Estimate stream frequencies with a Count-Min Sketch

class CountMinSketch #(
  parameter int WIDTH = 128,
  parameter int DEPTH = 4
);
  int unsigned counters[DEPTH][WIDTH];

  function new();
    if (WIDTH <= 0 || DEPTH <= 0)
      $fatal(1, "WIDTH and DEPTH must be positive");
    counters = '{default: 0};
  endfunction

  function automatic int unsigned hash_index(int x, int row);
    int unsigned mixed;
    mixed = int'(x) ^ (32'h9e37_79b9 * (row + 1));
    mixed ^= mixed >> 16;
    mixed *= 32'h85eb_ca6b;
    mixed ^= mixed >> 13;
    return mixed % WIDTH;
  endfunction

  function void push(int x);
    int unsigned column;
    // Implement here: update the state for one new observation.
  endfunction

  function int unsigned estimate(int x);
    int unsigned column;
    int unsigned minimum = 32'hffff_ffff;
    // Implement here: return the minimum selected row counter.
  endfunction
endclass