common_pkg.vhd

-------------------------------------------------------------------------------
--
-- Copyright (C) 2019
-- ASTRON (Netherlands Institute for Radio Astronomy) <http://www.astron.nl/>
-- P.O.Box 2, 7990 AA Dwingeloo, The Netherlands
--
-- This program 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 3 of the License, or
-- (at your option) any later version.
--
-- This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
--
-------------------------------------------------------------------------------

-- Author:
-- . Eric Kooistra
-- Purpose:
-- . Collection of commonly used base funtions
-- Interface:
-- . [n/a]
-- Description:
-- . This is a package containing generic constants and functions.
-- . More information can be found in the comments near the code.

LIBRARY IEEE;
USE IEEE.STD_LOGIC_1164.ALL;
USE IEEE.NUMERIC_STD.ALL;
USE IEEE.MATH_REAL.ALL;

PACKAGE common_pkg IS

  -- CONSTANT DECLARATIONS ----------------------------------------------------

  -- some integers
  CONSTANT c_0                    : NATURAL := 0;
  CONSTANT c_zero                 : NATURAL := 0;
  CONSTANT c_1                    : NATURAL := 1;
  CONSTANT c_one                  : NATURAL := 1;
  CONSTANT c_2                    : NATURAL := 2;
  CONSTANT c_4                    : NATURAL := 4;
  CONSTANT c_quad                 : NATURAL := 4;
  CONSTANT c_8                    : NATURAL := 8;
  CONSTANT c_16                   : NATURAL := 16;
  CONSTANT c_32                   : NATURAL := 32;
  CONSTANT c_48                   : NATURAL := 48;
  CONSTANT c_64                   : NATURAL := 64;
  CONSTANT c_128                  : NATURAL := 128;
  CONSTANT c_256                  : NATURAL := 256;
  
  -- widths and sizes
  CONSTANT c_halfword_sz          : NATURAL := 2;
  CONSTANT c_word_sz              : NATURAL := 4;
  CONSTANT c_longword_sz          : NATURAL := 8;
  CONSTANT c_nibble_w             : NATURAL := 4;
  CONSTANT c_byte_w               : NATURAL := 8;
  CONSTANT c_octet_w              : NATURAL := 8;
  CONSTANT c_halfword_w           : NATURAL := c_byte_w*c_halfword_sz;
  CONSTANT c_word_w               : NATURAL := c_byte_w*c_word_sz;
  CONSTANT c_integer_w            : NATURAL := 32;              -- unfortunately VHDL integer type is limited to 32 bit values
  CONSTANT c_natural_w            : NATURAL := c_integer_w-1;   -- unfortunately VHDL natural type is limited to 31 bit values (0 and the positive subset of the VHDL integer type0
  CONSTANT c_longword_w           : NATURAL := c_byte_w*c_longword_sz;
  
  -- logic