gcc/ada/5vintman.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 --                             $Revision$
  10 --                                                                          --
  11 --          Copyright (C) 1991-2001 Free Software Foundation, Inc.          --
  12 --                                                                          --
  13 -- GNARL is free software; you can  redistribute it  and/or modify it under --
  14 -- terms of the  GNU General Public License as published  by the Free Soft- --
  15 -- ware  Foundation;  either version 2,  or (at your option) any later ver- --
  16 -- sion. GNARL is distributed in the hope that it will be useful, but WITH- --
  17 -- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
  18 -- or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License --
  19 -- for  more details.  You should have  received  a copy of the GNU General --
  20 -- Public License  distributed with GNARL; see file COPYING.  If not, write --
  21 -- to  the Free Software Foundation,  59 Temple Place - Suite 330,  Boston, --
  22 -- MA 02111-1307, USA.                                                      --
  23 --                                                                          --
  24 -- As a special exception,  if other files  instantiate  generics from this --
  25 -- unit, or you link  this unit with other files  to produce an executable, --
  26 -- this  unit  does not  by itself cause  the resulting  executable  to  be --
  27 -- covered  by the  GNU  General  Public  License.  This exception does not --
  28 -- however invalidate  any other reasons why  the executable file  might be --
  29 -- covered by the  GNU Public License.                                      --
  30 --                                                                          --
  31 -- GNARL was developed by the GNARL team at Florida State University. It is --
  32 -- now maintained by Ada Core Technologies Inc. in cooperation with Florida --
  33 -- State University (http://www.gnat.com).                                  --
  34 --                                                                          --
  35 ------------------------------------------------------------------------------
  36 --
  37 --  This is the Alpha/VMS version of this package.
  38 --
  39 --  This package encapsulates and centralizes information about
  40 --  all uses of interrupts (or signals), including the
  41 --  target-dependent mapping of interrupts (or signals) to exceptions.
  42
  43 --  PLEASE DO NOT add any with-clauses to this package.
  44 --  This is designed to work for both tasking and non-tasking systems,
  45 --  without pulling in any of the tasking support.
  46
  47 --  PLEASE DO NOT remove the Elaborate_Body pragma from this package.
  48 --  Elaboration of this package should happen early, as most other
  49 --  initializations depend on it.
  50 --  Forcing immediate elaboration of the body also helps to enforce
  51 --  the design assumption that this is a second-level
  52 --  package, just one level above System.OS_Interface, with no
  53 --  cross-dependences.
  54
  55 --  PLEASE DO NOT put any subprogram declarations with arguments of
  56 --  type Interrupt_ID into the visible part of this package.
  57 --  The type Interrupt_ID is used to derive the type in Ada.Interrupts,
  58 --  and adding more operations to that type would be illegal according
  59 --  to the Ada Reference Manual.  (This is the reason why the signals sets
  60 --  below are implemented as visible arrays rather than functions.)
  61
  62 with System.OS_Interface;
  63 --  used for Signal
  64 --           sigset_t
  65
  66 package System.Interrupt_Management is
  67
  68    pragma Elaborate_Body;
  69
  70    type Interrupt_Mask is limited private;
  71
  72    type Interrupt_ID is new System.OS_Interface.Signal;
  73
  74    type Interrupt_Set is array (Interrupt_ID) of Boolean;
  75
  76    --  The following objects serve as constants, but are initialized
  77    --  in the body to aid portability.  This permits us
  78    --  to use more portable names for interrupts,
  79    --  where distinct names may map to the same interrupt ID value.
  80    --  For example, suppose SIGRARE is a signal that is not defined on
  81    --  all systems, but is always reserved when it is defined.
  82    --  If we have the convention that ID zero is not used for any "real"
  83    --  signals, and SIGRARE = 0 when SIGRARE is not one of the locally
  84    --  supported signals, we can write
  85    --     Reserved (SIGRARE) := true;
  86    --  and the initialization code will be portable.
  87
  88    Abort_Task_Interrupt : Interrupt_ID;
  89    --  The interrupt that is used to implement task abortion,
  90    --  if an interrupt is used for that purpose.
  91    --  This is one of the reserved interrupts.
  92
  93    Keep_Unmasked : Interrupt_Set := (others => False);
  94    --  Keep_Unmasked (I) is true iff the interrupt I is
  95    --  one that must be kept unmasked at all times,
  96    --  except (perhaps) for short critical sections.
  97    --  This includes interrupts that are mapped to exceptions
  98    --  (see System.Interrupt_Exceptions.Is_Exception), but may also
  99    --  include interrupts (e.g. timer) that need to be kept unmasked
 100    --  for other reasons.
 101    --  Where interrupts are implemented as OS signals, and signal masking
 102    --  is per-task, the interrupt should be unmasked in ALL TASKS.
 103
 104    Reserve : Interrupt_Set := (others => False);
 105    --  Reserve (I) is true iff the interrupt I is one that
 106    --  cannot be permitted to be attached to a user handler.
 107    --  The possible reasons are many.  For example,
 108    --  it may be mapped to an exception, used to implement task abortion,
 109    --  or used to implement time delays.
 110
 111    Keep_Masked : Interrupt_Set := (others => False);
 112    --  Keep_Masked (I) is true iff the interrupt I must always be masked.
 113    --  Where interrupts are implemented as OS signals, and signal masking
 114    --  is per-task, the interrupt should be masked in ALL TASKS.
 115    --  There might not be any interrupts in this class, depending on
 116    --  the environment.  For example, if interrupts are OS signals
 117    --  and signal masking is per-task, use of the sigwait operation
 118    --  requires the signal be masked in all tasks.
 119
 120    procedure Initialize_Interrupts;
 121    --  On systems where there is no signal inheritance between tasks (e.g
 122    --  VxWorks, GNU/LinuxThreads), this procedure is used to initialize
 123    --  interrupts handling in each task. Otherwise this function should
 124    --  only be called by initialize in this package body.
 125
 126 private
 127
 128    use type System.OS_Interface.unsigned_long;
 129
 130    type Interrupt_Mask is new System.OS_Interface.sigset_t;
 131
 132    --  Interrupts on VMS are implemented with a mailbox. A QIO read is
 133    --  registered on the Rcv channel and the interrupt occurs by registering
 134    --  a QIO write on the Snd channel. The maximum number of pending
 135    --  interrupts is arbitrarily set at 1000. One nice feature of using
 136    --  a mailbox is that it is trivially extendable to cross process
 137    --  interrupts.
 138
 139    Rcv_Interrupt_Chan : System.OS_Interface.unsigned_short := 0;
 140    Snd_Interrupt_Chan : System.OS_Interface.unsigned_short := 0;
 141    Interrupt_Mailbox  : Interrupt_ID := 0;
 142    Interrupt_Bufquo   : System.OS_Interface.unsigned_long
 143                         := 1000 * (Interrupt_ID'Size / 8);
 144
 145 end System.Interrupt_Management;