Specman/e list of lists (multidimensional array)

Question

How can I create a fixed multidimensional array in Specman/e using varibles?
And then access individual elements or whole rows?

For example in SystemVerilog I would have:

module top;

  function automatic my_func();
    bit [7:0] arr [4][8]; // matrix: 4 rows, 8 columns of bytes
    bit [7:0] row    [8]; // array : 8 elements        of bytes

    row = '{1, 2, 3, 4, 5, 6, 7, 8};

    $display("Array:");
    foreach (arr[i]) begin
      arr[i] = row;
      $display("row[%0d] = %p", i, row);
    end

    $display("\narr[2][3] = %0d", arr[2][3]);
  endfunction : my_func

  initial begin
    my_func();
  end

endmodule : top

This will produce this output:

Array:
row[0] = '{'h1, 'h2, 'h3, 'h4, 'h5, 'h6, 'h7, 'h8}
row[1] = '{'h1, 'h2, 'h3, 'h4, 'h5, 'h6, 'h7, 'h8}
row[2] = '{'h1, 'h2, 'h3, 'h4, 'h5, 'h6, 'h7, 'h8}
row[3] = '{'h1, 'h2, 'h3, 'h4, 'h5, 'h6, 'h7, 'h8}

arr[2][3] = 4

Can someone rewrite my_func() in Specman/e?

score 2 · Accepted Answer · answered May 07 '18 at 09:49

There are no fixed arrays in e. But you can define a variable of a list type, including a multi-dimensional list, such as:

var my_md_list: list of list of my_type;

It is not the same as a multi-dimensional array in other languages, in the sense that in general each inner list (being an element of the outer list) may be of a different size. But you still can achieve your purpose using it. For example, your code might be rewritten in e more or less like this:

var arr: list of list of byte;
var row: list of byte = {1;2;3;4;5;6;7;8};

for i from 0 to 3 do {
    arr.add(row.copy());
    print arr[i];
};

print arr[2][3];

Notice the usage of row.copy() - it ensures that each outer list element will be a copy of the original list. If we don't use copy(), we will get a list of many pointers to the same list. This may also be legitimate, depending on the purpose of your code.

score 2 · Answer 2 · answered May 07 '18 at 09:52

In case of a field (as opposed to a local variable), it is also possible to declare it with a given size. This size is, again, not "fixed" and can be modified at run time (by adding or removing items), but it determines the original size of the list upon creation, for example:

struct foo {
    my_list[4][8]: list of list of int;
};

Specman/e list of lists (multidimensional array)

2 Answers2