Carry Lookahead 16 bits
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--Book: Eletronica digital moderna e VHDL/490 - Pelo autor
-- Carry lookahead com 16 bits
--
architecture adder_carry_lookahead_16 of adder is
signal carry: std_logic_vector(n/16 downto 0);
component carry_lookahead_adder_16 is
port( a,b : in std_logic_vector(15 downto 0);
cin: in std_logic;
cout: out std_logic;
sum: out std_logic_vector(15 downto 0));
end component;
begin
carry(0) <= cin;
gen_adder: for i in 1 to n/16 generate
adder: carry_lookahead_adder_16
port map(
a => a(16*i-1 downto 16*i-16),
b => b(16*i-1 downto 16*i-16),
cin => carry(i-1),
sum => sum(16*i-1 downto 16*i-16),
cout => carry(i)
);
end generate;
end architecture;
---------------------------------------
--Book: Pedroni/490
--8 bits carry-lookahead
--Uso do component
library ieee;
use ieee.std_logic_1164.all;
entity carry_lookahead_adder_16 is
port( a,b : in std_logic_vector(15 downto 0);
cin: in std_logic;
cout: out std_logic;
sum: out std_logic_vector(15 downto 0));
end entity;
architecture structure of carry_lookahead_adder_16 is
signal g,p,c : std_logic_vector(15 downto 0);
begin
---computation of g and p;
g <= a and b;
p <= a xor b;
---computation of carry;
c(0) <= cin;
c(1) <= g(0) or
(p(0) and cin);
c(2) <= g(1) or
(p(1) and g(0)) or
(p(1) and p(0) and cin);
c(3) <= g(2) or
(p(2) and g(1)) or
(p(2) and p(1) and g(0)) or
(p(2) and p(1) and p(0) and cin);
c(4) <= g(3) or
(p(3) and g(2)) or
(p(3) and p(2) and g(1)) or
(p(3) and p(2) and p(1) and g(0)) or
(p(3) and p(2) and p(1) and p(0) and cin);
c(5) <= g(4) or
(p(4) and g(3)) or
(p(4) and p(3) and g(2)) or
(p(4) and p(3) and p(2) and g(1)) or
(p(4) and p(3) and p(2) and p(1) and g(0)) or
(p(4) and p(3) and p(2) and p(1) and p(0) and cin);
c(6) <= g(5) or
(p(5) and g(4)) or
(p(5) and p(4) and g(3)) or
(p(5) and p(4) and p(3) and g(2)) or
(p(5) and p(4) and p(3) and p(2) and g(1)) or
(p(5) and p(4) and p(3) and p(2) and p(1) and g(0)) or
(p(5) and p(4) and p(3) and p(2) and p(1) and p(0) and cin);
c(7) <= g(6) or
(p(6) and g(5)) or
(p(6) and p(5) and g(4)) or
(p(6) and p(5) and p(4) and g(3)) or
(p(6) and p(5) and p(4) and p(3) and g(2)) or
(p(6) and p(5) and p(4) and p(3) and p(2) and g(1)) or
(p(6) and p(5) and p(4) and p(3) and p(2) and p(1) and g(0)) or
(p(6) and p(5) and p(4) and p(3) and p(2) and p(1) and p(0) and cin);
c(8) <= g(7) or
(p(7) and g(6)) or
(p(7) and p(6) and g(5)) or
(p(7) and p(6) and p(5) and g(4)) or
(p(7) and p(6) and p(5) and p(4) and g(3)) or
(p(7) and p(6) and p(5) and p(4) and p(3) and g(2)) or
(p(7) and p(6) and p(5) and p(4) and p(3) and p(2) and g(1)) or
(p(7) and p(6) and p(5) and p(4) and p(3) and p(2) and p(1) and g(0)) or
(p(7) and p(6) and p(5) and p(4) and p(3) and p(2) and p(1) and p(0) and cin);
c(9) <= g(8) or
(p(8) and g(7)) or
(p(8) and p(7) and g(6)) or
(p(8) and p(7) and p(6) and g(5)) or
(p(8) and p(7) and p(6) and p(5) and g(4)) or
(p(8) and p(7) and p(6) and p(5) and p(4) and g(3)) or
(p(8) and p(7) and p(6) and p(5) and p(4) and p(3) and g(2)) or
(p(8) and p(7) and p(6) and p(5) and p(4) and p(3) and p(2) and g(1)) or
(p(8) and p(7) and p(6) and p(5) and p(4) and p(3) and p(2) and p(1) and g(0)) or
(p(8) and p(7) and p(6) and p(5) and p(4) and p(3) and p(2) and p(1) and p(0) and cin);
c(10) <= g(9) or
(p(9) and g(8)) or
(p(9) and p(8) and g(7)) or
(p(9) and p(8) and p(7) and g(6)) or
(p(9) and p(8) and p(7) and p(6) and g(5)) or
(p(9) and p(8) and p(7) and p(6) and p(5) and g(4)) or
