library ieee;
use ieee.std_logic_1164.all;

--@ Priority Encoder (2 to 1 bits)
--@ This is a combinatorial priority encoder that encodes the highest priority
--@ bit in the input vector to a 1-bit output code.
entity PriorityEncoder_2 is
    port (
        --@ Input vector to be encoded.  
        --@ The least significant bit has the highest priority.
        I_Select : in std_logic_vector(1 downto 0) := (others => '0');
        --@ Output code.
        --@ The output code is the index of the highest priority bit in the input vector.
        O_Code : out std_logic_vector(0 downto 0) := (others => '0')
    );
end entity PriorityEncoder_2;

architecture Combinatoric of PriorityEncoder_2 is
    --@ Internal signal to hold the encoded output.
    signal C_Code : std_logic_vector(0 downto 0);

    --@ Attribute to force the synthesis tool (XST, old Parser) to treat this as a combinatorial signal.
    attribute PRIORITY_EXTRACT : string;
    attribute PRIORITY_EXTRACT of C_Code : signal is "force";
begin
    C_Code <= "0" when I_Select(1) = '1' else
              "1" when I_Select(0) = '1' else
              "-";

    O_Code <= C_Code;
end architecture;

library ieee;
use ieee.std_logic_1164.all;

--@ Priority Encoder (4 to 2 bits)
--@ This is a combinatorial priority encoder that encodes the highest priority
--@ bit in the input vector to a 2-bit output code.
entity PriorityEncoder_4 is
    port (
        --@ Input vector to be encoded.  
        --@ The least significant bit has the highest priority.
        I_Select : in std_logic_vector(3 downto 0) := (others => '0');
        --@ Output code.
        --@ The output code is the index of the highest priority bit in the input vector.
        O_Code : out std_logic_vector(1 downto 0) := (others => '0')
    );
end entity PriorityEncoder_4;

architecture Combinatoric of PriorityEncoder_4 is
    --@ Internal signal to hold the encoded output.
    signal C_Code : std_logic_vector(1 downto 0);

    --@ Attribute to force the synthesis tool (XST, old Parser) to treat this as a combinatorial signal.
    attribute PRIORITY_EXTRACT : string;
    attribute PRIORITY_EXTRACT of C_Code : signal is "force";
begin
    C_Code <= "00" when I_Select(3) = '1' else
              "01" when I_Select(2) = '1' else
              "10" when I_Select(1) = '1' else
              "11" when I_Select(0) = '1' else
              "--";
              
              O_Code <= C_Code;
end architecture;

library ieee;
use ieee.std_logic_1164.all;

--@ Priority Encoder (8 to 3 bits)
--@ This is a combinatorial priority encoder that encodes the highest priority
--@ bit in the input vector to a 3-bit output code.
entity PriorityEncoder_8 is
    port (
        --@ Input vector to be encoded.  
        --@ The least significant bit has the highest priority.
        I_Select : in std_logic_vector(7 downto 0) := (others => '0');
        --@ Output code.
        --@ The output code is the index of the highest priority bit in the input vector.
        O_Code : out std_logic_vector(2 downto 0) := (others => '0')
    );
end entity PriorityEncoder_8;

architecture Combinatoric of PriorityEncoder_8 is
    --@ Internal signal to hold the encoded output.
    signal C_Code : std_logic_vector(2 downto 0);

    --@ Attribute to force the synthesis tool (XST, old Parser) to treat this as a combinatorial signal.
    attribute PRIORITY_EXTRACT : string;
    attribute PRIORITY_EXTRACT of C_Code : signal is "force";
begin
    C_Code <= "000" when I_Select(7) = '1' else
              "001" when I_Select(6) = '1' else
              "010" when I_Select(5) = '1' else
              "011" when I_Select(4) = '1' else
              "100" when I_Select(3) = '1' else
              "101" when I_Select(2) = '1' else
              "110" when I_Select(1) = '1' else
              "111" when I_Select(0) = '1' else
              "---";
              
              O_Code <= C_Code;
end architecture;

library ieee;
use ieee.std_logic_1164.all;

--@ Priority Encoder (16 to 4 bits)
--@ This is a combinatorial priority encoder that encodes the highest priority
--@ bit in the input vector to a 4-bit output code.
entity PriorityEncoder_16 is
    port (
        --@ Input vector to be encoded.  
        --@ The least significant bit has the highest priority.
        I_Select : in std_logic_vector(15 downto 0) := (others => '0');
        --@ Output code.
        --@ The output code is the index of the highest priority bit in the input vector.
        O_Code : out std_logic_vector(3 downto 0) := (others => '0')
    );
end entity PriorityEncoder_16;

architecture Combinatoric of PriorityEncoder_16 is
    --@ Internal signal to hold the encoded output.
    signal C_Code : std_logic_vector(3 downto 0);

