Is it possible to assign value larger than (2**31 - 1) to array size of new[] operator in dynamic array

SystemVerilog
1

Hi all,

I got an error when assign value larger than (231 - 1) to array size of new[] operator in dynamic array.
*** Error: Array size passed to ‘new’ must be an integral value between 0 and 2147483647 (231 - 1).


class packet ; 
     
     int unsigned length;
     bit [7:0] payload[];

     constraint len_c {
          length[1:0] == 2'b00
     };
     
     function void post_randomize();
          payload = new[length]; // -> Error here
          /* Create data for payload */
     endfunction 

endclass 

module top; 
    
    packet pkg;
      
    initial begin
       pkg = new();
       
       if (! pkg.randomize() with {
           length == 32'hFFFF_FFFC;
       } ) $display("Cant Randomize!");
    
       /* To do something */               

    end
 
endmodule

Could you please help me for this situation ?
Whether anyone have any solution to solve how to assign a large value to array size in dynamic array ?

Thank you very much for your kindly support.

B.R,
Thien

2

In reply to thienle:

Typically tools will have some limitations to prevent the user from causing issues by using all of the system memory.

Do you really want a dynamic array of 2 Billion bytes? The storage required for this will be very large and the performance will be extremely poor. You cannot effectively use an array of this size.

3

In reply to cgales:

Do you know what other type of array to solve this problem ?

Because I want to check toggle for all 32-bit reg, so I need to perform to 2GByte data.

Thank you very much.

B.R,
Thien

4

In reply to thienle:

I’m not sure what you mean by ‘check toggle for all 32-bit reg’. Do you want to check that each individual bit toggles?

Most simulators will provide toggle coverage so you just need to enable it. You can also use a covergroup.

5

In reply to cgales:

I strongly recommend cgales advice about use your tool’s coverage capabilities to collect toggle coverage.

Regardless of how you collect coverage, you would want to use an associate array to model a 2GB memory. They only allocate array elements that are explicitly written to. Any test that you could run would only have enough time to use a tiny fraction of the array, and that all you need to toggle a 32-bits of an address register.

6

In reply to cgales:

Do you want to check that each individual bit toggles
No, I don’t.
Exactly, I want to check toggle for variable length[31:28], so I need to expand array size in dynamic array.

Thank you very much

7

In reply to dave_59:

I got it.

Do you have any other method to use an associate array to model a 2GB memory ?
If possible, could you please share an code example about that method ?

Thank you very much.

8

In reply to thienle:

typedef bit [30:0] address_t; // 2GB needs 31 address bits

bit [7:0] memory[address_t] = '{default:0}; // any element you read that has not been written yet
                                            // returns this default value without having to allocate it
9

In reply to dave_59:

Let me try your code.

Thank you very much for your kindly support.