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[/] [System09/] [trunk/] [rtl/] [VHDL/] [bit_funcs.vhd] - Blame information for rev 147

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1 99 davidgb
--===========================================================================--
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--                                                                           --
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--  bit_funcs.vhd - Power2 & Log2 Funtions Package                           --
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--                                                                           --
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--===========================================================================--
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--
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--  File name      : bit_funcs.vhd
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--
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--  Purpose        : Implements power2 and log2 functions.
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--                  
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--  Dependencies   : ieee.std_logic_1164
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--                   ieee.std_logic_arith
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--                   ieee.std_logic_unsigned
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--
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--  Author         : John E. Kent
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--
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--  Email          : dilbert57@opencores.org      
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--
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--  Web            : http://opencores.org/project,system09
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--
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--  bit_func.vhd is a VHDL functions package for calulating power2 and log2.
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-- 
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--  Copyright (C) 2003 - 2010 John Kent
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--
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--  This program is free software: you can redistribute it and/or modify
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--  it under the terms of the GNU General Public License as published by
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--  the Free Software Foundation, either version 3 of the License, or
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--  (at your option) any later version.
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--
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--  This program is distributed in the hope that it will be useful,
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--  but WITHOUT ANY WARRANTY; without even the implied warranty of
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--  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
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--  GNU General Public License for more details.
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--
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--  You should have received a copy of the GNU General Public License
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--  along with this program.  If not, see <http://www.gnu.org/licenses/>.
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--
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--===========================================================================--
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--                                                                           --
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--                              Revision  History                            --
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--                                                                           --
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--===========================================================================--
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--
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-- Revision Name          Date             Description
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-- 0.1      John E. Kent  unknown          Initial version
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-- 1.0      John E. Kent  30th May 2010    Added GPL Header
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--
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49 65 davidgb
library IEEE;
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   use IEEE.std_logic_1164.all;
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   use IEEE.std_logic_arith.all;
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   use IEEE.std_logic_unsigned.all;
53 99 davidgb
 
54 65 davidgb
package bit_funcs is
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   function log2(v: in natural) return natural;
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   function pow2(v: in natural) return natural;
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end package bit_funcs;
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59 99 davidgb
package body bit_funcs is
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   function log2 (v : in natural) return natural is
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   variable temp, log: natural;
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   begin
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      temp := v / 2;
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      log := 0;
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      while (temp /= 0) loop
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        temp := temp/2;
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        log := log + 1;
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      end loop;
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      return log;
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   end function log2;
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   function pow2(v: in natural) return natural is
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      variable i: natural;
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      variable pown: natural;
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   begin
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      pown := 1;
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      for i in 0 to v loop
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         exit when (i=v);
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         pown := pown * 2;
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      end loop;
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      return pown;
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   end function pow2;
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end package body bit_funcs;

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