source: sandbox/MultiChannelUSB/amplitude.v@ 156

module amplitude
        #(
                parameter       width   =       12 // bit width of the input data
        )
        (
                input   wire                            clock, frame, reset,
                input   wire    [width-1:0]     cfg_data,
                input   wire    [width-1:0]     inp_data,
                output  wire    [width-1:0]     out_data,
                output  wire                            out_flag
        );

        reg                                     int_case_reg, int_case_next;
        reg                                     out_flag_reg, out_flag_next;
        reg                                     int_flag_reg, int_flag_next;
        reg             [width-1:0]     int_mini_reg, int_mini_next;
        reg             [width-1:0]     out_data_reg, out_data_next;
        reg             [width-1:0]     inp_data_reg [1:0], inp_data_next [1:0];

        wire                            int_comp_wire;
        reg                                     int_comp_reg, int_comp_next;

        assign int_comp_wire = (inp_data_reg[1] < inp_data);

        always @(posedge clock)
        begin
                if (reset)
                begin
                        int_case_reg <= 1'b0;
                        int_mini_reg <= {(width){1'b0}};
                        inp_data_reg[0] <= {(width){1'b0}};
                        inp_data_reg[1] <= {(width){1'b0}};
                        out_data_reg <= {(width){1'b0}};
                        out_flag_reg <= 1'b0;
                        int_flag_reg <= 1'b0;
                        int_comp_reg <= 1'b0;
                end
                else
                begin
                        int_case_reg <= int_case_next;
                        int_mini_reg <= int_mini_next;
                        inp_data_reg[0] <= inp_data_next[0];
                        inp_data_reg[1] <= inp_data_next[1];
                        out_data_reg <= out_data_next;
                        out_flag_reg <= out_flag_next;
                        int_flag_reg <= int_flag_next;
                        int_comp_reg <= int_comp_next;
                end
        end
        
        always @*
        begin
                int_case_next = int_case_reg;
                int_mini_next = int_mini_reg;
                inp_data_next[0] = inp_data_reg[0];
                inp_data_next[1] = inp_data_reg[1];
                out_data_next = out_data_reg;
                out_flag_next = out_flag_reg;
                int_flag_next = int_flag_reg;
                int_comp_next = int_comp_reg;
                
                case (int_case_reg)
                        0:
                        begin
                                if (frame)
                                begin
                                        inp_data_next[0] = inp_data;
                                        inp_data_next[1] = inp_data_reg[0];
                                        int_comp_next = int_comp_wire;
                                        out_data_next = {(width){1'b0}};
                                        out_flag_next = 1'b0;
                                        // minimum
                                        if ((~int_comp_reg) & (int_comp_wire))
                                        begin
                                                int_mini_next = inp_data_reg[0];
                                                int_flag_next = 1'b1;
                                        end
                                        // maximum
                                        else if ((int_comp_reg) & (~int_comp_wire) & (int_flag_reg))
                                        begin
                                                out_data_next = inp_data_reg[0] - int_mini_reg;
                                                int_flag_next = 1'b0;
                                                int_case_next = 1'b1;
                                        end
                end
                        end
                        
                        1:
                        begin
                                out_flag_next = (out_data_reg >= cfg_data);
                                int_case_next = 1'b0;
                        end

                endcase
        end

        assign out_data = out_data_reg;
        assign out_flag = out_flag_reg;

endmodule