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 Linyang Lee
 * SPDX-License-Identifier: Apache-2.0
 */

`default_nettype none

module tt_um_neural_navigators (
    input signed [7:0] ui_in,              // din, 8-bit data path; din
    input signed [7:0] uio_in,             // w, 8-bit data path; IOs; weight, w 
    output signed [7:0] uo_out,            // outreg, output; sum 
    output [7:0] uio_out,           // Output; IOs
    output [7:0] uio_oe,            // IOs: Enable path (active high: 0=input, 1=output)
    input  ena,                     // always 1 when the design is powered, so you can ignore it
    input  clk,                     // clock
    input  rst_n                    // reset_n - low to reset
);
  

    // Assign output pins
    assign uio_out = 0; 
    assign uio_oe  = 0;

    // Instantiate the neuron module
    top_layer u_toplayer (
        .clk(clk),
        .rst_n(rst_n),
        .din(ui_in),
        .w(uio_in),                         
        .out(uo_out)
    );

endmodule 

module fsm_16_states(
    input clk,
    input rst_n,
    input start,
    output reg [4:0] state
);

// State definitions
parameter s1   = 5'd0;
parameter s2   = 5'd1;
parameter s3   = 5'd2;
parameter s4   = 5'd3;
parameter s5   = 5'd4;
parameter s6   = 5'd5;
parameter s7   = 5'd6;
parameter s8   = 5'd7;
parameter s9   = 5'd8;
parameter s10  = 5'd9;
parameter s11  = 5'd10;
parameter s12  = 5'd11;
parameter s13  = 5'd12;
parameter s14  = 5'd13;
parameter s15  = 5'd14;
parameter s16  = 5'd15;


always @(posedge clk or negedge rst_n) begin
    if (!rst_n) begin
        state <= s1;
    end else if (start) begin
        case (state)
            s1: state <= s2;
            s2: state <= s3;
            s3: state <= s4;
            s4: state <= s5;
            s5: state <= s6;
            s6: state <= s7;
            s7: state <= s8;
            s8: state <= s9;
            s9: state <= s10;
            s10: state <= s11;
            s11: state <= s12;
            s12: state <= s13;
            s13: state <= s14;
            s14: state <= s15;
            s15: state <= s16;
            s16: state <= s1;

            default: begin
                // Handle any unexpected states
                state <= s1; // or some error state
            end
        endcase
    end else begin
        state <=s1;
    end
end

endmodule


module fsm_38_states(
    input clk,
    input rst_n,
    input start,
    output reg [8:0] state
);
// >>> Module Implementation Begin

// <<< Module Implementation End
endmodule




module fsm_260_states(
    input clk,
    input rst_n,
    output reg [8:0] state
);

