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) 2001-2011, 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 3,  or (at your option) any later ver- --
  14 -- sion.  GNAT 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.                                     --
  17 --                                                                          --
  18 -- As a special exception under Section 7 of GPL version 3, you are granted --
  19 -- additional permissions described in the GCC Runtime Library Exception,   --
  20 -- version 3.1, as published by the Free Software Foundation.               --
  21 --                                                                          --
  22 -- You should have received a copy of the GNU General Public License and    --
  23 -- a copy of the GCC Runtime Library Exception along with this program;     --
  24 -- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --
  25 -- <http://www.gnu.org/licenses/>.                                          --
  26 --                                                                          --
  27 -- GNARL was developed by the GNARL team at Florida State University.       --
  28 -- Extensive contributions were provided by Ada Core Technologies, Inc.     --
  29 --                                                                          --
  30 ------------------------------------------------------------------------------
  31
  32 --  This is a VxWorks version of this package
  33
  34 pragma Polling (Off);
  35 --  Turn off polling, we do not want ATC polling to take place during tasking
  36 --  operations. It causes infinite loops and other problems.
  37
  38 with System.OS_Interface;
  39
  40 package System.Task_Primitives is
  41    pragma Preelaborate;
  42
  43    type Lock is limited private;
  44    --  Should be used for implementation of protected objects
  45
  46    type RTS_Lock is limited private;
  47    --  Should be used inside the runtime system. The difference between Lock
  48    --  and the RTS_Lock is that the later one serves only as a semaphore so
  49    --  that do not check for ceiling violations.
  50
  51    type Suspension_Object is limited private;
  52    --  Should be used for the implementation of Ada.Synchronous_Task_Control
  53
  54    type Task_Body_Access is access procedure;
  55    --  Pointer to the task body's entry point (or possibly a wrapper
  56    --  declared local to the GNARL).
  57
  58    type Private_Data is limited private;
  59    --  Any information that the GNULLI needs maintained on a per-task basis.
  60    --  A component of this type is guaranteed to be included in the
  61    --  Ada_Task_Control_Block.
  62
  63    subtype Task_Address is System.Address;
  64    --  In some versions of Task_Primitives, notably for VMS, Task_Address is
  65    --  the short version of address defined in System.Aux_DEC. To avoid
  66    --  dragging Aux_DEC into tasking packages a tasking specific subtype is
  67    --  defined here.
  68
  69    Task_Address_Size : constant := Standard'Address_Size;
  70    --  The size of Task_Address
  71
  72    Alternate_Stack_Size : constant := 0;
  73    --  No alternate signal stack is used on this platform
  74
  75 private
  76
  77    type Priority_Type is (Prio_None, Prio_Protect, Prio_Inherit);
  78
  79    type Lock is record
  80       Mutex    : System.OS_Interface.SEM_ID;
  81       Protocol : Priority_Type;
  82
  83       Prio_Ceiling : System.OS_Interface.int;
  84       --  Priority ceiling of lock
  85    end record;
  86
  87    type RTS_Lock is new Lock;
  88
  89    type Suspension_Object is record
  90       State : Boolean;
  91       pragma Atomic (State);
  92       --  Boolean that indicates whether the object is open. This field is
  93       --  marked Atomic to ensure that we can read its value without locking
  94       --  the access to the Suspension_Object.
  95
  96       Waiting : Boolean;
  97       --  Flag showing if there is a task already suspended on this object
  98
  99       L : aliased System.OS_Interface.SEM_ID;
 100       --  Protection for ensuring mutual exclusion on the Suspension_Object
 101
 102       CV : aliased System.OS_Interface.SEM_ID;
 103       --  Condition variable used to queue threads until condition is signaled
 104    end record;
 105
 106    type Private_Data is record
 107       Thread : aliased System.OS_Interface.t_id := 0;
 108       pragma Atomic (Thread);
 109       --  Thread field may be updated by two different threads of control.
 110       --  (See, Enter_Task and Create_Task in s-taprop.adb).
 111       --  They put the same value (thr_self value). We do not want to
 112       --  use lock on those operations and the only thing we have to
 113       --  make sure is that they are updated in atomic fashion.
 114
 115       LWP : aliased System.OS_Interface.t_id := 0;
 116       --  The purpose of this field is to provide a better tasking support on
 117       --  gdb. The order of the two first fields (Thread and LWP) is important.
 118       --  On targets where lwp is not relevant, this is equivalent to Thread.
 119
 120       CV : aliased System.OS_Interface.SEM_ID;
 121
 122       L  : aliased RTS_Lock;
 123       --  Protection for all components is lock L
 124    end record;
 125
 126 end System.Task_Primitives;