    --@ Attribute to force the synthesis tool (XST, old Parser) to treat this as a combinatorial signal.
    attribute PRIORITY_EXTRACT : string;
    attribute PRIORITY_EXTRACT of C_Code : signal is "force";
begin
    C_Code <= "0000" when I_Select(15) = '1' else
              "0001" when I_Select(14) = '1' else
              "0010" when I_Select(13) = '1' else
              "0011" when I_Select(12) = '1' else
              "0100" when I_Select(11) = '1' else
              "0101" when I_Select(10) = '1' else
              "0110" when I_Select(9) = '1' else
              "0111" when I_Select(8) = '1' else
              "1000" when I_Select(7) = '1' else
              "1001" when I_Select(6) = '1' else
              "1010" when I_Select(5) = '1' else
              "1011" when I_Select(4) = '1' else
              "1100" when I_Select(3) = '1' else
              "1101" when I_Select(2) = '1' else
              "1110" when I_Select(1) = '1' else
              "1111" when I_Select(0) = '1' else
              "----";
              
              O_Code <= C_Code;
end architecture;

library ieee;
use ieee.std_logic_1164.all;

--@ Priority Encoder (32 to 5 bits)
--@ This is a combinatorial priority encoder that encodes the highest priority
--@ bit in the input vector to a 5-bit output code.
entity PriorityEncoder_32 is
    port (
        --@ Input vector to be encoded.  
        --@ The least significant bit has the highest priority.
        I_Select : in std_logic_vector(31 downto 0) := (others => '0');
        --@ Output code.
        --@ The output code is the index of the highest priority bit in the input vector.
        O_Code : out std_logic_vector(4 downto 0) := (others => '0')
    );
end entity PriorityEncoder_32;

architecture Combinatoric of PriorityEncoder_32 is
    --@ Internal signal to hold the encoded output.
    signal C_Code : std_logic_vector(4 downto 0);

    --@ Attribute to force the synthesis tool (XST, old Parser) to treat this as a combinatorial signal.
    attribute PRIORITY_EXTRACT : string;
    attribute PRIORITY_EXTRACT of C_Code : signal is "force";

begin
    C_Code <= "00000" when I_Select(31) = '1' else
              "00001" when I_Select(30) = '1' else
              "00010" when I_Select(29) = '1' else
              "00011" when I_Select(28) = '1' else
              "00100" when I_Select(27) = '1' else
              "00101" when I_Select(26) = '1' else
              "00110" when I_Select(25) = '1' else
              "00111" when I_Select(24) = '1' else
              "01000" when I_Select(23) = '1' else
              "01001" when I_Select(22) = '1' else
              "01010" when I_Select(21) = '1' else
              "01011" when I_Select(20) = '1' else
              "01100" when I_Select(19) = '1' else
              "01101" when I_Select(18) = '1' else
              "01110" when I_Select(17) = '1' else
              "01111" when I_Select(16) = '1' else
              "10000" when I_Select(15) = '1' else
              "10001" when I_Select(14) = '1' else
              "10010" when I_Select(13) = '1' else
              "10011" when I_Select(12) = '1' else
              "10100" when I_Select(11) = '1' else
              "10101" when I_Select(10) = '1' else
              "10110" when I_Select(9) = '1' else
              "10111" when I_Select(8) = '1' else
              "11000" when I_Select(7) = '1' else
              "11001" when I_Select(6) = '1' else
              "11010" when I_Select(5) = '1' else
              "11011" when I_Select(4) = '1' else
              "11100" when I_Select(3) = '1' else
              "11101" when I_Select(2) = '1' else
              "11110" when I_Select(1) = '1' else
              "11111" when I_Select(0) = '1' else
              "-----";
              
              O_Code <= C_Code;
end architecture;

library ieee;
use ieee.std_logic_1164.all;

--@ Priority Encoder (64 to 6 bits)
--@ This is a combinatorial priority encoder that encodes the highest priority
--@ bit in the input vector to a 6-bit output code.
entity PriorityEncoder_64 is
    port (
        --@ Input vector to be encoded.  
        --@ The least significant bit has the highest priority.
        I_Select : in std_logic_vector(63 downto 0) := (others => '0');
        --@ Output code.
        --@ The output code is the index of the highest priority bit in the input vector.
        O_Code : out std_logic_vector(5 downto 0) := (others => '0')
    );
end entity PriorityEncoder_64;

architecture Combinatoric of PriorityEncoder_64 is
    --@ Internal signal to hold the encoded output.
    signal C_Code : std_logic_vector(5 downto 0);

