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[/] [System09/] [trunk/] [rtl/] [VHDL/] [bit_funcs.vhd] - Rev 159
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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 -- -- -- --===========================================================================-- -- -- 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;
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