Command Line Arguments in Verilog

Command-line arguments are a common way to parameterize execution of programs. In Verilog, command-line arguments are typically handled through simulator-specific system tasks or functions.

module command_line_arguments;

  initial begin
    // In Verilog, we typically use simulator-specific system tasks
    // to access command-line arguments. Here's an example using
    // the $test$plusargs and $value$plusargs system functions,
    // which are supported by many Verilog simulators.

    // Check if a specific argument is present
    if ($test$plusargs("arg1")) begin
      $display("Argument 'arg1' is present");
    end

    // Get the value of a specific argument
    string arg_value;
    if ($value$plusargs("arg2=%s", arg_value)) begin
      $display("Value of arg2: %s", arg_value);
    end

    // Print all command-line arguments
    $display("All command-line arguments:");
    for (int i = 0; i < $argc; i++) begin
      $display("  Arg %0d: %s", i, $argv[i]);
    end
  end

endmodule

To experiment with command-line arguments in Verilog, you’ll need to use a Verilog simulator that supports these system tasks. The exact method of passing arguments may vary depending on the simulator you’re using.

For example, using the Icarus Verilog simulator:

$ iverilog -o command_line_arguments command_line_arguments.v
$ vvp command_line_arguments +arg1 +arg2=value
Argument 'arg1' is present
Value of arg2: value
All command-line arguments:
  Arg 0: command_line_arguments
  Arg 1: +arg1
  Arg 2: +arg2=value

Note that in Verilog, command-line argument handling is not as standardized as in other programming languages. The methods shown here ($test$plusargs, $value$plusargs, $argc, and $argv) are commonly supported, but you should consult your simulator’s documentation for the most accurate and up-to-date information on handling command-line arguments.

In hardware design with Verilog, command-line arguments are often used for simulation control and parameter passing, rather than for runtime behavior of the actual hardware being designed.