gcc/ada/s-interr.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 S                    --
   6 --                                                                          --
   7 --                                  S p e c                                 --
   8 --                                                                          --
   9 --                             $Revision: 1.18 $
  10 --                                                                          --
  11 --          Copyright (C) 1992-2001 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- --
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  16 -- sion. GNARL is distributed in the hope that it will be useful, but WITH- --
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  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 --
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  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 --  Note: the compiler generates direct calls to this interface, via Rtsfind.
  38 --  Any changes to this interface may require corresponding compiler changes.
  39
  40 --  This package encapsulates the implementation of interrupt or signal
  41 --  handlers.  It is logically an extension of the body of Ada.Interrupts.
  42 --  It is made a child of System to allow visibility of various
  43 --  runtime system internal data and operations.
  44
  45 --  See System.Interrupt_Management for core interrupt/signal interfaces.
  46
  47 --  These two packages are separated in order to allow
  48 --  System.Interrupt_Management to be used without requiring the whole
  49 --  tasking implementation to be linked and elaborated.
  50
  51 with System.Tasking;
  52 --  used for Task_ID
  53
  54 with System.Tasking.Protected_Objects.Entries;
  55 --  used for Protection_Entries
  56
  57 with System.OS_Interface;
  58 --  used for Max_Interrupt
  59
  60 package System.Interrupts is
  61
  62    pragma Elaborate_Body;
  63    --  Comment needed on why this is here ???
  64
  65    -------------------------
  66    -- Constants and types --
  67    -------------------------
  68
  69    Default_Interrupt_Priority : constant System.Interrupt_Priority :=
  70      System.Interrupt_Priority'Last;
  71    --  Default value used when a pragma Interrupt_Handler or Attach_Handler is
  72    --  specified without an Interrupt_Priority pragma, see D.3(10).
  73
  74    type Ada_Interrupt_ID is range 0 .. System.OS_Interface.Max_Interrupt;
  75    --  Avoid inheritance by Ada.Interrupts.Interrupt_ID of unwanted operations
  76
  77    type Interrupt_ID is range 0 .. System.OS_Interface.Max_Interrupt;
  78
  79    type Parameterless_Handler is access protected procedure;
  80
  81    ----------------------
  82    -- General services --
  83    ----------------------
  84
  85    --  Attempt to attach a Handler to an Interrupt to which an Entry is
  86    --  already bound will raise a Program_Error.
  87
  88    function Is_Reserved (Interrupt : Interrupt_ID) return Boolean;
  89
  90    function Is_Entry_Attached (Interrupt : Interrupt_ID) return Boolean;
  91
  92    function Is_Handler_Attached (Interrupt : Interrupt_ID) return Boolean;
  93
  94    function Current_Handler
  95      (Interrupt : Interrupt_ID)
  96       return Parameterless_Handler;
  97
  98    --  Calling the following procedures with New_Handler = null
  99    --  and Static = true means that we want to modify the current handler
 100    --  regardless of the previous handler's binding status.
 101    --  (i.e. we do not care whether it is a dynamic or static handler)
 102
 103    procedure Attach_Handler
 104      (New_Handler : Parameterless_Handler;
 105       Interrupt   : Interrupt_ID;
 106       Static      : Boolean := False);
 107
 108    procedure Exchange_Handler
 109      (Old_Handler : out Parameterless_Handler;
 110       New_Handler : Parameterless_Handler;
 111       Interrupt   : Interrupt_ID;
 112       Static      : Boolean := False);
 113
 114    procedure Detach_Handler
 115      (Interrupt : Interrupt_ID;
 116       Static    : Boolean := False);
 117
 118    function Reference
 119      (Interrupt : Interrupt_ID)
 120      return       System.Address;
 121
 122    ---------------------------------
 123    --  Interrupt entries services --
 124    ---------------------------------
 125
 126    --  Routines needed for Interrupt Entries
 127    --  Attempt to bind an Entry to an Interrupt to which a Handler is
 128    --  already attached will raise a Program_Error.
 129
 130    procedure Bind_Interrupt_To_Entry
 131      (T       : System.Tasking.Task_ID;
 132       E       : System.Tasking.Task_Entry_Index;
 133       Int_Ref : System.Address);
 134
 135    procedure Detach_Interrupt_Entries (T : System.Tasking.Task_ID);
 136    --  This procedure detaches all the Interrupt Entries bound to a task.
