gcc/ada/s-intman-vms.ads

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                 GNAT 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 --          Copyright (C) 1991-2005 Free Software Foundation, Inc.          --
  10 --                                                                          --
  11 -- GNARL 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. GNARL 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 GNARL; see file COPYING.  If not, write --
  19 -- to  the  Free Software Foundation,  51  Franklin  Street,  Fifth  Floor, --
  20 -- Boston, MA 02110-1301, 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 -- GNARL was developed by the GNARL team at Florida State University.       --
  30 -- Extensive contributions were provided by Ada Core Technologies, Inc.     --
  31 --                                                                          --
  32 ------------------------------------------------------------------------------
  33
  34 --  This is the Alpha/VMS version of this package
  35
  36 --  This package encapsulates and centralizes information about all uses of
  37 --  interrupts (or signals), including the target-dependent mapping of
  38 --  interrupts (or signals) to exceptions.
  39
  40 --  PLEASE DO NOT add any with-clauses to this package
  41
  42 --  PLEASE DO NOT put any subprogram declarations with arguments of type
  43 --  Interrupt_ID into the visible part of this package.
  44
  45 --  The type Interrupt_ID is used to derive the type in Ada.Interrupts, and
  46 --  adding more operations to that type would be illegal according to the Ada
  47 --  Reference Manual. (This is the reason why the signals sets below are
  48 --  implemented as visible arrays rather than functions.)
  49
  50 with System.OS_Interface;
  51 --  used for Signal
  52 --           sigset_t
  53
  54 package System.Interrupt_Management is
  55    pragma Preelaborate;
  56
  57    type Interrupt_Mask is limited private;
  58
  59    type Interrupt_ID is new System.OS_Interface.Signal;
  60
  61    type Interrupt_Set is array (Interrupt_ID) of Boolean;
  62
  63    --  The following objects serve as constants, but are initialized in the
  64    --  body to aid portability. This permits us to use more portable names for
  65    --  interrupts, where distinct names may map to the same interrupt ID
  66    --  value. For example, suppose SIGRARE is a signal that is not defined on
  67    --  all systems, but is always reserved when it is defined. If we have the
  68    --  convention that ID zero is not used for any "real" signals, and SIGRARE
  69    --  = 0 when SIGRARE is not one of the locally supported signals, we can
  70    --  write
  71
  72    --     Reserved (SIGRARE) := true;
  73
  74    --  Then the initialization code will be portable
  75
  76    Abort_Task_Interrupt : Interrupt_ID;
  77    --  The interrupt that is used to implement task abort, if an interrupt is
  78    --  used for that purpose. This is one of the reserved interrupts.
  79
  80    Keep_Unmasked : Interrupt_Set := (others => False);
  81    --  Keep_Unmasked (I) is true iff the interrupt I is one that must be kept
  82    --  unmasked at all times, except (perhaps) for short critical sections.
  83    --  This includes interrupts that are mapped to exceptions (see
  84    --  System.Interrupt_Exceptions.Is_Exception), but may also include
  85    --  interrupts (e.g. timer) that need to be kept unmasked for other
  86    --  reasons. Where interrupts are implemented as OS signals, and signal
  87    --  masking is per-task, the interrupt should be unmasked in ALL TASKS.
  88
  89    Reserve : Interrupt_Set := (others => False);
  90    --  Reserve (I) is true iff the interrupt I is one that cannot be permitted
  91    --  to be attached to a user handler. The possible reasons are many. For
  92    --  example it may be mapped to an exception used to implement task abort.
  93
  94    Keep_Masked : Interrupt_Set := (others => False);
  95    --  Keep_Masked (I) is true iff the interrupt I must always be masked.
  96    --  Where interrupts are implemented as OS signals, and signal masking is
  97    --  per-task, the interrupt should be masked in ALL TASKS. There might not
  98    --  be any interrupts in this class, depending on the environment. For
  99    --  example, if interrupts are OS signals and signal masking is per-task,
 100    --  use of the sigwait operation requires the signal be masked in all tasks.
 101
 102    procedure Initialize;
 103    --  Initialize the various variables defined in this package.
 104    --  This procedure must be called before accessing any object from this
 105    --  package and can be called multiple times.
 106
 107 private
 108    use type System.OS_Interface.unsigned_long;
 109
 110    type Interrupt_Mask is new System.OS_Interface.sigset_t;
 111
 112    --  Interrupts on VMS are implemented with a mailbox. A QIO read is
 113    --  registered on the Rcv channel and the interrupt occurs by registering
 114    --  a QIO write on the Snd channel. The maximum number of pending
 115    --  interrupts is arbitrarily set at 1000. One nice feature of using
 116    --  a mailbox is that it is trivially extendable to cross process
 117    --  interrupts.
 118
 119    Rcv_Interrupt_Chan : System.OS_Interface.unsigned_short := 0;
 120    Snd_Interrupt_Chan : System.OS_Interface.unsigned_short := 0;
 121    Interrupt_Mailbox  : Interrupt_ID := 0;
 122    Interrupt_Bufquo   : System.OS_Interface.unsigned_long :=
 123                           1000 * (Interrupt_ID'Size / 8);
 124
 125 end System.Interrupt_Management;