(p(9) and p(8) and p(7) and p(6) and p(5) and p(4) and g(3)) or
(p(9) and p(8) and p(7) and p(6) and p(5) and p(4) and p(3) and g(2)) or
(p(9) and p(8) and p(7) and p(6) and p(5) and p(4) and p(3) and p(2) and g(1)) or
(p(9) and p(8) and p(7) and p(6) and p(5) and p(4) and p(3) and p(2) and p(1) and g(0)) or
(p(9) and p(8) and p(7) and p(6) and p(5) and p(4) and p(3) and p(2) and p(1) and p(0) and cin);
c(11) <= g(10) or
(p(10) and g(9)) or
(p(10) and p(9) and g(8)) or
(p(10) and p(9) and p(8) and g(7)) or
(p(10) and p(9) and p(8) and p(7) and g(6)) or
(p(10) and p(9) and p(8) and p(7) and p(6) and g(5)) or
(p(10) and p(9) and p(8) and p(7) and p(6) and p(5) and g(4)) or
(p(10) and p(9) and p(8) and p(7) and p(6) and p(5) and p(4) and g(3)) or
(p(10) and p(9) and p(8) and p(7) and p(6) and p(5) and p(4) and p(3) and g(2)) or
(p(10) and p(9) and p(8) and p(7) and p(6) and p(5) and p(4) and p(3) and p(2) and g(1)) or
(p(10) and p(9) and p(8) and p(7) and p(6) and p(5) and p(4) and p(3) and p(2) and p(1) and g(0)) or
(p(10) and p(9) and p(8) and p(7) and p(6) and p(5) and p(4) and p(3) and p(2) and p(1) and p(0) and cin);
c(12) <= g(11) or
(p(11) and g(10)) or
(p(11) and p(10) and g(9)) or
(p(11) and p(10) and p(9) and g(8)) or
(p(11) and p(10) and p(9) and p(8) and g(7)) or
(p(11) and p(10) and p(9) and p(8) and p(7) and g(6)) or
(p(11) and p(10) and p(9) and p(8) and p(7) and p(6) and g(5)) or
(p(11) and p(10) and p(9) and p(8) and p(7) and p(6) and p(5) and g(4)) or
(p(11) and p(10) and p(9) and p(8) and p(7) and p(6) and p(5) and p(4) and g(3)) or
(p(11) and p(10) and p(9) and p(8) and p(7) and p(6) and p(5) and p(4) and p(3) and g(2)) or
(p(11) and p(10) and p(9) and p(8) and p(7) and p(6) and p(5) and p(4) and p(3) and p(2) and g(1)) or
(p(11) and p(10) and p(9) and p(8) and p(7) and p(6) and p(5) and p(4) and p(3) and p(2) and p(1) and g(0)) or
(p(11) and p(10) and p(9) and p(8) and p(7) and p(6) and p(5) and p(4) and p(3) and p(2) and p(1) and p(0) and cin);
c(13) <= g(12) or
(p(12) and g(11)) or
(p(12) and p(11) and g(10)) or
(p(12) and p(11) and p(10) and g(9)) or
(p(12) and p(11) and p(10) and p(9) and g(8)) or
(p(12) and p(11) and p(10) and p(9) and p(8) and g(7)) or
(p(12) and p(11) and p(10) and p(9) and p(8) and p(7) and g(6)) or
(p(12) and p(11) and p(10) and p(9) and p(8) and p(7) and p(6) and g(5)) or
(p(12) and p(11) and p(10) and p(9) and p(8) and p(7) and p(6) and p(5) and g(4)) or
(p(12) and p(11) and p(10) and p(9) and p(8) and p(7) and p(6) and p(5) and p(4) and g(3)) or
(p(12) and p(11) and p(10) and p(9) and p(8) and p(7) and p(6) and p(5) and p(4) and p(3) and g(2)) or
(p(12) and p(11) and p(10) and p(9) and p(8) and p(7) and p(6) and p(5) and p(4) and p(3) and p(2) and g(1)) or
(p(12) and p(11) and p(10) and p(9) and p(8) and p(7) and p(6) and p(5) and p(4) and p(3) and p(2) and p(1) and g(0)) or
(p(12) and p(11) and p(10) and p(9) and p(8) and p(7) and p(6) and p(5) and p(4) and p(3) and p(2) and p(1) and p(0) and cin);
c(14) <= g(13) or
(p(13) and g(12)) or
(p(13) and p(12) and g(11)) or
(p(13) and p(12) and p(11) and g(10)) or
(p(13) and p(12) and p(11) and p(10) and g(9)) or
(p(13) and p(12) and p(11) and p(10) and p(9) and g(8)) or
(p(13) and p(12) and p(11) and p(10) and p(9) and p(8) and g(7)) or
(p(13) and p(12) and p(11) and p(10) and p(9) and p(8) and p(7) and g(6)) or
(p(13) and p(12) and p(11) and p(10) and p(9) and p(8) and p(7) and p(6) and g(5)) or
(p(13) and p(12) and p(11) and p(10) and p(9) and p(8) and p(7) and p(6) and p(5) and g(4)) or
