Wire

October 15, 2025

Solving Approach

How do you plan to solve it?

1)If you are connecting the input and output connected directly the continuous assignment keyword "assign" is used because whenever the changes occurs in the input signal , the output value will change

Code

module top_module(input a, output y);
  assign y = a;
endmodule

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Testbench Code

`timescale 1ns/1ps

module tb;
  // Input
  reg a;
  // Output
  wire y;
  // Expected
  reg expected_y;

  // DUT
  top_module dut(.a(a), .y(y));

  // Mismatch (case-inequality handles X/Z correctly)
  wire mismatch = (y !== expected_y);

  integer TOTAL, PASS, FAIL;

  // Apply a value, derive expected, wait, update counters and print
  task apply_and_check;
    input a_val; // 1-bit, 4-state
    begin
      a = a_val;
      expected_y = a_val;   // pass-through golden: y should equal a (0/1/X/Z)
      #5;
      TOTAL = TOTAL + 1;
      if (!mismatch) PASS = PASS + 1; else FAIL = FAIL + 1;
      $display("a=%b | y=%b | expected_y=%b | mismatch=%b", a, y, expected_y, mismatch);
    end
  endtask

  initial begin
    $dumpfile("tb.vcd");
    // dump only input, output, expected, mismatch
    $dumpvars(0, tb.a, tb.y, tb.expected_y, tb.mismatch);

    TOTAL = 0; PASS = 0; FAIL = 0;

    // Tests: 0, 1, X, Z
    apply_and_check(1'b0);
    apply_and_check(1'b1);
    apply_and_check(1'bx);
    apply_and_check(1'bz);

    // Summary
    $display("TOTAL_TEST_CASES=%0d", TOTAL);
    $display("TOTAL_PASSED_TEST_CASES=%0d", PASS);
    $display("TOTAL_FAILED_TEST_CASES=%0d", FAIL);
    $display("ALL_TEST_CASES_PASSED=%s", (FAIL==0) ? "true" : "false");
    $finish;
  end
endmodule