ipirmpx.vhd

来自「X8086的VHDL源码」· VHDL 代码 · 共 55 行

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--   FILE NAME : IPIR_MPX_IPIR.vhd
--   FUNCTION  : IP or IR multiplexer
--   AUTHOR    : Kazuma Mishima
--   DATE      : 7/2001
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library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.STD_LOGIC_ARITH.ALL;
use IEEE.STD_LOGIC_UNSIGNED.ALL;
use WORK.UPAC.ALL;

entity IPIRMPX is
    port( I_CLK      :  in std_logic;
		  I_RST      :  in std_logic;
		  I_IPDATA   :  in std_logic_vector(15 downto 0); --input data from IP
          I_IRDATA   :  in std_logic_vector(15 downto 0); --input data from IR
          I_IPF      :  in std_logic; --address out from IP signal
          I_IRF      :  in std_logic; --address out from IR signal
		  O_IPIRDATA : out std_logic_vector(15 downto 0)  --output to ADD
		  );
end IPIRMPX;

architecture RTL of IPIRMPX is

signal sdt : std_logic;

begin

	SDT_REG : 
	process(I_CLK,I_RST,I_IPF,I_IRF)
	begin
		if (I_RST = RST_ACT) then
			sdt <= '0';
		elsif (I_CLK'event and I_CLK='0') then 
			if   (I_IPF='1' and I_IRF='0')then --from IP                          
				sdt <= '0';
			elsif(I_IPF='0' and I_IRF='1')then --from IR
				sdt <= '1';	  
			end if;
		end if;
	end process;

--OUTPUT EXT_BUS
	OUTPUT : 
	process(sdt,I_IPDATA,I_IRDATA)
	begin
		if(sdt = '0') then
			O_IPIRDATA <= I_IPDATA;
		else
			O_IPIRDATA <= I_IRDATA;
		end if;
	end process;

end RTL;