| ------------------------------------------------------------------------------ |
| -- -- |
| -- 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) 2004-2006, 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 2, 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. See the GNU General Public License -- |
| -- for more details. You should have received a copy of the GNU General -- |
| -- Public License distributed with GNAT; see file COPYING. If not, write -- |
| -- to the Free Software Foundation, 51 Franklin Street, Fifth Floor, -- |
| -- Boston, MA 02110-1301, USA. -- |
| -- -- |
| -- As a special exception, if other files instantiate generics from this -- |
| -- unit, or you link this unit with other files to produce an executable, -- |
| -- this unit does not by itself cause the resulting executable to be -- |
| -- covered by the GNU General Public License. This exception does not -- |
| -- however invalidate any other reasons why the executable file might be -- |
| -- covered by the GNU Public License. -- |
| -- -- |
| -- 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; |
