Recover in Verilog

Verilog doesn’t have direct equivalents for concepts like panic and recover, as it’s a hardware description language primarily used for designing digital circuits. However, we can demonstrate a similar concept using simulation-based error handling and reporting.

module recover_example;

  // This task simulates a condition that might cause an error
  task may_cause_error;
    $display("Simulating an error condition");
    $error("A problem occurred");
  endtask

  // This is our main simulation block
  initial begin
    // We use a try-catch like structure to handle errors
    fork
      begin
        may_cause_error();
      end
    join_none

    // This is similar to a deferred function in other languages
    // It will execute even if an error occurs
    final begin
      if ($error_count != 0) begin
        $display("Recovered. Error count: %0d", $error_count);
        $display("Error message: %s", $error_info);
      end
    end

    // This code will still run, unlike in languages with exceptions
    $display("After may_cause_error()");
  end

endmodule

In Verilog, we don’t have a direct equivalent to panic and recover. Instead, we use simulation-based error handling. The $error system task is used to report errors, and we can use the $error_count and $error_info system functions to retrieve information about errors that occurred during simulation.

The may_cause_error task simulates a condition that might cause an error. In our main simulation block (initial), we call this task inside a fork-join_none block, which allows the simulation to continue even if an error occurs.

The final block is similar to a deferred function in other languages. It will execute at the end of the simulation, even if errors have occurred. In this block, we check if any errors have been reported ($error_count != 0), and if so, we display information about the error.

Unlike languages with exceptions, Verilog will continue executing code after an error unless explicitly halted. This is why the “After may_cause_error()” message will still be displayed.

To run this Verilog code, you would typically use a Verilog simulator. The exact command will depend on your simulator, but it might look something like this:

$ vvp recover_example.v
Simulating an error condition
After may_cause_error()
Recovered. Error count: 1
Error message: A problem occurred

This example demonstrates how Verilog can handle and report errors in a way that’s somewhat analogous to the panic and recover mechanism in other languages, while still reflecting the unique characteristics of hardware description and simulation.