UNIT-3
DESIGN COMBINATIONAL CKT USING ARCHITECTURE MODEL
(a)DATA-FLOW MODEL
(b) BEHAVIOR MODEL
(c)STRUCTURAL MODEL
VHDL CODE FOR MULTIPLEXER WITH DATA FLOW MODEL.
library IEEE;
use IEEE.STD_LOGIC_1164.all;
entity MUX_4X1 is
port(
A : in STD_LOGIC;
B : in STD_LOGIC;
C : in STD_LOGIC;
D : in STD_LOGIC;
S : in STD_LOGIC_VECTOR(1 down to 0);
Y : out STD_LOGIC
);
end MUX_4X1;
architecture MUX_DATA of MUX_4X1 is
begin
Y<= A WHEN S(1)='0' AND S(0)='0' ELSE
B WHEN S(1)='0' AND S(0)='1' ELSE
C WHEN S(1)='1' AND S(0)='0' ELSE
D WHEN S(1)='1' AND S(0)='1' ;
end MUX_DATA;
VHDL CODE FOR MULTIPLEXER WITH BEHAVIORAL-MODEL DESIGN
library IEEE;
use IEEE.STD_LOGIC_1164.all;
entity MUX_4X1 is
port(
A : in STD_LOGIC;
B : in STD_LOGIC;
C : in STD_LOGIC;
D : in STD_LOGIC;
S : in STD_LOGIC_VECTOR(1 downto 0);
Y : out STD_LOGIC
);
end MUX_4X1;
architecture MUX_BEH of MUX_4X1 is
begin
PROCESS(A,B,C,D,S)
BEGIN
CASE S IS
WHEN "00" => Y<= A;
WHEN "01" => Y<= B;
WHEN "10" => Y<= C;
WHEN "11" => Y<= D;
WHEN OTHERS => NULL;
END CASE;
END PROCESS;
end MUX_BEH;
VHDL CODE FOR MULTIPLEXER WITH structural style model
library IEEE;
use IEEE.STD_LOGIC_1164.all;
entity MUX4X1 is
port(
A : in STD_LOGIC;
B : in STD_LOGIC;
C : in STD_LOGIC;
D : in STD_LOGIC;
S0 : in STD_logic;
S1 : IN STd_logic;
Y : out STD_LOGIC
);
end MUX4X1;
architecture MUX_STRU of MUX4X1 is
COMPONENT AND3
PORT( L,M,O: IN STD_LOGIC; N: OUT STD_LOGIC);
END COmponent;
COMPONENT OR4
PORT( H,I,J,K: IN STD_LOGIC; H1: OUT STD_LOGIC);
END COmponent;
COMPONENT INV_1
PORT( E: IN STD_LOGIC; F: OUT STD_LOGIC);
END COmponent;
for v0:and3 use entity work.and3(and3);
for v4:or4 use entity work.or4(or4);
for u0:inv_1 use entity work.inv_1(inv_1);
SIGNAL S0BAR,S1BAR,W,X,G,Z: STD_LOGIC;
BEGIN
U0: INV_1 PORT MAP (S0,S0BAR);
U1: INV_1 PORT MAP (S1,S1BAR);
V0: AND3 PORT MAP (A,S1BAR,S0BAR,W);
V1: AND3 PORT MAP (B,S1BAR,S0 ,X);
V2: AND3 PORT MAP (C,S1 ,S0BAR,G);
V3: AND3 PORT MAP (D,S1 ,S0 ,Z);
V4: OR4 PORT MAP ( W,X,G,Z,Y);
end MUX_STRU;
--1-bit comparator using behavioral style.
entity comp is
port ( a: in bit_vector(0 to 1);e: out bit_vector(2 downto 0));
end entity;
architecture comp_beha of comp is
begin
process(a)
variable temp : bit;
begin
case a is
when "00" => e <="100";
when "01" => e <="010";
when "10" => e <="001";
when "11" => e <="100";
when others => null;
end case;
end process;
end architecture;
--1-bit comparator using structural style model
library IEEE;
use IEEE.STD_LOGIC_1164.all;
entity COMP_1 is
port(
A : in STD_LOGIC;
B : in STD_LOGIC;
E : out STD_LOGIC;
L : out STD_LOGIC;
G : out STD_LOGIC
);
end COMP_1;
architecture COMP_STRU of COMP_1 is
component xnor2
port(l, m: in STD_LOGIC; n: out STD_LOGIC);
end component;
component and2
port(x, y: in STD_LOGIC; z: out STD_LOGIC);
end component;
component inv
port( s: in STD_LOGIC; t: out STD_LOGIC);
end component;
for A1:and2 use entity work.and2(and2);
for X1:xnor2 use entity work.xnor2(xnor2);
for I1:inv use entity work.inv(inv);
signal abar,bbar: STD_LOGIC;
begin
I1: INVPORT MAP( A, ABAR);
I2: INVPORT MAP (B,BBAR);
X1: xnor2 port map ( a, b, e);
A1: and2 port map( abar,b,l);
A2: and2 port map(a,bbar,g);
end COMP_STRU;
--4-bit comparator using data flowmodel.
