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-- Company: 

-- Engineer: 

-- 

-- Create Date:    00:04:51 11/17/2013 

-- Design Name: 

-- Module Name:    q_period - Behavioral 

-- Project Name: 

-- Target Devices: 

-- Tool versions: 

-- Description: 

--

-- Dependencies: 

--

-- Revision: 

-- Revision 0.01 - File Created

-- Additional Comments: 

--

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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 using

-- arithmetic functions with Signed or Unsigned values

--use IEEE.NUMERIC_STD.ALL;

-- Uncomment the following library declaration if instantiating

-- any Xilinx primitives in this code.

--library UNISIM;

--use UNISIM.VComponents.all;

--q_period entity

--parameter : period (local oscillator frequency / fiber bitrate )

--calulate :

-- period01 = 1/4 period

-- periodA =  1/2 period

-- period10 = 3/4 period

-- These parameters are used in the Receiver and in the Transmitter

entity q_period is

    Port ( period : in  STD_LOGIC_VECTOR (6 downto 0);

           period01 : out  STD_LOGIC_VECTOR (6 downto 0);

           periodA : out  STD_LOGIC_VECTOR (6 downto 0);

           period10 : out  STD_LOGIC_VECTOR (6 downto 0));

end q_period;

architecture Behavioral of q_period is

begin

process(period)

variable varA:STD_LOGIC_VECTOR (6 downto 0);

variable var01:STD_LOGIC_VECTOR (6 downto 0);

begin

        if(period(0)='1')then

                varA:=(6=>'0')&period(6 downto 1)+1;

        else

                varA:=(6=>'0')&period(6 downto 1);

        end if;

        var01:=(6 downto 5=>'0')&period(6 downto 2);

        periodA<=varA;

        period01<=var01;

        period10<=varA + var01;

end process;

end Behavioral;