(p(13) and p(12) and p(11) and p(10) and p(9) and p(8) and p(7) and p(6) and p(5) and p(4) and g(3)) or
(p(13) and p(12) and p(11) and p(10) and p(9) and p(8) and p(7) and p(6) and p(5) and p(4) and p(3) and g(2)) or
(p(13) and p(12) and p(11) and p(10) and p(9) and p(8) and p(7) and p(6) and p(5) and p(4) and p(3) and p(2) and g(1)) or
(p(13) and p(12) and p(11) and p(10) and p(9) and p(8) and p(7) and p(6) and p(5) and p(4) and p(3) and p(2) and p(1) and g(0)) or
(p(13) and p(12) and p(11) and p(10) and p(9) and p(8) and p(7) and p(6) and p(5) and p(4) and p(3) and p(2) and p(1) and p(0) and cin);
c(15) <= g(14) or
(p(14) and g(13)) or
(p(14) and p(13) and g(12)) or
(p(14) and p(13) and p(12) and g(11)) or
(p(14) and p(13) and p(12) and p(11) and g(10)) or
(p(14) and p(13) and p(12) and p(11) and p(10) and g(9)) or
(p(14) and p(13) and p(12) and p(11) and p(10) and p(9) and g(8)) or
(p(14) and p(13) and p(12) and p(11) and p(10) and p(9) and p(8) and g(7)) or
(p(14) and p(13) and p(12) and p(11) and p(10) and p(9) and p(8) and p(7) and g(6)) or
(p(14) and p(13) and p(12) and p(11) and p(10) and p(9) and p(8) and p(7) and p(6) and g(5)) or
(p(14) and p(13) and p(12) and p(11) and p(10) and p(9) and p(8) and p(7) and p(6) and p(5) and g(4)) or
(p(14) and p(13) and p(12) and p(11) and p(10) and p(9) and p(8) and p(7) and p(6) and p(5) and p(4) and g(3)) or
(p(14) and p(13) and p(12) and p(11) and p(10) and p(9) and p(8) and p(7) and p(6) and p(5) and p(4) and p(3) and g(2)) or
(p(14) and p(13) and p(12) and p(11) and p(10) and p(9) and p(8) and p(7) and p(6) and p(5) and p(4) and p(3) and p(2) and g(1)) or
(p(14) and p(13) and p(12) and p(11) and p(10) and p(9) and p(8) and p(7) and p(6) and p(5) and p(4) and p(3) and p(2) and p(1) and g(0)) or
(p(14) and p(13) and p(12) and p(11) and p(10) and p(9) and p(8) and p(7) and p(6) and p(5) and p(4) and p(3) and p(2) and p(1) and p(0) and cin);
cout <= g(15) or
(p(15) and g(14)) or
(p(15) and p(14) and g(13)) or
(p(15) and p(14) and p(13) and g(12)) or
(p(15) and p(14) and p(13) and p(12) and g(11)) or
(p(15) and p(14) and p(13) and p(12) and p(11) and g(10)) or
(p(15) and p(14) and p(13) and p(12) and p(11) and p(10) and g(9)) or
(p(15) and p(14) and p(13) and p(12) and p(11) and p(10) and p(9) and g(8)) or
(p(15) and p(14) and p(13) and p(12) and p(11) and p(10) and p(9) and p(8) and g(7)) or
(p(15) and p(14) and p(13) and p(12) and p(11) and p(10) and p(9) and p(8) and p(7) and g(6)) or
(p(15) and p(14) and p(13) and p(12) and p(11) and p(10) and p(9) and p(8) and p(7) and p(6) and g(5)) or
(p(15) and p(14) and p(13) and p(12) and p(11) and p(10) and p(9) and p(8) and p(7) and p(6) and p(5) and g(4)) or
(p(15) and p(14) and p(13) and p(12) and p(11) and p(10) and p(9) and p(8) and p(7) and p(6) and p(5) and p(4) and g(3)) or
(p(15) and p(14) and p(13) and p(12) and p(11) and p(10) and p(9) and p(8) and p(7) and p(6) and p(5) and p(4) and p(3) and g(2)) or
(p(15) and p(14) and p(13) and p(12) and p(11) and p(10) and p(9) and p(8) and p(7) and p(6) and p(5) and p(4) and p(3) and p(2) and g(1)) or
(p(15) and p(14) and p(13) and p(12) and p(11) and p(10) and p(9) and p(8) and p(7) and p(6) and p(5) and p(4) and p(3) and p(2) and p(1) and g(0)) or
(p(15) and p(14) and p(13) and p(12) and p(11) and p(10) and p(9) and p(8) and p(7) and p(6) and p(5) and p(4) and p(3) and p(2) and p(1) and p(0) and cin);
---computation of sum
sum <= p xor c;
end architecture;