use IEEE.STD_LOGIC_1164.all;
entity \4_bit\ is
port(
a : in STD_LOGIC_VECTOR(0 to 3);
b : in STD_LOGIC_VECTOR(0 to 3);
agtb : out STD_LOGIC;
aeqb : out STD_LOGIC;
altb : out STD_LOGIC
);
end \4_bit\;
architecture \4_bit_data\ of \4_bit\ is
begin
aeqb <= '1' when a=b else '0';
agtb<= '1' when a>b else '0';
altb <= '1' when a<b else'0';
end \4_bit_data\;
--4-bit comparator using behavioral style model.
library IEEE;
use IEEE.STD_LOGIC_1164.all;
entity \4_comp\ is
port(
a : in STD_LOGIC_VECTOR(0 to 3);
b : in STD_LOGIC_VECTOR(0 to 3);
agtb : out STD_LOGIC;
altb : out STD_LOGIC;
aeqb : out STD_LOGIC
);
end \4_comp\;
architecture \4_comp_beh\ of \4_comp\ is
begin
process(a,b)
begin
if(a>b) then
agtb<= '1';
aeqb<='0';
altb<= '0';
elsif(a<b) then
agtb<= '0';
aeqb<='0';
altb<= '1';
elsif(a=b)then
agtb<= '0';
aeqb<='1';
altb<= '0';
end if;
end process;
end \4_comp_beh\;
--4-bit comparator using structural style model.
library IEEE;
use IEEE.STD_LOGIC_1164.all;
entity \4_comp_stru\ is
port(
a : in STD_LOGIC_VECTOR(0 to 3);
b : in STD_LOGIC_VECTOR(0 to 3);
aeqb : inout STD_LOGIC;
agtb : inout STD_LOGIC;
altb : out STD_LOGIC
);
end \4_comp_stru\;
architecture \4_comp_str\ of \4_comp_stru\ is
component xnor2
port(l,m: in std_logic;n: out std_logic);
end component;
component and2
port(x,y: in std_logic; z: out std_logic);
end component;
component inv
port (u: in std_logic; v: out std_logic);
end component;
component and3
port(l,m,o: in std_logic;n: out std_logic);
end component;
component or4
port(m1,m2,m3,m4: in std_logic; mf: out std_logic);
end component;
component and4
port(q1,q2,q3,q4: in std_logic; qf: out std_logic);
end component;
component and5
port (e1,e2,e3,e4,e5: in std_logic; ef: out std_logic);
end component;
component nor2
port(l1,l2: in std_logic; lf: out std_logic);
end component;
signal i0,i1,i2,i3,j0,j1,j2,j3,j4,j5,h0,h1,h2,h3: std_logic;
begin
m1: inv port map (b(3),i3);
m2: inv port map (b(2),i2);
m3: inv port map (b(1),i1);
m4: inv port map (b(0),i0);
m5: xnor2 port map (a(3),b(3),j3);
m6: xnor2 port map (a(2),b(2),j2);
m7: xnor2 port map (a(1),b(1),j1);
m8: xnor2 port map (a(0),b(0),j0);
m9: and2 port map (a(3),i3,h3);
m10: and3 port map (a(2),i2,j3,h2);
m11: and4 port map (a(1),i1,j2,j3,h1);
m12: and5 port map (a(0),i0,j1,j2,j3,h0);
m13: and4 port map (j0,j1,j2,j3,aeqb);
m14: or4 port map (h0,h1,h2,h3,agtb);
m15: nor2 port map (aeqb,agtb,altb);
end \4_comp_str\;
--vhdl code for halfadder using data flow style model.
entity ha is
port( a, b: in bit; sum,carry: out bit);
end entity;
architecture ha1 of ha is
begin
sum<= a xor b;
carry<= a and b;
end architecture;
--vhdl code for halfadder using structural style model.
library IEEE;
use IEEE.STD_LOGIC_1164.all;
entity ha is
port(
a : in STD_LOGIC;
b : in STD_LOGIC;
sum : out STD_LOGIC;
carry : out STD_LOGIC
);
end ha;
architecture ha_stru of ha is
component xor2
port(l,m: in STD_LOGIC; n: out STD_LOGIC);
end component;
component and2
port(x,y: in STD_LOGIC; z: out STD_LOGIC);
end component;
for x1: xor2 use entity work.xor2(xor2);
for a1: and2 use entity work.and2(and2);
begin
x1: xor2 port map( a, b, sum);
a1: and2 port map(a,b,carry);
end ha_stru;
--vhdl code for halfadder using Behavioral style model.
