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Diffstat (limited to 'gcc/ada/5rtpopsp.adb')
| -rw-r--r-- | gcc/ada/5rtpopsp.adb | 266 |
1 files changed, 266 insertions, 0 deletions
diff --git a/gcc/ada/5rtpopsp.adb b/gcc/ada/5rtpopsp.adb new file mode 100644 index 00000000000..a1f15975793 --- /dev/null +++ b/gcc/ada/5rtpopsp.adb @@ -0,0 +1,266 @@ +------------------------------------------------------------------------------ +-- -- +-- 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 . O P E R A T I O N S . -- +-- S P E C I F I C -- +-- -- +-- B o d y -- +-- -- +-- $Revision: 1.7 $ +-- -- +-- Copyright (C) 1991-1999, 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). -- +-- -- +------------------------------------------------------------------------------ + +-- This is a POSIX version of this package where foreign threads are +-- recognized. +-- Currently, DEC Unix, SCO UnixWare 7 and RTEMS use this version. + +with System.Soft_Links; +-- used to initialize TSD for a C thread, in function Self + +separate (System.Task_Primitives.Operations) +package body Specific is + + ------------------ + -- Local Data -- + ------------------ + + -- The followings are logically constants, but need to be initialized + -- at run time. + + -- The following gives the Ada run-time direct access to a variable + -- context switched by RTEMS at the lowest level. + + RTEMS_Ada_Self : System.Address; + pragma Import (C, RTEMS_Ada_Self, "rtems_ada_self"); + + -- The following are used to allow the Self function to + -- automatically generate ATCB's for C threads that happen to call + -- Ada procedure, which in turn happen to call the Ada runtime system. + + type Fake_ATCB; + type Fake_ATCB_Ptr is access Fake_ATCB; + type Fake_ATCB is record + Stack_Base : Interfaces.C.unsigned := 0; + -- A value of zero indicates the node is not in use. + Next : Fake_ATCB_Ptr; + Real_ATCB : aliased Ada_Task_Control_Block (0); + end record; + + Fake_ATCB_List : Fake_ATCB_Ptr; + -- A linear linked list. + -- The list is protected by All_Tasks_L; + -- Nodes are added to this list from the front. + -- Once a node is added to this list, it is never removed. + + Fake_Task_Elaborated : aliased Boolean := True; + -- Used to identified fake tasks (i.e., non-Ada Threads). + + Next_Fake_ATCB : Fake_ATCB_Ptr; + -- Used to allocate one Fake_ATCB in advance. See comment in New_Fake_ATCB + + ----------------------- + -- Local Subprograms -- + ----------------------- + + --------------------------------- + -- Support for New_Fake_ATCB -- + --------------------------------- + + function New_Fake_ATCB return Task_ID; + -- Allocate and Initialize a new ATCB. This code can safely be called from + -- a foreign thread, as it doesn't access implicitely or explicitely + -- "self" before having initialized the new ATCB. + + ------------------- + -- New_Fake_ATCB -- + ------------------- + + function New_Fake_ATCB return Task_ID is + Self_ID : Task_ID; + P, Q : Fake_ATCB_Ptr; + Succeeded : Boolean; + + begin + -- This section is ticklish. + -- We dare not call anything that might require an ATCB, until + -- we have the new ATCB in place. + + Write_Lock (All_Tasks_L'Access); + Q := null; + P := Fake_ATCB_List; + + while P /= null loop + if P.Stack_Base = 0 then + Q := P; + end if; + + P := P.Next; + end loop; + + if Q = null then + + -- Create a new ATCB with zero entries. + + Self_ID := Next_Fake_ATCB.Real_ATCB'Access; + Next_Fake_ATCB.Stack_Base := 1; + Next_Fake_ATCB.Next := Fake_ATCB_List; + Fake_ATCB_List := Next_Fake_ATCB; + Next_Fake_ATCB := null; + + else + -- Reuse an existing fake ATCB. + + Self_ID := Q.Real_ATCB'Access; + Q.Stack_Base := 1; + end if; + + -- Record this as the Task_ID for the current thread. + + Self_ID.Common.LL.Thread := pthread_self; + + RTEMS_Ada_Self := To_Address (Self_ID); + + -- Do the standard initializations + + System.Tasking.Initialize_ATCB + (Self_ID, null, Null_Address, Null_Task, Fake_Task_Elaborated'Access, + System.Priority'First, Task_Info.Unspecified_Task_Info, 0, Self_ID, + Succeeded); + pragma Assert (Succeeded); + + -- Finally, it is safe to use an allocator in this thread. + + if Next_Fake_ATCB = null then + Next_Fake_ATCB := new Fake_ATCB; + end if; + + Self_ID.Common.State := Runnable; + Self_ID.Awake_Count := 1; + + -- Since this is not an ordinary Ada task, we will start out undeferred + + Self_ID.Deferral_Level := 0; + + System.Soft_Links.Create_TSD (Self_ID.Common.Compiler_Data); + + -- ???? + -- The following call is commented out to avoid dependence on + -- the System.Tasking.Initialization package. + -- It seems that if we want Ada.Task_Attributes to work correctly + -- for C threads we will need to raise the visibility of this soft + -- link to System.Soft_Links. + -- We are putting that off until this new functionality is otherwise + -- stable. + -- System.Tasking.Initialization.Initialize_Attributes_Link.all (T); + + for J in Known_Tasks'Range loop + if Known_Tasks (J) = null then + Known_Tasks (J) := Self_ID; + Self_ID.Known_Tasks_Index := J; + exit; + end if; + end loop; + + -- Must not unlock until Next_ATCB is again allocated. + + Unlock (All_Tasks_L'Access); + return Self_ID; + end New_Fake_ATCB; + + ---------------- + -- Initialize -- + ---------------- + + procedure Initialize (Environment_Task : Task_ID) is + + begin + RTEMS_Ada_Self := To_Address (Environment_Task); + + -- Create a free ATCB for use on the Fake_ATCB_List. + + Next_Fake_ATCB := new Fake_ATCB; + end Initialize; + + --------- + -- Set -- + --------- + + procedure Set (Self_Id : Task_ID) is + + begin + RTEMS_Ada_Self := To_Address (Self_Id); + end Set; + + ---------- + -- Self -- + ---------- + + -- To make Ada tasks and C threads interoperate better, we have + -- added some functionality to Self. Suppose a C main program + -- (with threads) calls an Ada procedure and the Ada procedure + -- calls the tasking runtime system. Eventually, a call will be + -- made to self. Since the call is not coming from an Ada task, + -- there will be no corresponding ATCB. + + -- (The entire Ada run-time system may not have been elaborated, + -- either, but that is a different problem, that we will need to + -- solve another way.) + + -- What we do in Self is to catch references that do not come + -- from recognized Ada tasks, and create an ATCB for the calling + -- thread. + + -- The new ATCB will be "detached" from the normal Ada task + -- master hierarchy, much like the existing implicitly created + -- signal-server tasks. + + -- We will also use such points to poll for disappearance of the + -- threads associated with any implicit ATCBs that we created + -- earlier, and take the opportunity to recover them. + + -- A nasty problem here is the limitations of the compilation + -- order dependency, and in particular the GNARL/GNULLI layering. + -- To initialize an ATCB we need to assume System.Tasking has + -- been elaborated. + + function Self return Task_ID is + Result : System.Address; + + begin + Result := RTEMS_Ada_Self; + + -- If the key value is Null, then it is a non-Ada task. + + if Result = System.Null_Address then + return New_Fake_ATCB; + end if; + + return To_Task_ID (Result); + end Self; + +end Specific; |