-- $Id$:

-- Error Decoder / clock activity handler / bus selector

-- Version 1.10

-- Last updated: 2012.08.24


library ieee;
use ieee.std_logic_1164.all;


-- ================================================


entity error_decoder is
port
        (
--        mrst            : in std_logic; -- master reset
--        mclk            : in std_logic; -- master clock 100kHz

--      state => 00 = ok; 01 = parity error; 10 = 2-Bit error; 11 1-Bit error (corrected)

        valid           : in std_logic_vector(2 downto 1); -- bit 31

        ham_err_summ    : in std_logic_vector(2 downto 1);

        spi_act_all     : in std_logic_vector(2 downto 1);

        bus_mux_sel     : out std_logic; -- bus multiplexer output signal

        out_reg_strobe  : out std_logic -- output register strobe output signal

        );

end error_decoder;


-- ================================================

architecture a of error_decoder is

signal ch_good : std_logic_vector (2 downto 1);


-- ================================================

begin

    ch_good <= valid and spi_act_all and not ham_err_summ;

--
--  ch_good(1) <= valid(1) when spi_act_all(1) = '1' and ham_err_summ(1) = '0' else '0';
--  ch_good(2) <= valid(2) when spi_act_all(2) = '1' and ham_err_summ(2) = '0' else '0';


-- ------------------------------------------------

--error_dec: process(mclk, mrst)
error_dec: process(ch_good)

    begin

--      if mrst = '1' then
--
--              out_reg_strobe <= '0';
--              bus_mux_sel     <= '0';
--              fail_led_1 <= '0';
--              fail_led_2 <= '0';
--
--      elsif rising_edge(mclk) then

            out_reg_strobe <= '0';
            bus_mux_sel <= '0';

            case ch_good is
                    when "11"   => null;                           -- if both channels have good data just keep the channel and update output register
                                   bus_mux_sel <= '0';
                                   out_reg_strobe <= '1';

                    when "01"   => bus_mux_sel <= '0'; -- if channel 1 has good data but channel 2 has not switch multiplexer to
                                                                                       -- channel 1 and strobe in data to output register with the following clock
                                   out_reg_strobe <= '1';

                    when "10"   => bus_mux_sel <= '1'; -- if channel 2 has good data but channel 1 has not switch multiplexer to
                                                                                       -- channel 2 and strobe in data to output register with the following clock
                                   out_reg_strobe <= '1';

                    when others => out_reg_strobe <= '0'; -- if none of the channels has good data just keep status and do NOT update output register
            end case;

--        end if;

end process;


-- ================================================

end;