1 ------------------------------------------------------------------------------
3 -- GNAT LIBRARY COMPONENTS --
5 -- 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 --
9 -- Copyright (C) 2004-2023, Free Software Foundation, Inc. --
11 -- GNAT is free software; you can redistribute it and/or modify it under --
12 -- terms of the GNU General Public License as published by the Free Soft- --
13 -- ware Foundation; either version 3, or (at your option) any later ver- --
14 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
15 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
16 -- or FITNESS FOR A PARTICULAR PURPOSE. --
18 -- As a special exception under Section 7 of GPL version 3, you are granted --
19 -- additional permissions described in the GCC Runtime Library Exception, --
20 -- version 3.1, as published by the Free Software Foundation. --
22 -- You should have received a copy of the GNU General Public License and --
23 -- a copy of the GCC Runtime Library Exception along with this program; --
24 -- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
25 -- <http://www.gnu.org/licenses/>. --
27 -- This unit was originally developed by Matthew J Heaney. --
28 ------------------------------------------------------------------------------
30 -- This package declares the prime numbers array used to implement hashed
31 -- containers. Bucket arrays are always allocated with a prime-number
32 -- length (computed using To_Prime below), as this produces better scatter
33 -- when hash values are folded.
35 package Ada
.Containers
.Prime_Numbers
is
38 type Primes_Type
is array (Positive range <>) of Hash_Type
;
40 Primes
: constant Primes_Type
:=
41 [53, 97, 193, 389, 769,
42 1543, 3079, 6151, 12289, 24593,
43 49157, 98317, 196613, 393241, 786433,
44 1572869, 3145739, 6291469, 12582917, 25165843,
45 50331653, 100663319, 201326611, 402653189, 805306457,
46 1610612741, 3221225473, 4294967291];
48 function To_Prime
(Length
: Count_Type
) return Hash_Type
;
49 -- Returns the smallest value in Primes not less than Length
51 end Ada
.Containers
.Prime_Numbers
;