Passing Multiple Enum through command line using UVM1.2

This post is related to my previous blog "http://munjalm.blogspot.com/2018/09/passing-enum-through-command-line_2.html" which describes passing enum through command line.

Consider a case where, user wants to randomize enum from few enum values only. In this case, multiple enums can be passed through command line using a delimiter. For example, +DATA_TYPE=DT_2,DT_4.

As "from_name" function converts the string into enum, the above string can be separated out and can be used in "from_name" to get the enum values. To get substring from a string, there are multiple ways:

(1) System verilog provides "substr" function through which we can get the substring. But in the case, we shall know the exact location from where we can the substring.

(2) Go through each character of a string and compare each character with delimiter. If it matches then separate out the sub string.

Here, UVM provides "uvm_split_string" function which splits the string based on a delimiter and returns a queue with sub string. This function contains 3 arguments which are described below:

First arg (string): Main string which will be divided into multiple string

Second arg(byte): Delimiter from where the main string will be separated

Third arg(string queue): It's a reference variable which contains all sub-strings separated with delimiter from main string.

Below is the example which helps to understand more:

Example:

  typedef enum {DT_1, DT_2, DT_3, DT_4} data_type_e;

  typedef uvm_enum_wrapper#(data_type_e) uvm_dt;

  data_type_e dt, dt_1;

  string str;

  initial begin

      string str_q[$];

      data_type_e dt_q[$];

      void'($value$plusargs("DATA_TYPE=%0s", str));

      uvm_split_string(str, ",", str_q);

      foreach (str_q[i]) begin

          if(!(uvm_dt::from_name(str_q[i], dt))) begin

              $display("Wrong Data Type Provided.");

          end

          else begin

              $display("Data Type=%0s",dt.name());

              dt_q.push_back(dt);

          end

      end

      foreach(dt_q[i]) $display("DT=%0s",dt_q[i].name());

      for(int i = 0; i < 10; ++i) begin

          if(!randomize(dt_1) with {dt_1 inside {dt_q};})

              $error("Randomization Failed.");

          else

              $display("Randomized DT=%0s", dt_1.name());

      end

  end

Command with Questa-tool:

vsim "+DATA_TYPE=DT_2,DT_4" -c -do "run -all;q" -f questa.tops

When above command is executed, dt_l value will be generated from DT_2 or DT_4 enum during randomization. 

Here, "DT_2,DT_4" is taken as a single string and is splitted across multiple string using "uvm_split_string" function and the splitted string is stored in "str_q" queue. Then the splitted string is converted into enum using "from_name" function and stored into "dt_q" queue from which dt_l is randomized.