vga.v

`timescale 1ns / 1ps

// VGA top module

module vga #(
    parameter DATA_ADDR_WIDTH = 6,
    parameter h_pol   = 0,
    parameter v_pol   = 1,
    parameter h_sync  = 184,
    parameter h_back  = 288,
    parameter h_disp  = 1680,
    parameter h_front = 104,
    parameter v_sync  = 3,
    parameter v_back  = 33,
    parameter v_disp  = 1050,
    parameter v_front = 1
) (
    input RESET,
    input [DATA_ADDR_WIDTH - 1 : 0] DATA_ADDR,
    input [7:0] DATA_IN,
    input WR_EN,
    input pixel_clk,
    input scroll,
    output [3:0] VGA_R,
    output [3:0] VGA_G,
    output [3:0] VGA_B,
    output VGA_HS,
    output VGA_VS
    );

    localparam addr_width = $clog2(h_disp * v_disp / (8 * 8));
    localparam x_width    = $clog2(h_disp);
    localparam y_width    = $clog2(v_disp);


    wire [7:0] char_read;
    wire [addr_width - 1 : 0] addr_read;
    wire [addr_width - 1 : 0] addr_write = DATA_ADDR;
    wire [addr_width - 1 : 0] addr_init;

    vga_model #(
        .h_disp ( h_disp ),
        .v_disp ( v_disp )
    ) model (
        // Global input
        .clk          ( pixel_clk  ),
        .addr_init    ( addr_init  ),
        // Input from controller
        .addr_read    ( addr_read  ),
        .char_read    ( char_read  ),
        // Input from user
        .addr_write   ( addr_write ),
        .write_enable ( WR_EN & ~scroll ),  // Not accept write request when scrolling.
        .char_write   ( DATA_IN    )
    );

    wire disp;
    wire [x_width - 1 : 0] x_pos;
    wire [y_width - 1 : 0] y_pos;

    vga_view #(
        .h_pol   ( h_pol   ),
        .v_pol   ( v_pol   ),
        .h_sync  ( h_sync  ),
        .h_back  ( h_back  ),
        .h_disp  ( h_disp  ),
        .h_front ( h_front ),
        .v_sync  ( v_sync  ),
        .v_back  ( v_back  ),
        .v_disp  ( v_disp  ),
        .v_front ( v_front )
    ) view (
        // Global input
        .clk    ( pixel_clk ),
        .reset  ( RESET     ),
        // Output to pins
        .vga_hs ( VGA_HS    ),
        .vga_vs ( VGA_VS    ),
        // Output to controller
        .disp   ( disp      ),
        .x_pos  ( x_pos     ),
        .y_pos  ( y_pos     )
    );

    vga_ctrl #(
        .h_disp ( h_disp ),
        .v_disp ( v_disp )
    ) ctrl (
        // Global input
        .clk    ( pixel_clk    ),
        .scroll ( scroll       ),
        // Input from model
        .char_read ( char_read ),
        // Input from viewer
        .disp   ( disp         ),
        .x_pos  ( x_pos        ),
        .y_pos  ( y_pos        ),
        // Output to model
        .addr_read ( addr_read ),
        .addr_init ( addr_init ),
        // Output to pins
        .vga_r  ( VGA_R        ),
        .vga_g  ( VGA_G        ),
        .vga_b  ( VGA_B        )
    );

endmodule