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   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT RUN-TIME COMPONENTS                         --
   4 --                                                                          --
   5 --         A D A . S Y N C H R O N O U S _ T A S K _ C O N T R O L          --
   6 --                                                                          --
   7 --                                 S p e c                                  --
   8 --                                                                          --
   9 --                                                                          --
  10 --          Copyright (C) 1992-1998 Free Software Foundation, Inc.          --
  11 --                                                                          --
  12 -- This specification is derived from the Ada Reference Manual for use with --
  13 -- GNAT. The copyright notice above, and the license provisions that follow --
  14 -- apply solely to the  contents of the part following the private keyword. --
  15 --                                                                          --
  16 -- GNAT is free software;  you can  redistribute it  and/or modify it under --
  17 -- terms of the  GNU General Public License as published  by the Free Soft- --
  18 -- ware  Foundation;  either version 2,  or (at your option) any later ver- --
  19 -- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
  20 -- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
  21 -- or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License --
  22 -- for  more details.  You should have  received  a copy of the GNU General --
  23 -- Public License  distributed with GNAT;  see file COPYING.  If not, write --
  24 -- to  the Free Software Foundation,  59 Temple Place - Suite 330,  Boston, --
  25 -- MA 02111-1307, USA.                                                      --
  26 --                                                                          --
  27 -- As a special exception,  if other files  instantiate  generics from this --
  28 -- unit, or you link  this unit with other files  to produce an executable, --
  29 -- this  unit  does not  by itself cause  the resulting  executable  to  be --
  30 -- covered  by the  GNU  General  Public  License.  This exception does not --
  31 -- however invalidate  any other reasons why  the executable file  might be --
  32 -- covered by the  GNU Public License.                                      --
  33 --                                                                          --
  34 -- GNAT was originally developed  by the GNAT team at  New York University. --
  35 -- It is now maintained by Ada Core Technologies Inc (http://www.gnat.com). --
  36 --                                                                          --
  37 ------------------------------------------------------------------------------
  38
  39 with System;
  40
  41 package Ada.Synchronous_Task_Control is
  42
  43    type Suspension_Object is limited private;
  44
  45    procedure Set_True (S : in out Suspension_Object);
  46
  47    procedure Set_False (S : in out Suspension_Object);
  48
  49    function Current_State (S : Suspension_Object) return Boolean;
  50
  51    procedure Suspend_Until_True (S : in out Suspension_Object);
  52
  53 private
  54
  55    --  ??? Using a protected object is overkill; suspension could be
  56    --      implemented more efficiently.
  57
  58    protected type Suspension_Object is
  59       entry Wait;
  60       procedure Set_False;
  61       procedure Set_True;
  62       function Get_Open return Boolean;
  63       entry Wait_Exception;
  64
  65       pragma Priority (System.Any_Priority'Last);
  66    private
  67       Open : Boolean := False;
  68    end Suspension_Object;
  69
  70 end Ada.Synchronous_Task_Control;