[VHDL] Encoder Modeling | 인코더 모델링

Encoder Modeling

인코더 모델링

* Encoder (URL)

Inputs				Outputs
\(i_3\)	\(i_2\)	\(i_1\)	\(i_0\)	\(o_1\)	\(o_0\)
0	0	0	1	0	0
0	0	1	0	0	1
0	1	0	0	1	0
1	0	0	0	1	1

1) Using \(\texttt{if}\) Statement

Library ieee;
    USE ieee.std_logic_1164.all;
    
ENTITY encoder4x2 IS
    PORT( i : IN  std_logic_vector(3 DOWNTO 0);
          o : OUT std_ logic_vector(1 DOWNTO 0) );
END encoder4x2;

ARCHITECTURE arch_encoder4x2_if OF encoder4x2 IS
BEGIN
    PROCESS(i)
    BEGIN
        IF (i = "0001") THEN
            o <= "00";
        ELSIF (i = "0010") THEN
            o <= "01";
       ELSIF (i = "0100") THEN
            o <= "10";
        ELSIF (i = "1000") THEN
            o <= "11";
        ELSE
            o <= "--";
        END IF;
    END PROCESS;
END arch_encoder4x2_if

2) Using \(\texttt{case}\) Statement

LIBRARY ieee;
    USE ieee.std_logic_1164.all;
    
ENTITY encoder4x2 IS
    PORT( i : IN  std_logic_vector(3 DOWNTO 0);
          o : OUT std_logic_vector(1 DOWNTO 0) );
END encoder4x2;

ARCHITECTURE arch_encoder4x2_case OF encoder4x2 IS
BEGIN
    PROCESS(i)
    BEGIN
        CASE(i) IS
            WHEN "0001" => o <= "00";
            WHEN "0010" => o <= "01";
            WHEN "0100" => o <= "10";
            WHEN "1000" => o <= "11";
            WHEN OTHERS => o <= "--";
        END CASE;
    END PROCESS;
END arch_encoder4x2_case;

3) Using with-select-when Statement

LIBRARY ieee;
    USE ieee.std_logic_1164.all;
    
ENTITY encoder4x2 IS
    PORT( i :  IN std_logic_vector(3 DOWNTO 0);
          o : OUT std_logic_vector(1 DOWNTO 0) );
END encoder4x2;

ARCHITECTURE arch_encoder4x2_with OF encoder4x2 IS
BEGIN
    WITH i SELECT
        o <= "00" WHEN "0001",
             "01" WHEN "0010",
             "10" WHEN "0100",
             "11" WHEN "1000",
             "--" WHEN OTHERS;
END arch_encoder4x2_with;

4) Using when-else Statement

LIBRARY ieee;
    USE ieee.std_logic_1164.all;

ENTITY encoder4x2 IS
    PORT( i :  IN std_logic_vector(3 DOWNTO 0);
          o : OUT std_logic_vector(1 DOWNTO 0) );
END encoder4x2;

ARCHITECTURE arch_encoder4x2_when OF encoder4x2 IS
BEGIN
    o <= "00" WHEN (i = "0001") ELSE
         "01" WHEN (i = "0010") ELSE
         "10" WHEN (i = "0100") ELSE
         "11" WHEN (i = "1000") ELSE
         "--";
END arch_encoder4x2_when;

---

Priority Encoder (우선순위 인코더)

Inputs				Outputs
\(i_3\)	\(i_2\)	\(i_1\)	\(i_0\)	\(o_1\)	\(o_0\)
0	0	0	1	0	0
0	0	1	X	0	1
0	1	X	X	1	0
1	X	X	X	1	1

1) Using \(\texttt{if}\) Statement

LIBRARY ieee;
    USE ieee.std_logic_1164.all;
    
ENTITY encoder_p4x2 IS
    PORT( i : IN  std_logic_vector(3 DOWNTO 0);
          o : OUT std_logic_vector(1 DOWNTO 0) );
END encoder_p4x2;

ARCHITECTURE design_if OF encoder_p4x2 IS
BEGIN
    PROCESS(i)
    BEGIN
        IF (i(0) = '1') THEN
            o <= "00";
        ELSIF (i(1) = '1') THEN
            o <= "01";
        ELSIF (i(2) = '1') THEN
            o <= "10";
        ELSIF(i(3) = '1') THEN
            o <= "11";
        ELSE
            o <= "--";
        END IF;
    END PROCESS;
END design_if;

2) Using \(\texttt{case}\) Statement

LIBRARY ieee;
    USE ieee.std_logic_1164.all;

ENTITY encoder_p4x2 IS
    PORT( i : IN  std_logic_vector(3 DOWNTO 0);
          o : OUT std_logic_vector(1 DOWNTO 0) );
END encoder_p4x2;

ARCHITECTURE design_case OF encoder_p4x2 IS
BEGIN
    PROCESS(i)
    BEGIN
        CASE(i) IS
            WHEN "0001" | "0011" | "0101" | "0111" |
                 "1001" | "1011" | "1101" | "1111"  => o <= "00";
            WHEN "0010" | "0110" | "1010" | "1110"  => o <= "01";
            WHEN "0100" | "1100"                    => o <= "10";
            WHEN "1000"                             => o <= "11";
            WHEN OTHERS                             => o <= "--";
        END CASE;
    END PROCESS;
END design_case;

3) Using \(\texttt{with-select-when}\)  Statement

LIBRARY ieee;
    USE ieee.std_logic_1164.all;

ENTITY encoder_p4x2 IS
    PORT( i : IN  std_logic_vector(3 DOWNTO 0);
          o : OUT std_logic_vector(1 DOWNTO 0) );
END encoder_p4x2;

ARCHITECTURE design_with OF encoder_p4x2 IS
BEGIN
    WITH i SELECT
        o <= "00" WHEN "0001" | "0011" | "0101" | "0111" |
                       "1001" | "1011" | "1101" | "1111",
             "01" WHEN "0010" | "0110" | "1010" | "1110",
             "10" WHEN "0100" | "1100",
             "11" WHEN "1000",
             "--" WHEN OTHERS;
END design_with;

4) Using \(\texttt{when-else}\) Statement

LIBRARY ieee;
    USE ieee.std_logic_1164.all;

ENTITY encoder_p4x2 IS
    PORT( i : IN  std_logic_vector(3 DOWNTO 0);
          o : OUT std_logic_vector(1 DOWNTO 0) );
END encoder_p4x2;

ARCHITECTURE design_when OF encoder_p4x2 IS
BEGIN
    o <= "00" WHEN (i(0) = '1') ELSE
         "01" WHEN (i(1) = '1') ELSE
         "10" WHEN (i(2) = '1') ELSE
         "11" WHEN (i(3) = '1') ELSE
         "--";
END design_when;