// State definitions
parameter s1   = 9'd0;
parameter s2   = 9'd1;
parameter s3   = 9'd2;
parameter s4   = 9'd3;
parameter s5   = 9'd4;
parameter s6   = 9'd5;
parameter s7   = 9'd6;
parameter s8   = 9'd7;
parameter s9   = 9'd8;
parameter s10  = 9'd9;
parameter s11  = 9'd10;
parameter s12  = 9'd11;
parameter s13  = 9'd12;
parameter s14  = 9'd13;
parameter s15  = 9'd14;
parameter s16  = 9'd15;
parameter s17  = 9'd16;
parameter s18  = 9'd17;
parameter s19  = 9'd18;
parameter s20  = 9'd19;
parameter s21  = 9'd20;
parameter s22  = 9'd21;
parameter s23  = 9'd22;
parameter s24  = 9'd23;
parameter s25  = 9'd24;
parameter s26  = 9'd25;
parameter s27  = 9'd26;
parameter s28  = 9'd27;
parameter s29  = 9'd28;
parameter s30  = 9'd29;
parameter s31  = 9'd30;
parameter s32  = 9'd31;
parameter s33  = 9'd32;
parameter s34  = 9'd33;
parameter s35  = 9'd34;
parameter s36  = 9'd35;
parameter s37  = 9'd36;
parameter s38  = 9'd37;
parameter s39  = 9'd38;
parameter s40  = 9'd39;
parameter s41  = 9'd40;
parameter s42  = 9'd41;
parameter s43  = 9'd42;
parameter s44  = 9'd43;
parameter s45  = 9'd44;
parameter s46  = 9'd45;
parameter s47  = 9'd46;
parameter s48  = 9'd47;
parameter s49  = 9'd48;
parameter s50  = 9'd49;
parameter s51  = 9'd50;
parameter s52  = 9'd51;
parameter s53  = 9'd52;
parameter s54  = 9'd53;
parameter s55  = 9'd54;
parameter s56  = 9'd55;
parameter s57  = 9'd56;
parameter s58  = 9'd57;
parameter s59  = 9'd58;
parameter s60  = 9'd59;
parameter s61  = 9'd60;
parameter s62  = 9'd61;
parameter s63  = 9'd62;
parameter s64  = 9'd63;
parameter s65  = 9'd64;
parameter s66  = 9'd65;
parameter s67  = 9'd66;
parameter s68  = 9'd67;
parameter s69  = 9'd68;
parameter s70  = 9'd69;
parameter s71  = 9'd70;
parameter s72  = 9'd71;
parameter s73  = 9'd72;
parameter s74  = 9'd73;
parameter s75  = 9'd74;
parameter s76  = 9'd75;
parameter s77  = 9'd76;
parameter s78  = 9'd77;
parameter s79  = 9'd78;
parameter s80  = 9'd79;
parameter s81  = 9'd80;
parameter s82  = 9'd81;
parameter s83  = 9'd82;
parameter s84  = 9'd83;
parameter s85  = 9'd84;
parameter s86  = 9'd85;
parameter s87  = 9'd86;
parameter s88  = 9'd87;
parameter s89  = 9'd88;
parameter s90  = 9'd89;
parameter s91  = 9'd90;
parameter s92  = 9'd91;
parameter s93  = 9'd92;
parameter s94  = 9'd93;
parameter s95  = 9'd94;
parameter s96  = 9'd95;
parameter s97  = 9'd96;
parameter s98  = 9'd97;
parameter s99  = 9'd98;
parameter s100 = 9'd99;
parameter s101 = 9'd100;
parameter s102 = 9'd101;
parameter s103 = 9'd102;
parameter s104 = 9'd103;
parameter s105 = 9'd104;
parameter s106 = 9'd105;
parameter s107 = 9'd106;
parameter s108 = 9'd107;
parameter s109 = 9'd108;
parameter s110 = 9'd109;
parameter s111 = 9'd110;
parameter s112 = 9'd111;
parameter s113 = 9'd112;
parameter s114 = 9'd113;
parameter s115 = 9'd114;
parameter s116 = 9'd115;
parameter s117 = 9'd116;
parameter s118 = 9'd117;
parameter s119 = 9'd118;
parameter s120 = 9'd119;
parameter s121 = 9'd120;
parameter s122 = 9'd121;
parameter s123 = 9'd122;
parameter s124 = 9'd123;
parameter s125 = 9'd124;
parameter s126 = 9'd125;
parameter s127 = 9'd126;
parameter s128 = 9'd127;
parameter s129 = 9'd128;
parameter s130 = 9'd129;
parameter s131 = 9'd130;
parameter s132 = 9'd131;