entity ha is
port( a, b: in bit; sum,carry: out bit);
end entity;
architecture ha1 of ha is
begin
process (a,b)
begin
if (a ='0' and b='0') then
sum <= '0';
carry<='0';
elsif( a='0' and b='1')then
sum<= '1';
carry<='0';
elsif( a='1' and b='0')then
sum<= '1';
carry<='0';
elsif( a='1' and b='1')then
sum<= '0';
carry<='1';
end if;
end process;
end architecture;
--vhdl code for half subtractor using Behavioral style model.
entity ha is
port( a, b: in bit; sum,borrow: out bit);
end entity;
architecture ha1 of ha is
begin
process (a,b)
begin
if (a ='0' and b='0') then
sum <= '0';
borrow<='0';
elsif( a='0' and b='1')then
sum<= '1';
borrow<='1';
elsif( a='1' and b='0')then
sum<= '1';
borrow<='0';
elsif( a='1' and b='1')then
sum<= '0';
borrow<='0';
end if;
end process;
end architecture;
--vhdl code for half subtractor using data flow style model.
entity ha is
port( a, b: in bit; sum,borrow: out bit);
end entity;
architecture ha1 of ha is
begin
sum<= a xor b;
carry<= not a and b;
end architecture;
--vhdl code for half-subtractor using structural style model.
library IEEE;
use IEEE.STD_LOGIC_1164.all;
entity hs is
port(
a : in STD_LOGIC;
b : in STD_LOGIC;
sum : out STD_LOGIC;
borrow : out STD_LOGIC
);
end hs;
architecture hs_stru of hs is
component inv
port(u: in STD_LOGIC; v: out STD_LOGIC);
end component;
component xor2
port(l,m: in STD_LOGIC; n: out STD_LOGIC);
end component;
component and2
port(x,y: in STD_LOGIC; z: out STD_LOGIC);
end component;
for i1: inv use entity work.inv(inv);
for x1: xor2 use entitywork.xor2(xor2);
for a1: and2 use entitywork.and2(and2);
signal nota: STD_LOGIC;
begin
i1:inv port map(a, nota);
x1: xor2 port map( a, b, sum);
a1: and2 port map(nota,b,borrow);
end hs_stru;
--vhdl code for full-adder using Behavioral style model.
entity fa is
port( a, b: in bit;carry: inout bit; sum: out bit);
end entity;
architecture fa1 of fa is
begin
process (a,b,carry)
begin
if (a ='0' and b='0'and carry='0') then
sum <= '0';
carry<='0';
elsif(a ='0' and b='1'and carry='0') then
sum <= '1';
carry<='0';
elsif( a='1' and b='0'and carry = '0')then
sum <= '1';
carry <='0';
elsif( a='1' and b='1'and carry= '0')then
sum <= '0';
carry <='1';
elsif( a='0' and b='0'and carry= '1')then
sum <= '1';
carry <='0';
elsif( a='0' and b='1'and carry= '1')then
sum <= '0';
carry <='1';
elsif( a='1' and b='0'and carry= '1')then
sum <= '0';
carry <='1';
elsif( a='1' and b='1'and carry= '1')then
sum <= '1';
carry <='1';
end if;
end process;
end architecture;
--vhdl code for full-adder using structural style model.
library IEEE;
use IEEE.STD_LOGIC_1164.all;
entity fa is
port(
a : in STD_LOGIC;
b : in STD_LOGIC;
c: in std_logic;
sum : out STD_LOGIC;
carry : out STD_LOGIC
);
end fa;
architecture fa_stru of fa is
component xor2
port( l,m:in std_logic;n: out std_logic);
end component;
component and2
port( x,y:in std_logic; z:out std_logic);
end component;
component or2
port (e,f: in std_logic; g: out std_logic);
end component;
for x1 : xor2 use entity work.xor2(xor2);
for x3: and2 use entitywork.and2(and2);
for x5: or2 use entity work.or2(or2);
signal a1,a2,a3: std_logic;
begin
x1: xor2 port map(a,b,a1);
x2:xor2 port map ( a1,c,sum);
x3: and2 port map (a,b,a2);
x4: and2 port map (a1,c,a3);
x5: or2 port map (a3,a2,carry);
end fa_stru;
--vhdl code for full-adder using data-flow model.
