------------------------------------------------------------------------------
--                                                                          --
--                         GNAT LIBRARY COMPONENTS                          --
--                                                                          --
--         A D A . C O N T A I N E R S . P R I M E _ N U M B E R S          --
--                                                                          --
--                                 S p e c                                  --
--                                                                          --
--          Copyright (C) 2004-2020, Free Software Foundation, Inc.         --
--                                                                          --
-- GNAT is free software;  you can  redistribute it  and/or modify it under --
-- terms of the  GNU General Public License as published  by the Free Soft- --
-- ware  Foundation;  either version 3,  or (at your option) any later ver- --
-- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
-- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
-- or FITNESS FOR A PARTICULAR PURPOSE.                                     --
--                                                                          --
-- As a special exception under Section 7 of GPL version 3, you are granted --
-- additional permissions described in the GCC Runtime Library Exception,   --
-- version 3.1, as published by the Free Software Foundation.               --
--                                                                          --
-- You should have received a copy of the GNU General Public License and    --
-- a copy of the GCC Runtime Library Exception along with this program;     --
-- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --
-- <http://www.gnu.org/licenses/>.                                          --
--                                                                          --
-- This unit was originally developed by Matthew J Heaney.                  --
------------------------------------------------------------------------------

--  This package declares the prime numbers array used to implement hashed
--  containers. Bucket arrays are always allocated with a prime-number
--  length (computed using To_Prime below), as this produces better scatter
--  when hash values are folded.

package Ada.Containers.Prime_Numbers is
   pragma Pure;

   type Primes_Type is array (Positive range <>) of Hash_Type;

   Primes : constant Primes_Type :=
     (53,         97,         193,       389,       769,
      1543,       3079,       6151,      12289,     24593,
      49157,      98317,      196613,    393241,    786433,
      1572869,    3145739,    6291469,   12582917,  25165843,
      50331653,   100663319,  201326611, 402653189, 805306457,
      1610612741, 3221225473, 4294967291);

   function To_Prime (Length : Count_Type) return Hash_Type;
   --  Returns the smallest value in Primes not less than Length

end Ada.Containers.Prime_Numbers;