parameter s133 = 9'd132;
parameter s134 = 9'd133;
parameter s135 = 9'd134;
parameter s136 = 9'd135;
parameter s137 = 9'd136;
parameter s138 = 9'd137;
parameter s139 = 9'd138;
parameter s140 = 9'd139;
parameter s141 = 9'd140;
parameter s142 = 9'd141;
parameter s143 = 9'd142;
parameter s144 = 9'd143;
parameter s145 = 9'd144;
parameter s146 = 9'd145;
parameter s147 = 9'd146;
parameter s148 = 9'd147;
parameter s149 = 9'd148;
parameter s150 = 9'd149;
parameter s151 = 9'd150;
parameter s152 = 9'd151;
parameter s153 = 9'd152;
parameter s154 = 9'd153;
parameter s155 = 9'd154;
parameter s156 = 9'd155;
parameter s157 = 9'd156;
parameter s158 = 9'd157;
parameter s159 = 9'd158;
parameter s160 = 9'd159;
parameter s161 = 9'd160;
parameter s162 = 9'd161;
parameter s163 = 9'd162;
parameter s164 = 9'd163;
parameter s165 = 9'd164;
parameter s166 = 9'd165;
parameter s167 = 9'd166;
parameter s168 = 9'd167;
parameter s169 = 9'd168;
parameter s170 = 9'd169;
parameter s171 = 9'd170;
parameter s172 = 9'd171;
parameter s173 = 9'd172;
parameter s174 = 9'd173;
parameter s175 = 9'd174;
parameter s176 = 9'd175;
parameter s177 = 9'd176;
parameter s178 = 9'd177;
parameter s179 = 9'd178;
parameter s180 = 9'd179;
parameter s181 = 9'd180;
parameter s182 = 9'd181;
parameter s183 = 9'd182;
parameter s184 = 9'd183;
parameter s185 = 9'd184;
parameter s186 = 9'd185;
parameter s187 = 9'd186;
parameter s188 = 9'd187;
parameter s189 = 9'd188;
parameter s190 = 9'd189;
parameter s191 = 9'd190;
parameter s192 = 9'd191;
parameter s193 = 9'd192;
parameter s194 = 9'd193;
parameter s195 = 9'd194;
parameter s196 = 9'd195;
parameter s197 = 9'd196;
parameter s198 = 9'd197;
parameter s199 = 9'd198;
parameter s200 = 9'd199;
parameter s201 = 9'd200;
parameter s202 = 9'd201;
parameter s203 = 9'd202;
parameter s204 = 9'd203;
parameter s205 = 9'd204;
parameter s206 = 9'd205;
parameter s207 = 9'd206;
parameter s208 = 9'd207;
parameter s209 = 9'd208;
parameter s210 = 9'd209;
parameter s211 = 9'd210;
parameter s212 = 9'd211;
parameter s213 = 9'd212;
parameter s214 = 9'd213;
parameter s215 = 9'd214;
parameter s216 = 9'd215;
parameter s217 = 9'd216;
parameter s218 = 9'd217;
parameter s219 = 9'd218;
parameter s220 = 9'd219;
parameter s221 = 9'd220;
parameter s222 = 9'd221;
parameter s223 = 9'd222;
parameter s224 = 9'd223;
parameter s225 = 9'd224;
parameter s226 = 9'd225;
parameter s227 = 9'd226;
parameter s228 = 9'd227;
parameter s229 = 9'd228;
parameter s230 = 9'd229;
parameter s231 = 9'd230;
parameter s232 = 9'd231;
parameter s233 = 9'd232;
parameter s234 = 9'd233;
parameter s235 = 9'd234;
parameter s236 = 9'd235;
parameter s237 = 9'd236;
parameter s238 = 9'd237;
parameter s239 = 9'd238;
parameter s240 = 9'd239;
parameter s241 = 9'd240;
parameter s242 = 9'd241;
parameter s243 = 9'd242;
parameter s244 = 9'd243;
parameter s245 = 9'd244;
parameter s246 = 9'd245;
parameter s247 = 9'd246;
parameter s248 = 9'd247;
parameter s249 = 9'd248;
parameter s250 = 9'd249;
parameter s251 = 9'd250;
parameter s252 = 9'd251;
parameter s253 = 9'd252;
parameter s254 = 9'd253;
parameter s255 = 9'd254;
parameter s256 = 9'd255;
parameter s257 = 9'd256;
parameter s258 = 9'd257;
parameter s259 = 9'd258;
parameter s260 = 9'd259;



