log2ceil Implementation fails for 31 bit values

[maleiter]

The current log2ceil implementation fails in the range of (2**30 + 1 to positive'high) since the internal tmp variable is multiplied by 2 before comparison.

My testbench:

library ieee;
use ieee.std_logic_1164.all;

entity log2ceil_test is
end entity;

architecture tb of log2ceil_test is

  function log2ceil(arg : positive) return natural is
    variable tmp          : positive := 2;
    variable log          : natural  := 1;
  begin
    if arg = 1 then
      return 0;
    end if;

    while arg > tmp loop
      tmp := tmp * 2;
      log := log + 1;
    end loop;
    return log;
  end function;
  
begin
  stim : process

  begin
    report "2**30-1";
    assert log2ceil(2 ** 30 - 1) = 30 ;

    report "2**30";
    assert log2ceil(2 ** 30) = 30 ;

    report "2**30+1";
    assert log2ceil(2 ** 30 + 1) = 31 ;

    report "2**31-1";
    assert log2ceil(positive'high) = 31 ;
    wait;
  end process;
end architecture;

[Paebbels]

@stefanunrein can we take this one as a late candidate for #38 ?

[Paebbels]

Fixed in v3.0.0 see #40.