VHDL 实现 汉明编码和译码

汉明编码解码的原理就不用多i说了，疑惑的的地方可以翻一翻樊昌信老先生的《通信原理》。

     （7，4）汉明编码每组码元共有7位，4个信息位C6 C5 C4 C3   + 3个监督位C2 C1 C0

那么监督矩阵和生成矩阵分别是：

因为（7，4）汉明编码是7位，所以在最末位添加一个0补成8bit方便串口发送和接收。由此可以得到下面这个表格：

上面给出了编码，对于解码通过

计算出S2 S1 S0 就能知道当出现1bit的误码时对应的哪一位是错误的，也就能纠正过来。

具体S2 S1 S0 是对应哪一位的错误可以自己假设一个错误的bit位带入计算，得到S2 S1 S0和误码位置的关系。

下面是vHDL代码：

编码

library ieee;use ieee.std_logic_1164.all;use ieee.std_logic_unsigned.all;entity HCode isport(data_in :in  std_logic_vector(3 downto 0);H_out   :out std_logic_vector(7 downto 0));end HCode;architecture bv of HCode isbeginprocess(data_in)begincase data_in iswhen "0000"=> H_out <="00000000";when "0001"=> H_out <="00011010";when "0010"=> H_out <="00101110";when "0011"=> H_out <="00110100";when "0100"=> H_out <="01000110";when "0101"=> H_out <="01011100";when "0110"=> H_out <="01101000";when "0111"=> H_out <="01110010";when "1000"=> H_out <="10001100";when "1001"=> H_out <="10010110";when "1010"=> H_out <="10100010";when "1011"=> H_out <="10111000";when "1100"=> H_out <="11001010";when "1101"=> H_out <="11010000";when "1110"=> H_out <="11100100";when "1111"=> H_out <="11111110";end case;end process;end bv;

解码：(本来S算出来应该是3bit，但是为了方便数码管显示我强行加了一个0 凑够4bit)

library ieee;use ieee.std_logic_1164.all;use ieee.std_logic_unsigned.all;entity Hdecode isport(                                           --a bit is wrongHcode :in  std_logic_vector(7 downto 0);  --input hamming codeDecode:out std_logic_vector(3 downto 0);  --output signalS     :out std_logic_vector(3 downto 0)   --where is wrong );end entity;architecture BV of Hdecode issignal SS :std_logic_vector(3 downto 0):="0000";beginprocess(Hcode)beginSS(3) <='0';SS(2) <=Hcode(7) xor Hcode(5) xor Hcode(4) xor Hcode(3) ;SS(1) <=Hcode(7) xor Hcode(6) xor Hcode(5) xor Hcode(2) ;SS(0) <=Hcode(6) xor Hcode(5) xor Hcode(4) xor Hcode(1) ;--SS <= SS+'1';case SS iswhen "0000" =>  Decode <= (Hcode(7),Hcode(6),Hcode(5),Hcode(4));        S<="0000";when "0001" =>  Decode <= (Hcode(7),Hcode(6),Hcode(5),Hcode(4));        S<="0001";when "0010" =>  Decode <= (Hcode(7),Hcode(6),Hcode(5),Hcode(4));        S<="0010";when "0011" =>  Decode <= (Hcode(7),not Hcode(6),Hcode(5),Hcode(4));    S<="0110";       when "0100" =>  Decode <= (Hcode(7),Hcode(6),Hcode(5), Hcode(4));       S<="0011";when "0101" =>  Decode <= (Hcode(7),Hcode(6), Hcode(5),not Hcode(4));   S<="0100";when "0110" =>  Decode <= (not Hcode(7),Hcode(6),Hcode(5),Hcode(4));    S<="0111";when "0111" =>  Decode <= (Hcode(7),Hcode(6),not Hcode(5),Hcode(4));    S<="0101";when others =>  S<="1111";end case;--S <= SS;end process;end BV;