`timescale 1ns / 1ps
`default_nettype none

//////////////////////////////////////////////////////////////////////////////////
// Company: 
// Engineer: 
// 
// Create Date:    00:24:56 05/08/2016 
// Design Name: 
// Module Name:    control_enable_options 
// Project Name: 
// Target Devices: 
// Tool versions: 
// Description: 
//
// Dependencies: 
//
// Revision: 
// Revision 0.01 - File Created
// Additional Comments: 
//
//////////////////////////////////////////////////////////////////////////////////
module control_enable_options(
    input wire clk,
    input wire rst_n,
    input wire [7:0] zxuno_addr,
    input wire zxuno_regrd,
    input wire zxuno_regwr,
    input wire [7:0] din,
    output reg [7:0] dout,
    output reg oe_n,
    output wire disable_ay,
    output wire disable_turboay,
    output wire disable_7ffd,
    output wire disable_1ffd,
    output wire disable_romsel7f,
    output wire disable_romsel1f,
    output wire enable_timexmmu,
    output wire disable_spisd,
    output wire disable_timexscr,
    output wire disable_ulaplus,
    output wire disable_radas
    );

    parameter DEVOPTIONS = 8'h0E;
    parameter DEVOPTS2   = 8'h0F;
    
    reg [7:0] devoptions = 8'h00;  // initial value
    reg [7:0] devopts2 = 8'h00;    // initial value
    assign disable_ay = devoptions[0];
    assign disable_turboay = devoptions[1];
    assign disable_7ffd = devoptions[2];
    assign disable_1ffd = devoptions[3];
    assign disable_romsel7f = devoptions[4];
    assign disable_romsel1f = devoptions[5];
    assign enable_timexmmu = devoptions[6];
    assign disable_spisd = devoptions[7];
    assign disable_timexscr = devopts2[0];
    assign disable_ulaplus = devopts2[1];
    assign disable_radas = devopts2[2];
    
    always @(posedge clk) begin
        if (rst_n == 1'b0) begin
            devoptions <= 8'h00;  // or after a hardware reset (not implemented yet)
            devopts2 <= 8'h00;
        end
        else if (zxuno_addr == DEVOPTIONS && zxuno_regwr == 1'b1)
            devoptions <= din;
        else if (zxuno_addr == DEVOPTS2 && zxuno_regwr == 1'b1)
            devopts2 <= din;
    end
    
    always @* begin
        oe_n = 1'b1;
        dout = 8'hFF;
        if (zxuno_regrd == 1'b1)            
            if (zxuno_addr == DEVOPTIONS) begin
                oe_n = 1'b0;
                dout = devoptions;
            end
            else if (zxuno_addr == DEVOPTS2) begin
                oe_n = 1'b0;
                dout = devopts2;
            end
        end
endmodule