1、EDA期末考试题大全附带:一问答题1信号赋值语句在什么情况下作为并行语句?在什么情况下作顺序语句?信号赋值和变量赋值符号分别是什么?两种赋值符号有什么区别? 信号赋值语句在进程外作并行语句,并发执行,与语句所处的位置无关。信号赋值语句在进程内或子程序内做顺序语句,按顺序执行,与语句所处的位置有关。 信号赋值符号为“qqqq=d; END CASE; 答案:CASE语句缺“WHEN OTHERS”语句。2.已知data_in1, data_in2为STD_LOGIC_VECTOR(15 DOWNTO 0) 类型的输入端口,data_out为STD_LOGIC_VECTOR(15 DOWNTO 0
2、)类型的输出端口,add_sub为STD_LOGIC类型的输入端口,请判断下面给出的程序片段: LIBRARY IEEE; USE IEEE.STD_LOGIC_1164.ALL; ENTITY add IS PORT(data_in1, data_in2:IN INTEGER; data_out:OUT INTEGER); END add; ARCHTECTURE add_arch OF add IS CONSTANT a:INTEGER=2; BEGIN data_out=( data_in1+ data_in2) * a; END addsub_arch;答案:常量声明时赋初值的“=”符
3、号应改用“:=”符号。3.已知Q为STD_LOGIC类型的输出端口,请判断下面的程序片段: ARCHITECTURE test_arch OF test IS BEGIN SIGNAL B:STD_LOGIC; QQQ=0; END CASE; END archtest;答案:CASE语句应该存在于进程PROCESS内。三程序设计LIBRARY IEEE;USE IEEE.STD_LOGIC_1164.ALL;USE IEEE.STD_LOGIC_UNSIGNED.ALL;ENTITY ADDER4B IS -4位二进制并行加法器 PORT(CIN:IN STD_LOGIC; -低位进位 A:
4、 IN STD_LOGIC_VECTOR(3 DOWNTO 0); -4位加数 B: IN STD_LOGIC_VECTOR(3 DOWNTO 0); -4位被加数 S: OUT STD_LOGIC_VECTOR(3 DOWNTO 0); -4位和 CONT: OUT STD_LOGIC); END ADDER4B;ARCHITECTURE ART OF ADDER4B IS SIGNAL SINT:STD_LOGIC_VECTOR(4 DOWNTO 0); SIGNAL AA,BB: STD_LOGIC_VECTOR(4 DOWNTO 0); BEGIN AA=0& A; -将4位加数矢量扩
5、为5位,为进位提供空间 BB=0& B; -将4位被加数矢量扩为5位,为进位提供空间 SINT=AA+BB+CIN ; S=SINT(3 DOWNTO 0); CONTCIN,A=A(3 DOWNTO 0),B=B(3 DOWNTO0), S=S(3 DOWNTO 0),COUT=CARRY_OUT);U2:ADDER4B -例化(安装)一个4位二进制加法器U2 PORT MAP(CIN=CARRY_OUT,A=A(7 DOWNTO 4),B=B(7 DOWNTO 4), S=S (7 DOWNTO 4);CONT=CONT);END ART;3.触发器和缓冲器D触发器:Process(clk
6、) begin if(clkevent and clk=1) then q = d; end if;end process; 缓冲器:Process(clk)begin if(clk=1) then q = d; end if;end process; T触发器:Process(clk)begin if(clkevent and clk=1) then if(t = 1) then q = not(q); else q = q; end if; end if;end process; 4.16位锁存器的源程序LIBRARY IEEE;USE IEEE.STD_LOGIC_1164.ALL;EN
7、TITY REG16B IS -16位锁存器 PORT (CLK:IN STD_LOGIC; -锁存信号 CLR:IN STD_LOGIC; -清零信号 D:IN STD_LOGIC_VECTOR (8 DOWNTO 0) -8位数据输入 Q:OUT STD_LOGIC_VECTOR(15 DOWNTO 0);-16位数据输出END REG16B;ARCHITECTURE ART OF REG16B IS SIGNAL R16S:STD_LOGIC_VECTOR(15 DOWNTO 0); -16位寄存器设置BEGINPROCESS (CLK,CLR) BEGIN IF CLR = 1 THE
8、N R16S= 00000; -异步复位信号 ELSIF CLKEVENT AND CLK = 1 THEN -时钟到来时,锁存输入值 R16S(6 DOWNTO 0)=R16S(7 DOWNTO 1);-右移低8位 R16S(15 DOWNTO 7)=D; -将输入锁到高能位 END IF; END PROCESS; Q=R16S;END ART;LIBRARY IEEE;USE IEEE.STD_LOGIC_1164.ALL; -8位右移寄存器ENTITY SREG8B IS PORT (CLK:IN STD_LOGIC; LOAD :IN STD _LOGIC; BIN:IN STD_L
