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Multi Dimensional Dynamic Array Constraint support Issue in System Verilog/UVM

mahee424

I've the below example for multi dimensional dynamic array randomization;

program main();

    class base;

       rand int array_of_frames[][][];

       rand int frame_height;

       rand int frame_width;

       rand int no_of_frames;

       constraint no_of_frames_c { no_of_frames>1;no_of_frames<3;}

       constraint frame_height_c { frame_height>10;frame_height<20;}

       constraint frame_width_c {frame_width>1;frame_width<100;}

       constraint array_of_frames_c {       

             array_of_frames.size == no_of_frames;  

             foreach (array_of_frames[i]) {           array_of_frames[i].size == frame_height;          }  

            foreach (array_of_frames[i,j]) {            array_of_frames[i][j].size == frame_width;      }  

      }

  function void post_randomize();

   for(int i=0; i<array_of_frames.size; i++) begin    

      for(int j=0; j<array_of_frames[i].size; j++) begin          

         for(int k=0; k<array_of_frames[i][j].size; k++) begin              

               $write("0x%x ", (array_of_frames[i][j][k] & 32'hFF));      

        end        

       $display(" ");  

     end      

   $display(" ");  

 end

endfunction

endclass

base b0 = new();

initial  

void'(b0.randomize());

 endprogram

After simulation I've been observed the below message from irun.log;

 

void'(b0.randomize());
|
ncsim: *W,SVRNDF (./multi_ddynamic_array.sv,53|19): The randomize method call failed.
Observed simulation time : 0 FS + 1
ncsim: *W,RNDOCS: These constraints contribute to the set of conflicting constraints:

constraint frame_height_c { frame_height>10;frame_height<20;} (./multi_ddynamic_array.sv,19)
foreach (array_of_frames[i]) { (./multi_ddynamic_array.sv,25)
ncsim: *W,RNDOCS: These variables contribute to the set of conflicting constraints:

rand variables:
frame_height [./multi_ddynamic_array.sv, 11]

I'm using the below NCSIM Version;

   /tools/icad/cadence_lnx/ius/141.014/tools/bin/irun

Please help in this regard whether I've missed something on constraints. However the above code is working fine with the other tools.

Thanks,

Regards,

Mahesh.

  • Hi,

       Does anyone tell me that the above issue will get resolved by using the latest IUS  version 15.20?

    Thanks,

    Regards,

    Mahesh.

  • in reply to mahee424

    Hi Mahesh.

    Firstly, Incisive is reaching the end of its life, it hasn't had new features added to it since the end of 2016 when Xcelium was launched to replace Incisive.

    Looking at your constraints, I think you'd be much better off if you only randomize the frame_height, frame_width and num_of_frames variables. Forcing the constraint solver to create the dynamic arrays the way you are is not efficient. Given that you already have a post_randomize, it would be more efficient to use $urandom to put random numbers into the array elements. If you're generating any realistic sized image frames then you should consider doing a frame at a time, or even a line at a time, to save wasting vast amounts of memory. You'll also waste less time on randomisation if you only generate items at the moment you need them. The following adaptation of your example should work better, but it's still not what I'd recommend for a real world testbench.

    program main();

        class base;

           int array_of_frames[][][];

           rand int frame_height;

           rand int frame_width;

           rand int no_of_frames;

           constraint no_of_frames_c { no_of_frames>1;no_of_frames<3;}

           constraint frame_height_c { frame_height>10;frame_height<20;}

           constraint frame_width_c {frame_width>1;frame_width<100;}

     

      function void post_randomize();

      array_of_frames = new[no_of_frames];

       foreach (array_of_rames[frame]) begin

          array_of_frames[frame] = new[frame_height]; 

          foreach (array_of_frames[frame][line]) begin          

           array_of_frames[frame][line] = new[frame_width];

           foreach (array_of_frames[frame][line][pixel]) begin

                array_of_frames[frame][line][pixel] = $urandom;

                   $write("0x%x ", (array_of_frames[frame][line][pixel]) & 32'hFF));      

            end        

           $display(" ");  

         end      

       $display(" ");  

     end

    endfunction

    endclass

    base b0 = new();

    initial  

    void'(b0.randomize());

     endprogram

  • in reply to StephenH

    Hi Stephen,

         Thanks a lot for the suggestion and i will try here to make use of xcelium quickly as possible.

    Thanks,

    Mahesh.

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