最高优先级编码器.txt
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上传日期:2013-03-21
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- -- Highest Priority Encoder
- -- download from www.pld.com.cn & www.fpga.com.cn
- LIBRARY ieee;
- USE ieee.std_logic_1164.ALL;
- 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;