3:8 decoder with enable

[HaYZaM]

ENTITY Decoder3_8_Enable IS
  port (a: in std_logic_vector(2 downto 0);
        e: in std_logic ;
        y:out std_logic_vector(7 downto 0));
END ENTITY Decoder3_8_Enable;

--
ARCHITECTURE RTL OF Decoder3_8 IS
BEGIN
  process (e , a)
    begin
      if e = '1' then
         if a="000" then y="00000001"
      elsif a="001" then y="00000010"
      elsif a="010" then y="00000100"
      elsif a="011" then y="00001000"
      elsif a="100" then y="00010000"
      elsif a="101" then y="00100000"
      elsif a="110" then y="01000000"
      elsif a="111" then y="10000000"
      else'--------';
      end if;
   end process  
END ARCHITECTURE RTL;

the code doesnt work , anyone know why ?!!

 

[manasiw2]

Hi
check this modified code...its syntactically correct...please check functionality.



library ieee;
use ieee.std_logic_1164.all;

ENTITY Decoder3_8_Enable IS
port (a: in std_logic_vector(2 downto 0);
e: in std_logic ;
y: out std_logic_vector(7 downto 0)
);
END Decoder3_8_Enable;

--
ARCHITECTURE RTL OF Decoder3_8_Enable IS
BEGIN
process (e , a)
begin
if e = '1' then
if a = "000" then y <="00000001";
elsif a = "001" then y <="00000010";
elsif a = "010" then y <="00000100";
elsif a = "011" then y <="00001000";
elsif a = "100" then y <="00010000";
elsif a = "101" then y <="00100000";
elsif a = "110" then y <="01000000";
elsif a = "111" then y <="10000000";
else null;
end if;
end if;
end process;
END ARCHITECTURE RTL;

 

[forums4f]

library ieee;
use ieee.std_logic_1164.all;
use ieee.numeric_std_all
entity dec is
port(
a:in std_ulogic_vector(2 downto 0);
z : out std_ulogic_vector(7 downto 0);
e : in std_ulogic); --enable
end entity ;
architecture shiftdec of dec is
constant z_out:bit_vector(7 downto 0):=(0=>'1',others=>'0'); --"00000001";
begin
z<=to_stdulogicvector(z_out sll to_integer(unsigned(a))) when e='1' else 'Z';
end architecture;
-----------------------
also
u can use conv_std_logic_vector (parameter,bit_number)
conv_integer(parameter)

use ieee.std_logic_1164.all
or
use ieee.std_logic_signed.all