library IEEE;
use IEEE.STD_LOGIC_1164.all;
entity fa1 is
port(
a : in STD_LOGIC;
b : in STD_LOGIC;
c : in STD_LOGIC;
sum : out STD_LOGIC;
carry : out STD_LOGIC
);
end fa1;
architecture fa_data1 of fa1 is
begin
sum <= a xor b xor c;
carry <= (a and b) or (c and (a xor b));
end fa_data1;
--vhdl code for full-subtractor using data-flow model.
library IEEE;
use IEEE.STD_LOGIC_1164.all;
entity fs is
port(
a : in STD_LOGIC;
borrow<= '1';
elsif(a="011") then
diff <= '0';
borrow<= '1';
elsif(a="100") then
diff <= '1';
borrow<= '0';
elsif(a="101") then
diff <= '0';
borrow<= '0';
elsif(a="110") then
diff <= '0';
borrow<= '0';
elsif(a="111") then
diff <= '1';
borrow<= '1';
end if;
end process;
end fs_beh;
--vhdl code for full-Created by bsaitmbtractor using structural style model.
library IEEE;
use IEEE.STD_LOGIC_1164.all;
entity fsub is
port(
a : in STD_LOGIC;
b : in STD_LOGIC;
c: in std_logic;
diff : out STD_LOGIC;
borrow : out STD_LOGIC
);
end fsub;
architecture fs_str of fsub is
component xor2
port(l,m: in std_logic;n: out std_logic);
end component;
component and2
port(x,y: in std_logic; z: out std_logic);
end component;
component inv
port (u: in std_logic; v: out std_logic);
end component;
component or2
port(e,f: in std_logic; g: out std_logic);
end component;
for b1: xor2 use entity work.xor2(xor2);
for b3: inv use entity work.inv(inv);
for b5: and2 use entitywork.and2(and2);
for b7: or2 useentity work.or2(or2);
signal q1,q2,q3,q4,q5: std_logic;
begin
b1:xor2 port map ( a,b,q3);
b2:xor2 port map ( q3,c,diff);
b3:inv port map ( a,q1);
b4:inv port map ( q3,q4);
b5:and2 port map ( q1,b,q2);
b6:and2 port map ( q4,c,q5);
b7: or2 port map (q5,q2,borrow);
end fs_str;
--vhdl code for B2G code converter using data-flow model.
library IEEE;
use IEEE.STD_LOGIC_1164.all;
entity b2g is
port(
a : in STD_LOGIC;
b : in STD_LOGIC;
c : in STD_LOGIC;
d : in STD_LOGIC;
w : out STD_LOGIC;
x : out STD_LOGIC;
y : out STD_LOGIC;
z : out STD_LOGIC
);
end b2g;
architecture b2g_data of b2g is
begin
w<= a;
x<= a xor b;
y<= b xor c;
z<= c xor d;
end b2g_data;
--vhdl code for B2G code converter using behavioral model.
entity b2g is
port(
b : in STD_LOGIC_VECTOR(3 downto 0);
g : out STD_LOGIC_VECTOR(3 downto 0)
);
end b2g;
architecture b2g_beh of b2g is
begin
process (b)
begin
case b is
when "0000"=> g<="0000";
when "0001"=> g<="0001";
when "0010"=> g<="0011";
when "0011"=> g<="0010";
when "0100"=> g<="0110";
when "0101"=> g<="0111";
when "0110"=> g<="0101";
when "0111"=> g<="0100";
when "1000"=> g<="1100";
when "1001"=> g<="1101";
when "1010"=> g<="1111";
when "1011"=> g<="1110";
when "1100"=> g<="1010";
when "1101"=> g<="1011";
when "1110"=> g<="1001";
when "1111"=> g<="1000";
when others=> null;
end case;
end process;
end b2g_beh;
--vhdl code for B2G code converter using structural style model.
library IEEE;
use IEEE.STD_LOGIC_1164.all;
entity b2g is
port(
a : in STD_LOGIC;
b : in STD_LOGIC;
c : in STD_LOGIC;
d : in STD_LOGIC;
w : out STD_LOGIC;
x : out STD_LOGIC;
y : out STD_LOGIC;
z : out STD_LOGIC
);
end b2g;
architecture b2g_stru of b2g is
component xor2
port (l,m: in Std_logic; n: out std_logic);
end component;
component buff
port (u: in std_logic; v:out std_logic);
end component;
for x1: buff use entity work.buff(buff);
for x2: xor2 use entity work.xor2(xor2);
begin
x1: buff port map (a,w);
x2: xor2 port map (a,b,x);
x3: xor2 port map (b,c,y);
x4: xor2 port map (c,d,z);
end b2g_stru;
--vhdl code for G2B code converter using data-flow model.
