module axil_reg_if_rd #
(
    // Width of data bus in bits
    parameter DATA_WIDTH = 32,
    // Width of address bus in bits
    parameter ADDR_WIDTH = 32,
    // Width of wstrb (width of data bus in words)
    parameter STRB_WIDTH = (DATA_WIDTH/8),
    // Timeout delay (cycles)
    parameter TIMEOUT = 4
)
(
    input  wire                   clk,
    input  wire                   rst,

    /*
     * AXI-Lite slave interface
     */
    input  wire [ADDR_WIDTH-1:0]  s_axil_araddr,
    input  wire [2:0]             s_axil_arprot,
    input  wire                   s_axil_arvalid,
    output wire                   s_axil_arready,
    output wire [DATA_WIDTH-1:0]  s_axil_rdata,
    output wire [1:0]             s_axil_rresp,
    output wire                   s_axil_rvalid,
    input  wire                   s_axil_rready,

    /*
     * Register interface
     */
    output wire [ADDR_WIDTH-1:0]  reg_rd_addr,
    output wire                   reg_rd_en,
    input  wire [DATA_WIDTH-1:0]  reg_rd_data,
    input  wire                   reg_rd_wait,
    input  wire                   reg_rd_ack
);

parameter TIMEOUT_WIDTH = $clog2(TIMEOUT);

reg [TIMEOUT_WIDTH-1:0] timeout_count_reg = 0, timeout_count_next;

reg [ADDR_WIDTH-1:0] s_axil_araddr_reg = {ADDR_WIDTH{1'b0}}, s_axil_araddr_next;
reg s_axil_arvalid_reg = 1'b0, s_axil_arvalid_next;
reg [DATA_WIDTH-1:0] s_axil_rdata_reg = {DATA_WIDTH{1'b0}}, s_axil_rdata_next;
reg s_axil_rvalid_reg = 1'b0, s_axil_rvalid_next;

reg reg_rd_en_reg = 1'b0, reg_rd_en_next;

assign s_axil_arready = !s_axil_arvalid_reg;
assign s_axil_rdata = s_axil_rdata_reg;
assign s_axil_rresp = 2'b00;
assign s_axil_rvalid = s_axil_rvalid_reg;

assign reg_rd_addr = s_axil_araddr_reg;
assign reg_rd_en = reg_rd_en_reg;

always @* begin
    timeout_count_next = timeout_count_reg;

    s_axil_araddr_next = s_axil_araddr_reg;
    s_axil_arvalid_next = s_axil_arvalid_reg;
    s_axil_rdata_next = s_axil_rdata_reg;
    s_axil_rvalid_next = s_axil_rvalid_reg && !s_axil_rready;

    if (reg_rd_en_reg && (reg_rd_ack || timeout_count_reg == 0)) begin
        s_axil_arvalid_next = 1'b0;
        s_axil_rdata_next = reg_rd_data;
        s_axil_rvalid_next = 1'b1;
    end

    if (!s_axil_arvalid_reg) begin
        s_axil_araddr_next = s_axil_araddr;
        s_axil_arvalid_next = s_axil_arvalid;
        timeout_count_next = TIMEOUT-1;
    end

    if (reg_rd_en && !reg_rd_wait && timeout_count_reg != 0)begin
        timeout_count_next = timeout_count_reg - 1;
    end

    reg_rd_en_next = s_axil_arvalid_next && !s_axil_rvalid_next;
end

always @(posedge clk) begin
    timeout_count_reg <= timeout_count_next;

    s_axil_araddr_reg <= s_axil_araddr_next;
    s_axil_arvalid_reg <= s_axil_arvalid_next;
    s_axil_rdata_reg <= s_axil_rdata_next;
    s_axil_rvalid_reg <= s_axil_rvalid_next;

    reg_rd_en_reg <= reg_rd_en_next;

    if (rst) begin
        s_axil_arvalid_reg <= 1'b0;
        s_axil_rvalid_reg <= 1'b0;
        reg_rd_en_reg <= 1'b0;
    end
end

endmodule