如何修改8位汉明码的VHDL代码

Question

如何修改以下8位汉明码的VHDL代码我应该更改什么？

library IEEE; 
use IEEE.std_logic_1164.all; 
use IEEE.std_logic_unsigned.all; 

entity hamcorr is 
 port ( 
 DU: IN STD_LOGIC_VECTOR (1 to 7); 
 DC: OUT STD_LOGIC_VECTOR (1 to 7); 
 NOERROR: OUT STD_LOGIC 
 ); 
end hamcorr; 

architecture hamcorr of hamcorr is 

function syndrome (D: STD_LOGIC_VECTOR) 
 return STD_LOGIC_VECTOR is 
 variable SYN: STD_LOGIC_VECTOR (2 downto 0); 
begin 
 SYN(0) := D(1) xor D(3) xor D(5) xor D(7); 
 SYN(1) := D(2) xor D(3) xor D(6) xor D(7); 
 SYN(2) := D(4) xor D(5) xor D(6) xor D(7); 
 return(SYN); 
end syndrome; 

begin 
process (DU) 
 variable i: INTEGER; 
 begin 
 DC <= DU; 
 i := CONV_INTEGER(syndrome(DU)); 
 if i = 0 then NOERROR <= '1'; 
 else NOERROR <= '0'; DC(i) <= not DU(i); end if; 
 end process; 
end hamcorr;

提前致谢。