Custom Errors in Verilog

module custom_error;
  // In Verilog, we don't have built-in error handling like in Go.
  // Instead, we'll use a simple error flag and message.

  // Define a custom error type
  reg [31:0] arg_error_arg;
  reg [127:0] arg_error_message;
  reg arg_error_flag;

  // Function to set the error
  task set_arg_error;
    input [31:0] arg;
    input [127:0] message;
    begin
      arg_error_arg = arg;
      arg_error_message = message;
      arg_error_flag = 1'b1;
    end
  endtask

  // Function that might produce an error
  function automatic [31:0] f;
    input [31:0] arg;
    begin
      if (arg == 42) begin
        set_arg_error(arg, "can't work with it");
        f = -1;
      end else begin
        f = arg + 3;
      end
    end
  endfunction

  // Main block
  initial begin
    reg [31:0] result;
    result = f(42);

    if (arg_error_flag) begin
      $display("%0d", arg_error_arg);
      $display("%0s", arg_error_message);
    end else begin
      $display("No error occurred");
    end
  end

endmodule

In Verilog, we don’t have built-in error handling mechanisms like in other high-level programming languages. Instead, we’ve implemented a simple error handling system using flags and messages.

We define a custom error type using registers to store the error information:

reg [31:0] arg_error_arg;
reg [127:0] arg_error_message;
reg arg_error_flag;

We then create a task to set the error:

task set_arg_error;
  input [31:0] arg;
  input [127:0] message;
  begin
    arg_error_arg = arg;
    arg_error_message = message;
    arg_error_flag = 1'b1;
  end
endtask

The f function is implemented to potentially produce an error:

function automatic [31:0] f;
  input [31:0] arg;
  begin
    if (arg == 42) begin
      set_arg_error(arg, "can't work with it");
      f = -1;
    end else begin
      f = arg + 3;
    end
  end
endfunction

In the main block, we call the function and check for errors:

initial begin
  reg [31:0] result;
  result = f(42);

  if (arg_error_flag) begin
    $display("%0d", arg_error_arg);
    $display("%0s", arg_error_message);
  end else begin
    $display("No error occurred");
  end
end

To run this Verilog code, you would typically use a Verilog simulator like Icarus Verilog or ModelSim. The output would be:

42
can't work with it

This example demonstrates how to implement a basic error handling mechanism in Verilog, which doesn’t have built-in error types or exception handling like higher-level languages.

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Custom Errors in Verilog