gcc/ada/s-intman.ads

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                GNU ADA RUN-TIME LIBRARY (GNARL) COMPONENTS               --
   4 --                                                                          --
   5 --            S Y S T E M . I N T E R R U P T _ M A N A G E M E N T         --
   6 --                                                                          --
   7 --                                  S p e c                                 --
   8 --                                                                          --
   9 --                                                                          --
  10 --          Copyright (C) 1991-2001 Free Software Foundation, Inc.          --
  11 --                                                                          --
  12 -- GNARL is free software; you can  redistribute it  and/or modify it under --
  13 -- terms of the  GNU General Public License as published  by the Free Soft- --
  14 -- ware  Foundation;  either version 2,  or (at your option) any later ver- --
  15 -- sion. GNARL is distributed in the hope that it will be useful, but WITH- --
  16 -- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
  17 -- or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License --
  18 -- for  more details.  You should have  received  a copy of the GNU General --
  19 -- Public License  distributed with GNARL; see file COPYING.  If not, write --
  20 -- to  the Free Software Foundation,  59 Temple Place - Suite 330,  Boston, --
  21 -- MA 02111-1307, USA.                                                      --
  22 --                                                                          --
  23 -- As a special exception,  if other files  instantiate  generics from this --
  24 -- unit, or you link  this unit with other files  to produce an executable, --
  25 -- this  unit  does not  by itself cause  the resulting  executable  to  be --
  26 -- covered  by the  GNU  General  Public  License.  This exception does not --
  27 -- however invalidate  any other reasons why  the executable file  might be --
  28 -- covered by the  GNU Public License.                                      --
  29 --                                                                          --
  30 -- GNARL was developed by the GNARL team at Florida State University. It is --
  31 -- now maintained by Ada Core Technologies Inc. in cooperation with Florida --
  32 -- State University (http://www.gnat.com).                                  --
  33 --                                                                          --
  34 ------------------------------------------------------------------------------
  35
  36 --  This package encapsulates and centralizes information about
  37 --  all uses of interrupts (or signals), including the
  38 --  target-dependent mapping of interrupts (or signals) to exceptions.
  39
  40 --  PLEASE DO NOT add any with-clauses to this package.
  41 --  This is designed to work for both tasking and non-tasking systems,
  42 --  without pulling in any of the tasking support.
  43
  44 --  PLEASE DO NOT remove the Elaborate_Body pragma from this package.
  45 --  Elaboration of this package should happen early, as most other
  46 --  initializations depend on it.
  47 --  Forcing immediate elaboration of the body also helps to enforce
  48 --  the design assumption that this is a second-level
  49 --  package, just one level above System.OS_Interface, with no
  50 --  cross-dependences.
  51
  52 --  PLEASE DO NOT put any subprogram declarations with arguments of
  53 --  type Interrupt_ID into the visible part of this package.
  54 --  The type Interrupt_ID is used to derive the type in Ada.Interrupts,
  55 --  and adding more operations to that type would be illegal according
  56 --  to the Ada Reference Manual.  (This is the reason why the signals sets
  57 --  below are implemented as visible arrays rather than functions.)
  58
  59 with System.OS_Interface;
  60 --  used for Signal
  61 --           sigset_t
  62
  63 package System.Interrupt_Management is
  64
  65    pragma Elaborate_Body;
  66
  67    type Interrupt_Mask is limited private;
  68
  69    type Interrupt_ID is new System.OS_Interface.Signal;
  70
  71    type Interrupt_Set is array (Interrupt_ID) of Boolean;
  72
  73    --  The following objects serve as constants, but are initialized
  74    --  in the body to aid portability.  This permits us
  75    --  to use more portable names for interrupts,
  76    --  where distinct names may map to the same interrupt ID value.
  77    --  For example, suppose SIGRARE is a signal that is not defined on
  78    --  all systems, but is always reserved when it is defined.
  79    --  If we have the convention that ID zero is not used for any "real"
  80    --  signals, and SIGRARE = 0 when SIGRARE is not one of the locally
  81    --  supported signals, we can write
  82    --     Reserved (SIGRARE) := true;
  83    --  and the initialization code will be portable.
  84
  85    Abort_Task_Interrupt : Interrupt_ID;
  86    --  The interrupt that is used to implement task abortion,
  87    --  if an interrupt is used for that purpose.
  88    --  This is one of the reserved interrupts.
  89
  90    Keep_Unmasked : Interrupt_Set := (others => False);
  91    --  Keep_Unmasked (I) is true iff the interrupt I is
  92    --  one that must be kept unmasked at all times,
  93    --  except (perhaps) for short critical sections.
  94    --  This includes interrupts that are mapped to exceptions
  95    --  (see System.Interrupt_Exceptions.Is_Exception), but may also
  96    --  include interrupts (e.g. timer) that need to be kept unmasked
  97    --  for other reasons.
  98    --  Where interrupts are implemented as OS signals, and signal masking
  99    --  is per-task, the interrupt should be unmasked in ALL TASKS.
 100
 101    Reserve : Interrupt_Set := (others => False);
 102    --  Reserve (I) is true iff the interrupt I is one that
 103    --  cannot be permitted to be attached to a user handler.
 104    --  The possible reasons are many.  For example,
 105    --  it may be mapped to an exception, used to implement task abortion,
 106    --  or used to implement time delays.
 107
 108    Keep_Masked : Interrupt_Set := (others => False);
 109    --  Keep_Masked (I) is true iff the interrupt I must always be masked.
 110    --  Where interrupts are implemented as OS signals, and signal masking
 111    --  is per-task, the interrupt should be masked in ALL TASKS.
 112    --  There might not be any interrupts in this class, depending on
 113    --  the environment.  For example, if interrupts are OS signals
 114    --  and signal masking is per-task, use of the sigwait operation
 115    --  requires the signal be masked in all tasks.
 116
 117    procedure Initialize_Interrupts;
 118    --  On systems where there is no signal inheritance between tasks (e.g
 119    --  VxWorks, GNU/LinuxThreads), this procedure is used to initialize
 120    --  interrupts handling in each task. Otherwise this function should
 121    --  only be called by initialize in this package body.
 122
 123 private
 124    type Interrupt_Mask is new System.OS_Interface.sigset_t;
 125    --  in some implementation Interrupt_Mask can be represented
 126    --  as a linked list.
 127 end System.Interrupt_Management;