always @(posedge clk or negedge rst_n) begin
    if (!rst_n) begin
        state <= s1;
    end else begin
        case (state)
            s1: state <= s2;
            s2: state <= s3;
            s3: state <= s4;
            s4: state <= s5;
            s5: state <= s6;
            s6: state <= s7;
            s7: state <= s8;
            s8: state <= s9;
            s9: state <= s10;
            s10: state <= s11;
            s11: state <= s12;
            s12: state <= s13;
            s13: state <= s14;
            s14: state <= s15;
            s15: state <= s16;
            s16: state <= s17;
            s17: state <= s18;
            s18: state <= s19;
            s19: state <= s20;
            s20: state <= s21;
            s21: state <= s22;
            s22: state <= s23;
            s23: state <= s24;
            s24: state <= s25;
            s25: state <= s26;
            s26: state <= s27;
            s27: state <= s28;
            s28: state <= s29;
            s29: state <= s30;
            s30: state <= s31;
            s31: state <= s32;
            s32: state <= s33;
            s33: state <= s34;
            s34: state <= s35;
            s35: state <= s36;
            s36: state <= s37;
            s37: state <= s38;
            s38: state <= s39;
            s39: state <= s40;
            s40: state <= s41;
            s41: state <= s42;
            s42: state <= s43;
            s43: state <= s44;
            s44: state <= s45;
            s45: state <= s46;
            s46: state <= s47;
            s47: state <= s48;
            s48: state <= s49;
            s49: state <= s50;
            s50: state <= s51;
            s51: state <= s52;
            s52: state <= s53;
            s53: state <= s54;
            s54: state <= s55;
            s55: state <= s56;
            s56: state <= s57;
            s57: state <= s58;
            s58: state <= s59;
            s59: state <= s60;
            s60: state <= s61;
            s61: state <= s62;
            s62: state <= s63;
            s63: state <= s64;
            s64: state <= s65;
            s65: state <= s66;
            s66: state <= s67;
            s67: state <= s68;
            s68: state <= s69;
            s69: state <= s70;
            s70: state <= s71;
            s71: state <= s72;
            s72: state <= s73;
            s73: state <= s74;
            s74: state <= s75;
            s75: state <= s76;
            s76: state <= s77;
            s77: state <= s78;
            s78: state <= s79;
            s79: state <= s80;
            s80: state <= s81;
            s81: state <= s82;
            s82: state <= s83;
            s83: state <= s84;
            s84: state <= s85;
            s85: state <= s86;
            s86: state <= s87;
            s87: state <= s88;
            s88: state <= s89;
            s89: state <= s90;
            s90: state <= s91;
            s91: state <= s92;
            s92: state <= s93;
            s93: state <= s94;
            s94: state <= s95;
            s95: state <= s96;
            s96: state <= s97;
            s97: state <= s98;
            s98: state <= s99;
            s99: state <= s100;
            s100: state <= s101;
            s101: state <= s102;
            s102: state <= s103;
            s103: state <= s104;
            s104: state <= s105;
            s105: state <= s106;
            s106: state <= s107;
            s107: state <= s108;
            s108: state <= s109;
            s109: state <= s110;
            s110: state <= s111;
            s111: state <= s112;
            s112: state <= s113;
            s113: state <= s114;
            s114: state <= s115;
            s115: state <= s116;
            s116: state <= s117;
            s117: state <= s118;
            s118: state <= s119;
            s119: state <= s120;
            s120: state <= s121;
            s121: state <= s122;
            s122: state <= s123;
            s123: state <= s124;
            s124: state <= s125;
            s125: state <= s126;
            s126: state <= s127;
            s127: state <= s128;
            s128: state <= s129;
            s129: state <= s130;
            s130: state <= s131;
            s131: state <= s132;
            s132: state <= s133;
            s133: state <= s134;
            s134: state <= s135;
            s135: state <= s136;
            s136: state <= s137;
            s137: state <= s138;
            s138: state <= s139;
            s139: state <= s140;
            s140: state <= s141;
            s141: state <= s142;
            s142: state <= s143;
            s143: state <= s144;
            s144: state <= s145;
            s145: state <= s146;
            s146: state <= s147;
            s147: state <= s148;
            s148: state <= s149;
            s149: state <= s150;
            s150: state <= s151;
            s151: state <= s152;
            s152: state <= s153;
            s153: state <= s154;
            s154: state <= s155;
            s155: state <= s156;
            s156: state <= s157;
            s157: state <= s158;
            s158: state <= s159;
            s159: state <= s160;
            s160: state <= s161;
            s161: state <= s162;
            s162: state <= s163;
            s163: state <= s164;
            s164: state <= s165;
            s165: state <= s166;
            s166: state <= s167;
            s167: state <= s168;
            s168: state <= s169;
            s169: state <= s170;
            s170: state <= s171;
            s171: state <= s172;
            s172: state <= s173;
            s173: state <= s174;
            s174: state <= s175;
            s175: state <= s176;
            s176: state <= s177;
            s177: state <= s178;
            s178: state <= s179;
            s179: state <= s180;
            s180: state <= s181;
            s181: state <= s182;
            s182: state <= s183;
            s183: state <= s184;
            s184: state <= s185;
            s185: state <= s186;
            s186: state <= s187;
            s187: state <= s188;
            s188: state <= s189;
            s189: state <= s190;
            s190: state <= s191;
            s191: state <= s192;
            s192: state <= s193;
            s193: state <= s194;
            s194: state <= s195;
            s195: state <= s196;
            s196: state <= s197;
            s197: state <= s198;
            s198: state <= s199;
            s199: state <= s200;
            s200: state <= s201;
            s201: state <= s202;
            s202: state <= s203;
            s203: state <= s204;
            s204: state <= s205;
            s205: state <= s206;
            s206: state <= s207;
            s207: state <= s208;
            s208: state <= s209;
            s209: state <= s210;
            s210: state <= s211;
            s211: state <= s212;
            s212: state <= s213;
            s213: state <= s214;
            s214: state <= s215;
            s215: state <= s216;
            s216: state <= s217;
            s217: state <= s218;
            s218: state <= s219;
            s219: state <= s220;
            s220: state <= s221;
            s221: state <= s222;
            s222: state <= s223;
            s223: state <= s224;
            s224: state <= s225;
            s225: state <= s226;
            s226: state <= s227;
            s227: state <= s228;
            s228: state <= s229;
            s229: state <= s230;
            s230: state <= s231;
            s231: state <= s232;
            s232: state <= s233;
            s233: state <= s234;
            s234: state <= s235;
            s235: state <= s236;
            s236: state <= s237;
            s237: state <= s238;
            s238: state <= s239;
            s239: state <= s240;
            s240: state <= s241;
            s241: state <= s242;
            s242: state <= s243;
            s243: state <= s244;
            s244: state <= s245;
            s245: state <= s246;
            s246: state <= s247;
            s247: state <= s248;
            s248: state <= s249;
            s249: state <= s250;
            s250: state <= s251;
            s251: state <= s252;
            s252: state <= s253;
            s253: state <= s254;
            s254: state <= s255;
            s255: state <= s256;
            s256: state <= s257;
            s257: state <= s258;
            s258: state <= s259;
            //s259: state <= s1;
            s259: state <= s260;
            s260: state <= s1; // or another state as needed

