module fpga (
    /*
     * Clock: 100MHz
     * Reset: Push button, active low
     */
    input  wire       clk,
    input  wire       reset_n,
    /*
     * GPIO
     */
    input  wire       btnu,
    input  wire       btnl,
    input  wire       btnd,
    input  wire       btnr,
    input  wire       btnc,
    input  wire [7:0] sw,
    output wire [7:0] led,
    /*
     * Ethernet: 1000BASE-T GMII
     */
    input  wire       phy_rx_clk,
    input  wire [7:0] phy_rxd,
    input  wire       phy_rx_dv,
    input  wire       phy_rx_er,
    output wire       phy_gtx_clk,
    output wire [7:0] phy_txd,
    output wire       phy_tx_en,
    output wire       phy_tx_er,
    output wire       phy_reset_n,
    /*
     * UART: 500000 bps, 8N1
     */
    input  wire       uart_rxd,
    output wire       uart_txd
);

// Clock and reset

wire clk_ibufg;
wire clk_bufg;
wire clk_dcm_out;

// Internal 125 MHz clock
wire clk_int;
wire rst_int;

wire dcm_rst;
wire [7:0] dcm_status;
wire dcm_locked;
wire dcm_clkfx_stopped = dcm_status[2];

assign dcm_rst = ~reset_n | (dcm_clkfx_stopped & ~dcm_locked);

IBUFG
clk_ibufg_inst(
    .I(clk),
    .O(clk_ibufg)
);

DCM_SP #(
    .CLKIN_PERIOD(10),
    .CLK_FEEDBACK("NONE"),
    .CLKDV_DIVIDE(2.0),
    .CLKFX_MULTIPLY(5.0),
    .CLKFX_DIVIDE(4.0),
    .PHASE_SHIFT(0),
    .CLKOUT_PHASE_SHIFT("NONE"),
    .DESKEW_ADJUST("SYSTEM_SYNCHRONOUS"),
    .STARTUP_WAIT("FALSE"),
    .CLKIN_DIVIDE_BY_2("FALSE")
)
clk_dcm_inst (
    .CLKIN(clk_ibufg),
    .CLKFB(1'b0),
    .RST(dcm_rst),
    .PSEN(1'b0),
    .PSINCDEC(1'b0),
    .PSCLK(1'b0),
    .CLK0(),
    .CLK90(),
    .CLK180(),
    .CLK270(),
    .CLK2X(),
    .CLK2X180(),
    .CLKDV(),
    .CLKFX(clk_dcm_out),
    .CLKFX180(),
    .STATUS(dcm_status),
    .LOCKED(dcm_locked),
    .PSDONE()
);

BUFG
clk_bufg_inst (
    .I(clk_dcm_out),
    .O(clk_int)
);

sync_reset #(
    .N(4)
)
sync_reset_inst (
    .clk(clk_int),
    .rst(~dcm_locked),
    .sync_reset_out(rst_int)
);

// GPIO
wire btnu_int;
wire btnl_int;
wire btnd_int;
wire btnr_int;
wire btnc_int;
wire [7:0] sw_int;

debounce_switch #(
    .WIDTH(13),
    .N(4),
    .RATE(125000)
)
debounce_switch_inst (
    .clk(clk_int),
    .rst(rst_int),
    .in({btnu,
        btnl,
        btnd,
        btnr,
        btnc,
        sw}),
    .out({btnu_int,
        btnl_int,
        btnd_int,
        btnr_int,
        btnc_int,
        sw_int})
);

sync_signal #(
    .WIDTH(1),
    .N(2)
)
sync_signal_inst (
    .clk(clk_int),
    .in({uart_rxd}),
    .out({uart_rxd_int})
);

fpga_core
core_inst (
    /*
     * Clock: 125MHz
     * Synchronous reset
     */
    .clk(clk_int),
    .rst(rst_int),
    /*
     * GPIO
     */
    .btnu(btnu_int),
    .btnl(btnl_int),
    .btnd(btnd_int),
    .btnr(btnr_int),
    .btnc(btnc_int),
    .sw(sw_int),
    .led(led),
    /*
     * Ethernet: 1000BASE-T GMII
     */
    .phy_rx_clk(phy_rx_clk),
    .phy_rxd(phy_rxd),
    .phy_rx_dv(phy_rx_dv),
    .phy_rx_er(phy_rx_er),
    .phy_gtx_clk(phy_gtx_clk),
    .phy_txd(phy_txd),
    .phy_tx_en(phy_tx_en),
    .phy_tx_er(phy_tx_er),
    .phy_reset_n(phy_reset_n),
    /*
     * UART: 115200 bps, 8N1
     */
    .uart_rxd(uart_rxd_int),
    .uart_txd(uart_txd)
);

endmodule