library IEEE;
use IEEE.STD_LOGIC_1164.all;
entity g2b is
port(
a : in STD_LOGIC;
b : in STD_LOGIC;
c : in STD_LOGIC;
d : in STD_LOGIC;
w : out STD_LOGIC;
x : out STD_LOGIC;
y : out STD_LOGIC;
z : out STD_LOGIC
);
end g2b;
architecture g2b_data of g2b is
begin
w <= a;
x <= a xor b;
y <= a xor b xor c;
z <= a xor b xor c xor d;
end g2b_data;
--vhdl code for G2B code converter using behavioral model.
entity g2b is
port(
g : in STD_LOGIC_VECTOR(3 downto 0);
b : out STD_LOGIC_VECTOR(3 downto 0)
);
end g2b;
architecture g2b_beh of g2b is
begin
process (g)
begin
case b is
when "0000"=> b<="0000";
when "0001"=> b<="0001";
when "0011"=> b<="0010";
when "0010"=> b<="0011";
when "0110"=> b<="0100";
when "0111"=> b<="0101";
when "0101"=> b<="0110";
when "0100"=> b<="0111";
when "1100"=> b<="1000";
when "1101"=> b<="1001";
when "1111"=> b<="1010";
when "1110"=> b<="1011";
when "1010"=> b<="1100";
when "1011"=> b<="1101";
when "1001"=> b<="1110";
when "1000"=> b<="1111";
when others=> null;
end case;
end process;
end g2b_beh;
--vhdl code for G2B code converter using structural style model.
library IEEE;
use IEEE.STD_LOGIC_1164.all;
entity g2b is
port(
w : in STD_LOGIC;
x : in STD_LOGIC;
y : in STD_LOGIC;
z : in STD_LOGIC;
a : out STD_LOGIC;
b : out STD_LOGIC;
c : out STD_LOGIC;
d : out STD_LOGIC
);
end g2b;
architecture g2b_stru of g2b is
component xor2
port (l,m: in Std_logic; n: out std_logic);
end component;
component buff
port (u: in std_logic; v:out std_logic);
end component;
for x1: buff use entity work.buff(buff);
for x2: xor2 use entity work.xor2(xor2);
begin
x1: buff port map (w,a);
x2: xor2 port map (w,x,b);
x3: xor2 port map (x,y,c);
x4: xor2 port map (y,z,d);
end g2b_stru;
--vhdl code for Bcd27-segment code converter using data-flow model.
library IEEE;
use IEEE.STD_LOGIC_1164.all;
entity bcd_7 is
port(
a : in STD_LOGIC;
b : in STD_LOGIC;
c : in STD_LOGIC;
d : in STD_LOGIC;
e : out STD_LOGIC;
f : out STD_LOGIC;
g : out STD_LOGIC;
h : out STD_LOGIC;
i : out STD_LOGIC;
j : out STD_LOGIC;
k : out STD_LOGIC
);
end bcd_7;
architecture bcd_7_data of bcd_7 is
begin
e<= a or ( c and d) or ( b and d) or (not b and not d);
f<= not b or (not c and not d)or (c and d);
g<= b or not c or d;
h<= (not b and not d)or (c and not d)or (not b and c) or( b and not c and d);
i<= (not b and not d)or ( c and not d);
j<= a or (not c and not d)or (b and not c)or (b and not d);
k<= a or (b and not c) or (c and not d)or (not b and c);
end bcd_7_data;
--vhdl code for Bcd2 7-segment code converter using behavioral model.
library IEEE;
use IEEE.STD_LOGIC_1164.all;
entity bcd_seven is
port(
bcd : in STD_LOGIC_VECTOR(3 downto 0);
segment : out STD_LOGIC_VECTOR(6 downto 0)
);
end bcd_seven;
architecture bcd_beh of bcd_seven is
begin
process(bcd)
begin
case bcd is
when "0000"=>segment<="1111110";
when "0001"=>segment<="0110000";
when "0010"=>segment<="1101101";
when "0011"=>segment<="1111001";
when "0100"=>segment<="0110011";
when "0101"=>segment<="1011011";
when "0110"=>segment<="0011111";
when "0111"=>segment<="1110000";
when "1000"=>segment<="1111111";
when "1001"=>segment<="1110011";
when others => null;
end case;
end process;
end bcd_beh;
--vhdl code for Bcd2 7-segment code converter using structural style model.
