a2cb348ef4
2005-09-01 Robert Dewar <dewar@adacore.com> * a-dirval-mingw.adb, a-direct.adb, a-coinve.adb, g-dynhta.adb, g-dynhta.ads, cstand.adb, exp_smem.adb, g-debuti.ads, g-dirope.adb, g-table.adb, lib-sort.adb, sem_maps.adb, exp_fixd.adb, exp_aggr.adb, a-intnam-mingw.ads, a-intnam-vxworks.ads, g-arrspl.adb, g-arrspl.ads, g-awk.adb, g-awk.ads, g-boubuf.ads, g-boubuf.ads, g-boubuf.ads, g-bubsor.ads, g-bubsor.adb, g-busora.adb, g-busora.ads, g-busorg.adb, g-busorg.ads, g-calend.adb, g-calend.ads, g-casuti.adb, g-casuti.ads, g-catiio.adb, g-catiio.ads, g-cgi.adb, g-cgi.ads, g-cgicoo.adb, g-cgicoo.ads, g-cgideb.adb, g-cgideb.ads, g-comlin.adb, g-comver.ads, g-semaph.ads, g-socthi.ads, sem_ch7.adb, a-direio.adb, a-caldel.ads, i-cstrea-vms.adb, a-ztedit.adb, a-ztenau.adb, g-socthi-vms.adb, g-socthi-vms.ads, g-socthi-mingw.adb, g-socthi-mingw.ads, g-socthi-vxworks.ads, a-intnam-irix.ads, a-intnam-irix.ads, a-intnam-hpux.ads, a-intnam-os2.ads, a-intnam-os2.ads, a-caldel-vms.adb, a-calend-vms.adb, a-calend-vms.ads, g-heasor.adb, g-heasor.ads, g-hesora.adb, g-hesora.ads, g-hesorg.adb, g-hesorg.ads, g-htable.adb, g-htable.ads, g-io.adb, g-io.ads, g-io_aux.adb, g-io_aux.ads, g-locfil.ads, g-memdum.adb, g-memdum.ads, g-traceb.adb, g-traceb.ads, i-cobol.adb, i-cobol.ads, i-cstrea.ads, i-cstrin.adb, a-wtedit.adb, a-tifiio.adb, a-wtenau.adb, a-wtenau.adb, a-teioed.adb: Minor reformatting From-SVN: r103894
100 lines
4.6 KiB
Ada
100 lines
4.6 KiB
Ada
------------------------------------------------------------------------------
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-- --
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-- GNAT LIBRARY COMPONENTS --
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-- --
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-- G N A T . S E M A P H O R E S --
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-- --
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-- S p e c --
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-- --
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-- Copyright (C) 2003-2005, AdaCore --
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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 2, 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. See the GNU General Public License --
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-- for more details. You should have received a copy of the GNU General --
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-- Public License distributed with GNAT; see file COPYING. If not, write --
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-- to the Free Software Foundation, 51 Franklin Street, Fifth Floor, --
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-- Boston, MA 02110-1301, USA. --
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-- --
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-- As a special exception, if other files instantiate generics from this --
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-- unit, or you link this unit with other files to produce an executable, --
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-- this unit does not by itself cause the resulting executable to be --
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-- covered by the GNU General Public License. This exception does not --
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-- however invalidate any other reasons why the executable file might be --
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-- covered by the GNU Public License. --
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-- --
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-- GNAT was originally developed by the GNAT team at New York University. --
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-- It is now maintained by Ada Core Technologies Inc (http://www.gnat.com). --
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-- --
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------------------------------------------------------------------------------
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-- This package provides classic counting semaphores and binary semaphores.
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-- Both types are visibly defined as protected types so that users can make
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-- conditional and timed calls when appropriate.
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with System;
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package GNAT.Semaphores is
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Default_Ceiling : constant System.Priority := System.Default_Priority;
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-- A convenient value for the priority discriminants that follow
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------------------------
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-- Counting_Semaphore --
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------------------------
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protected type Counting_Semaphore
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(Initial_Value : Natural;
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-- A counting semaphore contains an internal counter. The initial
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-- value of this counter is set by clients via the discriminant.
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Ceiling : System.Priority)
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-- Users must specify the ceiling priority for the object. If the
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-- Real-Time Systems Annex is not in use this value is not important.
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is
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pragma Priority (Ceiling);
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entry Seize;
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-- Blocks caller until/unless the semaphore's internal counter is
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-- greater than zero. Decrements the semaphore's internal counter when
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-- executed.
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procedure Release;
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-- Increments the semaphore's internal counter
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private
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Count : Natural := Initial_Value;
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end Counting_Semaphore;
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----------------------
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-- Binary_Semaphore --
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----------------------
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protected type Binary_Semaphore
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(Initially_Available : Boolean;
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-- Binary semaphores are either available or not; there is no internal
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-- count involved. The discriminant value determines whether the
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-- individual object is initially available.
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Ceiling : System.Priority)
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-- Users must specify the ceiling priority for the object. If the
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-- Real-Time Systems Annex is not in use this value is not important.
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is
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pragma Priority (Ceiling);
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entry Seize;
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-- Blocks the caller unless/until semaphore is available. After
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-- execution the semaphore is no longer available.
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procedure Release;
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-- Makes the semaphore available
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private
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Available : Boolean := Initially_Available;
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end Binary_Semaphore;
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end GNAT.Semaphores;
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