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A bus is a set of signals which are grouped together conceptually (and often physically). One way to represent a bus is with std_logic_vector, which is somewhat similar to an array in software programming languages.
We can declare a 3-bit input bus called votes with
votes : in std_logic_vector(2 downto 0)
With this declaration, you can use votes(0) to refer to bit 0 of votes, votes(1) for bit 1, and votes(2) for bit 2. The (2 downto 0) part specifies that this is a 3-bit bus where votes(2) is the MSB and votes(0) is the LSB.
Complete the architecture to build a majority encoder: the output y is 1 if the majority (i.e., at least two) of the input bits are 1, and 0 otherwise.
library IEEE;
use IEEE.std_logic_1164.all;
entity majority is
port(
votes : in std_logic_vector(2 downto 0);
y : out std_logic
);
end majority;
architecture synth of majority is
begin
y <= '0'; -- A broken clock is right twice a day...
end;
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