library IEEE;
use IEEE.STD_LOGIC_1164.all;
entity bcd is
port(
a : in STD_LOGIC;
b : in STD_LOGIC;
c : in STD_LOGIC;
d : in STD_LOGIC;
e : out STD_LOGIC;
f : out STD_LOGIC;
g : out STD_LOGIC;
h : out STD_LOGIC;
i : out STD_LOGIC;
j : out STD_LOGIC;
k : out STD_LOGIC
);
end bcd;
architecture bcd_stru of bcd is
component or4
port(a1,a2,a3,a4: in std_logic; af:out std_logic);
end component;
component and2
port(x,y: in std_logic;z: out std_logic);
end component;
component and3
port(l,m,o:in std_logic;n : out std_logic);
end component;
component inv_1
port(e: in std_logic; f: out std_logic);
end component;
component or3
port(k1,k2,k3: in std_logic;k4: out std_logic);
end component;
component or2
port (m1,m2: in std_logic;m3: out std_logic);
end component;
for x1: or4 use entity work.or4(or4);
for a1:and2 use entity work.and2(and2);
for b1: and3 use entity work.and3(and3);
for i1: inv_1 use entity work. inv_1(inv_1);
for z1: or3 use entity work.or3(or3);
for l1: or2 use entity work.or2(or2);
signal n1,n2,n3: std_logic;
signal b2,b3,b4,b5,b6,b7,b8,b9,b10,b11,b12:std_logic;
begin
i1: inv_1 port map(b,n1);
i2: inv_1 port map (c,n2);
i3: inv_1 port map (d,n3);
a1: and2 port map (c,d,b2);
a2: and2 port map (b,d,b3);
a3: and2 port map (n1,n3,b4);
a4: and2 port map (n3,n2,b5);
a5: and2 port map (n1,n3,b6);
a6: and2 port map (c,n3,b7);
a7: and2 port map (c,n1,b8);
a8: and2 port map (b,n3,b9);
a9: and2 port map (b,n2,b10);
a10: and2 port map (n2,n3,b11);
b1: and3 port map(b,n2,d,b12);
x1: or4 port map (a,b2,b3,b4,e);
z1:or3 port map (n1,b2,b5,f);
z2:or3 port map (b,n2,d,g);
x2:or4 port map (b6,b7,b8,b12,h);
l1:or2 port map (b6,b7,i);
x3:or4 port map (a,b9,b10,b11,j);
x4:or4 port map (a,b7,b8,b10,k);
end bcd_stru;
--vhdl code for Bcd-2-excess3 code converter using data-flow model.
library IEEE;
use IEEE.STD_LOGIC_1164.all;
entity bcd_3 is
port(
a : in STD_LOGIC;
b : in STD_LOGIC;
c : in STD_LOGIC;
d : in STD_LOGIC;
w : out STD_LOGIC;
x : out STD_LOGIC;
y : out STD_LOGIC;
z : out STD_LOGIC
);
end bcd_3;
architecture bcd_xce3_data of bcd_3 is
begin
w<= a or ( b and c) or (b and d);
x<= (not b and c)or (not b and d)or (b and not c and not d);
y<=(c and d)or (not c and not d);
z<= not d;
end bcd_xce3_data;
--vhdl code for Bcd-2-excess3 code converter using behavioral model.
library IEEE;
use IEEE.STD_LOGIC_1164.all;
entity bcd_excess is
port(
b : in STD_LOGIC_VECTOR(3 downto 0);
excess3 : out STD_LOGIC_VECTOR(3 downto 0)
);
end bcd_excess;
architecture bcd_excess_beh of bcd_excess is
begin
process (b)
begin
case b is
when "0000"=>excess3<="0011";
when "0001"=>excess3<="0100";
when "0010"=>excess3<="0101";
when "0011"=>excess3<="0101";
when "0100"=>excess3<="0111";
when "0101"=>excess3<="1000";
when "0110"=>excess3<="1001";
when "0111"=>excess3<="1010";
when "1000"=>excess3<="1011";
when "1001"=>excess3<="1100";
when "1010"=>excess3<="1110";
when others => null;
end case;
end process;
end bcd_excess_beh;
--vhdl code for Bcd-2-excess3 code converter using structural style model.
library IEEE;
use IEEE.STD_LOGIC_1164.all;
entity bcd_excess is
port(
a : in STD_LOGIC;
b : in STD_LOGIC;
c : in STD_LOGIC;
d : in STD_LOGIC;
w : out STD_LOGIC;
x : out STD_LOGIC;
y : out STD_LOGIC;
z : out STD_LOGIC
);
end bcd_excess;
architecture bcd_exces_stru of bcd_excess is
component or2
port(m1,m2: in std_logic; m3: out std_logic);
end component;
component and2
port(x,y: in std_logic; z: out std_logic);
end component;
component inv_1
port(e: in std_logic; f: out std_logic);
end component;
for x1: or2 use entity work.or2(or2);
for x5: inv_1 use entity work.inv_1(inv_1);
for x8: and2 use entity and2(and2);
signal a1,a2,a3,a4:std_logic;
signal n1,n2,n3: std_logic ;
begin
x1: or2 port map (a,a1,w);
x2:or2 port map (a2,a3,x);
x3:or2 port map (n2,a4,y);
x4: or2 port map (c,d,n3);
x5:inv_1 port map (d,z);
x6:inv_1 port map (b,n1);
x7:inv_1 port map (n3,n2);
x8: and2 port map (b,n3,a1);
x9: and2 port map (n1,n3,a2);
x10: and2 port map (b,n2,a3);
x11: and2 port map (c,d,a4);
end bcd_exces_stru;
--VHDL Code for decoder 2X4 using data flow model.
