79 lines
4.1 KiB
Ada
79 lines
4.1 KiB
Ada
------------------------------------------------------------------------------
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-- --
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-- GNAT RUN-TIME COMPONENTS --
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-- --
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-- A D A . S Y N C H R O N O U S _ B A R R I 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) 1992-2011, Free Software Foundation, Inc. --
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-- --
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-- This specification is derived from the Ada Reference Manual for use with --
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-- GNAT. The copyright notice above, and the license provisions that follow --
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-- apply solely to the contents of the part following the private keyword. --
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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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-- GNAT was originally developed by the GNAT team at New York University. --
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-- Extensive contributions were provided by Ada Core Technologies Inc. --
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-- --
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------------------------------------------------------------------------------
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package body Ada.Synchronous_Barriers is
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protected body Synchronous_Barrier is
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-- The condition "Wait'Count = Release_Threshold" opens the barrier when
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-- the required number of tasks is reached. The condition "Keep_Open"
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-- leaves the barrier open while there are queued tasks. While there are
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-- tasks in the queue no new task will be queued (no new protected
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-- action can be started on a protected object while another protected
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-- action on the same protected object is underway, RM 9.5.1 (4)),
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-- guaranteeing that the barrier will remain open only for those tasks
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-- already inside the queue when the barrier was open.
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entry Wait (Notified : out Boolean)
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when Keep_Open or else Wait'Count = Release_Threshold
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is
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begin
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-- If we are executing the entry it means that the required number of
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-- tasks have been queued in the entry. Keep_Open barrier will remain
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-- true until all queued tasks are out.
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Keep_Open := Wait'Count > 0;
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-- The last released task will close the barrier and get the Notified
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-- token.
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Notified := Wait'Count = 0;
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end Wait;
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end Synchronous_Barrier;
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----------------------
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-- Wait_For_Release --
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----------------------
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procedure Wait_For_Release
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(The_Barrier : in out Synchronous_Barrier;
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Notified : out Boolean)
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is
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begin
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The_Barrier.Wait (Notified);
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end Wait_For_Release;
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end Ada.Synchronous_Barriers;
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