Source file VHDL/priority_rot.vhd

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--===========================================================================-- 
--                                                                           -- 
--  priority_rot.vhd - Synthesizable Rotating Priority Encoder               -- 
--                                                                           -- 
--===========================================================================-- 
-- 
--  File name      : priority_rot.vhd 
-- 
--  Purpose        : Implements a rotating priority encoder 
-- 
--  Dependencies   : ieee.std_logic_1164 
--                   ieee.std_logic_unsigned 
--                   ieee.std_logic_arith 
--                   unisim.vcomponents 
-- 
--  Author         : John E. Kent 
-- 
--  Email          : dilbert57 at the domain opencores.org 
-- 
--  Web            : http://opencores.org/project,system09 
-- 
--  Priority_rot.vhd is a rotating priority encoder written in VHDL. 
-- 
--  Copyright (C) 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                            -- 
--                                                                           -- 
--===========================================================================-- 
-- 
-- Version  Author        Date               Description 
-- 0.1      John Kent     30th May 2010      Initial version 
-- 
library ieee; 
  use ieee.std_logic_1164.all; 
  use ieee.std_logic_unsigned.all; 
  use ieee.std_logic_arith.all; 
 
library unisim; 
  use unisim.vcomponents.all; 
 
--* @brief Synthesizable Rotating Priority Encoder 
--* 
--*  priority_rot is a rotating priority encoder written in VHDL. 
--* 
--* @author John E. Kent 
--* @version 0.1 from 30th May 2010 
 
entity priority_rot is 
   generic ( 
      WIDTH : integer := 8 
   ) 
	port ( 
		clk      : in  std_logic; 
		rst      : in  std_logic; 
	   input    : in  std_logic_vector(WIDTH-1 downto 0); 
	   output   : out std_logic_vector(log2(WIDTH)-1 downto 0); 
      valid    : out std_logic 
   ) 
		); 
end priority_rot; 
 
--* Implements a rotating priority encoder. 
--* 
--* @author John E. Kent 
--* @version 0.1 from 30th May 2010 
 
architecture rtl of priority_rot is 
 
constant OUT_WIDTH : integer := log2(WIDTH); 
 
begin 
 
  for i in 1 to WIDTH loop 
    j := log2( i ); 
    -- if( input(i-1) = '1' ) then 
 
  end loop; 
end architecture;