library IEEE;
use IEEE.STD_LOGIC_1164.all;
entity decoder2_4 is
port(
s0 : in STD_LOGIC;
s1 : in STD_LOGIC;
en : in STD_LOGIC;
z : out STD_LOGIC_VECTOR(3 downto 0)
);
end decoder2_4;
architecture decoder_data of decoder2_4 is
signal s0bar,s1bar:std_logic;
begin
s0bar<= not s0;
s1bar<= not s1;
z(3)<= s0bar and s1bar and en;
z(2)<= s0bar and s1 and en;
z(1)<= s0 and s1bar and en;
z(0)<= s0 and s1 and en;
end decoder_data;
--VHDL Code for decoder 2X4 using behavioral model.
library IEEE;
use IEEE.STD_LOGIC_1164.all;
entity decoder is
port(
en : in STD_LOGIC;
s0 : in STD_LOGIC;
s1 : in STD_LOGIC;
z : out STD_LOGIC_VECTOR(3 downto 0)
);
end decoder;
architecture decoder_beh of decoder is
begin
process(s0,s1,en)
variable s0bar,s1bar: std_logic;
begin
s0bar:= not s0;
s1bar:= not s1;
if (en='1')then
z(3)<= s0bar and s1bar;
z(2)<=s0bar and s1;
z(1)<= s0 and s1bar;
z(0)<= s0 and s1;
else
z<="0000";
end if;
end process;
end decoder_beh;
--VHDL Code for decoder 2X4 using structural style model
library IEEE;
use IEEE.STD_LOGIC_1164.all;
entity decoder is
port(
en : in STD_LOGIC;
s0 : in STD_LOGIC;
s1 : in STD_LOGIC;
z : out STD_LOGIC_VECTOR(0 to 3)
);
end decoder;
architecture decoder_stru of decoder is
component and3
port(l,m,o:in std_logic; n: out std_logic);
end component;
component inv_1
port(e: in std_logic; f: out std_logic);
end component;
for x1: and3 use entity work.and3(and3);
for x5: inv_1 use entity work.inv_1(inv_1);
signal s0bar,s1bar: std_logic;
begin
x1: and3 port map (s0bar,s1bar,en,z(0));
x2: and3 port map (s0bar,s1,en,z(1));
x3: and3 port map (s0,s1bar,en,z(2));
x4: and3 port map (s0,s1,en,z(3));
x5: inv_1 port map (s0,s0bar);
x6: inv_1 port map (s1,s1bar);
end decoder_stru;
--VHDL Code for encoder 8X3 using data flow model.
library IEEE;
use IEEE.STD_LOGIC_1164.all;
entity \encoder 8x3\ is
port(
a : out STD_LOGIC;
b : out STD_LOGIC;
c : out STD_LOGIC;
d : in STD_LOGIC_VECTOR(0 to 7)
);
end \encoder 8x3\;
architecture encoder_data of \encoder 7x3\ is
begin
a <= d(4)or d(5)or d(6)or d(7);
b <= d(2) or d(3)or d(6) or d(7);
c <=d(1) or d(3) or d(5) or d(7);
end encoder_data;
--VHDL Code for encoder 8X3 using behavioral model.
library IEEE;
use IEEE.STD_LOGIC_1164.all;
entity encoder is
port(
d : in STD_LOGIC_VECTOR(0 to 7);
a : out STD_LOGIC_vector(0 to 2 )
);
end encoder;
architecture encoder_beh of encoder is
begin
process (d)
begin
case d is
when "10000000"=> a<= "000";
when "01000000"=> a<="001";
when "00100000"=> a<="010";
when "00010000"=> a<="011";
when "00001000"=> a<="100";
when "00000100"=> a<="101";
when "00000010"=> a<="110";
when "00000001"=> a<="111";
when others => null;
end case;
end process;
end encoder_beh;
--VHDL Code for parity encoder 8X3 using structural style model.
