gcc/ada/s-taspri-vms.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) 1991-2009, 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 OpenVMS/Alpha version of this package
  33
  34 --  This package provides low-level support for most tasking features
  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 Interfaces.C;
  41
  42 with System.OS_Interface;
  43 with System.Aux_DEC;
  44
  45 package System.Task_Primitives is
  46    pragma Preelaborate;
  47
  48    type Lock is limited private;
  49    --  Should be used for implementation of protected objects
  50
  51    type RTS_Lock is limited private;
  52    --  Should be used inside the runtime system. The difference between Lock
  53    --  and the RTS_Lock is that the later one serves only as a semaphore so
  54    --  that do not check for ceiling violations.
  55
  56    type Suspension_Object is limited private;
  57    --  Should be used for the implementation of Ada.Synchronous_Task_Control
  58
  59    type Task_Body_Access is access procedure;
  60    --  Pointer to the task body's entry point (or possibly a wrapper
  61    --  declared local to the GNARL).
  62
  63    type Private_Data is limited private;
  64    --  Any information that the GNULLI needs maintained on a per-task basis.
  65    --  A component of this type is guaranteed to be included in the
  66    --  Ada_Task_Control_Block.
  67
  68    subtype Task_Address is System.Aux_DEC.Short_Address;
  69    --  Task_Address is the short version of address defined in System.Aux_DEC.
  70    --  To avoid dragging Aux_DEC into tasking packages a tasking specific
  71    --  subtype is defined here.
  72
  73    Task_Address_Size : constant := System.Aux_DEC.Short_Address_Size;
  74    --  The size of Task_Address
  75
  76    Alternate_Stack_Size : constant := 0;
  77    --  No alternate signal stack is used on this platform
  78
  79 private
  80
  81    type Exc_Stack_T is array (0 .. 8192) of aliased Character;
  82    for Exc_Stack_T'Alignment use Standard'Maximum_Alignment;
  83    type Exc_Stack_Ptr_T is access all Exc_Stack_T;
  84
  85    type Lock is record
  86       L         : aliased System.OS_Interface.pthread_mutex_t;
  87       Prio      : Interfaces.C.int;
  88       Prio_Save : Interfaces.C.int;
  89    end record;
  90
  91    type RTS_Lock is new System.OS_Interface.pthread_mutex_t;
  92
  93    type Suspension_Object is record
  94       State   : Boolean;
  95       pragma Atomic (State);
  96       --  Boolean that indicates whether the object is open. This field is
  97       --  marked Atomic to ensure that we can read its value without locking
  98       --  the access to the Suspension_Object.
  99
 100       Waiting : Boolean;
 101       --  Flag showing if there is a task already suspended on this object
 102
 103       L : aliased System.OS_Interface.pthread_mutex_t;
 104       --  Protection for ensuring mutual exclusion on the Suspension_Object
 105
 106       CV : aliased System.OS_Interface.pthread_cond_t;
 107       --  Condition variable used to queue threads until ondition is signaled
 108    end record;
 109
 110    type Private_Data is record
 111       Thread : aliased System.OS_Interface.pthread_t;
 112       pragma Atomic (Thread);
 113       --  Thread field may be updated by two different threads of control.
 114       --  (See, Enter_Task and Create_Task in s-taprop.adb). They put the
 115       --  same value (thr_self value). We do not want to use lock on those
 116       --  operations and the only thing we have to make sure is that they
 117       --  are updated in atomic fashion.
 118
 119       CV : aliased System.OS_Interface.pthread_cond_t;
 120
 121       L : aliased RTS_Lock;
 122       --  Protection for all components is lock L
 123
 124       Exc_Stack_Ptr : Exc_Stack_Ptr_T;
 125       --  ??? This needs comments
 126
 127       AST_Pending : Boolean;
 128       --  Used to detect delay and sleep timeouts
 129
 130    end record;
 131
 132 end System.Task_Primitives;