Methods of getting two power values

Hi Everyone,

      Today we are going to see how to generate the two power values.

Unique character of two power values:

   Every two power value contains only one bit is one at a time.

 

    Ex:

        consider 4 bit values.

            0=0001

            2=0010

            4=0100

            8=1000

            

 Method 1:  

          First we have to find the number of ones in a given number. if number of one is equal to one that number must be a two power value.

          Kindly refer my fist blog for counting the number of ones. if (cnt==1) then we can say the generated number is a two power value. 

Method 2:

          By using left shift operation we can produce two power values.

                 module TB;

                             bit[3:0] x;

                              int data[*];

                             initial begin

                                  x=$urandom;

                                for(int i=0;i<x;i++) begin

                                  data[i]=1<<i;

                                  $display("Two power values %0d %0d ",x,data[i]);

                               end

                            end

                endmodule

Here x will be randomized based on x loop will iterate. "i" will be the power of two. Let consider 2**5.

Binary form of one =00001=> shift the one to left direction for five times. Result is 10000. Convert into decimal.Hence the output will be 32. This is the logic behind this code. 

Method 3:

          By writing constraint.

                class two_power;

                    randc bit [3:0] data;

                    constraint  genration{(data&(data-1))==0};} //It will generate 0,2,4,8 vlaues

                    constraint  genration{(data!=0)->(data&(data-1))==0};} //It will generate 2,4,8 vlaues     

                 endclass

    Constraint explanation:

     8&(8-1) will produce a result as zero. So 8 is a two power value.

     3&(3-1) will produce a result as not equal to zero so 3 is not a two power value.

Method 4:

        It's a normal syntax (2**x).

            module TB;

                             bit[3:0] x;

                              int y;

                             initial begin

                                  x=$urandom;

                                for(int i=0;i<x;i++) begin

                                  y=2**i;

                                  $display("Two power values %0d %0d ",i,y);

                               end

                            end

                endmodule

Method 5:

         By using system function($pow(x,y)) we can generate two power values. By using this system function we can find any power values.

         module TB;

                             bit[3:0] x;

                              int y;

                             initial begin

                                  x=$urandom;

                                for(int i=0;i<x;i++) begin

                                  y=$pow(2,i);

                                  $display("Two power values %0d %0d ",i,y);

                               end

                            end

                endmodule

Hope this concepts will be useful to everyone!!!

If you found any mistakes kindly comment it!!!!

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