library IEEE;use IEEE.std_logic_1164.all;package logic_pack is    function resolve(s : std_ulogic_vector) return std_ulogic;  SUBTYPE logic is resolve std_ulogic;  TYPE logic_vector IS ARRAY (NATURAL RANGE <>) OF logic;  TYPE std_logic_array IS ARRAY (NATURAL RANGE <>,NATURAL RANGE <>) OF std_logic;end logic_pack;package body logic_pack is    TYPE stdlogic_table IS ARRAY(std_ulogic, std_ulogic) OF std_ulogic;    -------------------------------------------------------------------        -- resolution function    -------------------------------------------------------------------        CONSTANT resolve_table : stdlogic_table := (    --      ---------------------------------------------------------    --      |  U    X    0    1    Z    W    L    H    -        |   |      --      ---------------------------------------------------------            ( 'U', 'U', 'U', 'U', 'U', 'U', 'U', 'U', 'U' ), -- | U |            ( 'U', 'X', 'X', 'X', 'X', 'X', 'X', 'X', 'X' ), -- | X |            ( 'U', 'X', '0', '0', '0', '0', '0', '0', 'X' ), -- | 0 |            ( 'U', 'X', '0', '1', '1', '1', '1', '1', 'X' ), -- | 1 |            ( 'U', 'X', '0', '1', 'Z', 'W', 'L', 'H', 'X' ), -- | Z |            ( 'U', 'X', '0', '1', 'W', 'W', 'W', 'W', 'X' ), -- | W |            ( 'U', 'X', '0', '1', 'L', 'W', 'L', 'W', 'X' ), -- | L |            ( 'U', 'X', '0', '1', 'H', 'W', 'W', 'H', 'X' ), -- | H |            ( 'U', 'X', 'X', 'X', 'X', 'X', 'X', 'X', 'X' )  -- | - |        );            FUNCTION resolve ( s : std_ulogic_vector ) RETURN std_ulogic IS        VARIABLE result : std_ulogic := 'Z';  -- weakest state default    BEGIN        -- the test for a single driver is essential otherwise the        -- loop would return 'X' for a single driver of '-' and that        -- would conflict with the value of a single driver unresolved        -- signal.        IF    (s'LENGTH = 1) THEN    RETURN s(s'LOW);        ELSE            FOR i IN s'RANGE LOOP                result := resolve_table(result, s(i));            END LOOP;        END IF;        RETURN result;    END resolve;end logic_pack;