59 lines
2.8 KiB
Ada
59 lines
2.8 KiB
Ada
------------------------------------------------------------------------------
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-- --
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-- GNAT LIBRARY COMPONENTS --
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-- --
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-- 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 --
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-- --
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-- B o d y --
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-- --
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-- Copyright (C) 2004-2009, Free Software Foundation, Inc. --
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-- --
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-- GNAT is free software; you can redistribute it and/or modify it under --
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-- terms of the GNU General Public License as published by the Free Soft- --
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-- ware Foundation; either version 3, or (at your option) any later ver- --
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-- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
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-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
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-- or FITNESS FOR A PARTICULAR PURPOSE. --
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-- --
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-- As a special exception under Section 7 of GPL version 3, you are granted --
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-- additional permissions described in the GCC Runtime Library Exception, --
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-- version 3.1, as published by the Free Software Foundation. --
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-- --
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-- You should have received a copy of the GNU General Public License and --
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-- a copy of the GCC Runtime Library Exception along with this program; --
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-- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
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-- <http://www.gnu.org/licenses/>. --
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-- --
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-- This unit was originally developed by Matthew J Heaney. --
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------------------------------------------------------------------------------
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package body Ada.Containers.Prime_Numbers is
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--------------
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-- To_Prime --
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--------------
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function To_Prime (Length : Count_Type) return Hash_Type is
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I, J, K : Integer'Base;
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Index : Integer'Base;
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begin
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I := Primes'Last - Primes'First;
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Index := Primes'First;
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while I > 0 loop
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J := I / 2;
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K := Index + J;
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if Primes (K) < Hash_Type (Length) then
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Index := K + 1;
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I := I - J - 1;
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else
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I := J;
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end if;
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end loop;
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return Primes (Index);
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end To_Prime;
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end Ada.Containers.Prime_Numbers;
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