gcc/ada/s-taspri-vxworks.ads

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                  GNAT 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) 2001-2008, Free Software Foundation, Inc.         --
  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,  51  Franklin  Street,  Fifth  Floor, --
  20 -- Boston, MA 02110-1301, 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.       --
  30 -- Extensive contributions were provided by Ada Core Technologies, Inc.     --
  31 --                                                                          --
  32 ------------------------------------------------------------------------------
  33
  34 --  This is a VxWorks version of this package
  35
  36 pragma Polling (Off);
  37 --  Turn off polling, we do not want ATC polling to take place during tasking
  38 --  operations. It causes infinite loops and other problems.
  39
  40 with System.OS_Interface;
  41
  42 package System.Task_Primitives is
  43    pragma Preelaborate;
  44
  45    type Lock is limited private;
  46    --  Should be used for implementation of protected objects
  47
  48    type RTS_Lock is limited private;
  49    --  Should be used inside the runtime system. The difference between Lock
  50    --  and the RTS_Lock is that the later one serves only as a semaphore so
  51    --  that do not check for ceiling violations.
  52
  53    type Suspension_Object is limited private;
  54    --  Should be used for the implementation of Ada.Synchronous_Task_Control
  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 basis.
  62    --  A component of this type is guaranteed to be included in the
  63    --  Ada_Task_Control_Block.
  64
  65    subtype Task_Address is System.Address;
  66    --  In some versions of Task_Primitives, notably for VMS, Task_Address is
  67    --  the short version of address defined in System.Aux_DEC. To avoid
  68    --  dragging Aux_DEC into tasking packages a tasking specific subtype is
  69    --  defined here.
  70
  71    Task_Address_Size : constant := Standard'Address_Size;
  72    --  The size of Task_Address
  73
  74    Alternate_Stack_Size : constant := 0;
  75    --  No alternate signal stack is used on this platform
  76
  77 private
  78
  79    type Priority_Type is (Prio_None, Prio_Protect, Prio_Inherit);
  80
  81    type Lock is record
  82       Mutex    : System.OS_Interface.SEM_ID;
  83       Protocol : Priority_Type;
  84
  85       Prio_Ceiling : System.OS_Interface.int;
  86       --  Priority ceiling of lock
  87    end record;
  88
  89    type RTS_Lock is new Lock;
  90
  91    type Suspension_Object is record
  92       State : Boolean;
  93       pragma Atomic (State);
  94       --  Boolean that indicates whether the object is open. This field is
  95       --  marked Atomic to ensure that we can read its value without locking
  96       --  the access to the Suspension_Object.
  97
  98       Waiting : Boolean;
  99       --  Flag showing if there is a task already suspended on this object
 100
 101       L : aliased System.OS_Interface.SEM_ID;
 102       --  Protection for ensuring mutual exclusion on the Suspension_Object
 103
 104       CV : aliased System.OS_Interface.SEM_ID;
 105       --  Condition variable used to queue threads until condition is signaled
 106    end record;
 107
 108    type Private_Data is record
 109       Thread : aliased System.OS_Interface.t_id := 0;
 110       pragma Atomic (Thread);
 111       --  Thread field may be updated by two different threads of control.
 112       --  (See, Enter_Task and Create_Task in s-taprop.adb).
 113       --  They put the same value (thr_self value). We do not want to
 114       --  use lock on those operations and the only thing we have to
 115       --  make sure is that they are updated in atomic fashion.
 116
 117       LWP : aliased System.OS_Interface.t_id := 0;
 118       --  The purpose of this field is to provide a better tasking support on
 119       --  gdb. The order of the two first fields (Thread and LWP) is important.
 120       --  On targets where lwp is not relevant, this is equivalent to Thread.
 121
 122       CV : aliased System.OS_Interface.SEM_ID;
 123
 124       L  : aliased RTS_Lock;
 125       --  Protection for all components is lock L
 126    end record;
 127
 128 end System.Task_Primitives;