Source file VHDL/bit_funcs.vhd

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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 at the domain 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                            -- 
--                                                                           -- 
--===========================================================================-- 
-- 
-- 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; 
 
--* @brief Power2 & Log2 Functions Package 
--* 
--* @author John E. Kent 
--* @version 1.0 from 30th May 2010 
 
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;