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: 1.2 $
  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.       --
  32 -- Extensive contributions were provided by Ada Core Technologies Inc.      --
  33 --                                                                          --
  34 ------------------------------------------------------------------------------
  35 --
  36 --  This is the Alpha/VMS version of this package.
  37 --
  38 --  This package encapsulates and centralizes information about
  39 --  all uses of interrupts (or signals), including the
  40 --  target-dependent mapping of interrupts (or signals) to exceptions.
  41
  42 --  PLEASE DO NOT add any with-clauses to this package.
  43 --  This is designed to work for both tasking and non-tasking systems,
  44 --  without pulling in any of the tasking support.
  45
  46 --  PLEASE DO NOT remove the Elaborate_Body pragma from this package.
  47 --  Elaboration of this package should happen early, as most other
  48 --  initializations depend on it.
  49 --  Forcing immediate elaboration of the body also helps to enforce
  50 --  the design assumption that this is a second-level
  51 --  package, just one level above System.OS_Interface, with no
  52 --  cross-dependences.
  53
  54 --  PLEASE DO NOT put any subprogram declarations with arguments of
  55 --  type Interrupt_ID into the visible part of this package.
  56 --  The type Interrupt_ID is used to derive the type in Ada.Interrupts,
  57 --  and adding more operations to that type would be illegal according
  58 --  to the Ada Reference Manual.  (This is the reason why the signals sets
  59 --  below are implemented as visible arrays rather than functions.)
  60
  61 with System.OS_Interface;
  62 --  used for Signal
  63 --           sigset_t
  64
  65 package System.Interrupt_Management is
  66
  67    pragma Elaborate_Body;
  68
  69    type Interrupt_Mask is limited private;
  70
  71    type Interrupt_ID is new System.OS_Interface.Signal;
  72
  73    type Interrupt_Set is array (Interrupt_ID) of Boolean;
  74
  75    --  The following objects serve as constants, but are initialized
  76    --  in the body to aid portability.  This permits us
  77    --  to use more portable names for interrupts,
  78    --  where distinct names may map to the same interrupt ID value.
  79    --  For example, suppose SIGRARE is a signal that is not defined on
  80    --  all systems, but is always reserved when it is defined.
  81    --  If we have the convention that ID zero is not used for any "real"
  82    --  signals, and SIGRARE = 0 when SIGRARE is not one of the locally
  83    --  supported signals, we can write
  84    --     Reserved (SIGRARE) := true;
  85    --  and the initialization code will be portable.
  86
  87    Abort_Task_Interrupt : Interrupt_ID;
  88    --  The interrupt that is used to implement task abortion,
  89    --  if an interrupt is used for that purpose.
  90    --  This is one of the reserved interrupts.
  91
  92    Keep_Unmasked : Interrupt_Set := (others => False);
  93    --  Keep_Unmasked (I) is true iff the interrupt I is
  94    --  one that must be kept unmasked at all times,
  95    --  except (perhaps) for short critical sections.
  96    --  This includes interrupts that are mapped to exceptions
  97    --  (see System.Interrupt_Exceptions.Is_Exception), but may also
  98    --  include interrupts (e.g. timer) that need to be kept unmasked
  99    --  for other reasons.
 100    --  Where interrupts are implemented as OS signals, and signal masking
 101    --  is per-task, the interrupt should be unmasked in ALL TASKS.
 102
 103    Reserve : Interrupt_Set := (others => False);
 104    --  Reserve (I) is true iff the interrupt I is one that
 105    --  cannot be permitted to be attached to a user handler.
 106    --  The possible reasons are many.  For example,
 107    --  it may be mapped to an exception, used to implement task abortion,
 108    --  or used to implement time delays.
 109
 110    Keep_Masked : Interrupt_Set := (others => False);
 111    --  Keep_Masked (I) is true iff the interrupt I must always be masked.
 112    --  Where interrupts are implemented as OS signals, and signal masking
 113    --  is per-task, the interrupt should be masked in ALL TASKS.
 114    --  There might not be any interrupts in this class, depending on
 115    --  the environment.  For example, if interrupts are OS signals
 116    --  and signal masking is per-task, use of the sigwait operation
 117    --  requires the signal be masked in all tasks.
 118
 119    procedure Initialize_Interrupts;
 120    --  On systems where there is no signal inheritance between tasks (e.g
 121    --  VxWorks, GNU/LinuxThreads), this procedure is used to initialize
 122    --  interrupts handling in each task. Otherwise this function should
 123    --  only be called by initialize in this package body.
 124
 125 private
 126
 127    use type System.OS_Interface.unsigned_long;
 128
 129    type Interrupt_Mask is new System.OS_Interface.sigset_t;
 130
 131    --  Interrupts on VMS are implemented with a mailbox. A QIO read is
 132    --  registered on the Rcv channel and the interrupt occurs by registering
 133    --  a QIO write on the Snd channel. The maximum number of pending
 134    --  interrupts is arbitrarily set at 1000. One nice feature of using
 135    --  a mailbox is that it is trivially extendable to cross process
 136    --  interrupts.
 137
 138    Rcv_Interrupt_Chan : System.OS_Interface.unsigned_short := 0;
 139    Snd_Interrupt_Chan : System.OS_Interface.unsigned_short := 0;
 140    Interrupt_Mailbox  : Interrupt_ID := 0;
 141    Interrupt_Bufquo   : System.OS_Interface.unsigned_long
 142                         := 1000 * (Interrupt_ID'Size / 8);
 143
 144 end System.Interrupt_Management;