RandCovPoint Behavior

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  • October 21, 2013 at 07:02 #723
    RIAND
    Member

    Hi,

    I’ve started to play with OS-VVM and i have two questions :

    The first is about RandCovPoint. Lets look at the coverage model

    FreqCov.AddCross(
                         GenBin(4,1,500 , 1000,6) &  GenBin(4,2,1001, 6000,6) & GenBin(4,1,6001,10000,6),                                                                         
                         GenBin(0,1),                           
                         GenBin(20)& GenBin(50)& GenBin(80)                               
                          ); 

    My question is when using RandCovPoint and IsCovered to cover the all model.
    Is there a guarantee that the coverage model will try (When possible) to return as much different value as possible from the first Bin  “GenBin(4,1,500 , 1000,6) & GenBin(4,2,1001, 6000,6) & GenBin(4,1,6001,10000,6)”

    The second question is simpler but i can not find the information.
    how can i use to_string with a seed to print it out ? I’ve tried TO_STRING(FreqCov.GetSeed) without success.

    Best regards
    Jc 

    October 21, 2013 at 09:30 #724
    Jim Lewis
    Member

    Hi Jc,

    Short answer is, each item within a given bin is selected with a uniform distribution.  Let’s just look at your first bin and modify it slightly (so it divides nicely) and only consider it as an item bin:

    GenBin(4,1,500 , 1000,5)

    This creates the bins:

    Goal    Range
      4     500-599
      4     600-699
      4     700-799
      4     800-899
      4     900-1000

    As a result, each of these bins will get selected 4 times (due to coverage goal). Internally within a range, RandCovPoint uses RandomPkg.RandInt(Min, Max) to generate a value. So the values will have a uniform distribution. Keep in mind, uniform is uniform over a large set of numbers, so values may repeat.

    If you want no repeating, then rather than using a coverage goal, divide your coverage bins into smaller pieces.  IE: change the coverage goal to 1 and the bin divisor to 20 (my previous divisor: 5 * previous coverage goal: 4)

    GenBin(1,1,500 , 1000,20)

    This creates the bins:

    Goal    Range
      1     500-524
      1     525-549
      1     550-574
      1     575-599
      1     600-624
      1     625-649
      1     650-674
      1     675-699
      1     700-724
      1     725-749
      1     750-774
      1     775-799
      1     800-824
      1     825-849
      1     850-874
      1     875-899
      1     900-924
      1     925-949
      1     950-974
      1     975-1000

    Moving on to your second question.  Everything to do with the seed is in the package RandomBasePkg.  So simply reference it and you will be fine:

    use osvvm.RandomBasePkg.all ;

    Great questions. 

    Best Regards,

    Jim

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