$clog2 in Verilog

The $clog2 function returns the ceiling of the logarithm to the base 2.

Here is a sample Verilog code that depicts $clog2 function

function integer clog2;
input integer value;
begin
value = value-1;
for (clog2=0; value>0; clog2=clog2+1)
value = value>>1;
end
endfunction

module tb;
parameter A = $clog2(325);
parameter B = $clog2(64);
endmodule

The above piece of Verilog, it generates a value 9 for A.
The above piece of Verilog, it generates a value 6 for B.