I want to create a package which contain
- procedure for full adder
- procedure for parallel adder using full adder defined in the same package
but there is some error. Please check the source code
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library ieee;
use ieee.std_logic_1164.all;
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package digital_package is
procedure full_adder(signal a,b,cin:in std_logic;
signal s,c: out std_logic);
procedure parallel_adder (signal a,b:in std_logic_vector(3 downto 0);
signal cin: in std_logic;
signal s: out std_logic_vector(3 downto 0);
signal cout: out std_logic);
end digital_package;
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package body digital_package is
procedure full_adder(signal a,b,cin: in std_logic;
signal s,c: out std_logic) is
begin
s<=a xor b xor cin;
c<=(cin and(a xor b)) or (a and b);
end full_adder;
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procedure parallel_adder (signal a,b: in std_logic_vector(3 downto 0);
signal cin: in std_logic;
signal s: out std_logic_vector(3 downto 0);
signal cout: out std_logic) is
signal t:std_logic_vector(3 downto 0);
begin
full_adder(a(0),b(0),cin,s(0),t(0));
full_adder(a(1),b(1),t(0),s(1),t(1));
full_adder(a(2),b(2),t(1),s(2),t(2));
full_adder(a(3),b(3),t(2),s(3),cout);
end parallel_adder;
end digital_package;
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