example8-6.vhd

vhdl 实例 通过实例学习vhdl 编程

LIBRARY IEEE;
USE IEEE.Std_Logic_1164.ALL;
ENTITY ground IS
  PORT (x : OUT Std_Logic);
END ground;
ARCHITECTURE dirt OF ground IS
BEGIN
  x <= '0';
END dirt;
CONFIGURATION groundcon OF ground IS
  FOR dirt
  END FOR;
END groundcon;

LIBRARY IEEE;
USE IEEE.Std_Logic_1164.ALL;
ENTITY vcc IS
  PORT (x : OUT Std_Logic);
END vcc;
ARCHITECTURE plus5 OF vcc IS
BEGIN
  x <= '1';
END plus5;
CONFIGURATION vcccon OF vcc IS
  FOR plus5
  END FOR;
END vcccon;

LIBRARY IEEE;
USE IEEE.Std_Logic_1164.ALL;
ENTITY dep IS
  PORT (top : IN Std_Logic;
        bottom : OUT Std_Logic);
END dep;
ARCHITECTURE behave OF dep IS
BEGIN
  bottom <= '1' WHEN top = '1' ELSE
            '0' WHEN top = '0' ELSE
            'X' WHEN top = 'X' ELSE
            top;
END behave;
CONFIGURATION depcon OF dep IS
  FOR behave
  END FOR;
END depcon;

LIBRARY IEEE;
USE IEEE.Std_Logic_1164.ALL;
ENTITY uxfr IS
  PORT (left, sw : IN Std_Logic;
        right : OUT Std_Logic);
END uxfr;
ARCHITECTURE behave OF uxfr IS
BEGIN
p1 : PROCESS (left, sw)
  BEGIN
    CASE sw IS
      WHEN '1' | 'H' =>
        right <= left;
      WHEN '0' | 'L' =>
        right <= 'Z';
      WHEN OTHERS =>
        right <= 'X';
    END CASE;
  END PROCESS p1;
END behave;
CONFIGURATION uxfrcon OF uxfr IS
  FOR behave
  END FOR;
END uxfrcon;

LIBRARY IEEE;
USE IEEE.Std_Logic_1164.ALL;
ENTITY test11 IS
  PORT (in11 : IN Std_Logic;
        out11 : OUT Std_Logic);
END test11;
ARCHITECTURE example1 OF test11 IS
  COMPONENT ground
    PORT (x : OUT Std_Logic);
  END COMPONENT;
  COMPONENT vcc
    PORT (x : OUT Std_Logic);
  END COMPONENT;
  COMPONENT dep
    PORT (top : IN Std_Logic;
          bottom : OUT Std_Logic);
  END COMPONENT;
  COMPONENT uxfr
    PORT (left, sw : IN Std_Logic;
          right : OUT Std_Logic);
  END COMPONENT;
SIGNAL s1, s2 : Std_Logic;
BEGIN
  x1 : dep PORT MAP (top => s2, bottom => out11);
  x2 : uxfr PORT MAP (left => s1, sw => in11, right => out11);
  x3 : ground PORT MAP (x => s1);
  x4 : vcc PORT MAP (x => s2);
END example1;
CONFIGURATION con11 OF test11 IS
  FOR example1
    FOR x1 : dep USE CONFIGURATION WORK.depcon;
    END FOR;
    FOR x2 : uxfr USE CONFIGURATION WORK.uxfrcon;
    END FOR;
    FOR x3 : ground USE CONFIGURATION WORK.groundcon;
    END FOR;
    FOR x4 : vcc USE CONFIGURATION WORK.vcccon;
    END FOR;
  END FOR;
END con11;