module fpga (
    /*
     * Clock: 200MHz
     * Reset: Push button, active high
     */
    input  wire       sys_clk_p,
    input  wire       sys_clk_n,
    input  wire       reset,
    /*
     * GPIO
     */
    input  wire       btnu,
    input  wire       btnl,
    input  wire       btnd,
    input  wire       btnr,
    input  wire       btnc,
    input  wire [7:0] sw,
    output wire       ledu,
    output wire       ledl,
    output wire       ledd,
    output wire       ledr,
    output wire       ledc,
    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,
    /*
     * Silicon Labs CP2103 USB UART
     */
    output wire       uart_rxd,
    input  wire       uart_txd,
    input  wire       uart_rts,
    output wire       uart_cts
);

// Clock and reset

wire sys_clk_ibufg;
wire sys_clk_bufg;
wire clk_125mhz_mmcm_out;

// Internal 125 MHz clock
wire clk_125mhz_int;
wire rst_125mhz_int;

wire mmcm_rst = reset;
wire mmcm_locked;
wire mmcm_clkfb;

IBUFGDS
clk_ibufgds_inst(
    .I(sys_clk_p),
    .IB(sys_clk_n),
    .O(sys_clk_ibufg)
);

// MMCM instance
// 200 MHz in, 125 MHz out
// PFD range: 10 MHz to 450 MHz
// VCO range: 600 MHz to 1200 MHz
// M = 5, D = 1 sets Fvco = 1000 MHz (in range)
// Divide by 8 to get output frequency of 125 MHz
MMCM_BASE #(
    .BANDWIDTH("OPTIMIZED"),
    .CLKOUT0_DIVIDE_F(8),
    .CLKOUT0_DUTY_CYCLE(0.5),
    .CLKOUT0_PHASE(0),
    .CLKOUT1_DIVIDE(1),
    .CLKOUT1_DUTY_CYCLE(0.5),
    .CLKOUT1_PHASE(0),
    .CLKOUT2_DIVIDE(1),
    .CLKOUT2_DUTY_CYCLE(0.5),
    .CLKOUT2_PHASE(0),
    .CLKOUT3_DIVIDE(1),
    .CLKOUT3_DUTY_CYCLE(0.5),
    .CLKOUT3_PHASE(0),
    .CLKOUT4_DIVIDE(1),
    .CLKOUT4_DUTY_CYCLE(0.5),
    .CLKOUT4_PHASE(0),
    .CLKOUT5_DIVIDE(1),
    .CLKOUT5_DUTY_CYCLE(0.5),
    .CLKOUT5_PHASE(0),
    .CLKOUT6_DIVIDE(1),
    .CLKOUT6_DUTY_CYCLE(0.5),
    .CLKOUT6_PHASE(0),
    .CLKFBOUT_MULT_F(5),
    .CLKFBOUT_PHASE(0),
    .DIVCLK_DIVIDE(1),
    .REF_JITTER1(0.100),
    .CLKIN1_PERIOD(5.0),
    .STARTUP_WAIT("FALSE"),
    .CLKOUT4_CASCADE("FALSE")
)
clk_mmcm_inst (
    .CLKIN1(sys_clk_ibufg),
    .CLKFBIN(mmcm_clkfb),
    .RST(mmcm_rst),
    .PWRDWN(1'b0),
    .CLKOUT0(clk_125mhz_mmcm_out),
    .CLKOUT0B(),
    .CLKOUT1(),
    .CLKOUT1B(),
    .CLKOUT2(),
    .CLKOUT2B(),
    .CLKOUT3(),
    .CLKOUT3B(),
    .CLKOUT4(),
    .CLKOUT5(),
    .CLKOUT6(),
    .CLKFBOUT(mmcm_clkfb),
    .CLKFBOUTB(),
    .LOCKED(mmcm_locked)
);

BUFG
clk_125mhz_bufg_inst (
    .I(clk_125mhz_mmcm_out),
    .O(clk_125mhz_int)
);

sync_reset #(
    .N(4)
)
sync_reset_125mhz_inst (
    .clk(clk_125mhz_int),
    .rst(~mmcm_locked),
    .sync_reset_out(rst_125mhz_int)
);

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

wire ledu_int;
wire ledl_int;
wire ledd_int;
wire ledr_int;
wire ledc_int;
wire [7:0] led_int;

wire uart_rxd_int;
wire uart_txd_int;
wire uart_rts_int;
wire uart_cts_int;

debounce_switch #(
    .WIDTH(13),
    .N(4),
    .RATE(125000)
)
debounce_switch_inst (
    .clk(clk_125mhz_int),
    .rst(rst_125mhz_int),
    .in({btnu,
        btnl,
        btnd,
        btnr,
        btnc,
        sw}),
    .out({btnu_int,
        btnl_int,
        btnd_int,
        btnr_int,
        btnc_int,
        sw_int})
);

sync_signal #(
    .WIDTH(2),
    .N(2)
)
sync_signal_inst (
    .clk(clk_125mhz_int),
    .in({uart_txd,
        uart_rts}),
    .out({uart_txd_int,
        uart_rts_int})
);

assign ledu = ledu_int;
assign ledl = ledl_int;
assign ledd = ledd_int;
assign ledr = ledr_int;
assign ledc = ledc_int;
assign led = led_int;

assign uart_rxd = uart_rxd_int;
assign uart_cts = uart_cts_int;

fpga_core
core_inst (
    /*
     * Clock: 125MHz
     * Synchronous reset
     */
    .clk_125mhz(clk_125mhz_int),
    .rst_125mhz(rst_125mhz_int),
    /*
     * GPIO
     */
    .btnu(btnu_int),
    .btnl(btnl_int),
    .btnd(btnd_int),
    .btnr(btnr_int),
    .btnc(btnc_int),
    .sw(sw_int),
    .ledu(ledu_int),
    .ledl(ledl_int),
    .ledd(ledd_int),
    .ledr(ledr_int),
    .ledc(ledc_int),
    .led(led_int),
    /*
     * 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_int),
    .uart_rts(uart_rts_int),
    .uart_cts(uart_cts_int)
);

endmodule