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[/] [openrisc/] [trunk/] [gnu-dev/] [or1k-gcc/] [gcc/] [ada/] [s-taprob.ads] - Blame information for rev 706

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1 706 jeremybenn
------------------------------------------------------------------------------
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--                                                                          --
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--                 GNAT RUN-TIME LIBRARY (GNARL) COMPONENTS                 --
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--                                                                          --
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--      S Y S T E M . T A S K I N G . P R O T E C T E D _ O B J E C T S     --
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--                                                                          --
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--                                  S p e c                                 --
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--                                                                          --
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--          Copyright (C) 1992-2011, Free Software Foundation, Inc.         --
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--                                                                          --
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-- GNARL 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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-- GNARL was developed by the GNARL team at Florida State 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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--  This package provides necessary definitions to handle simple (i.e without
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--  entries) protected objects.
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--  All the routines that handle protected objects with entries have been moved
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--  to two children: Entries and Operations. Note that Entries only contains
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--  the type declaration and the OO primitives. This is needed to avoid
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--  circular dependency.
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--  This package is part of the high level tasking interface used by the
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--  compiler to expand Ada 95 tasking constructs into simpler run time calls
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--  (aka GNARLI, GNU Ada Run-time Library Interface)
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--  Note: the compiler generates direct calls to this interface, via Rtsfind.
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--  Any changes to this interface may require corresponding compiler changes
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--  in exp_ch9.adb and possibly exp_ch7.adb and exp_attr.adb
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package System.Tasking.Protected_Objects is
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   pragma Elaborate_Body;
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   ---------------------------------
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   -- Compiler Interface (GNARLI) --
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   ---------------------------------
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   --  The compiler will expand in the GNAT tree the following construct:
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   --  protected PO is
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   --     procedure P;
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   --  private
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   --     open : boolean := false;
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   --  end PO;
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   --  protected body PO is
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   --     procedure P is
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   --        ...variable declarations...
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   --     begin
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   --        ...B...
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   --     end P;
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   --  end PO;
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   --  as follows:
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   --  protected type poT is
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   --     procedure p;
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   --  private
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   --     open : boolean := false;
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   --  end poT;
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   --  type poTV is limited record
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   --     open : boolean := false;
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   --     _object : aliased protection;
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   --  end record;
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   --  procedure poPT__pN (_object : in out poTV);
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   --  procedure poPT__pP (_object : in out poTV);
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   --  freeze poTV [
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   --     procedure poTVI (_init : in out poTV) is
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   --     begin
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   --        _init.open := false;
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   --        object-init-proc (_init._object);
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   --        initialize_protection (_init._object'unchecked_access,
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   --          unspecified_priority);
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   --        return;
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   --     end _init_proc;
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   --  ]
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   --  po : poT;
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   --  poTVI (poTV!(po));
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   --  procedure poPT__pN (_object : in out poTV) is
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   --     poR : protection renames _object._object;
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   --     openP : boolean renames _object.open;
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   --     ...variable declarations...
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   --  begin
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   --     ...B...
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   --     return;
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   --  end poPT__pN;
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   --  procedure poPT__pP (_object : in out poTV) is
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   --     procedure _clean is
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   --     begin
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   --        unlock (_object._object'unchecked_access);
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   --        return;
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   --     end _clean;
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   --  begin
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   --     lock (_object._object'unchecked_access);
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   --     B2b : begin
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   --        poPT__pN (_object);
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   --     at end
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   --        _clean;
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   --     end B2b;
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   --     return;
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   --  end poPT__pP;
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   Null_Protected_Entry : constant := Null_Entry;
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   Max_Protected_Entry : constant := Max_Entry;
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   type Protected_Entry_Index is new Entry_Index
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     range Null_Protected_Entry .. Max_Protected_Entry;
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   type Barrier_Function_Pointer is access
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     function
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       (O    : System.Address;
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        E    : Protected_Entry_Index)
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        return Boolean;
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   --  Pointer to a function which evaluates the barrier of a protected
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   --  entry body. O is a pointer to the compiler-generated record
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   --  representing the protected object, and E is the index of the
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   --  entry serviced by the body.
