;
    x_d12 <= x_d11;
    x_d13 <= x_d12;
    x_d14 <= x_d13;
    x_d15 <= x_d14;
    x_d16 <= x_d15;
    x_d17 <= x_d16;
    x_d18 <= x_d17;
    x_d19 <= x_d18;
    x_d20 <= x_d19;
    x_d21 <= x_d20;
    x_d22 <= x_d21;
    x_d23 <= x_d22;
    x_d24 <= x_d23;
    x_d25 <= x_d24;
    x_d26 <= x_d25;
    x_d27 <= x_d26;

    y_d2  <= y_d1;
    y_d3  <= y_d2;
    y_d4  <= y_d3;
    y_d5  <= y_d4;
    y_d6  <= y_d5;
    y_d7  <= y_d6;
    y_d8  <= y_d7;
    y_d9  <= y_d8;
    y_d10 <= y_d9;
    y_d11 <= y_d10;
    y_d12 <= y_d11;
    y_d13 <= y_d12;
    y_d14 <= y_d13;
    y_d15 <= y_d14;
    y_d16 <= y_d15;
    y_d17 <= y_d16;
    y_d18 <= y_d17;
    y_d19 <= y_d18;
    y_d20 <= y_d19;
    y_d21 <= y_d20;
    y_d22 <= y_d21;
    y_d23 <= y_d22;
    y_d24 <= y_d23;
    y_d25 <= y_d24;
    y_d26 <= y_d25;
    y_d27 <= y_d26;
  end


  //
  //  Write Frame Buffer per pixel
  //
  always @(posedge gclk)
  begin
    x = `DISP_X_DELAY;
    y = (`DISP_Y_DELAY - 1);
    r = span_r;
    g = span_g;
    b = span_b;
    a = span_a;
    if(span_clr_we)
      ret_val = $put_pixel(x, y, r, g, b, a);
      if(ret_val == -1)
        $write("Error in put_pixel\n");
  end

  //
  //  Close Frame Buffer
  //
  always @(top_level.driver.WriteFrameBuffer)
  begin
  if ($getstr$plusarg("fb=", filename) == 1)
    begin
      $write("Writing frame buffer\n");
      if ($write_frame_buffer(filename) == -1)
      begin
        $write("Cannot write frame buffer\n");
      end
      else
        $finish();
    end
  end

endmodule