gcc/ada/s-intman-vms.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 --          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,  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 -- 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 --  This is designed to work for both tasking and non-tasking systems, without
  43 --  pulling in any of the tasking support.
  44
  45 --  PLEASE DO NOT remove the Elaborate_Body pragma from this package.
  46 --  Elaboration of this package should happen early, as most other
  47
  48 --  Forcing immediate elaboration of the body also helps to enforce the design
  49 --  assumption that this is a second-level package, just one level above
  50 --  System.OS_Interface, with no cross-dependences.
  51
  52 --  PLEASE DO NOT put any subprogram declarations with arguments of type
  53 --  Interrupt_ID into the visible part of this package.
  54
  55 --  The type Interrupt_ID is used to derive the type in Ada.Interrupts, and
  56 --  adding more operations to that type would be illegal according to the Ada
  57 --  Reference Manual. (This is the reason why the signals sets below are
  58 --  implemented as visible arrays rather than functions.)
  59
  60 with System.OS_Interface;
  61 --  used for Signal
  62 --           sigset_t
  63
  64 package System.Interrupt_Management is
  65
  66    pragma Elaborate_Body;
  67
  68    type Interrupt_Mask is limited private;
  69
  70    type Interrupt_ID is new System.OS_Interface.Signal;
  71
  72    type Interrupt_Set is array (Interrupt_ID) of Boolean;
  73
  74    --  The following objects serve as constants, but are initialized in the
  75    --  body to aid portability. This permits us to use more portable names for
  76    --  interrupts, where distinct names may map to the same interrupt ID
  77    --  value. For example, suppose SIGRARE is a signal that is not defined on
  78    --  all systems, but is always reserved when it is defined. If we have the
  79    --  convention that ID zero is not used for any "real" signals, and SIGRARE
  80    --  = 0 when SIGRARE is not one of the locally supported signals, we can
  81    --  write
  82
  83    --     Reserved (SIGRARE) := true;
  84
  85    --  Then the initialization code will be portable
  86
  87    Abort_Task_Interrupt : Interrupt_ID;
  88    --  The interrupt that is used to implement task abort, if an interrupt is
  89    --  used for that purpose. This is one of the reserved interrupts.
  90
  91    Keep_Unmasked : Interrupt_Set := (others => False);
  92    --  Keep_Unmasked (I) is true iff the interrupt I is one that must be kept
  93    --  unmasked at all times, except (perhaps) for short critical sections.
  94    --  This includes interrupts that are mapped to exceptions (see
  95    --  System.Interrupt_Exceptions.Is_Exception), but may also include
  96    --  interrupts (e.g. timer) that need to be kept unmasked for other
  97    --  reasons. Where interrupts are implemented as OS signals, and signal
  98    --  masking 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 cannot be permitted
 102    --  to be attached to a user handler. The possible reasons are many. For
 103    --  example it may be mapped to an exception used to implement task abort.
 104
 105    Keep_Masked : Interrupt_Set := (others => False);
 106    --  Keep_Masked (I) is true iff the interrupt I must always be masked.
 107    --  Where interrupts are implemented as OS signals, and signal masking is
 108    --  per-task, the interrupt should be masked in ALL TASKS. There might not
 109    --  be any interrupts in this class, depending on the environment. For
 110    --  example, if interrupts are OS signals and signal masking is per-task,
 111    --  use of the sigwait operation requires the signal be masked in all tasks.
 112
 113    procedure Initialize_Interrupts;
 114    --  On systems where there is no signal inheritance between tasks (e.g
 115    --  VxWorks, GNU/LinuxThreads), this procedure is used to initialize
 116    --  interrupts handling in each task. Otherwise this function should
 117    --  only be called by initialize in this package body.
 118
 119 private
 120    use type System.OS_Interface.unsigned_long;
 121
 122    type Interrupt_Mask is new System.OS_Interface.sigset_t;
 123
 124    --  Interrupts on VMS are implemented with a mailbox. A QIO read is
 125    --  registered on the Rcv channel and the interrupt occurs by registering
 126    --  a QIO write on the Snd channel. The maximum number of pending
 127    --  interrupts is arbitrarily set at 1000. One nice feature of using
 128    --  a mailbox is that it is trivially extendable to cross process
 129    --  interrupts.
 130
 131    Rcv_Interrupt_Chan : System.OS_Interface.unsigned_short := 0;
 132    Snd_Interrupt_Chan : System.OS_Interface.unsigned_short := 0;
 133    Interrupt_Mailbox  : Interrupt_ID := 0;
 134    Interrupt_Bufquo   : System.OS_Interface.unsigned_long :=
 135                           1000 * (Interrupt_ID'Size / 8);
 136
 137 end System.Interrupt_Management;