            default: begin
                // Handle any unexpected states
                state <= s1; // or some error state
            end
        endcase
    end
end

endmodule


module layer1(
    input clk,
    input rst_n,
    input signed [7:0] din,             // 8-bit input for neurons
    input signed [7:0] w,               // 8-bit weight input for neurons
    output reg [255:0] reg_layer1,      // Register to store the sum of each neuron
    output reg done                     // Done signal
);

    reg [5:0] neuron_index;             // Index to track current neuron
    reg [8:0] statel1;                    // State counter for each neuron
    wire signed [7:0] sum;              // Sum output from neuron

    // Instantiate the neuron module
    neuron u_neuron (
        .clk(clk),
        .rst_n(rst_n),
        .din(din),
        .w(w),
        .sum(sum)
    );

    always @(posedge clk or negedge rst_n) begin
        if (!rst_n) begin
            neuron_index <= 0;
            reg_layer1 <= 0;
            done <= 0;
            statel1 <= 0;

        end else if (!done) begin
            // Process each neuron 
            if (statel1 < 259) begin
                statel1 <= statel1 + 1;
            end else if (statel1 == 259) begin
                // Store the sum once the neuron processing is complete
                reg_layer1[(neuron_index * 8) +: 8] <= sum;
                statel1 <= 0;                // Reset state for next neuron
                neuron_index <= neuron_index + 1; // Move to the next neuron
            end
            
            // Check if all neurons are processed
            if (neuron_index == 32) begin
                done <= 1;  // Assert done when all neurons are processed
            end
        end
    end
endmodule


module layer2(
    input clk,
    input rst_n,
    input start,
    input signed [7:0] b,             // 8-bit input for neurons
    input signed [7:0] w,               // 8-bit weight input for neurons
    input [255:0] reg_layer1,           // 256-bit register from layer1
    output reg [255:0] reg_layer2,      // Register to store the sum of each neuron
    output reg done                     // Done signal
);

    reg [5:0] neuron_index;             // Index to track current neuron (0 to 31)
    reg [8:0] statel2;                    // State counter for each neuron
    wire signed [7:0] sum;              // Sum output from neuron


    // Instantiate the neuron module
    neuron_hidden u_neuron (
        .clk(clk),
        .rst_n(rst_n),
        .start(start),
        .b(b),
        .w(w),
        .reg_layer1(reg_layer1),
        .sum(sum)
    );


    always @(posedge clk or negedge rst_n) begin
        if (!rst_n) begin
            neuron_index <= 0;
            reg_layer2 <= 0;
            done <= 0;
            statel2 <= 0;
        end else if (start && !done) begin
            // Process each neuron 
            if (statel2 < 37) begin
                statel2 <= statel2 + 1;
            end else if (statel2 == 37) begin
                // Store the sum once the neuron processing is complete
                reg_layer2[(neuron_index * 8) +: 8] <= sum;
                statel2 <= 0;                // Reset state for next neuron
                neuron_index <= neuron_index + 1; // Move to the next neuron
            end
            
            // Check if all neurons are processed
            if (neuron_index == 32) begin
                done <= 1;  // Assert done when all neurons are processed
            end
        end
    end
endmodule

module layer3(
    input clk,
    input rst_n,
    input start,
    input signed [7:0] b,             // 8-bit input for neurons
    input signed [7:0] w,               // 8-bit weight input for neurons
    input [255:0] reg_layer2,           // 256-bit register from layer1
    output reg [79:0] outreg, 
    output reg done                     // Done signal
);

   
    reg [5:0] neuron_index;             // Index to track current neuron 
    reg [8:0] stateout;                    // State counter for each neuron
    wire signed [7:0] sum;              // Sum output from neuron

    // Instantiate the neuron module
    neuron_hidden u_neuron (
        .clk(clk),
        .rst_n(rst_n),
        .start(start),
        .b(b),
        .w(w),
        .reg_layer1(reg_layer2),
        .sum(sum)
    );

    //offset stateout from state in neuron by half-clock cycle
    always @(negedge clk or negedge rst_n) begin
        if (!rst_n) begin
            neuron_index <= 0;
            outreg <= 0;
            done <= 0;
            stateout <= 0;
        end else if (start && !done) begin
            // Process each neuron for 260 states
            if (stateout < 37) begin
                stateout <= stateout + 1;
            end else if (stateout == 37) begin
                // Store the sum once the neuron processing is complete
                outreg[(neuron_index * 8) +: 8] <= sum;
                stateout <= 0;                // Reset state for next neuron
                neuron_index <= neuron_index + 1; // Move to the next neuron
            end
            
            // Check if all neurons are processed
            if (neuron_index == 10) begin
                done <= 1;  // Assert done when all neurons are processed
            end
        end
    end
endmodule

module neuron (
    input clk, rst_n,
    input signed [7:0] din,             // 8-bit data input, including bias at state 256
    input signed [7:0] w,               // Signed Weight input
    output reg signed [7:0] sum         // Signed Accumulated result
);

    reg signed [23:0] acc;              // Internal Accumulator
    reg signed [15:0] mult;             // Signed Multiplication result
    wire [8:0] state;                   // State wire from FSM
    reg signed [7:0] b;                 // 8-bit register to hold the bias value
    wire signed [23:0] b_ext;           // 24-bit extended bias
    wire signed [7:0] relu_out;         // ReLU module output