library IEEE;
use IEEE.STD_LOGIC_1164.all;
entity encoder is
port(
d : in STD_LOGIC_VECTOR(0 to 3);
a : out STD_LOGIC_VECTOR(0 to 1);
en: out std_logic
);
end encoder;
architecture encoder_stru of encoder is
component or2
port(m1,m2: in std_logic; m3: out std_logic);
end component;
component or3
port (k1,k2,k3: in std_logic;k4: out std_logic);
endcomponent;
component and2
port(x,y: in std_logic; z: out std_logic);
end component;
component inv
port (u: in std_logic; v: out std_logic);
end component;
for x1:or2 use entity work.or2(or2);
for x3: or3 use entity work.or3(or3);
for x4: and2 use entity work.and2(and2);
for x5:inv use entity work.inv(inv);
signal a1,a2,a3:std_logic;
begin
x1: or2 port map (d(3),a2,a(1));
x2: or2 port map (d(3),d(2),a(0));
x3: or3 port map (a3,d(1),d(0),en);
x4: and2 port map (a1,d(1),a2);
x5: inv port map ( d(2),a1);
end encoder_stru;
--VHDL Code for parity generator using behavioral model.
library IEEE;
use IEEE.STD_LOGIC_1164.all;
entity parity is
port(
d : in STD_LOGIC_VECTOR(3 downto 0);
par_even : out STD_LOGIC;
par_odd : out STD_LOGIC);
end parity;
architecture parity of parity is
begin
p1:process(d)
begin
case d is
when "0000"=> par_even<='0';par_odd<='1';
when "0001"=> par_even<='1'; par_odd<='0';
when "0010"=> par_even<='1'; par_odd<='0';
when "0011"=> par_even<='0'; par_odd<='1';
when "0100"=> par_even<='1'; par_odd<='0';
when "0101"=> par_even<='0'; par_odd<='1';
when "0110"=> par_even<='0'; par_odd<='1';
when "0111"=> par_even<='1'; par_odd<='0';
when "1000"=> par_even<='1'; par_odd<='0';
when "1001"=> par_even<='0'; par_odd<='1';
when "1010"=> par_even<='0'; par_odd<='1';
when "1011"=> par_even<='1'; par_odd<='0';
when "1100"=> par_even<='0'; par_odd<='1';
when "1101"=> par_even<='1'; par_odd<='0';
when "1110"=> par_even<='1'; par_odd<='0';
when "1111"=> par_even<='0'; par_odd<='1';
when others=> null;
end case;
end process;
end parity;
--VHDL Code for parity generator using data flow model.
library IEEE;
use IEEE.STD_LOGIC_1164.all;
entity parity_gen_data is
port(
d0 : in STD_LOGIC;
d1 : in STD_LOGIC;
d2 : in STD_LOGIC;
d3 : in STD_LOGIC;
parity_even : inout STD_LOGIC;
parity_odd : out STD_LOGIC
);
end parity_gen_data;
--}} End of automatically maintained section
architecture parity_gen_data of parity_gen_data is
signal d4,d5: std_logic;
begin
d4 <= d0 xor d1;
d5 <= d4 xor d2;
parity_even <= d5 xor d3;
parity_odd <= not parity_even;
end parity_gen_data;
--VHDL Code for parity generator using structural style model.
library IEEE;
use IEEE.STD_LOGIC_1164.all;
entity parity_gen_stru is
port(
d0 : in STD_LOGIC;
d1 : in STD_LOGIC;
d2 : in STD_LOGIC;
d3 : in STD_LOGIC;
parity_even : inout STD_LOGIC;
parity_odd : out STD_LOGIC
);
end parity_gen_stru;
--}} End of automatically maintained section
architecture parity_gen_stru of parity_gen_stru is
component xor2
port(a,b: in std_logic; c: out std_logic);
end component;
component inv
port (i: in std_logic; j: out std_logic);
end component;
for x1: xor2 use entity work.xor2(xor2);
for i1: inv use entity work.inv(inv);
signal d4,d5: std_logic;
begin
x1: xor2 port map (d0,d1,d4);
x2: xor2 port map (d4,d2,d5);
x3: xor2 port map (d5,d3,parity_even);
i1: inv port map (parity_even ,parity_odd);
end parity_gen_stru;
--VHDL Code for parity checker(even-parity) using data flow model.
library IEEE;
use IEEE.STD_LOGIC_1164.all;
entity perity_checker is
port(
d3 : in STD_LOGIC;
d2 : in STD_LOGIC;
d1 : in STD_LOGIC;
d0 : in STD_LOGIC;
parity_even : in STD_LOGIC;
parity_even_checker : out STD_LOGIC
);
end perity_checker;
--}} End of automatically maintained section
architecture perity_checker of perity_checker is
signal d4,d5,d6: std_logic;
begin
d4 <= d3 xor d2;
d5<= d4 xor d1;
d6<= d5 xor d0;
parity_even_checker <= d6 xor parity_even;
-- enter your statements here --
end perity_checker;
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