gcc/ada/s-thread.ads

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT COMPILER COMPONENTS                         --
   4 --                                                                          --
   5 --                       S Y S T E M . T H R E A D S                        --
   6 --                                                                          --
   7 --                                 S p e c                                  --
   8 --                                                                          --
   9 --          Copyright (C) 1992-2003 Free Software Foundation, Inc.          --
  10 --                                                                          --
  11 -- GNAT 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.  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.  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 GNAT;  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 -- GNAT was originally developed  by the GNAT team at  New York University. --
  30 -- Extensive contributions were provided by Ada Core Technologies Inc.      --
  31 --                                                                          --
  32 ------------------------------------------------------------------------------
  33
  34 --  This package provides facilities to register a thread to the runtime,
  35 --  and allocate its task specific datas.
  36
  37 with Ada.Exceptions;
  38
  39 package System.Threads is
  40
  41    subtype EO is Ada.Exceptions.Exception_Occurrence;
  42
  43    subtype EOA is Ada.Exceptions.Exception_Occurrence_Access;
  44
  45    type ATSD is limited private;
  46    --  Type of the Ada thread specific data. It contains datas needed
  47    --  by the GNAT runtime.
  48
  49    type ATSD_Access is access ATSD;
  50
  51    --  Get/Set for the attributes of the current thread
  52
  53    function  Get_Jmpbuf_Address return  Address;
  54    pragma Inline (Get_Jmpbuf_Address);
  55
  56    procedure Set_Jmpbuf_Address (Addr : Address);
  57    pragma Inline (Get_Jmpbuf_Address);
  58
  59    function  Get_Sec_Stack_Addr return  Address;
  60    pragma Inline (Get_Sec_Stack_Addr);
  61
  62    procedure Set_Sec_Stack_Addr (Addr : Address);
  63    pragma Inline (Set_Sec_Stack_Addr);
  64
  65    function Get_Current_Excep return EOA;
  66    pragma Inline (Get_Current_Excep);
  67
  68    --------------------------
  69    -- Thread Body Handling --
  70    --------------------------
  71
  72    --  The subprograms in this section are called by the expansion of a
  73    --  subprogram body to which a Thread_Body pragma has been applied:
  74
  75    --  Given a subprogram body
  76
  77    --     procedure xyz (params ....) is    -- can also be a function
  78    --       <user declarations>
  79    --     begin
  80    --       <user statements>
  81    --     <user exception handlers>
  82    --     end xyz;
  83
  84    --  The expansion resulting from use of the Thread_Body pragma is:
  85
  86    --     procedure xyz (params ...) is
  87
  88    --       _Secondary_Stack : aliased
  89    --          Storage_Elements.Storage_Array
  90    --            (1 .. Storage_Offset (Sec_Stack_Size));
  91    --       for _Secondary_Stack'Alignment use Standard'Maximum_Alignment;
  92
  93    --       _Process_ATSD : aliased System.Threads.ATSD;
  94
  95    --     begin
  96    --        System.Threads.Thread_Body_Enter;
  97    --          (_Secondary_Stack'Address,
  98    --           _Secondary_Stack'Length,
  99    --           _Process_ATSD'Address);
 100
 101    --        declare
 102    --           <user declarations>
 103    --        begin
 104    --           <user statements>
 105    --        <user exception handlers>
 106    --        end;
 107
 108    --       System.Threads.Thread_Body_Leave;
 109
 110    --     exception
 111    --        when E : others =>
 112    --          System.Threads.Thread_Body_Exceptional_Exit (E);
 113    --     end;
 114
 115    --  Note the exception handler is omitted if pragma Restriction
 116    --  No_Exception_Handlers is currently active.
 117
 118    --  Note: the secondary stack size (Sec_Stack_Size) comes either from
 119    --  the pragma, if specified, or is the default value taken from
 120    --  the declaration in System.Secondary_Stack.
 121
 122    procedure Thread_Body_Enter
 123      (Sec_Stack_Address    : System.Address;
 124       Sec_Stack_Size       : Natural;
 125       Process_ATSD_Address : System.Address);
 126    --  Enter thread body, see above for details
 127
 128    procedure Thread_Body_Leave;
 129    --  Leave thread body (normally), see above for details
 130
 131    procedure Thread_Body_Exceptional_Exit
 132      (EO : Ada.Exceptions.Exception_Occurrence);
 133    --  Leave thread body (abnormally on exception), see above for details
 134
 135 private
 136
 137    ------------------------
 138    -- Task Specific Data --
 139    ------------------------
 140
 141    type ATSD is limited record
 142       Jmpbuf_Address : Address := Null_Address;
 143       --  Address of jump buffer used to store the address of the
 144       --  current longjmp/setjmp buffer for exception management.
 145       --  These buffers are threaded into a stack, and the address
 146       --  here is the top of the stack. A null address means that
 147       --  no exception handler is currently active.
 148
 149       Sec_Stack_Addr : Address := Null_Address;
 150       --  Address of currently allocated secondary stack
 151
 152       Current_Excep : aliased EO;
 153       --  Exception occurrence that contains the information for the
 154       --  current exception. Note that any exception in the same task
 155       --  destroys this information, so the data in this variable must
 156       --  be copied out before another exception can occur.
 157
 158    end record;
 159
 160 end System.Threads;