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   type Entry_Action_Pointer is access
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     procedure
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       (O : System.Address;
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        P : System.Address;
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        E : Protected_Entry_Index);
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   --  Pointer to a procedure which executes the sequence of statements
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   --  of a protected entry body. O is a pointer to the compiler-generated
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   --  record representing the protected object, P is a pointer to the
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   --  record of entry parameters, and E is the index of the
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   --  entry serviced by the body.
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   type Entry_Body is record
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      Barrier : Barrier_Function_Pointer;
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      Action  : Entry_Action_Pointer;
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   end record;
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   --  The compiler-generated code passes objects of this type to the GNARL
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   --  to allow it to access the executable code of an entry body.
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   type Entry_Body_Access is access all Entry_Body;
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   type Protection is limited private;
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   --  This type contains the GNARL state of a protected object. The
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   --  application-defined portion of the state (i.e. private objects)
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   --  is maintained by the compiler-generated code.
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   --  Note that there are now 2 Protection types. One for the simple
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   --  case (no entries) and one for the general case that needs the whole
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   --  Finalization mechanism.
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   --  This split helps in the case of restricted run time where we want to
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   --  minimize the size of the code.
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   type Protection_Access is access all Protection;
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   Null_PO : constant Protection_Access := null;
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   function Get_Ceiling
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     (Object : Protection_Access) return System.Any_Priority;
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   --  Returns the new ceiling priority of the protected object
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   procedure Initialize_Protection
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     (Object           : Protection_Access;
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      Ceiling_Priority : Integer);
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   --  Initialize the Object parameter so that it can be used by the runtime
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   --  to keep track of the runtime state of a protected object.
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   procedure Lock (Object : Protection_Access);
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   --  Lock a protected object for write access. Upon return, the caller
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   --  owns the lock to this object, and no other call to Lock or
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   --  Lock_Read_Only with the same argument will return until the
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   --  corresponding call to Unlock has been made by the caller.
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   procedure Lock_Read_Only (Object : Protection_Access);
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   --  Lock a protected object for read access. Upon return, the caller
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   --  owns the lock for read access, and no other calls to Lock with the
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   --  same argument will return until the corresponding call to Unlock
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   --  has been made by the caller. Other calls to Lock_Read_Only may (but
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   --  need not) return before the call to Unlock, and the corresponding
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   --  callers will also own the lock for read access.
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   procedure Set_Ceiling
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     (Object : Protection_Access;
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      Prio   : System.Any_Priority);
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   --  Sets the new ceiling priority of the protected object
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   procedure Unlock (Object : Protection_Access);
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   --  Relinquish ownership of the lock for the object represented by
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   --  the Object parameter. If this ownership was for write access, or
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   --  if it was for read access where there are no other read access
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   --  locks outstanding, one (or more, in the case of Lock_Read_Only)
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   --  of the tasks waiting on this lock (if any) will be given the
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   --  lock and allowed to return from the Lock or Lock_Read_Only call.
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private
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   type Protection is record
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      L : aliased Task_Primitives.Lock;
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      --  Lock used to ensure mutual exclusive access to the protected object
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      Ceiling : System.Any_Priority;
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      --  Ceiling priority associated to the protected object
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      New_Ceiling : System.Any_Priority;
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      --  New ceiling priority associated to the protected object. In case
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      --  of assignment of a new ceiling priority to the protected object the
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      --  frontend generates a call to set_ceiling to save the new value in
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      --  this field. After such assignment this value can be read by means
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      --  of the 'Priority attribute, which generates a call to get_ceiling.
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      --  However, the ceiling of the protected object will not be changed
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      --  until completion of the protected action in which the assignment
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      --  has been executed (AARM D.5.2 (10/2)).
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      Owner : Task_Id;
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      --  This field contains the protected object's owner. Null_Task
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      --  indicates that the protected object is not currently being used.
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      --  This information is used for detecting the type of potentially
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      --  blocking operations described in the ARM 9.5.1, par. 15 (external
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      --  calls on a protected subprogram with the same target object as that
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      --  of the protected action).
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   end record;
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   procedure Finalize_Protection (Object : in out Protection);
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   --  Clean up a Protection object (in particular, finalize the associated
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   --  Lock object). The compiler generates calls automatically to this
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   --  procedure
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end System.Tasking.Protected_Objects;

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