verilog $ferror example

The $ferror system task in Verilog is used to check if there are any file input/output errors. Here is an example of how to use $ferror in Verilog:

module file_example;

  reg [7:0] data;
  integer file_handle;
  
  initial begin
    file_handle = $fopen("data.txt", "r");
    if (file_handle == 0) begin
      $display("Error: Cannot open file");
      $finish;
    end
    while (!$feof(file_handle)) begin
      $fread(data, file_handle);
      if ($ferror) begin
        $display("Error reading file");
        $fclose(file_handle);
        $finish;
      end
      $display("Read data: %d", data);
    end
    $fclose(file_handle);
  end
  
endmodule

In this example, we declare a reg variable called "data" to store the data read from the file. We also define an integer variable called "file_handle" to hold the file handle returned by $fopen.

Inside the initial block, we attempt to open the file "data.txt" in read mode using $fopen. If the file cannot be opened, we display an error message and exit the simulation using $finish.

We then enter a loop that reads data from the file using $fread. If $ferror returns true, we display an error message and close the file using $fclose. Otherwise, we display the data read from the file.

Once we have finished reading the file, we close it using $fclose.

Note that we use $feof to check if we have reached the end of the file, and $fread to read data from the file. These are other system tasks in Verilog that are commonly used with $ferror.