gcc/ada/5qtaspri.ads

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                 GNU ADA RUN-TIME LIBRARY (GNARL) COMPONENTS              --
   4 --                                                                          --
   5 --                 S Y S T E M . T A S K _ P R I M I T I V E S              --
   6 --                                                                          --
   7 --                                  S p e c                                 --
   8 --                                                                          --
   9 --            Copyright (C) 1991-2001, Florida State University             --
  10 --                                                                          --
  11 -- GNARL is free software; you can  redistribute it  and/or modify it under --
  12 -- terms of the  GNU General Public License as published  by the Free Soft- --
  13 -- ware  Foundation;  either version 2,  or (at your option) any later ver- --
  14 -- sion. GNARL is distributed in the hope that it will be useful, but WITH- --
  15 -- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
  16 -- or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License --
  17 -- for  more details.  You should have  received  a copy of the GNU General --
  18 -- Public License  distributed with GNARL; see file COPYING.  If not, write --
  19 -- to  the Free Software Foundation,  59 Temple Place - Suite 330,  Boston, --
  20 -- MA 02111-1307, USA.                                                      --
  21 --                                                                          --
  22 -- As a special exception,  if other files  instantiate  generics from this --
  23 -- unit, or you link  this unit with other files  to produce an executable, --
  24 -- this  unit  does not  by itself cause  the resulting  executable  to  be --
  25 -- covered  by the  GNU  General  Public  License.  This exception does not --
  26 -- however invalidate  any other reasons why  the executable file  might be --
  27 -- covered by the  GNU Public License.                                      --
  28 --                                                                          --
  29 -- GNARL was developed by the GNARL team at Florida State University. It is --
  30 -- now maintained by Ada Core Technologies Inc. in cooperation with Florida --
  31 -- State University (http://www.gnat.com).                                  --
  32 --                                                                          --
  33 ------------------------------------------------------------------------------
  34
  35 --  RT_GNU/Linux version
  36
  37 pragma Polling (Off);
  38 --  Turn off polling, we do not want ATC polling to take place during
  39 --  tasking operations. It causes infinite loops and other problems.
  40
  41 with System.OS_Interface;
  42
  43 package System.Task_Primitives is
  44
  45    type Lock is limited private;
  46    --  Used for implementation of protected objects.
  47
  48    type Lock_Ptr is limited private;
  49
  50    type RTS_Lock is limited private;
  51    --  Used inside the runtime system. The difference between Lock and the
  52    --  RTS_Lock is that the later one serves only as a semaphore so that do
  53    --  not check for ceiling violations.
  54    type RTS_Lock_Ptr is limited private;
  55
  56    type Task_Body_Access is access procedure;
  57    --  Pointer to the task body's entry point (or possibly a wrapper
  58    --  declared local to the GNARL).
  59
  60    type Private_Data is limited private;
  61    --  Any information that the GNULLI needs maintained on a per-task
  62    --  basis.  A component of this type is guaranteed to be included
  63    --  in the Ada_Task_Control_Block.
  64
  65 private
  66
  67    type RT_GNU_Linux_Lock is record
  68       Ceiling_Priority     : System.Any_Priority;
  69       Pre_Locking_Priority : System.Any_Priority;
  70       --  Used to store the task's active priority before it
  71       --  acquires the lock
  72
  73       Owner : System.Address;
  74       --  This is really a Task_ID, but we can't use that type
  75       --  here because this System.Tasking is "with"
  76       --  the current package -- a circularity.
  77    end record;
  78
  79    type Lock is new RT_GNU_Linux_Lock;
  80    type RTS_Lock is new RT_GNU_Linux_Lock;
  81
  82    type RTS_Lock_Ptr is access all RTS_Lock;
  83    type Lock_Ptr is access all Lock;
  84
  85    type Private_Data is record
  86       Stack : System.Address;
  87       --  A stack space needed for the task. the space is allocated
  88       --  when the task is being created and is deallocated when
  89       --  the TCB for the task is finalized
  90
  91       Uses_Fp : Integer;
  92       --  A flag to indicate whether the task is going to use floating-
  93       --  point unit. It's set to 1, indicating FP unit is always going
  94       --  to be used. The reason is that it is in this private record and
  95       --  necessary operation has to be provided for a user to call so as
  96       --  to change its value
  97
  98       Magic : Integer;
  99       --  A special value is going to be stored in it when a task is
 100       --  created. The value is RT_TASK_MAGIC (16#754d2774#) as declared
 101       --  in System.OS_Interface
 102
 103       State : System.OS_Interface.Rt_Task_States;
 104       --  Shows whether the task is RT_TASK_READY, RT_TASK_DELAYED or
 105       --  RT_TASK_DORMANT to support suspend, wait, wakeup.
 106
 107       Stack_Bottom : System.Address;
 108
 109       Active_Priority  : System.Any_Priority;
 110       --  Active priority of the task
 111
 112       Period : System.OS_Interface.RTIME;
 113       --  Intended originally to store the period of the task, but not used
 114       --  in the current implementation
 115
 116       Resume_Time : System.OS_Interface.RTIME;
 117       --  Store the time the task has to be awakened
 118
 119       Next : System.Address;
 120       --  This really is a Task_ID, used to link the Available_TCBs.
 121
 122       Succ : System.Address;
 123       pragma Volatile (Succ);
 124       Pred : System.Address;
 125       pragma Volatile (Pred);
 126       --  These really are Task_ID, used to implement a circular doubly
 127       --  linked list for task queue
 128
 129       L : aliased RTS_Lock;
 130
 131       Outer_Lock : RTS_Lock_Ptr := null;
 132       --  Used to track which Lock the task is holding is the outermost
 133       --  one in order to implement priority setting and inheritance
 134    end record;
 135
 136    --  ????  May need to use pragma Atomic or Volatile on some
 137    --  components; may also need to specify aliased for some.
 138 end System.Task_Primitives;