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--===========================================================================--

--                                                                           --

--  bit_funcs.vhd - Power2 & Log2 Funtions Package                           --

--                                                                           --

--===========================================================================--

--

--  File name      : bit_funcs.vhd

--

--  Purpose        : Implements power2 and log2 functions.

--                  

--  Dependencies   : ieee.std_logic_1164

--                   ieee.std_logic_arith

--                   ieee.std_logic_unsigned

--

--  Author         : John E. Kent

--

--  Email          : dilbert57@opencores.org      

--

--  Web            : http://opencores.org/project,system09

--

--  bit_func.vhd is a VHDL functions package for calulating power2 and log2.

-- 

--  Copyright (C) 2003 - 2010 John Kent

--

--  This program is free software: you can redistribute it and/or modify

--  it under the terms of the GNU General Public License as published by

--  the Free Software Foundation, either version 3 of the License, or

--  (at your option) any later version.

--

--  This program is distributed in the hope that it will be useful,

--  but WITHOUT ANY WARRANTY; without even the implied warranty of

--  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

--  GNU General Public License for more details.

--

--  You should have received a copy of the GNU General Public License

--  along with this program.  If not, see <http://www.gnu.org/licenses/>.

--

--===========================================================================--

--                                                                           --

--                              Revision  History                            --

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--===========================================================================--

--

-- Revision Name          Date             Description

-- 0.1      John E. Kent  unknown          Initial version

-- 1.0      John E. Kent  30th May 2010    Added GPL Header

--

library IEEE;

   use IEEE.std_logic_1164.all;

   use IEEE.std_logic_arith.all;

   use IEEE.std_logic_unsigned.all;

package bit_funcs is

   function log2(v: in natural) return natural;

   function pow2(v: in natural) return natural;

end package bit_funcs;

package body bit_funcs is

   function log2 (v : in natural) return natural is

   variable temp, log: natural;

   begin

      temp := v / 2;

      log := 0;

      while (temp /= 0) loop

        temp := temp/2;

        log := log + 1;

      end loop;

      return log;

   end function log2;

   function pow2(v: in natural) return natural is

      variable i: natural;

      variable pown: natural;

   begin

      pown := 1;

      for i in 0 to v loop

         exit when (i=v);

         pown := pown * 2;

      end loop;

      return pown;

   end function pow2;

end package body bit_funcs;