    // Instantiate fsm_260_states with the slower clock
    fsm_260_states instCtrl(.clk(clk), .rst_n(rst_n), .state(state));

    // Instantiate ReLU module with 24-bit input
    relu #(.IN_WIDTH(24)) relu_ins(
        .out(relu_out),
        .in(acc) // Pass the accumulator value to ReLU
    );

    // Sign extension for bias to 24 bits
    assign b_ext = {{16{b[7]}}, b}; // Extend b from 8-bit to 24-bit

    always @(posedge clk or negedge rst_n) begin
        if (!rst_n) begin
            acc <= 24'b0;
            sum <= 8'b0;
            mult <= 16'b0;
            b <= 8'b0;
        end else begin
            if (state < 9'd256) begin
                // Perform signed multiplication with updated din and w
                mult <= din * w;
                // Accumulate the result
                acc <= acc + mult;
            end else if (state == 9'd256) begin
                // Assign din to b when state is 256
                b <= din;
            end else if (state == 9'd257) begin
                // Add bias (extended) at state 256
                acc <= acc + b_ext;
            end else if (state == 9'd258) begin
                sum <= relu_out;
                // Reset acc for the next operation
                acc <= 24'b0;
                mult <= 16'b0;
            /*end else if (state == 9'd259) begin
                // Reset acc for the next operation
                mult <= 16'b0;*/
            end
        end
    end
endmodule


module neuron_out (
    input clk, rst_n, start,
    input signed [7:0] b,                // 8-bit data input, including bias at state 256
    input signed [7:0] w,                // Signed Weight input
    input [79:0] outreg,                 // 256-bit register from layer1
    output reg signed [7:0] sum         // Signed Accumulated result
);

    reg signed [23:0] acc;               // Internal Accumulator
    reg signed [15:0] mult;              // Signed Multiplication result
    wire [4:0] state_nout;               // State wire from FSM
    reg signed [7:0] din;                // 8-bit register to hold din
    wire signed [23:0] b_ext;            // 24-bit extended bias
    wire signed [7:0] relu_out;          // ReLU module output
    

    // Instantiate FSM
    fsm_16_states instCtrl(.clk(clk), .rst_n(rst_n), .start(start),.state(state_nout));

    // Instantiate ReLU module with 24-bit input
    relu #(.IN_WIDTH(24)) relu_ins(
        .out(relu_out),
        .in(acc) // Pass the accumulator value to ReLU
    );

    // Sign extension for bias to 24 bits
    assign b_ext = {{16{b[7]}}, b}; // Extend b from 8-bit to 24-bit

    always @(posedge clk or negedge rst_n) begin
        if (!rst_n) begin
            acc <= 24'b0;
            sum <= 8'b0;
            mult <= 16'b0;
            din <= 8'b0;

        end else if (start) begin
            if (state_nout < 9'd12) begin
                // Select the correct din segment from outreg based on state
                din <= outreg[(state_nout * 8) +: 8]; // Extract the correct 8-bit segment
                
                // Perform signed multiplication with selected din and w
                mult <= din * w;
                
                // Accumulate the result
                acc <= acc + mult;
            end else if (state_nout == 9'd13) begin
                din <= 8'b0;
                acc <= acc + b_ext;
            end else if (state_nout == 9'd14) begin
                // Final output with ReLU activation
                sum <= relu_out;
                
                // Reset acc for the next operation
                acc <= 24'b0;
                mult <= 16'b0;
               
            end
        end
    end
endmodule


module neuron_hidden (
    input clk, 
    input rst_n,
    input start,
    input signed [7:0] b,                // 8-bit data input, including bias at state 256
    input signed [7:0] w,                // Signed Weight input
    input [255:0] reg_layer1,            // 256-bit register from layer1
    output reg signed [7:0] sum          // Signed Accumulated result
);

    reg signed [23:0] acc;               // Internal Accumulator
    reg signed [15:0] mult;              // Signed Multiplication result
    wire [8:0] state;                    // State wire from FSM
    reg signed [7:0] din;                // 8-bit register to hold din
    wire signed [23:0] b_ext;            // 24-bit extended bias
    wire signed [7:0] relu_out;          // ReLU module output

    // Instantiate FSM with 38 states
    fsm_38_states instCtrl(
        .clk(clk), 
        .rst_n(rst_n), 
        .start(start), 
        .state(state)
    );

    // Instantiate ReLU module with 24-bit input
    relu #(.IN_WIDTH(24)) relu_ins(
        .out(relu_out),
        .in(acc) // Pass the accumulator value to ReLU
    );