    --@ Attribute to force the synthesis tool (XST, old Parser) to treat this as a combinatorial signal.
    attribute PRIORITY_EXTRACT : string;
    attribute PRIORITY_EXTRACT of C_Code : signal is "force";

begin
    C_Code <= "000000" when I_Select(63) = '1' else
              "000001" when I_Select(62) = '1' else
              "000010" when I_Select(61) = '1' else
              "000011" when I_Select(60) = '1' else
              "000100" when I_Select(59) = '1' else
              "000101" when I_Select(58) = '1' else
              "000110" when I_Select(57) = '1' else
              "000111" when I_Select(56) = '1' else
              "001000" when I_Select(55) = '1' else
              "001001" when I_Select(54) = '1' else
              "001010" when I_Select(53) = '1' else
              "001011" when I_Select(52) = '1' else
              "001100" when I_Select(51) = '1' else
              "001101" when I_Select(50) = '1' else
              "001110" when I_Select(49) = '1' else
              "001111" when I_Select(48) = '1' else
              "010000" when I_Select(47) = '1' else
              "010001" when I_Select(46) = '1' else
              "010010" when I_Select(45) = '1' else
              "010011" when I_Select(44) = '1' else
              "010100" when I_Select(43) = '1' else
              "010101" when I_Select(42) = '1' else
              "010110" when I_Select(41) = '1' else
              "010111" when I_Select(40) = '1' else
              "011000" when I_Select(39) = '1' else
              "011001" when I_Select(38) = '1' else
              "011010" when I_Select(37) = '1' else
              "011011" when I_Select(36) = '1' else
              "011100" when I_Select(35) = '1' else
              "011101" when I_Select(34) = '1' else
              "011110" when I_Select(33) = '1' else
              "011111" when I_Select(32) = '1' else
              "100000" when I_Select(31) = '1' else
              "100001" when I_Select(30) = '1' else
              "100010" when I_Select(29) = '1' else
              "100011" when I_Select(28) = '1' else
              "100100" when I_Select(27) = '1' else
              "100101" when I_Select(26) = '1' else
              "100110" when I_Select(25) = '1' else
              "100111" when I_Select(24) = '1' else
              "101000" when I_Select(23) = '1' else
              "101001" when I_Select(22) = '1' else
              "101010" when I_Select(21) = '1' else
              "101011" when I_Select(20) = '1' else
              "101100" when I_Select(19) = '1' else
              "101101" when I_Select(18) = '1' else
              "101110" when I_Select(17) = '1' else
              "101111" when I_Select(16) = '1' else
              "110000" when I_Select(15) = '1' else
              "110001" when I_Select(14) = '1' else
              "110010" when I_Select(13) = '1' else
              "110011" when I_Select(12) = '1' else
              "110100" when I_Select(11) = '1' else
              "110101" when I_Select(10) = '1' else
              "110110" when I_Select(9) = '1' else
              "110111" when I_Select(8) = '1' else
              "111000" when I_Select(7) = '1' else
              "111001" when I_Select(6) = '1' else
              "111010" when I_Select(5) = '1' else
              "111011" when I_Select(4) = '1' else
              "111100" when I_Select(3) = '1' else
              "111101" when I_Select(2) = '1' else
              "111110" when I_Select(1) = '1' else
              "111111" when I_Select(0) = '1' else
              "------";
              
              O_Code <= C_Code;
end architecture;

library ieee;
use ieee.std_logic_1164.all;
use ieee.numeric_std.all;
use ieee.math_real.all;

--@ Priority Encoder (Generic)
--@ This is a combinatorial priority encoder that encodes the highest priority
--@ bit in the input vector to a 6-bit output code.
entity PriorityEncoder_G is
    generic (
        --@ Code width with minimum 2 bits and maximum 6 bits.
        G_CodeWidth : integer := 6
    );
    port (
        --@ Input vector to be encoded.  
        --@ The least significant bit has the highest priority.
        I_Select : in std_logic_vector(2 ** G_CodeWidth - 1 downto 0);
        --@ Output code.
        --@ The output code is the index of the highest priority bit in the input vector.
        O_Code : out std_logic_vector(G_CodeWidth - 1 downto 0)
    );
end entity PriorityEncoder_G;

architecture Combinatoric of PriorityEncoder_G is
    signal C_Select : std_logic_vector(63 downto 0) := (others => '-');
    signal C_Code : std_logic_vector(5 downto 0) := (others => '-');
begin

    entity_inst : entity work.PriorityEncoder_64
        port map(
            I_Select => C_Select,
            O_Code => C_Code
        );

    C_Select(G_CodeWidth * 2 - 1 downto 0) <= I_Select;
    O_Code <= C_Code(G_CodeWidth - 1 downto 0);
end architecture;