VHDL code for logarithme

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like log base 2?

this function will return the nearest log2 of a number (but I wouldnt recommend synthesising as a real time function) Its useful for determining how many bits you need for a vector.

function log2(x : integer) return integer is
  variable temp : integer :=x;
  variable n : integer := 1;
begin
  while temp > 1 loop
    temp := temp/2;
    n := n + 1;
  end loop;
 
  return n;
end function log2;

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Think you very much for your reply,

ok for this function it is clear, but that i need is a function that can execute during a minimum of clock cycle.

ThAnk you