    // Sign extension for bias to 24 bits
    assign b_ext = {{16{b[7]}}, b}; // Extend b from 8-bit to 24-bit

    always @(posedge clk or negedge rst_n) begin
        if (!rst_n) begin
            // Reset all registers and signals
            acc <= 24'b0;
            sum <= 8'b0;
            mult <= 16'b0;
            din <= 8'b0;
        end else if (start) begin
            // Only operate when start is asserted
            if (state < 9'd34) begin
                // Select the correct din segment from reg_layer1 based on state
                din <= reg_layer1[(state * 8) +: 8]; // Extracts the correct 8-bit segment
                
                // Perform signed multiplication with selected din and w
                mult <= din * w;
                
                // Accumulate the result
                acc <= acc + mult;
            end else if (state == 9'd35) begin
                // Add bias in the specific state
                din <= 8'b0;
                acc <= acc + b_ext;
            end else if (state == 9'd36) begin
                // Final output with ReLU activation
                sum <= relu_out;
                
                // Reset acc for the next operation
                acc <= 24'b0;
                mult <= 16'b0;
            end

        end
    end
endmodule



module outlayer(
    input clk,
    input rst_n,
    input start,
    input signed [7:0] b,             // 8-bit input for neurons
    input signed [7:0] w,               // 8-bit weight input for neurons
    input [79:0] outreg,      // Register to store the sum of each neuron
    output signed [7:0] out,
    output reg done                     // Done signal
);

    //reg [5:0] neuron_index;             // Index to track current neuron 
    reg [8:0] state_nout;                    // State counter
    //wire signed [7:0] sum;              // Sum output from neuron

    // Instantiate the neuron module
    neuron_out u_neuron (
        .clk(clk),
        .rst_n(rst_n),
        .start(start),
        .b(b),
        .w(w),
        .outreg(outreg),
        .sum(out)
    );

    //offset state_nout from state in neuron by half-clock cycle
    always @(negedge clk or negedge rst_n) begin
        if (!rst_n) begin
            //neuron_index <= 0;
            done <= 0;
            state_nout <= 0;
        end else if (start && !done) begin
            // Process each neuron for 260 states
            if (state_nout < 15) begin
                state_nout <= state_nout + 1;
            end else if (state_nout == 15) begin

                state_nout <= 0;               
                done<=1;
            end
            
        end
    end
endmodule

module relu #(
    parameter IN_WIDTH = 1
) (
    output reg signed [7:0] out,
    input signed [IN_WIDTH-1:0] in
);

always @(*) begin
    if (in >= 128) begin
        out = 8'd127;  // Clamp to 127
    end else if (in <= -128) begin
        out = -8'd128;  // Clamp to -128
    end else begin
        out = $signed(in[7:0]);  // Safely truncate to 8-bit signed output
    end
end

endmodule

module top_layer(
    input clk,
    input rst_n,
    input signed [7:0] din,             // 8-bit input for neurons + bias in layer1 and as bias in layer2 and outlayer
    input signed [7:0] w,               // 8-bit weight input for all neurons
    output [7:0] out                   // Output   
);

    // Intermediate signals
    wire [255:0] reg_layer1;            // Output from layer1 to input of layer2
    wire done_layer1;                   // Done signal from layer1
    wire [255:0] reg_layer2;            // Output from layer2 to input of layer3
    wire done_layer2;                   // Done signal from layer2
    wire [79:0] outreg;
    wire done_layer3;                   // Done signal from layer3
    wire done_outlayer;

    // Internal signals for delay
    reg delayed_done_layer1;
    reg delayed_done_layer2;
    reg delayed_done_layer3;            // Delayed done signal for layer3
    reg [1:0] delay_counter_layer1;
    reg [1:0] delay_counter_layer2;
    reg [1:0] delay_counter_layer3;     // Delay counter for layer3

    // Instantiate layer1
    layer1 u_layer1 (
        .clk(clk),
        .rst_n(rst_n),
        .din(din),                      // Input to layer1
        .w(w),                          // Weight input for layer1
        .reg_layer1(reg_layer1),        // Output register to layer2
        .done(done_layer1)              // Done signal from layer1
    );

    // Instantiate layer2
    layer2 u_layer2 (
        .clk(clk),
        .rst_n(rst_n),
        .start(delayed_done_layer1),    // Start layer2 when delayed_done_layer1 is asserted
        .b(din),                        // Use din as bias input for layer2
        .w(w),                          // Weight input for layer2
        .reg_layer1(reg_layer1),        // Input register from layer1
        .reg_layer2(reg_layer2),        // Output register to layer3
        .done(done_layer2)              // Done signal from layer2
    );

    // Instantiate layer3
    layer3 u_layer3 (
        .clk(clk),
        .rst_n(rst_n),
        .start(delayed_done_layer2),    // Start layer3 when delayed_done_layer2 is asserted
        .b(din),                        // Use din as bias input for layer3
        .w(w),                          // Weight input for layer3
        .reg_layer2(reg_layer2),        // Input register from layer2
        .outreg(outreg),                // Final output register
        .done(done_layer3)              // Done signal for layer3
    );

