diff options
Diffstat (limited to 'libraries/openieee/std_logic_1164.v87')
| -rw-r--r-- | libraries/openieee/std_logic_1164.v87 | 143 |
1 files changed, 143 insertions, 0 deletions
diff --git a/libraries/openieee/std_logic_1164.v87 b/libraries/openieee/std_logic_1164.v87 new file mode 100644 index 000000000..964ed956c --- /dev/null +++ b/libraries/openieee/std_logic_1164.v87 @@ -0,0 +1,143 @@ +-- 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 COPYING3. If not see +-- <http://www.gnu.org/licenses/>. + +-- 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, r : std_ulogic) return UX01; + function "nand" (l, r : std_ulogic) return UX01; + function "or" (l, r : std_ulogic) return UX01; + function "nor" (l, r : std_ulogic) return UX01; + function "xor" (l, r : std_ulogic) return UX01; +--function "xnor" (l, 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 (b : std_ulogic_vector) return std_logic_vector; + function to_stdulogicvector (b : bit_vector) return std_ulogic_vector; + function to_stdulogicvector (b : 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; |