Random value generator

SystemVerilog
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1

Hi Everyone
In the system verilog testbench how can I randomize an array??? In the example below I want 8 random variables for In_arr… how can I randomize the In_arr and use the same random variable in two different modules so that I can check how my checker is working for the given example…I tried writing it but it is not taking any inputs.

class stimulus;

rand logic [7:0] In_arr;	//Declare random properties in class
 
  constraint Limit {		//Randomization controlled by constaint block
    In_arr  inside {[0:255]};
  }

   module top;
   int b[8]= {1,2,3,4,5,6,7,8}; 
arbitrary	
   int t[8]= {In_arr};  
   int sum;
   initial begin	
      for(int n = 0; n<8; ++n)begin
	 sum = 0;
	 for(int k = 0; k<=n; ++k)begin
            sum += b[k]*t[n-k];
	 end
	 $display(n,, sum); 
      end
   end
endmodule

And Also I have created another class from where I called the random variable in the top module. but the above program is not taking any of my inputs.

2

In reply to confused kid:
please use code tags to format your code. I have done that for you in the example above. Also, try to make your example correct syntactically, or place comments in the spots that are pseudo-code.

There is no special trick for randomizing an array of integers, you just declare it as rand, or you can call randomize on it directly.

class stimulus;
  rand bit[7:0] t[8];
  // there's no need to constrain the elements inside [0:255] because that is the
  // only range of values the array elements can hold.
endclass

I do not know what you mean by " is not taking any of my inputs" what inputs?

3

In reply to dave_59:

Hi Dave,

I wrote the entire scoreboard for the example above but after my compilation it’s giving me outputs something like this

In_array 0
Received_output 00000000
Generated_output 00000000
:::::success:::::::::

I ran the simulation for 500 clock cycles every time its showing the similar output. I thought their was some mistake the way I’m randomizing the array. I want to generate 8 random variables in the same array and then use each element one after the other for 8 cycles of sum +=b[k]*t[n-k]. I hope you understood my question.

4

In reply to confused kid:
I can’t help you any further because I have no idea what the output is supposed to represent.

5

In reply to dave_59:

Hi dave,

The output is the represent for sum which I’m calculating in both the modules and comparing it in the scoreboard.

Can you please give me method where I can randomize the array so that I can get values something like this t[8] = {25,36,88,96,75,64,78} or any other 8 bit values. so that I can use the same random values generated in my other modules too.