verilator/test_regress/t/t_time_passed.v

// DESCRIPTION: Verilator: Verilog Test module
//
// This file ONLY is placed under The Creative Commons Public Domain, for
// any use, without warranty, 2020 by Wilson Snyder.
// SPDX-License-Identifier: CC0-1.0

`timescale 1ns / 1ps
module t (  /*AUTOARG*/
  // Inputs
  clk
  );
  input clk;

  integer cyc = 0;

  time in;
  // verilator lint_off REALCVT
  initial in = 5432109876.543210ns;  // Will round to time units
  // verilator lint_on REALCVT

  // This shows time changes when passed between modules with different units
  // See also discussion in uvm_tlm2_time.svh

  ps ps (.*);
  ns ns (.*);

  always @(posedge clk) begin
    cyc <= cyc + 1;
    if (cyc == 60) begin
      $write("*-* All Finished *-*\n");
      $finish;
    end
  end
endmodule

`timescale 1ps / 1ps

module ps (
    input clk,
    input integer cyc,
    input time in
);

  always @(posedge clk) begin
    if (cyc == 10) begin
      $timeformat(-9, 6, "ns", 16);
      $write("%m: Input time %t %d\n", in, in);
    end
  end
endmodule

`timescale 1ns / 1ps

module ns (
    input clk,
    input integer cyc,
    input time in
);

  always @(posedge clk) begin
    if (cyc == 20) begin
      $timeformat(-9, 6, "ns", 16);
      $write("%m: Input time %t %d\n", in, in);
    end
  end
endmodule