source: sandbox/MultiChannelUSB/uwt_bior31.v@ 185

module uwt_bior31
        #(
                parameter       level   =       1, // transform level
                parameter       width   =       12 // bit width of the input data (unsigned)

        )
        (
                input   wire                                    clock, frame, reset,
                input   wire    [width-1:0]             inp_data,
                output  wire    [widthr-1:0]    out_data,
                output  wire    [1:0]                   out_flag
        );

        localparam      widthr = width + 3;

        localparam      index1 = 1 << (level - 1);
        localparam      index2 = 2 << (level - 1);
        localparam      index3 = 3 << (level - 1);
        
        // Tapped delay line
        reg             [width-1:0]             tap_data_reg [index3:0], tap_data_next [index3:0];
        
        wire    [1:0]                   int_comp_wire;
        reg             [1:0]                   int_comp_reg, int_comp_next;

        reg             [1:0]                   out_flag_reg, out_flag_next;
        
        wire    [widthr-1:0]    add_data_wire [1:0];
        reg             [widthr-1:0]    add_data_reg [1:0], add_data_next [1:0];

        reg             [widthr-1:0]    out_data_reg, out_data_next;

        integer i;
        
        assign add_data_wire[0] = tap_data_reg[index3] + {tap_data_reg[index2][width-2:0], 1'b0} + tap_data_reg[index2];
        assign add_data_wire[1] = {tap_data_reg[index1][width-2:0], 1'b0} + tap_data_reg[index1] + tap_data_reg[0];
        assign int_comp_wire[0] = (add_data_reg[0] > add_data_reg[1]);
        assign int_comp_wire[1] = (add_data_reg[0] < add_data_reg[1]);

        always @(posedge clock)
        begin
                if (reset)
                begin
                        add_data_reg[0] <= {(widthr){1'b0}};
                        add_data_reg[1] <= {(widthr){1'b0}};
                        out_data_reg <= {(widthr){1'b0}};
                        int_comp_reg <= 2'd0;
                        out_flag_reg <= 2'd0;

                        for(i = 0; i <= index3; i = i + 1)
                        begin
                                tap_data_reg[i] <= {(width){1'b0}};
                        end
                end
                else
                begin
                        add_data_reg[0] <= add_data_next[0];
                        add_data_reg[1] <= add_data_next[1];
                        out_data_reg <= out_data_next;
                        int_comp_reg <= int_comp_next;
                        out_flag_reg <= out_flag_next;

                        for(i = 0; i <= index3; i = i + 1)
                        begin
                                tap_data_reg[i] <= tap_data_next[i];
                        end                     
                end
        end
        
        always @*
        begin
                add_data_next[0] = add_data_reg[0];
                add_data_next[1] = add_data_reg[1];
                out_data_next = out_data_reg;
                int_comp_next = int_comp_reg;
                out_flag_next = out_flag_reg;

                for(i = 0; i <= index3; i = i + 1)
                begin
                        tap_data_next[i] = tap_data_reg[i];
                end

                if (frame)
                begin           
                        // Tapped delay line: shift one
                        for(i = 0; i < index3; i = i + 1)
                        begin
                                tap_data_next[i+1] = tap_data_reg[i];
                        end
                        
                        // Input in register 0
                        tap_data_next[0] = inp_data;

                        add_data_next[0] = add_data_wire[0];
                        add_data_next[1] = add_data_wire[1];
                        
                        out_data_next = add_data_next[0] + add_data_next[1];
        
                        int_comp_next = int_comp_wire;
                        out_flag_next[0] = (~int_comp_reg[0]) & (int_comp_wire[0]);
                        out_flag_next[1] = (~int_comp_reg[1]) & (int_comp_wire[1]);

                end

        end

        // output logic
        assign  out_data = out_data_reg;
        assign  out_flag = out_flag_reg;

endmodule