Dynamic arrays

Me again.
Sorry for the bad legibility!

First of all, I believe the formatting only works when you use the "Reply" button and not in the "Quick Reply".

As for your problem, what are you trying to do by passing the ('b0) to the DA constructor? According to LRM 5.6.1, The argument in the ( ) must be "a dynamic array of a data type equivalent to the array on the left-hand side, but it need not have the same size".

I assume you're trying to initialize the array to be 'b0. If that is the case, you don't have to do anything, since the type bit will initialize to 0 by default.

Tim

Thanks for your reply. I think this is the problem, but I'm not sure yet how to solve the problem. I want to set the array with a function called:

set_crc (16, 'b1111000011110000);

But the compiler tolds me, that only dynamic arrays are allowed as parameter in this context. So, I have to look for another solution. If somebody has a good idea, I would be very thankful.

Sebastian

Here is a testcase I used:

module test;

class testclass;

  int crc_type;
  bit crc_polynomial[];

  function void set_crc(int crc_type, ref bit crc_polynomial[]);
    if ( crc_type != crc_polynomial.size() )
    begin
      $display("crc_type (%0d) and dimension of polynomial (%0d) does not match!", crc_type, crc_polynomial.size());
      $display("Not assigning any value");
      return;
    end
    this.crc_type = crc_type;
    this.crc_polynomial = new[this.crc_type+1](crc_polynomial);
& nbsp; endfunction

  function void print();
    $write("type = %0d  value = ", crc_type);
    for (int i=crc_polynomial.size()-1; i>=0; i--)
      $write(crc_polynomial[i]);
    $display();
  endfunction
endclass

testclass tc;
bit poly[];

initial begin
  tc = new;
  set_poly(8, 'b11110000);
  tc.set_crc(8, poly);
  tc.print();
end

function void set_poly(int size, longint vect);
  poly = new[size];
  for (int i=0; i     poly[i] = vect[i];
  $display("%0b ", vect);
  for (int i=poly.size()-1; i>=0; i--)
    $write(poly[i]);
  $display();
endfunction

endmodule

Tim

Hi Tim,

thank you very much for your source file, I will try it immediately.

Sebastian

Hey, me again,

I have know developed a new idea, which should work, but before implementing this, I would ask you, if it can work.

I save the crc_checksum (in this example CRC16) in an array looking like this: bit [7:0] crc_checksum [2]. During calculation, this sum has to be left shifted. If it would be an integer (like in C) it would be: crc_checksum = crc_checksum << 1;

Does this work with an array of this type too? The reason, why I cannot use an integer is, because I do not know, which type of CRC, it could be 8, 16, 32 or 64.

Thanks for your help!
Sebastian

You can do it if you are using packed arrays. Packed arrays can be read and loaded in parallel as if all their bits are concatenated into a single large vector. This code works for me in IUS 6.11 (I had to try it since I don't write code using this capability every day and I wanted to see if it actually worked).

module testit;

  reg [1:0] [7:0] a;

  initial
  begin
    $display("Packed array testcase");
    a[1] = 8'b10;
    a[0] = 8'b01;
    #10 $displayb ( a[1], , a[0] );
    #10 a = a << 3;
    #10 $displayb ( a[1], , a[0] );
    #100 $finish;
  end
 
endmodule

In my previous post, the omega symbol should be "[ 1" , the epsilon symbol should be "[ 7", and the Y (ypsilon?) symbol should be "[ 0".