verilator/test_regress/t/t_sampled_expr.v

// DESCRIPTION: Verilator: Verilog Test module
//
// This file ONLY is placed under the Creative Commons Public Domain.
// SPDX-FileCopyrightText: 2022 Antmicro Ltd
// SPDX-License-Identifier: CC0-1.0

// verilog_format: off
module t (
  input clk
  );

  reg [3:0] a, b;

  Test1 t1(clk, a, b);
  Test2 t2(clk, a, b);
  Test3 t3(clk);

  initial begin
    a = 0;
    b = 0;
  end

  always @(posedge clk) begin
    a <= a + 1;
    b = b + 1;

    $display("a = %0d, b = %0d, %0d == %0d", a, b, $sampled(a), $sampled(b));

    if (b >= 10) begin
      $write("*-* All Finished *-*\n");
      $finish;
    end
  end
endmodule

module Test1(
  clk, a, b
  );

  input clk;
  input [3:0] a, b;

  assert property (@(posedge clk) $sampled(a == b) == ($sampled(a) == $sampled(b)));
endmodule

module Test2(
  clk, a, b
  );

  input clk;
  input [3:0] a, b;

  assert property (@(posedge clk) eq(a, b));

  function [0:0] eq([3:0] x, y);
    return x == y;
  endfunction
endmodule

module Test3(
  clk
  );

  input clk;

  assert property (@(posedge clk) $sampled($time) == $time);
endmodule