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.       --
  31 -- Extensive contributions were provided by Ada Core Technologies Inc.      --
  32 --                                                                          --
  33 ------------------------------------------------------------------------------
  34
  35 --  This package encapsulates and centralizes information about
  36 --  all uses of interrupts (or signals), including the
  37 --  target-dependent mapping of interrupts (or signals) to exceptions.
  38
  39 --  PLEASE DO NOT add any with-clauses to this package.
  40 --  This is designed to work for both tasking and non-tasking systems,
  41 --  without pulling in any of the tasking support.
  42
  43 --  PLEASE DO NOT remove the Elaborate_Body pragma from this package.
  44 --  Elaboration of this package should happen early, as most other
  45 --  initializations depend on it.
  46 --  Forcing immediate elaboration of the body also helps to enforce
  47 --  the design assumption that this is a second-level
  48 --  package, just one level above System.OS_Interface, with no
  49 --  cross-dependences.
  50
  51 --  PLEASE DO NOT put any subprogram declarations with arguments of
  52 --  type Interrupt_ID into the visible part of this package.
  53 --  The type Interrupt_ID is used to derive the type in Ada.Interrupts,
  54 --  and adding more operations to that type would be illegal according
  55 --  to the Ada Reference Manual.  (This is the reason why the signals sets
  56 --  below are implemented as visible arrays rather than functions.)
  57
  58 with System.OS_Interface;
  59 --  used for Signal
  60 --           sigset_t
  61
  62 package System.Interrupt_Management is
  63
  64    pragma Elaborate_Body;
  65
  66    type Interrupt_Mask is limited private;
  67
  68    type Interrupt_ID is new System.OS_Interface.Signal;
  69
  70    type Interrupt_Set is array (Interrupt_ID) of Boolean;
  71
  72    --  The following objects serve as constants, but are initialized
  73    --  in the body to aid portability.  This permits us
  74    --  to use more portable names for interrupts,
  75    --  where distinct names may map to the same interrupt ID value.
  76    --  For example, suppose SIGRARE is a signal that is not defined on
  77    --  all systems, but is always reserved when it is defined.
  78    --  If we have the convention that ID zero is not used for any "real"
  79    --  signals, and SIGRARE = 0 when SIGRARE is not one of the locally
  80    --  supported signals, we can write
  81    --     Reserved (SIGRARE) := true;
  82    --  and the initialization code will be portable.
  83
  84    Abort_Task_Interrupt : Interrupt_ID;
  85    --  The interrupt that is used to implement task abortion,
  86    --  if an interrupt is used for that purpose.
  87    --  This is one of the reserved interrupts.
  88
  89    Keep_Unmasked : Interrupt_Set := (others => False);
  90    --  Keep_Unmasked (I) is true iff the interrupt I is
  91    --  one that must be kept unmasked at all times,
  92    --  except (perhaps) for short critical sections.
  93    --  This includes interrupts that are mapped to exceptions
  94    --  (see System.Interrupt_Exceptions.Is_Exception), but may also
  95    --  include interrupts (e.g. timer) that need to be kept unmasked
  96    --  for other reasons.
  97    --  Where interrupts are implemented as OS signals, and signal masking
  98    --  is per-task, the interrupt should be unmasked in ALL TASKS.
  99
 100    Reserve : Interrupt_Set := (others => False);
 101    --  Reserve (I) is true iff the interrupt I is one that
 102    --  cannot be permitted to be attached to a user handler.
 103    --  The possible reasons are many.  For example,
 104    --  it may be mapped to an exception, used to implement task abortion,
 105    --  or used to implement time delays.
 106
 107    Keep_Masked : Interrupt_Set := (others => False);
 108    --  Keep_Masked (I) is true iff the interrupt I must always be masked.
 109    --  Where interrupts are implemented as OS signals, and signal masking
 110    --  is per-task, the interrupt should be masked in ALL TASKS.
 111    --  There might not be any interrupts in this class, depending on
 112    --  the environment.  For example, if interrupts are OS signals
 113    --  and signal masking is per-task, use of the sigwait operation
 114    --  requires the signal be masked in all tasks.
 115
 116    procedure Initialize_Interrupts;
 117    --  On systems where there is no signal inheritance between tasks (e.g
 118    --  VxWorks, GNU/LinuxThreads), this procedure is used to initialize
 119    --  interrupts handling in each task. Otherwise this function should
 120    --  only be called by initialize in this package body.
 121
 122 private
 123    type Interrupt_Mask is new System.OS_Interface.sigset_t;
 124    --  in some implementation Interrupt_Mask can be represented
 125    --  as a linked list.
 126 end System.Interrupt_Management;