+++ /dev/null
-------------------------------------------------------------------------------
--- --
--- GNU ADA RUN-TIME LIBRARY (GNARL) COMPONENTS --
--- --
--- S Y S T E M . T A S K I N G . I N I T I A L I Z A T I O N --
--- --
--- S p e c --
--- --
--- $Revision: 1.1.16.1 $
--- --
--- Copyright (C) 1992-1999, Free Software Foundation, Inc. --
--- --
--- 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. --
--- Extensive contributions were provided by Ada Core Technologies Inc. --
--- --
-------------------------------------------------------------------------------
-
--- This package provides overall initialization of the tasking portion of the
--- RTS. This package must be elaborated before any tasking features are used.
--- It also contains initialization for Ada Task Control Block (ATCB) records.
-
-package System.Tasking.Initialization is
-
- procedure Remove_From_All_Tasks_List (T : Task_ID);
- -- Remove T from All_Tasks_List.
-
- ------------------------------------------------
- -- Static (Compile-Time) Configuration Flags --
- ------------------------------------------------
-
- -- ?????
- -- Maybe this does not belong here? Where else?
- -- For now, it is here because so is Change_Base_Priority,
- -- and the two are used together.
-
- Dynamic_Priority_Support : constant Boolean := True;
- -- Should we poll for pending base priority changes at every
- -- abort completion point?
-
- ---------------------------------
- -- Tasking-Specific Soft Links --
- ---------------------------------
-
- -- These permit us to leave out certain portions of the tasking
- -- run-time system if they are not used. They are only used internally
- -- by the tasking run-time system.
- -- So far, the only example is support for Ada.Task_Attributes.
-
- type Proc_T is access procedure (T : Task_ID);
-
- procedure Finalize_Attributes (T : Task_ID);
- procedure Initialize_Attributes (T : Task_ID);
-
- Finalize_Attributes_Link : Proc_T := Finalize_Attributes'Access;
- -- should be called with abortion deferred and T.L write-locked
-
- Initialize_Attributes_Link : Proc_T := Initialize_Attributes'Access;
- -- should be called with abortion deferred, but holding no locks
-
- -------------------------
- -- Abort Defer/Undefer --
- -------------------------
-
- -- Defer_Abort defers the affects of low-level abort and priority change
- -- in the calling task until a matching Undefer_Abort call is executed.
-
- -- Undefer_Abort DOES MORE than just undo the effects of one call to
- -- Defer_Abort. It is the universal "polling point" for deferred
- -- processing, including the following:
-
- -- 1) base priority changes
-
- -- 2) exceptions that need to be raised
-
- -- 3) abort/ATC
-
- -- Abort deferral MAY be nested (Self_ID.Deferral_Level is a count),
- -- but to avoid waste and undetected errors, it generally SHOULD NOT
- -- be nested. The symptom of over-deferring abort is that an exception
- -- may fail to be raised, or an abort may fail to take place.
-
- -- Therefore, there are two sets of the inlinable defer/undefer
- -- routines, which are the ones to be used inside GNARL.
- -- One set allows nesting. The other does not. People who
- -- maintain the GNARL should try to avoid using the nested versions,
- -- or at least look very critically at the places where they are
- -- used.
-
- -- In general, any GNARL call that is potentially blocking, or
- -- whose semantics require that it sometimes raise an exception,
- -- or that is required to be an abort completion point, must be
- -- made with abort Deferral_Level = 1.
-
- -- In general, non-blocking GNARL calls, which may be made from inside
- -- a protected action, are likely to need to allow nested abort
- -- deferral.
-
- -- With some critical exceptions (which are supposed to be documented),
- -- internal calls to the tasking runtime system assume abort is already
- -- deferred, and do not modify the deferral level.
-
- -- There is also a set of non-linable defer/undefer routines,
- -- for direct call from the compiler. These are not in-lineable
- -- because they may need to be called via pointers ("soft links").
- -- For the sake of efficiency, the version with Self_ID as parameter
- -- should used wherever possible. These are all nestable.
-
- -- Non-nestable inline versions --
-
- procedure Defer_Abort (Self_ID : Task_ID);
- pragma Inline (Defer_Abort);
-
- procedure Undefer_Abort (Self_ID : Task_ID);
- pragma Inline (Undefer_Abort);
-
- -- Nestable inline versions --
-
- procedure Defer_Abort_Nestable (Self_ID : Task_ID);
- pragma Inline (Defer_Abort_Nestable);
-
- procedure Undefer_Abort_Nestable (Self_ID : Task_ID);
- pragma Inline (Undefer_Abort_Nestable);
-
- -- NON-INLINE versions without Self_ID for code generated by the
- -- expander and for hard links
-
- procedure Defer_Abortion;
- procedure Undefer_Abortion;
-
- -- ?????
- -- Try to phase out all uses of the above versions.
-
- function Check_Abort_Status return Integer;
- -- Returns Boolean'Pos (True) iff abort signal should raise
- -- Standard.Abort_Signal. Only used by IRIX currently.
-
- ---------------------------
- -- Change Base Priority --
- ---------------------------
-
- procedure Change_Base_Priority (T : Task_ID);
- -- Change the base priority of T.
- -- Has to be called with the affected task's ATCB write-locked.
- -- May temporariliy release the lock.
-
- procedure Poll_Base_Priority_Change (Self_ID : Task_ID);
- -- Has to be called with Self_ID's ATCB write-locked.
- -- May temporariliy release the lock.
- pragma Inline (Poll_Base_Priority_Change);
-
- ----------------------
- -- Task Lock/Unlock --
- ----------------------
-
- procedure Task_Lock (Self_ID : Task_ID);
- procedure Task_Unlock (Self_ID : Task_ID);
- -- These are versions of Lock_Task and Unlock_Task created for use
- -- within the GNARL.
-
- procedure Final_Task_Unlock (Self_ID : Task_ID);
- -- This version is only for use in Terminate_Task, when the task
- -- is relinquishing further rights to its own ATCB.
- -- There is a very interesting potential race condition there, where
- -- the old task may run concurrently with a new task that is allocated
- -- the old tasks (now reused) ATCB. The critical thing here is to
- -- not make any reference to the ATCB after the lock is released.
- -- See also comments on Terminate_Task and Unlock.
-
- procedure Wakeup_Entry_Caller
- (Self_ID : Task_ID;
- Entry_Call : Entry_Call_Link;
- New_State : Entry_Call_State);
- pragma Inline (Wakeup_Entry_Caller);
- -- This is called at the end of service of an entry call,
- -- to abort the caller if he is in an abortable part, and
- -- to wake up the caller if he is on Entry_Caller_Sleep.
- -- Call it holding the lock of Entry_Call.Self.
- --
- -- Timed_Call or Simple_Call:
- -- The caller is waiting on Entry_Caller_Sleep, in
- -- Wait_For_Completion, or Wait_For_Completion_With_Timeout.
- --
- -- Conditional_Call:
- -- The caller might be in Wait_For_Completion,
- -- waiting for a rendezvous (possibly requeued without abort)
- -- to complete.
- --
- -- Asynchronous_Call:
- -- The caller may be executing in the abortable part o
- -- an async. select, or on a time delay,
- -- if Entry_Call.State >= Was_Abortable.
-
- procedure Locked_Abort_To_Level
- (Self_ID : Task_ID;
- T : Task_ID;
- L : ATC_Level);
- pragma Inline (Locked_Abort_To_Level);
- -- Abort a task to a specified ATC level.
- -- Call this only with T locked.
-
-end System.Tasking.Initialization;
projects / msp430-gcc.git / blobdiff