Time Formatting Parsing in Verilog

Verilog supports time-related operations through the use of system tasks and functions. Here’s how we can work with time in Verilog:

module time_example;

  // Define a task for printing
  task print;
    input [1000:0] str;
    begin
      $display(str);
    end
  endtask

  initial begin
    // Get the current simulation time
    $display("Current simulation time: %0t", $time);

    // Format time as a string
    $display("Formatted time: %0t", $sformat("%0t", $time));

    // Parse a time string (not directly supported in Verilog)
    // Instead, we can use $sscanf to extract time components
    reg [63:0] year, month, day, hour, minute, second;
    reg [1000:0] time_str = "2012-11-01T22:08:41";
    $sscanf(time_str, "%d-%d-%dT%d:%d:%d", year, month, day, hour, minute, second);
    $display("Parsed time: %0d-%0d-%0dT%0d:%0d:%0d", year, month, day, hour, minute, second);

    // Custom time formatting
    $display("Custom format: %0t", $sformat("%0d:%0d:%0d", hour, minute, second));

    // Delay to demonstrate time passing
    #100;
    $display("Time after delay: %0t", $time);

    // Error handling for time parsing is not directly supported in Verilog
    // You would need to implement your own error checking logic
  end

endmodule

In Verilog, time-related operations are quite different from high-level programming languages:

1. Verilog uses simulation time, which is controlled by the simulator.

2. The $time system function returns the current simulation time.

3. Time formatting is typically done using the $sformat system task, which allows for custom formatting of values.

4. Verilog doesn’t have built-in time parsing functions. Instead, you can use $sscanf to extract time components from a string.

5. For purely numeric representations, you can use $sformat or direct string formatting in $display.

6. Error handling for time parsing is not built into Verilog. You would need to implement your own error checking logic if required.

To run this Verilog code, you would typically use a Verilog simulator such as ModelSim, VCS, or Icarus Verilog. The exact commands may vary depending on your simulation environment.

$ iverilog time_example.v
$ ./a.out
Current simulation time: 0
Formatted time: 0
Parsed time: 2012-11-01T22:08:41
Custom format: 22:08:41
Time after delay: 100

This example demonstrates basic time operations in Verilog, although it’s important to note that Verilog’s approach to time is fundamentally different from software programming languages, as it’s designed for hardware simulation.