shifter.vhd

来自「8位双向移位寄存器: 实现串行数据与并行数据的转换,移位寄存数据功能的」· VHDL 代码 · 共 34 行

LIBRARY IEEE;
USE IEEE.STD_LOGIC_1164.ALL;
ENTITY SHIFTER IS
   PORT(DATA:IN STD_LOGIC_VECTOR(7 DOWNTO 0);
        SHIFT_LEFT:IN STD_LOGIC;
        SHIFT_RIGHT:IN STD_LOGIC;
        RESET:IN STD_LOGIC;
        MODE:IN STD_LOGIC_VECTOR(1 DOWNTO 0);
        CLK:IN STD_LOGIC;
        QOUT:BUFFER STD_LOGIC_VECTOR(7 DOWNTO 0));
END SHIFTER;
ARCHITECTURE ART OF SHIFTER IS
  BEGIN
  PROCESS
  BEGIN
  WAIT UNTIL(RISING_EDGE(CLK));
  IF(RESET='0')THEN
    QOUT<="00000000";    					
ELSE					
CASE MODE IS
WHEN "01"=>QOUT<=SHIFT_RIGHT&QOUT(7 DOWNTO 1);							
WHEN "10"=>QOUT<=QOUT(6 DOWNTO 0)&SHIFT_LEFT; 
							
WHEN "11"=>QOUT<=DATA;

WHEN OTHERS=>NULL;
   END CASE;
   END IF;
   END PROCESS;
END ART;