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
`timescale 1ns / 1ps
module tt_um_mac(
     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
);

    wire [3:0] A, B;
    wire [7:0] Prod;        // 8-bit product from Dadda multiplier
    reg [7:0] Acc;          // 8-bit accumulator register
    wire [7:0] Sum;         // 8-bit sum from Kogge-Stone adder
    assign uio_oe = 8'b0;  // Assuming uio is always input in this context
    assign A = ui_in[3:0];
    assign B = uio_in[3:0];
    assign uio_out = 8'b0;

    wire _unused = &{ena};

    // Pipeline registers for stages
    reg [7:0] Prod_stage;   // Register to hold product in pipeline
    reg [7:0] Sum_stage;    // Register to hold sum in pipeline

    // Instantiate Dadda Multiplier
    DaddaMultiplier4x4 U1 (.A(A), .B(B), .Prod(Prod));

    // Pipeline stage 1: Store multiplication result
    always @(posedge clk or negedge rst_n) begin
        if (!rst_n)
            Prod_stage <= 8'b0;
        else
            Prod_stage <= Prod; // Store the product in pipeline stage 1
    end

    // Instantiate Kogge-Stone Adder for accumulation
    KoggeStoneAdder8bit U2 (.A(Prod_stage), .B(Acc), .Sum(Sum));

    // Pipeline stage 2: Store sum result
    always @(posedge clk or negedge rst_n) begin
        if (!rst_n)
            Sum_stage <= 8'b0;
        else
            Sum_stage <= Sum; // Store the sum in pipeline stage 2
    end

    // Accumulator register with optimized feedback
    always @(posedge clk or negedge rst_n) begin
        if (!rst_n)
            Acc <= 8'b0;        // Reset accumulator to 0
        else
            Acc <= Sum_stage;   // Update accumulator with the sum
    end

    // Output the accumulated result
    assign uo_out = Acc;
endmodule  
   
module DaddaMultiplier4x4(
    input [3:0] A, B,
    output [7:0] Prod
);
// >>> Module Implementation Begin

// <<< Module Implementation End
endmodule


module half_adder(
    input A, B,
    output Sum, Carry
);
    assign Sum = A ^ B;
    assign Carry = A & B;
endmodule
module full_adder(
    input A, B, Cin,
    output Sum, Carry
);
    assign Sum = A ^ B ^ Cin;
    assign Carry = (A & B) | (A & Cin) | (B & Cin);
endmodule
module KoggeStoneAdder8bit(
    input [7:0] A, B,
    output [7:0] Sum
);
    wire [7:0] P; 
    wire [7:0] G; 
    wire [7:0] C; 
    assign P = A ^ B; 
    assign G = A & B; 
    assign C[0] = 1'b0; 
    genvar i;
    generate
        for (i = 0; i < 7; i = i + 1) begin : carry_gen
            assign C[i + 1] = G[i] | (P[i] & C[i]);
        end
    endgenerate
    assign Sum = P ^ C; 
endmodule


Reference solution:
rtl/generated.v:     wire [15:0] partial_products;
    wire [7:0] sum1, carry1, sum2, carry2;
    assign partial_products[0] = A[0] & B[0];
    assign partial_products[1] = A[0] & B[1];
    assign partial_products[2] = A[0] & B[2];
    assign partial_products[3] = A[0] & B[3];
    assign partial_products[4] = A[1] & B[0];
    assign partial_products[5] = A[1] & B[1];
    assign partial_products[6] = A[1] & B[2];
    assign partial_products[7] = A[1] & B[3];
    assign partial_products[8] = A[2] & B[0];
    assign partial_products[9] = A[2] & B[1];
    assign partial_products[10] = A[2] & B[2];
    assign partial_products[11] = A[2] & B[3];
    assign partial_products[12] = A[3] & B[0];
    assign partial_products[13] = A[3] & B[1];
    assign partial_products[14] = A[3] & B[2];
    assign partial_products[15] = A[3] & B[3];
    assign sum1[0] = partial_products[0];
    half_adder ha1(partial_products[1], partial_products[4], sum1[1], carry1[0]);
    full_adder fa1(partial_products[2], partial_products[5], partial_products[8], sum1[2], carry1[1]);
    full_adder fa2(partial_products[3], partial_products[6], partial_products[9], sum1[3], carry1[2]);
    half_adder ha2(partial_products[7], partial_products[10], sum1[4], carry1[3]);
    half_adder ha3(partial_products[11], partial_products[14], sum1[5], carry1[4]);
    assign sum1[6] = partial_products[12];
    assign sum1[7] = partial_products[15];
    assign Prod[0] = sum1[0]; 
    half_adder ha4(sum1[1], carry1[0], Prod[1], carry2[0]);
    full_adder fa3(sum1[2], carry1[1], carry2[0], sum2[0], carry2[1]);
    full_adder fa4(sum1[3], carry1[2], carry2[1], sum2[1], carry2[2]);
    full_adder fa5(sum1[4], carry1[3], carry2[2], sum2[2], carry2[3]);
    full_adder fa6(sum1[5], carry1[4], carry2[3], sum2[3], carry2[4]);
    assign Prod[2] = sum2[0];
    assign Prod[3] = sum2[1];
    assign Prod[4] = sum2[2];
    assign Prod[5] = sum2[3];
    assign Prod[6] = sum1[6] ^ carry2[4];
    assign Prod[7] = sum1[7] & carry2[4];