8位移位寄存器LIBRARY ieee; USE ieee.std_logic_1164.all; ENTITY shifter IS PORT ( data_in: IN STD_LOGIC_VECTOR(7 DOWNTO 0);--输入的数据 n: IN STD_LOGIC_VECTOR(2 DOWNTO 0);--移位的数量 dir: IN STD_LOGIC--移动的方向 0:左 1:右 kind: IN STD_LOGIC_VECTOR(1 DOWNTO 0);--移动类型 00:算术移 01:逻辑移 10:循环移 clock: IN BIT;--手动时钟PULSE data_out: OUT STD_LOGIC_VECTOR(7 DOWNTO 0)--移位的结果 ); END shifter;ARCHITECTURE behav of shifter IS BEGIN PROCESS (data_in, n, dir, kind) VARIABLE x,y : STD_LOGIC_VECTOR(7 DOWNTO 0); VARIABLE ctrl0,ctrl1,ctrl2 : STD_LOGIC_VECTOR (3 DOWNTO 0); BEGIN IF (clock'EVENT AND clock = '1')THEN--产生控制向量ctrl ctrl0 := n(0) & dir & kind(1) & kind(0); ctrl1 := n(1) & dir & kind(1) & kind(0); ctrl2 := n(2) & dir & kind(1) & kind(0); ctrl2 := n(2) & dir & kind(1) & kind(0); CASE ctrl0 IS WHEN "0000" | "0001" | "0010" | "0100" | "0101" | "0110" => x := data_in; --n=0时不移动 WHEN "1000" => x := data_in(6 DOWNTO 0) & data_in(0);--算术左移1位 WHEN "1001" => x := data_in(6 DOWNTO 0) & '0';--逻辑左移1位 WHEN "1010" => x := data_in(6 DOWNTO 0) & data_in(7); --循环左移1位 WHEN "1100" => x := data_in(7) & data_in(7 DOWNTO 1);-算术右移1位 WHEN "1101" => x := '0' & data_in(7 DOWNTO 1);--逻辑右移1位 WHEN "1110" => x := data_in(0) & data_in(7 DOWNTO 1);--循环右移1位 WHEN others => null; END CASE; CASE ctrl1 IS WHEN "0000" | "0001" | "0010" | "0100" | "0101" | "0110" => y := x; --n=0时不移动 WHEN "1000" => y := x(5 DOWNTO 0) & x(0) & x(0);--算术左移2位 WHEN "1001" => y := x(5 DOWNTO 0) & "00";--逻辑左移2位 WHEN "1010" => y := x(5 DOWNTO 0) & x(7 DOWNTO 6);--循环左移2位 WHEN "1100" => y := x(7) & x(7) & x(7 DOWNTO 2);--算术右移2位 WHEN "1101" => y := "00" & x(7 DOWNTO 2);--逻辑右移2位 WHEN "1110" => y := x(1 DOWNTO 0) & x(7 DOWNTO 2);--循环右移2位 WHEN others => null; END CASE;CASE ctrl2 IS WHEN "0000" | "0001" | "0010" | "0100" | "0101" | "0110" => data_out <= y; --n=0时不移动 WHEN "1000" => data_out <= y(3 DOWNTO 0) & y(0) & y(0) & y(0) & y(0); --算术左移4位 WHEN "1001" => data_out <= y(3 DOWNTO 0) & "0000"; --逻辑左移4位 WHEN "1010" | "1110" => data_out <= y(3 DOWNTO 0) & y(7 DOWNTO 4);--循环左(右)移4位 WHEN "1100" => data_out <= y(7) & y(7) & y(7) & y(7) & y(7 DOWNTO 4);--算术右移4位 WHEN "1101" => data_out <= "0000" & y(7 DOWNTO 4);--逻辑右移4位 WHEN others => null; END CASE; END IF; END PROCESS; END behav; |
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