-- This is an implementation of ieee.std_logic_1164 based only on the -- specifications. This file is part of GHDL. -- Copyright (C) 2015 Tristan Gingold -- -- GHDL is free software; you can redistribute it and/or modify it under -- the terms of the GNU General Public License as published by the Free -- Software Foundation; either version 2, or (at your option) any later -- version. -- -- GHDL is distributed in the hope that it will be useful, but WITHOUT ANY -- WARRANTY; without even the implied warranty of MERCHANTABILITY or -- FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License -- for more details. -- -- You should have received a copy of the GNU General Public License -- along with GCC; see the file COPYING2. If not see -- . -- This package is valid for VHDL version until but not including 2008. -- For VHDL87, the functions xnor should be removed. package std_logic_1164 is -- Unresolved logic state. type std_ulogic is ('U', -- Uninitialized, this is also the default value. 'X', -- Unknown / conflict value (forcing level). '0', -- 0 (forcing level). '1', -- 1 (forcing level). 'Z', -- High impedance. 'W', -- Unknown / conflict (weak level). 'L', -- 0 (weak level). 'H', -- 1 (weak level). '-' -- Don't care. ); -- Vector of logic state. type std_ulogic_vector is array (natural range <>) of std_ulogic; -- Resolution function. -- If S is empty, returns 'Z'. -- If S has one element, return the element. -- Otherwise, 'U' is the strongest. -- then 'X' -- then '0' and '1' -- then 'W' -- then 'H' and 'L' -- then 'Z'. function resolved (s : std_ulogic_vector) return std_ulogic; -- Resolved logic state. subtype std_logic is resolved std_ulogic; -- Vector of std_logic. type std_logic_vector is array (natural range <>) of std_logic; -- Subtypes of std_ulogic. The names give the values. subtype X01 is resolved std_ulogic range 'X' to '1'; subtype X01Z is resolved std_ulogic range 'X' to 'Z'; subtype UX01 is resolved std_ulogic range 'U' to '1'; subtype UX01Z is resolved std_ulogic range 'U' to 'Z'; -- Logical operators. -- For logical operations, the inputs are first normalized to UX01: -- 0 and L are normalized to 0, 1 and 1 are normalized to 1, U isnt changed, -- all other states are normalized to X. -- Then the classical electric rules are followed. function "and" (l : std_ulogic; r : std_ulogic) return UX01; function "nand" (l : std_ulogic; r : std_ulogic) return UX01; function "or" (l : std_ulogic; r : std_ulogic) return UX01; function "nor" (l : std_ulogic; r : std_ulogic) return UX01; function "xor" (l : std_ulogic; r : std_ulogic) return UX01; function "xnor" (l : std_ulogic; r : std_ulogic) return UX01; function "not" (l : std_ulogic) return UX01; -- Logical operators for vectors. -- An assertion of severity failure fails if the length of L and R aren't -- equal. The result range is 1 to L'Length. function "and" (l, r : std_logic_vector) return std_logic_vector; function "nand" (l, r : std_logic_vector) return std_logic_vector; function "or" (l, r : std_logic_vector) return std_logic_vector; function "nor" (l, r : std_logic_vector) return std_logic_vector; function "xor" (l, r : std_logic_vector) return std_logic_vector; function "xnor" (l, r : std_logic_vector) return std_logic_vector; function "not" (l : std_logic_vector) return std_logic_vector; function "and" (l, r : std_ulogic_vector) return std_ulogic_vector; function "nand" (l, r : std_ulogic_vector) return std_ulogic_vector; function "or" (l, r : std_ulogic_vector) return std_ulogic_vector; function "nor" (l, r : std_ulogic_vector) return std_ulogic_vector; function "xor" (l, r : std_ulogic_vector) return std_ulogic_vector; function "xnor" (l, r : std_ulogic_vector) return std_ulogic_vector; function "not" (l : std_ulogic_vector) return std_ulogic_vector; -- Conversion functions. -- The result range (for vectors) is S'Length - 1 downto 0. -- XMAP is return for values not in '0', '1', 'L', 'H'. function to_bit (s : std_ulogic; xmap : bit := '0') return bit; function to_bitvector (s : std_logic_vector; xmap : bit := '0') return bit_vector; function to_bitvector (s : std_ulogic_vector; xmap : bit := '0') return bit_vector; function to_stdulogic (b : bit) return std_ulogic; function to_stdlogicvector (b : bit_vector) return std_logic_vector; function to_stdlogicvector (s : std_ulogic_vector) return std_logic_vector; function to_stdulogicvector (b : bit_vector) return std_ulogic_vector; function to_stdulogicvector (s : std_logic_vector) return std_ulogic_vector; -- Normalization. -- The result range (for vectors) is 1 to S'Length. function to_X01 (s : std_logic_vector) return std_logic_vector; function to_X01 (s : std_ulogic_vector) return std_ulogic_vector; function to_X01 (s : std_ulogic) return X01; function to_X01 (b : bit_vector) return std_logic_vector; function to_X01 (b : bit_vector) return std_ulogic_vector; function to_X01 (b : bit) return X01; function to_X01Z (s : std_logic_vector) return std_logic_vector; function to_X01Z (s : std_ulogic_vector) return std_ulogic_vector; function to_X01Z (s : std_ulogic) return X01Z; function to_X01Z (b : bit_vector) return std_logic_vector; function to_X01Z (b : bit_vector) return std_ulogic_vector; function to_X01Z (b : bit) return X01Z; function to_UX01 (s : std_logic_vector) return std_logic_vector; function to_UX01 (s : std_ulogic_vector) return std_ulogic_vector; function to_UX01 (s : std_ulogic) return UX01; function to_UX01 (b : bit_vector) return std_logic_vector; function to_UX01 (b : bit_vector) return std_ulogic_vector; function to_UX01 (b : bit) return UX01; -- Edge detection. -- An edge is detected in case of event on s, and X01 normalized value -- rises from 0 to 1 or falls from 1 to 0. function rising_edge (signal s : std_ulogic) return boolean; function falling_edge (signal s : std_ulogic) return boolean; -- Test for unknown. Only 0, 1, L and H are known values. function is_X (s : std_ulogic_vector) return boolean; function is_X (s : std_logic_vector) return boolean; function is_X (s : std_ulogic) return boolean; end std_logic_1164;