Constraints for a queue/array: Need help to understand how to implement this #3 condition

SystemVerilog
,
7

In reply to dave_59:

Thank you Dave! Knowing this way of using array method makes me feel a little wiser !!
I did slight modification to first 2 conditions and here is the complete code that generates expected output.


module top;
typedef enum { ADD=1,MUL,SUB,NOP} instruction_e;
class A;
  rand instruction_e list[] = new[20];
  constraint q_c {
    foreach (list[i]) {
      if (i< 18 && list[i] == ADD) {
         list[i+1] != ADD;
         list[i+2] != ADD;
      }
      else 
      if (i< 19 && list[i] == ADD) {
         list[i+1] != ADD;
      }
      
      if (i< 17 && list[i] == MUL) {
        list[i+1] != MUL;
        list[i+2] != MUL;
        list[i+3] != MUL;
      } else 
      if (i< 18 && list[i] == MUL) {
        list[i+1] != MUL;
        list[i+2] != MUL;
      } else 
      if (i< 19 && list[i] == MUL) {
        list[i+1] != MUL;
      }
          
      foreach (list[j])
        if(i<j && list[i]==SUB && list[j]==SUB)
          list.sum() with (int'(item.index inside {[i+1:j-1]} && item != NOP)) >= 3;
    }
  }
endclass
   A a_h;
	initial begin
      repeat (10) begin
          a_h = new();
        assert(a_h.randomize() );
        $display("***************************** list =  %0p ****************************************", a_h.list);
		end
  	end 
endmodule