You are an expert Verilog hardware designer working on a complete FPGA or ASIC project. You are given the full source code of a Verilog project. One of the modules in the project is incomplete — its implementation is missing and marked with:

// >>> Module Implementation Begin

// <<< Module Implementation End

Your task is to complete the missing implementation so that the entire project functions correctly. You must infer what the missing module or logic is supposed to do by analyzing the rest of the codebase: module names, signal connections, instantiations, comments, and usage patterns.

Follow these rules:

1. Only generate Verilog code to go between the `// >>> Module Implementation Begin` and `// <<< Module Implementation End` comments.
2. Use Verilog-2001 syntax. Ensure the code is synthesizable.
3. Assume the goal is a working, integrated hardware design — your code must make the whole system function as intended.
4. Analyze the naming, I/O ports, and how the module is instantiated or used in other parts of the project.
5. Implement correct behavior based on design context. Do not guess randomly — reason it out.
6. Avoid vendor-specific features unless explicitly required.
7. Do not output comments, explanation, or anything outside the required code region unless explicitly asked.

Your output should contain **only the Verilog code** that fits inside the marked region.

/*
 * Copyright (c) 2024 Your Name
 * SPDX-License-Identifier: Apache-2.0
 */

`default_nettype none

module tt_um_mroblesh (
    input  wire [7:0] ui_in,    // Dedicated inputs
    output wire [7:0] uo_out,   // Dedicated outputs
    input  wire [7:0] uio_in,   // IOs: Input path
    output wire [7:0] uio_out,  // IOs: Output path
    output wire [7:0] uio_oe,   // IOs: Enable path (active high: 0=input, 1=output)
    input  wire       ena,      // always 1 when the design is powered, so you can ignore it
    input  wire       clk,      // clock
    input  wire       rst_n     // reset_n - low to reset
);
// >>> Module Implementation Begin

// <<< Module Implementation End
endmodule




module FrequencyDecoder (
    input wire clk,                // System clock
    input wire reset,              // Reset signal
    input wire signal_in,          // 1-bit frequency input signal
    input wire [1:0] sample_rate, // 00: 
    //output reg freq_range,        // 0 when low frequency (0-255), 1 when high frequency (0-66280)
    output wire [7:0] freq_out // 8-bit output representing frequency
);
    
    wire [31:0] sample_period;    // Number of clock cycles per sampling period
    reg [31:0] counter;        // Counter to measure the number of clock cycles
    reg [31:0] frequency;      // Measured frequency (not scaled)
    reg [7:0] freq_trunc; // trancated
    reg [0:0] signal_in_prev;  // Previous signal_in to detect rising edges

    assign freq_out = freq_trunc;


    // Assuming 10 MHz Clock Speed
    // 00: 100000 CC    100 Hz      10 ms
    // 01: 10000 CC     1 kHz       1 ms
    // 10: 1000 CC      10 kHz      100 us
    // 11: 100 CC       100 kHz     10 us
    // Multiply freq_out by sample rate to get frequency of input
    assign sample_period = sample_rate[1] ? (sample_rate[0] ? 32'd99 : 32'd999) 
                                          : (sample_rate[0] ? 32'd9999 : 32'd99999);


    
    // Initialize counter and sampling period on reset
    always @(posedge clk) begin
        if (reset) begin
            counter <= 32'b0;
            frequency <= 32'b0;
            //freq_range <= 1'b0;
            freq_trunc <= 8'b0;
        end else begin
            // Update progression within sampling period
            counter <= counter + 1;

            // Count cycles of input signal 'signal_in'
            if (signal_in & ~signal_in_prev)    // Rising edge
                frequency <= frequency + 1;
            
            // Check if sampling period is complete
            if (counter >= sample_period) begin
                if (frequency > 255) begin
                    //freq_range <= 1;    // Set to high frequency range
                        
                    // Normalize the frequency value to fit in 8-bits, maximum of 66280
                    freq_trunc <= (frequency[15:8] > 255) ? 255 : frequency[15:8];
                end else begin
                    //freq_range <= 0;    // Set to low frequency range
                    // No need to normalize
                    freq_trunc <= frequency[7:0];
                end
                
                // Reset counter after sampling
                counter <= 32'b0;
                // Reset frequency after sampling
                frequency <= 32'b0;
            end

            // Record signal_in value
            signal_in_prev <= signal_in;
        end
    end
endmodule

module FrequencyEncoder(
    input [7:0] in_bus,    // 8-bit input bus
    input clk,              // System clock
    input wire reset,              // Reset signal
    output reg out         // 1-bit frequency output
);

    reg [15:0] counter;    // Counter for clock division (larger value for lower frequencies)
    reg [15:0] divide_value; // Division factor based on input bus

    // Update the divide_value on every clock cycle based on the input bus
    always @(posedge clk) begin
        if (reset) begin
            divide_value <= 0;
        end else begin
            divide_value <= 16'h00FF - {8'h00, in_bus};  // Lower input value corresponds to longer period (lower frequency)
        end
    end

    // Clock division and output toggling logic
    always @(posedge clk) begin
        // Increment the counter
        if (reset) begin
            counter <= 0;
            out <= 0;
        end else if (counter >= divide_value) begin
            counter <= 16'd0;    // Reset the counter when it exceeds the divide_value
            out <= ~out;         // Toggle the output signal
        end else begin
            counter <= counter + 1; // Increment counter
        end
    end

endmodule


Reference solution:
rtl/generated.v: 
  // All output pins must be assigned. If not used, assign to 0.
  assign uio_out[7:0] = 8'b0;
  assign uio_oe  = 0;

  // List all unused inputs to prevent warnings
  wire _unused = &{ena, uio_in, 1'b0};

  // One idea is to have a Decoder, Encoder on one chip
  // uio_in[0] selects between these 2
  // 0 - Frequency Decoder
  // 1 - Frequency Encoder
  // When FreqDecode selected, there will be additional inputs added to select between
  // different sampling periods (ui_in)
  //

  wire [0:0] signal_in;
  wire [1:0] sample_rate;
  wire [7:0] in_bus;
  assign signal_in = uio_in[0] ? 1'b0 : ui_in[0]; // 0 unless in decode mode, in which case takes LSB of ui_in
  assign sample_rate = uio_in[0] ? 2'b0 : uio_in[7:6];  // 0 unless in decode mode
  assign in_bus = uio_in[0] ? ui_in : 8'b0; // 0 unless in encode mode, takes ui_in bus

  wire [7:0] freq_out;
  wire [0:0] out;
  assign uo_out[0] = uio_in[0] ? out : freq_out[0];
  assign uo_out[7:1] = uio_in[0] ? 7'b0 : freq_out[7:1];

  // Instantiate FreqDecode module
  FrequencyDecoder decoder_inst (
    .clk(clk),
    .reset(~rst_n),
    .signal_in(signal_in),
    .sample_rate(sample_rate),

    //.freq_range(uio_out[5]),
    .freq_out(freq_out)
  );

  FrequencyEncoder encoder_inst (
    .clk(clk),
    .reset(~rst_n),
    .in_bus(in_bus),
    .out(out)
  );