9、OGIC_VECTOR(7DOWNTO 0); QB:OUT STD_LOGIC );END SREG8B;ARCHITECTURE ART OF SREG8B IS SIGNAL REG8B:STD_LOGIC_VECTOR(7 DOWNTO 0); BEGIN PROCESS (CLK,LOAD) BEGIN IF CLKEVENT AND CLK= 1 THEN IF LOAD = 1 THEN REG8=DIN; -装载新数据 ELSE REG8(6 DOWNTO0)=REG8(7 DOWNTO 1);-数据右移 END IF; END IF; END PROCESS; QB= REG
10、8 (0); -输出最低位END ART;68位乘法器的源程序LIBRARY IEEE;USE IEEE.STD_LOGIC_1164.ALL; -8位乘法器顶层设计ENTITY MULTI8X8 IS PORT(CLK:IN STD_LOGIC; START:IN STD_LOGIC;-乘法启动信号,高电平复位与加载,低电平运算 A:IN STD_LOGIC_VECTOR(7 DOWNTO 0); -8位被乘数 B:IN STD_LOGIC_VECTOR(7 DOWNTO 0); -8位乘数 ARIEND:OUT STD_LOGIC; -乘法运算结束标志位 DOUT:OUT STD_LOGI
11、C_VECTOR(15 DOWNTO 0);-16位乘积输出END MULTI8X8;ARCHITECTURE ART OF MULTI8X8 IS COMPONENT ARICTL -待调用的乘法控制器端口定义 PORT(CLK:IN STD_LOGIC;START:IN STD_LOGIC; CLKOUT:OUT STD_LOGIC;RSTALL:OUT STD_LOGIC; ARIEND:OUT STD_LOGIC);END COMPONENT;COMPONENT ANDARITH -待调用的控制与门端口定义 PORT(ABIN:IN STD_LOGIC; DIN:IN STD_LOGI
12、C_VECTOR(7 DOWNTO 0); DOUT:OUT_STD_LOGIC_VECTOR( 7 DOWNTO 0) );END COMPONENT;COMPONENT ADDER8B -待调用的8位加法器端口定义COMPONENT SREG8B -待调用的8位右移寄存器端口定义 COMPONENT REG16B -待调用的16右移寄存器端口定义 SIGNAL GNDINT:STD_LOGIC;SIGNAL INTCLK:STD_LOGIC;SIGNAL RSTALL:STD_LOGIC;SIGNAL QB:STD_LOGIC;SIGNAL ANDSD:STD_LOGIC_VECTOR(7
13、 DOWNTO 0);SIGNAL DTBIN:STD_LOGIC_VECTOR(8 DOWNTO 0);SIGNAL DTBOUT:STD_LOGIC_VECTOR(15 DOWNTO 0);BEGINDOUT=DTBOUT;GNDINTCLK, START=START, CLKOUT=INTCLK, RSTALL=RSTALL, ARIEND=ARIEND); U2:SREG8B PORT MAP(CLK=INTCLK, LOAD=RSTALL. DIN=B, QB=QB);U3:ANDARITH PORT MAP(ABIN=QB,DIN=A,DOUT=ANDSD);U4:ADDER8B
14、PORT MAP(CIN=GNDINT,A=DTBOUT(15 DOWNTO 8), B=ANDSD, S=DTBIN(7 DOWNTO 0),COUT =DTBIN(8);U5:REG16B PORT MAP(CLK =INTCLK,CLR=RSTALL, D=DTBIN, Q=DTBOUT);END ART;7有时钟使能的十进制计数器的源程序LIBRARY IEEE;USE IEEE.STD_LOGIC_1164.ALL; -有时钟使能的十进制计数器ENTITY CNT10 ISPORT (CLK:IN STD_LOGIC; -计数时钟信号 CLR:IN STD_LOGIC; -清零信号
15、END:IN STD_LOGIC; -计数使能信号 CQ:OUT INTEGER RANGE 0 TO 15; -4位计数结果输出 CARRY_OUT:OUT STD_LOGIC); -计数进位 END CNT10;ARCHITECTURE ART OF CNT10 IS SIGNAL CQI :INTEGER RANGE 0 TO 15; BEGIN PROCESS(CLK,CLR,ENA) BEGIN IF CLR= 1 THEN CQI= 0; -计数器异步清零 ELSIF CLKEVENT AND CLK= 1 THEN IF ENA= 1 THEN IF CQI9 THEN CQI=
