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普通编码器（8——3编码器）
代码语言：javascript复制LIBRARY IEEE;
USE IEEE.STD_LOGIC_1164.ALL;
ENTITY encode8_3 IS
PORT(input:IN STD_LOGIC_VECTOR(7 DOWNTO 0);
output:OUT STD_LOGIC_VECTOR(2 DOWNTO 0));
END encode8_3;
ARCHITECTURE encode8_3_behavior OF encode8_3 IS
BEGIN
PROCESS(input)
BEGIN
CASE encode8_3 IS
WHEN "00000001" => output<="000";
WHEN "00000010" => output<="001";
WHEN "00000100" => output<="010";
WHEN "00001000" => output<="011";
WHEN "00010000" => output<="100";
WHEN "00100000" => output<="101";
WHEN "01000000" => output<="110";
WHEN "10000000" => output<="111";
WHEN OTHERS => NULL;
END CASE;
END PROCESS;
END encode8_3_behavior;优先级编码器（8——3编码器）
代码语言：javascript复制--优先级8——3编码器
LIBRARY IEEE;
USE IEEE.STD_LOGIC_1164.ALL;
ENTITY encode8_3 IS
PORT(input:IN STD_LOGIC_VECTOR(7 DOWNTO 0);
output:OUT STD_LOGIC_VECTOR(2 DOWNTO 0));
END encode8_3;
ARCHITECTURE encode8_3_behavior OF encode8_3 IS
BEGIN
PROCESS(input)
BEGIN
IF input(7)='1' THEN
output<="111";
ELSIF input(6)='1' THEN
output<="110";
ELSIF input(5)='1' THEN
output<="101";
ELSIF input(4)='1' THEN
output<="100";
ELSIF input(3)='1' THEN
output<="011";
ELSIF input(2)='1' THEN
output<="010";
ELSIF input(1)='1' THEN
output<="001";
ELSIF input(0)='1' THEN
output<="000";
ELSE
NULL;
END IF;
END PROCESS;
END encode8_3_behavior;译码器（3——8译码器）
代码语言：javascript复制--3——8译码器
LIBRARY IEEE;
USE IEEE.STD_LOGIC_1164.ALL;
ENTITY decode3_8 IS
PORT(input:IN STD_LOGIC_VECTOR(2 DOWNTO 0);
output:OUT STD_LOGIC_VECTOR(7 DOWNTO 0));
END decode3_8;
ARCHITECTURE decode3_8_behavior OF decode3_8 IS
BEGIN
PROCESS(input)
BEGIN
CASE input IS
WHEN "000" => output<="00000001";
WHEN "001" => output<="00000010";
WHEN "010" => output<="00000100";
WHEN "011" => output<="00001000";
WHEN "100" => output<="00010000";
WHEN "101" => output<="00100000";
WHEN "110" => output<="01000000";
WHEN "111" => output<="10000000";
WHEN OTHERS => output<="ZZZZZZZZ";
END CASE;
END PROCESS;
END decode3_8_behavior;
