gcc/ada/libgnarl/a-synbar__posix.ads

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT RUN-TIME COMPONENTS                         --
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   5 --             A D A . S Y N C H R O N O U S _ B A R R I E R S              --
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   7 --                                  S p e c                                 --
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   9 --          Copyright (C) 1992-2018, Free Software Foundation, Inc.         --
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  11 -- This specification is derived from the Ada Reference Manual for use with --
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  34 ------------------------------------------------------------------------------
  35
  36 --  This is the spec of this package using POSIX barriers
  37
  38 with System;
  39 private with Ada.Finalization;
  40 private with Interfaces.C;
  41
  42 package Ada.Synchronous_Barriers is
  43    pragma Preelaborate (Synchronous_Barriers);
  44
  45    subtype Barrier_Limit is Positive range 1 .. Positive'Last;
  46
  47    type Synchronous_Barrier (Release_Threshold : Barrier_Limit) is
  48       limited private;
  49
  50    procedure Wait_For_Release
  51      (The_Barrier : in out Synchronous_Barrier;
  52       Notified    : out Boolean);
  53
  54 private
  55    --  POSIX barrier data type
  56
  57    SIZEOF_PTHREAD_BARRIER_T : constant :=
  58      (if System.Word_Size = 64 then 32 else 20);
  59    --  Value defined according to the linux definition in pthreadtypes.h. On
  60    --  other system, e.g. MIPS IRIX, the object is smaller, so it works
  61    --  correctly although we are wasting some space.
  62
  63    type pthread_barrier_t_view is (size_based, align_based);
  64
  65    type pthread_barrier_t (Kind : pthread_barrier_t_view := size_based) is
  66       record
  67          case Kind is
  68             when size_based =>
  69                size : Interfaces.C.char_array (1 .. SIZEOF_PTHREAD_BARRIER_T);
  70             when align_based =>
  71                align : Interfaces.C.long;
  72          end case;
  73       end record;
  74    pragma Unchecked_Union (pthread_barrier_t);
  75
  76    type Synchronous_Barrier (Release_Threshold : Barrier_Limit) is
  77      new Ada.Finalization.Limited_Controlled with
  78         record
  79            POSIX_Barrier : aliased pthread_barrier_t;
  80         end record;
  81
  82    overriding procedure Initialize (Barrier : in out Synchronous_Barrier);
  83    overriding procedure Finalize   (Barrier : in out Synchronous_Barrier);
  84 end Ada.Synchronous_Barriers;