16、CQI+1; ELSE CQI=0;END IF; -等于9,则计数器清零 END IF; END IF; END PROCESS; PROCESS (CQI) BEGIN IF CQI=9 THEN CARRY_OUT= 1; -进位输出 ELSE CARRY_OUT= 0;END IF; END PROCESS; CQ=CQI;END ART;8) 六进制计数器的源程序CNT6.VHD(十进制计数器的源程序CNT10.VHD与此类似)LIBRARY IEEE;USE IEEE.STD_LOGIC_1164.ALL;USE IEEE.STD_LOGIC_UNSIGNED.ALL;ENTITY
17、 CNT6 ISPORT (CLK:IN STD_LOGIC; CLR:IN STD_LOGIC; ENA: IN STD_LOGIC; CQ:OUT STD_LOGIC_VECTOR(3 DOWNTO 0); CARRY_OUT: OUT STD_LOGIC );END CNT6;ARCHITECTURE ART OF CNT6 ISSIGNAL CQI:STD_LOGIC_VECTOR(3 DOWNTO 0);BEGINPROCESS(CLK,CLR,ENA)BEGIN IF CLR=1 THEN CQI=0000; ELSIF CLKEVENT AND CLK=1 THEN IF ENA
18、=1 THEN IF CQI=“0101” THEN CQI=“0000”; ELSE CQI=CQI+1;END IF; END IF; END IF; END PROCESS; PROCESS(CQI) BEGIN IF CQI=“0000” THEN CARRY_OUT=1; ELSE CARRY_OUT=0;END IF; END PROCESS; CQ=CQI;END ART;9十进制计数器LIBRARY ieee;USE ieee.std_logic_1164.ALL;USE ieee.std_logic_unsigned.ALL;ENTITY count10 ISPORT(clk
19、: IN STD_LOGIC; seg: OUT STD_LOGIC_VECTOR(6 DOWNTO 0);END count10;ARCHITECTURE a1 OF count10 ISsignal sec: STD_LOGIC;signal q : STD_LOGIC_VECTOR(21 DOWNTO 0);signal num: STD_LOGIC_VECTOR(3 DOWNTO 0);BEGINprocess(clk) -get 1 hz clock pulsebeginif clkevent and clk=1 then q=q+1; end if;sec=q(21); -get
20、1 hz clock pulseend process;timing: process(sec) beginif secevent and sec=1 then if num9 then num=num+1; else num=0000; end if;end if;end process;B1: block -bcd-7segsBegin -gfedcba seg= 0111111 when num=0 else 0000110 when num=1 else 1011011 when num=2 else 1001111 when num=3 else 1100110 when num=4
21、 else 1101101 when num=5 else 1111101 when num=6 else 0000111 when num=7 else 1111111 when num=8 else 1101111 when num=9 else 0000000;end block;END a1;104MHz到1Hz的分频器LIBRARY ieee;USE ieee.std_logic_1164.ALL;USE ieee.std_logic_unsigned.ALL;ENTITY count ISPORT( clk: in STD_LOGIC; q: out STD_LOGIC;END c
22、ount;ARCHITECTURE a OF count ISsignal tmp: STD_LOGIC_vector(21 downto 0);Beginprocess(clk) beginif clkevent and clk=1 then tmp=tmp+1;end if;end process;q=tmp(21);END a;11与门ENTITY shili2 is port ( input1 : in std_logic; inptu2 : in std_logic; output1 : out std_logic );end entity;architecture one of shili2 is begin output1=input1 and input2; end entity;12.四输入与门电路library ieee;use ieee.std_logic_1164.all;entity and4 is port(a,b,c,d:in std_logic; y:out std_logic;end and4; architecture and4_1 of and4 is begin yyyyyyyyyyyyyyyyyy=x;end case;end process;en
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