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-- ***** BEGIN LICENSE BLOCK *****
-- 
-- 
--  Version: MPL 1.1/GPL 2.0/LGPL 2.1
-- 
--  The contents of this file are subject to the Mozilla Public License
--  Version 1.1 (the "License"); you may not use this file except in compliance
--  with the License. You may obtain a copy of the License at
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--  Software distributed under the License is distributed on an "AS IS" basis,
--  WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License for
--  the specific language governing rights and limitations under the License.
-- 
--  The Original Code is BBC Research and Development code.
-- 
--  The Initial Developer of the Original Code is the British Broadcasting
--  Corporation.
--  Portions created by the Initial Developer are Copyright (C) 2006.
--  All Rights Reserved.
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--  Contributor(s): Peter Bleackley (Original author)
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library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.STD_LOGIC_ARITH.ALL;
use IEEE.STD_LOGIC_UNSIGNED.ALL;
 
---- Uncomment the following library declaration if instantiating
---- any Xilinx primitives in this code.
--library UNISIM;
--use UNISIM.VComponents.all;
 
entity EXP_GOLOMB_COUNTER is
    Port ( DATA_IN : in std_logic_vector(31 downto 0);
           TEST : in std_logic;
           RESET : in std_logic;
           CLOCK : in std_logic;
           COUNTING : out std_logic;
           DATA_OUT : out std_logic);
end EXP_GOLOMB_COUNTER;
 
architecture RTL of EXP_GOLOMB_COUNTER is
signal DATA2 : std_logic_vector (32 downto 0);
signal LOG : std_logic_vector (4 downto 0);
signal OUT_ADDRESS : std_logic_vector( 4 downto 0); 
signal MODE : std_logic;
signal OUTPUT_ACTIVE : std_logic;
begin
 
DATA2 <= ('0' & DATA_IN) + "000000000000000000000000000000001";
 
LOGARITHM : process (CLOCK)
begin
	if CLOCK'event and CLOCK = '1' then
		if DATA2(32) = '1' then
			LOG <= "11111";
		elsif DATA2(31) = '1' then
			LOG <= "11110";
		elsif DATA2(30) = '1' then
			LOG <= "11101";
		elsif DATA2(29) = '1' then
			LOG <= "11100";
		elsif DATA2(28) = '1' then
			LOG <= "11011";
		elsif DATA2(27) = '1' then
			LOG <= "11010";
		elsif DATA2(26) = '1' then
			LOG <= "11001";
		elsif DATA2(25) = '1' then
			LOG <= "11000";
		elsif DATA2(24) = '1' then
			LOG <= "10111";
		elsif DATA2(23) = '1' then
			LOG <= "10110";
		elsif DATA2(22) = '1' then
			LOG <= "10101";
		elsif DATA2(21) = '1' then
			LOG <= "10100";
		elsif DATA2(20) = '1' then
			LOG <= "10011";
		elsif DATA2(19) = '1' then
			LOG <= "10010";
		elsif DATA2(18) = '1' then
			LOG <= "10001";
		elsif DATA2(17) = '1' then
			LOG <= "10000";
		elsif DATA2(16) = '1' then
			LOG <= "01111";
		elsif DATA2(15) = '1' then
			LOG <= "01110";
		elsif DATA2(14) = '1' then
			LOG <= "01101";
		elsif DATA2(13) = '1' then
			LOG <= "01100";
		elsif DATA2(12) = '1' then
			LOG <= "01011";
		elsif DATA2(11) = '1' then
			LOG <= "01010";
		elsif DATA2(10) = '1' then
			LOG <= "01001";
		elsif DATA2(9) = '1' then
			LOG <= "01000";
		elsif DATA2(8) = '1' then
			LOG <= "00111";
		elsif DATA2(7) = '1' then
			LOG <= "00110";
		elsif DATA2(6) = '1' then
			LOG <= "00101";
		elsif DATA2(5) = '1' then
			LOG <= "00100";
		elsif DATA2(4) = '1' then
			LOG <= "00011";
		elsif DATA2(3) = '1' then
			LOG <= "00010";
		elsif DATA2(2) = '1' then
			LOG <= "00001";
		else
			LOG <= "00000";
		end if;
	end if;
end process LOGARITHM;
 
 
OUTPUT: process (CLOCK)
begin
	if CLOCK'event and CLOCK = '1' then
		if RESET = '1' then
			MODE <= '0';
			OUT_ADDRESS <= "00000";
			DATA_OUT <= '0';
			OUTPUT_ACTIVE <= '0';
		elsif OUTPUT_ACTIVE = '1' then
			if MODE = '1' then 
				DATA_OUT <= DATA2(conv_integer(OUT_ADDRESS));
				MODE <= '0';
			else
				if	OUT_ADDRESS	= "00000" then
					DATA_OUT <= '1';
					OUTPUT_ACTIVE <= '0';
				else
					DATA_OUT <= '0';
					OUT_ADDRESS <= OUT_ADDRESS - "00001";
					MODE <= '1';
				end if;
			end if;
		elsif TEST = '1' then
			OUTPUT_ACTIVE <= '1';
			OUT_ADDRESS <= LOG;
			MODE <= '0';
		end if;
	end if;
end process OUTPUT;
 
COUNTING <= OUTPUT_ACTIVE;				 
 
 
end RTL;