source: trunk/MultiChannelUSB/configuration.v@ 90

module configuration
        (
                input   wire                    clock, reset,

                input   wire                    bus_ssel, bus_wren,
                input   wire    [3:0]   bus_addr,
                input   wire    [15:0]  bus_mosi,

                output  wire    [15:0]  bus_miso,
                output  wire                    bus_busy,
                
                output  wire    [255:0] cfg_bits
        );

        wire    [15:0]  int_ssel_wire;
        wire    [15:0]  int_miso_wire;
        reg             [15:0]  int_miso_reg [3:0];

        wire    [15:0]  int_q_wire [15:0];
        wire    [255:0] int_bits_wire;

        integer i;
        genvar j;

        generate
                for (j = 0; j < 16; j = j + 1)
                begin : BUS_OUTPUT
                        assign int_bits_wire[j*16+15:j*16] = int_q_wire[j];
                        lpm_ff #(
                                .lpm_fftype("DFF"),
                                .lpm_type("LPM_FF"),
                                .lpm_width(16)) cfg_reg_unit (
                                .enable(int_ssel_wire[j] & bus_ssel & bus_wren),
                                .sclr(reset),
                                .clock(clock),
                                .data(bus_mosi),
                                .q(int_q_wire[j]),
                                .aclr(),
                                .aload(),
                                .aset(),
                                .sload(),
                                .sset());
                                end
        endgenerate

        lpm_mux #(
                .lpm_size(16),
                .lpm_type("LPM_MUX"),
                .lpm_width(16),
                .lpm_widths(4)) bus_miso_mux_unit (
                .sel(bus_addr),
                .data(int_bits_wire),
                .result(int_miso_wire));


        lpm_decode #(
                .lpm_decodes(16),
                .lpm_type("LPM_DECODE"),
                .lpm_width(4)) lpm_decode_unit (
                .data(bus_addr),
                .eq(int_ssel_wire),
                .aclr(),
                .clken(),
                .clock(),
                .enable());

        always @(posedge clock)
        begin
                if (reset)
                begin
                        for(i = 0; i <= 3; i = i + 1)
                        begin
                                int_miso_reg[i] <= 16'd0;
                        end
                end
                else
                begin
                        for(i = 0; i < 3; i = i + 1)
                        begin
                                int_miso_reg[i+1] <= int_miso_reg[i];
                        end
                        int_miso_reg[0] <= int_miso_wire;
                end
        end

        // output logic
        assign  bus_miso = int_miso_reg[3];
        assign  bus_busy = 1'b0;
        assign  cfg_bits = int_bits_wire;

endmodule