计算机组成原理课程设计(vhdl语言实现)

注明:在vhdl语言中，--代表注释，等价于//

1. 一位全加器设计

LIBRARY IEEE;
USE IEEE.STD_LOGIC_1164.ALL;
ENTITY add IS
PORT(a,b,cin:IN STD_LOGIC;
Co,S:OUT STD_LOGIC);
END ENTITY add;
ARCHITECTURE fc1 OF add is
BEGIN
S<= a xor b xor cin;   --这两个为推得的表达式
Co<= (a and b) or (a and cin) or (b and cin);
END ARCHITECTURE fc1;

2.并行八位寄存器设计（移位寄存器）

--这是并行八位移位寄存器
LIBRARY IEEE;
USE IEEE.STD_LOGIC_1164.ALL;
ENTITY EIGHT IS
PORT(CLK,LOAD:IN STD_LOGIC;
VIN:IN STD_LOGIC_VECTOR(7 DOWNTO 0);
VOUT:OUT STD_LOGIC_VECTOR(7 DOWNTO 0));
END EIGHT;
ARCHITECTURE happen of EIGHT IS
SIGNAL REG : STD_LOGIC_VECTOR(7 DOWNTO 0);  --REG信号，百度了一下作用，信号一般是用于端口和端口之间的通信
BEGIN
PROCESS(CLK,LOAD) --CLK,LOAD变化的时候会执行
BEGIN
IF CLK'EVENT AND CLK = '1' THEN --上升沿的时候
IF LOAD = '1' THEN REG <=VIN;  --如果load = 1，不变
ELSE REG(6 DOWNTO 0) <= REG(7 DOWNTO 1);  --如果load = 0,高七位赋值给低七位，也就是都往右移动1个单位
END IF;
END IF;
END PROCESS;
VOUT<=REG;
END happen;

3.同步二进制计数器

LIBRARY IEEE;
use IEEE.STD_LOGIC_1164.all;
use IEEE.STD_LOGIC_ARITH.all;--算术运算
use IEEE.STD_LOGIC_UNSIGNED.all;--无符号

ENTITY counter is
PORT(clk:in STD_LOGIC;
rst:in STD_LOGIC;
B:BUFFER STD_LOGIC_VECTOR(3 DOWNTO 0)); --4位
end counter;
ARCHITECTURE Behavior of counter is
BEGIN
PROCESS(clk,rst) --只要有发生改变就一直执行，个人感觉类似C语言的while
BEGIN
if rst = '1' then B <= "0000"; --清零
else if(clk'event and clk = '1') then  --上升沿执行加1
IF B ="1111" THEN B<="0000"; --防止溢出,置0
ELSE
B<=B+1;
end if;
end if;
end if;
end process;
end Behavior;

4.多位二进制加法器

library ieee;
use ieee.std_logic_1164.all;
LIBRARY ieee;
use ieee.std_logic_unsigned.all;
entity Data is
port(a:in std_logic_vector(3 downto 0);
b:in std_logic_vector(3 downto 0);
cin:in std_logic; --表示进位
s:out std_logic_vector(3 downto 0); --求和
co:out std_logic); --储存进位
end entity Data;

architecture ADD of Data is
signal c,d:std_logic_vector(4 downto 0);
signal e:std_logic_vector(4 downto 0);
begin
c<='0' & a; -- 0和a合并
d<='0' & b; -- 0和b合并
e<=c+d+cin; --全加器的功能
co<=e(4);
s<=e(3 downto 0);
end architecture ADD;

5.多路开关

library IEEE;
use IEEE.std_logic_1164.all;
entity choose is
port(a,b,c,d,e,f,g,h:in std_logic_vector(7 downto 0);  --有8个数，所以开0-7
input:in std_logic_vector(2 downto 0);		--最多三位，所以开0-2
val:out std_logic_vector(7 downto 0));      --同上上
end choose;
architecture choose1 of choose is
begin
process(input)
begin
case input is
when "000" => val <= a;   --选择
when "001" => val <= b;
when "010" => val <= c;
when "011" => val <= d;
when "100" => val <= e;
when "101" => val <= f;
when "110" => val <= g;
when others => val <= h;  --第一次写的时候"111"报错，百度了一下,估计是没写全的缘故
--所以还是用others简单暴力
end case;
end process;
end choose1;

6.运算部件(ALU)的实现

library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.STD_LOGIC_ARITH.ALL;
use IEEE.STD_LOGIC_UNSIGNED.ALL;

entity ALU is
Port ( A		:	in std_logic_vector(7 downto 0);
B		:	in std_logic_vector(7 downto 0);
S	    :	in std_logic_vector(2 downto 0);  --选择
Cin		:   in std_logic;   --进位
Cout		:	out std_logic;
F		:	out std_logic_vector(7 downto 0));
end ALU;

architecture Behavioral of ALU is
signal A0,B0,F0: STD_LOGIC_VECTOR(8 DOWNTO 0);   --防止溢出
begin

process (A,B,S,Cin)
begin

--算术单元
Cout<='0';
if (S = "011") then
F <= A-B-Cin;

elsif (S = "101") then
A0 <= '0'&A(7 DOWNTO 0);  --在八位前面补0
B0 <= '0'&B(7 DOWNTO 0);
F0 <= A0+B0+Cin;   --相加，因为有cin进位所以可能会有溢出,故F0,A0,B0开九位
F  <=F0(7 DOWNTO 0);  --抛弃第九位只要后面的低八位，因为溢出没意义
Cout<=F0(8);  --第九位
---逻辑单元
elsif (S = "000") then  -- A && B
F <=A AND B;

elsif (S = "001") then --A || B
F <= A OR B;

elsif (S = "010") then  --非A
F <= NOT A;
elsif (S = "100") then   --A异或B
F <= A XOR B;

elsif (S = "110") then
F <= '0' &A(7 downto 1);   --最高位为0,高七位各向后移动一个单位

elsif s = "111" then    --最低位为Cin,第七位各向前移动一个单位
F <=A(6 downto 0) & Cin;
Cout<=A(7);
end if;
end process;

end Behavioral;

7.移位寄存器

--将一个八位二进制的数据每一位一次右移,若最高位为1，那么剩下的最后也会都为1，最高位0同理
LIBRARY IEEE;
USE IEEE.STD_LOGIC_1164.ALL;
ENTITY move IS
PORT(CLK,LOAD:IN STD_LOGIC;
DIN:IN STD_LOGIC_VECTOR(7 DOWNTO 0);
DOUT:OUT STD_LOGIC_VECTOR(7 DOWNTO 0));
END move;
ARCHITECTURE behavior of move IS
SIGNAL REG:STD_LOGIC_VECTOR(7 DOWNTO 0);
BEGIN
PROCESS(CLK,LOAD) --只要CLK,LOAD有变化就一直执行，个人理解应该等价于c的while
BEGIN
IF CLK'EVENT AND CLK = '1' THEN --上升沿有效
IF LOAD = '1' THEN REG<= DIN;	--如果上升沿到来时，load为1，那么8位并行置入移位二进制中
ELSE REG(6 DOWNTO 0) <= REG(7 DOWNTO 1); --否则为高七位的值赋值给低七位
END IF;
END IF;
END PROCESS;
DOUT<=REG;
END behavior;