优先级编码器.vhd

含有各类寄存器

--Highest Priority Encoder
entity priority is
port(I : in bit_vector(7 downto 0); --inputs to be prioritised
A : out bit_vector(2 downto 0); --encoded output
GS : out bit); --group signal output
end priority;
architecture v1 of priority is
begin
process(I)
begin
GS <= '1'; --set default outputs
A <= "000";
if I(7) = '1' then
A <= "111";
elsif I(6) = '1' then
A <= "110";
elsif I(5) = '1' then
A <= "101";
elsif I(4) = '1' then
A <= "100";
elsif I(3) = '1' then
A <= "011";
elsif I(2) = '1' then
A <= "010";
elsif I(1) = '1' then
A <= "001";
elsif I(0) = '1' then
A <= "000";
else
GS <= '0';
end if;
end process;
end v1;