------------------------------------------------------------------------------ -- -- -- GNU ADA RUN-TIME LIBRARY (GNARL) COMPONENTS -- -- -- -- S Y S T E M . T A S K _ P R I M I T I V E S -- -- -- -- S p e c -- -- -- -- -- -- Copyright (C) 1991-2001, Florida State University -- -- -- -- GNARL is free software; you can redistribute it and/or modify it under -- -- terms of the GNU General Public License as published by the Free Soft- -- -- ware Foundation; either version 2, or (at your option) any later ver- -- -- sion. GNARL is distributed in the hope that it will be useful, but WITH- -- -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY -- -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License -- -- for more details. You should have received a copy of the GNU General -- -- Public License distributed with GNARL; see file COPYING. If not, write -- -- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, -- -- MA 02111-1307, USA. -- -- -- -- As a special exception, if other files instantiate generics from this -- -- unit, or you link this unit with other files to produce an executable, -- -- this unit does not by itself cause the resulting executable to be -- -- covered by the GNU General Public License. This exception does not -- -- however invalidate any other reasons why the executable file might be -- -- covered by the GNU Public License. -- -- -- -- GNARL was developed by the GNARL team at Florida State University. It is -- -- now maintained by Ada Core Technologies Inc. in cooperation with Florida -- -- State University (http://www.gnat.com). -- -- -- ------------------------------------------------------------------------------ -- RT_GNU/Linux version pragma Polling (Off); -- Turn off polling, we do not want ATC polling to take place during -- tasking operations. It causes infinite loops and other problems. with System.OS_Interface; package System.Task_Primitives is type Lock is limited private; -- Used for implementation of protected objects. type Lock_Ptr is limited private; type RTS_Lock is limited private; -- Used inside the runtime system. The difference between Lock and the -- RTS_Lock is that the later one serves only as a semaphore so that do -- not check for ceiling violations. type RTS_Lock_Ptr is limited private; type Task_Body_Access is access procedure; -- Pointer to the task body's entry point (or possibly a wrapper -- declared local to the GNARL). type Private_Data is limited private; -- Any information that the GNULLI needs maintained on a per-task -- basis. A component of this type is guaranteed to be included -- in the Ada_Task_Control_Block. private type RT_GNU_Linux_Lock is record Ceiling_Priority : System.Any_Priority; Pre_Locking_Priority : System.Any_Priority; -- Used to store the task's active priority before it -- acquires the lock Owner : System.Address; -- This is really a Task_ID, but we can't use that type -- here because this System.Tasking is "with" -- the current package -- a circularity. end record; type Lock is new RT_GNU_Linux_Lock; type RTS_Lock is new RT_GNU_Linux_Lock; type RTS_Lock_Ptr is access all RTS_Lock; type Lock_Ptr is access all Lock; type Private_Data is record Stack : System.Address; -- A stack space needed for the task. the space is allocated -- when the task is being created and is deallocated when -- the TCB for the task is finalized Uses_Fp : Integer; -- A flag to indicate whether the task is going to use floating- -- point unit. It's set to 1, indicating FP unit is always going -- to be used. The reason is that it is in this private record and -- necessary operation has to be provided for a user to call so as -- to change its value Magic : Integer; -- A special value is going to be stored in it when a task is -- created. The value is RT_TASK_MAGIC (16#754d2774#) as declared -- in System.OS_Interface State : System.OS_Interface.Rt_Task_States; -- Shows whether the task is RT_TASK_READY, RT_TASK_DELAYED or -- RT_TASK_DORMANT to support suspend, wait, wakeup. Stack_Bottom : System.Address; Active_Priority : System.Any_Priority; -- Active priority of the task Period : System.OS_Interface.RTIME; -- Intended originally to store the period of the task, but not used -- in the current implementation Resume_Time : System.OS_Interface.RTIME; -- Store the time the task has to be awakened Next : System.Address; -- This really is a Task_ID, used to link the Available_TCBs. Succ : System.Address; pragma Volatile (Succ); Pred : System.Address; pragma Volatile (Pred); -- These really are Task_ID, used to implement a circular doubly -- linked list for task queue L : aliased RTS_Lock; Outer_Lock : RTS_Lock_Ptr := null; -- Used to track which Lock the task is holding is the outermost -- one in order to implement priority setting and inheritance end record; -- ???? May need to use pragma Atomic or Volatile on some -- components; may also need to specify aliased for some. end System.Task_Primitives;