37 lines
1.2 KiB
VHDL
37 lines
1.2 KiB
VHDL
-- (C) Copyright Collin J. Doering 2015
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--
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-- This program is free software: you can redistribute it and/or modify
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-- it under the terms of the GNU General Public License as published by
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-- the Free Software Foundation, either version 3 of the License, or
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-- (at your option) any later version.
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--
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-- This program is distributed in the hope that it will be useful,
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-- but WITHOUT ANY WARRANTY; without even the implied warranty of
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-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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-- GNU General Public License for more details.
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--
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-- You should have received a copy of the GNU General Public License
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-- along with this program. If not, see <http://www.gnu.org/licenses/>.
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-- File: adder.vhdl
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-- Author: Collin J. Doering <collin.doering@rekahsoft.ca>
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-- Date: May 22, 2015
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library IEEE;
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use IEEE.std_logic_1164.all;
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entity adder is
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-- i0, i1 and the carry-in ci are inputs of the adder.
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-- s is the sum output, co is the carry-out.
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port (a, b, ci : in std_logic;
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s, co : out std_logic);
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end adder;
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architecture adder_arch of adder is
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begin
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-- Compute the sum.
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s <= a xor b xor ci;
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-- Compute the carry.
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co <= (a and b) or (a and ci) or (b and ci);
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end adder_arch;
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