    // Instantiate neuron_out
    outlayer u_outlayer (
        .clk(clk),
        .rst_n(rst_n),
        .start(delayed_done_layer3),    // Start neuron_out when delayed_done_layer3 is asserted
        .b(din),                        // Use din as bias input for neuron_out
        .w(w),                          // Weight input for neuron_out
        .outreg(outreg),                // Input register, connect outreg from layer3
        .out(out),           // Output sum from neuron_out
        .done(done_outlayer)
    );

    // Handle delays for done_layer1, done_layer2, and done_layer3
    always @(posedge clk or negedge rst_n) begin
        if (!rst_n) begin
            delayed_done_layer1 <= 0;
            delayed_done_layer2 <= 0;
            delayed_done_layer3 <= 0;
            delay_counter_layer1 <= 0;
            delay_counter_layer2 <= 0;
            delay_counter_layer3 <= 0;
        end else begin
            // Handle delay for done_layer1
            if (done_layer1) begin
                delay_counter_layer1 <= 2;  // Start 2-cycle delay
            end else if (delay_counter_layer1 > 0) begin
                delay_counter_layer1 <= delay_counter_layer1 - 1;
            end
            delayed_done_layer1 <= (delay_counter_layer1 > 0);

            // Handle delay for done_layer2
            if (done_layer2) begin
                delay_counter_layer2 <= 2;  // Start 2-cycle delay
            end else if (delay_counter_layer2 > 0) begin
                delay_counter_layer2 <= delay_counter_layer2 - 1;
            end
            delayed_done_layer2 <= (delay_counter_layer2 > 0);

            // Handle delay for done_layer3
            if (done_layer3) begin
                delay_counter_layer3 <= 2;  // Start 2-cycle delay
            end else if (delay_counter_layer3 > 0) begin
                delay_counter_layer3 <= delay_counter_layer3 - 1;
            end
            delayed_done_layer3 <= (delay_counter_layer3 > 0);
        end
    end

endmodule


Reference solution:
rtl/generated.v: 
// State definitions
parameter s1   = 9'd0;
parameter s2   = 9'd1;
parameter s3   = 9'd2;
parameter s4   = 9'd3;
parameter s5   = 9'd4;
parameter s6   = 9'd5;
parameter s7   = 9'd6;
parameter s8   = 9'd7;
parameter s9   = 9'd8;
parameter s10  = 9'd9;
parameter s11  = 9'd10;
parameter s12  = 9'd11;
parameter s13  = 9'd12;
parameter s14  = 9'd13;
parameter s15  = 9'd14;
parameter s16  = 9'd15;
parameter s17  = 9'd16;
parameter s18  = 9'd17;
parameter s19  = 9'd18;
parameter s20  = 9'd19;
parameter s21  = 9'd20;
parameter s22  = 9'd21;
parameter s23  = 9'd22;
parameter s24  = 9'd23;
parameter s25  = 9'd24;
parameter s26  = 9'd25;
parameter s27  = 9'd26;
parameter s28  = 9'd27;
parameter s29  = 9'd28;
parameter s30  = 9'd29;
parameter s31  = 9'd30;
parameter s32  = 9'd31;
parameter s33  = 9'd32;
parameter s34  = 9'd33;
parameter s35  = 9'd34;
parameter s36  = 9'd35;
parameter s37  = 9'd36;
parameter s38  = 9'd37;


always @(posedge clk or negedge rst_n) begin
    if (!rst_n) begin
        state <= s1;
    end else if (start) begin
        case (state)
            s1: state <= s2;
            s2: state <= s3;
            s3: state <= s4;
            s4: state <= s5;
            s5: state <= s6;
            s6: state <= s7;
            s7: state <= s8;
            s8: state <= s9;
            s9: state <= s10;
            s10: state <= s11;
            s11: state <= s12;
            s12: state <= s13;
            s13: state <= s14;
            s14: state <= s15;
            s15: state <= s16;
            s16: state <= s17;
            s17: state <= s18;
            s18: state <= s19;
            s19: state <= s20;
            s20: state <= s21;
            s21: state <= s22;
            s22: state <= s23;
            s23: state <= s24;
            s24: state <= s25;
            s25: state <= s26;
            s26: state <= s27;
            s27: state <= s28;
            s28: state <= s29;
            s29: state <= s30;
            s30: state <= s31;
            s31: state <= s32;
            s32: state <= s33;
            s33: state <= s34;
            s34: state <= s35;
            s35: state <= s36;
            s36: state <= s37;
            s37: state <= s38;
            s38: state <= s1;
            //s36: state <= s1;

            default: begin
                // Handle any unexpected states
                state <= s1; // or some error state
            end
        endcase
    end else begin
        state <=s1;
    end
end