 137
 138    -------------------------------
 139    --  POSIX.5 signals services --
 140    -------------------------------
 141
 142    --  Routines needed for POSIX dot5 POSIX_Signals
 143
 144    procedure Block_Interrupt (Interrupt : Interrupt_ID);
 145    --  Block the Interrupt on the process level
 146
 147    procedure Unblock_Interrupt (Interrupt : Interrupt_ID);
 148
 149    function Unblocked_By
 150      (Interrupt   : Interrupt_ID)
 151       return System.Tasking.Task_ID;
 152    --  It returns the ID of the last Task which Unblocked this Interrupt.
 153    --  It returns Null_Task if no tasks have ever requested the
 154    --  Unblocking operation or the Interrupt is currently Blocked.
 155
 156    function Is_Blocked (Interrupt : Interrupt_ID) return Boolean;
 157    --  Comment needed ???
 158
 159    procedure Ignore_Interrupt (Interrupt : Interrupt_ID);
 160    --  Set the sigacion for the interrupt to SIG_IGN.
 161
 162    procedure Unignore_Interrupt (Interrupt : Interrupt_ID);
 163    --  Comment needed ???
 164
 165    function Is_Ignored (Interrupt : Interrupt_ID) return Boolean;
 166    --  Comment needed ???
 167
 168    --  Note : Direct calls to sigaction, sigprocmask, thr_sigsetmask or any
 169    --  other low-level interface that changes the signal action or signal mask
 170    --  needs a careful thought.
 171
 172    --  One may acheive the effect of system calls first making RTS blocked
 173    --  (by calling Block_Interrupt) for the signal under consideration.
 174    --  This will make all the tasks in RTS blocked for the Interrupt.
 175
 176    ----------------------
 177    -- Protection types --
 178    ----------------------
 179
 180    --  Routines and types needed to implement Interrupt_Handler and
 181    --  Attach_Handler.
 182
 183    --  There are two kinds of protected objects that deal with interrupts:
 184
 185    --  (1) Only Interrupt_Handler pragmas are used. We need to be able to
 186    --  tell if an Interrupt_Handler applies to a given procedure, so
 187    --  Register_Interrupt_Handler has to be called for all the potential
 188    --  handlers, it should be done by calling Register_Interrupt_Handler
 189    --  with the handler code address. On finalization, which can happen only
 190    --  has part of library level finalization since PO with
 191    --  Interrupt_Handler pragmas can only be declared at library level,
 192    --  nothing special needs to be done since the default handlers have been
 193    --  restored as part of task completion which is done just before global
 194    --  finalization.  Dynamic_Interrupt_Protection should be used in this
 195    --  case.
 196
 197    --  (2) Attach_Handler pragmas are used, and possibly Interrupt_Handler
 198    --  pragma. We need to attach the handlers to the given interrupts when
 199    --  the objet is elaborated. This should be done by constructing an array
 200    --  of pairs (interrupt, handler) from the pragmas and calling
 201    --  Install_Handlers with it (types to be used are New_Handler_Item and
 202    --  New_Handler_Array). On finalization, we need to restore the handlers
 203    --  that were installed before the elaboration of the PO, so we need to
 204    --  store these previous handlers. This is also done by Install_Handlers,
 205    --  the room for these informations is provided by adding a discriminant
 206    --  which is the number of Attach_Handler pragmas and an array of this
 207    --  size in the protection type, Static_Interrupt_Protection.
 208
 209    procedure Register_Interrupt_Handler
 210      (Handler_Addr : System.Address);
 211    --  This routine should be called by the compiler to allow the
 212    --  handler be used as an Interrupt Handler. That means call this
 213    --  procedure for each pragma Interrup_Handler providing the
 214    --  address of the handler (not including the pointer to the
 215    --  actual PO, this way this routine is called only once for
 216    --  each type definition of PO).
 217
 218    type Static_Handler_Index is range 0 .. Integer'Last;
 219    subtype Positive_Static_Handler_Index is
 220      Static_Handler_Index range 1 .. Static_Handler_Index'Last;
 221    --  Comment needed ???
 222
 223    type Previous_Handler_Item is record
 224       Interrupt : Interrupt_ID;
 225       Handler   : Parameterless_Handler;
 226       Static    : Boolean;
 227    end record;
 228    --  Contains all the information needed to restore a previous handler.
 229
 230    type Previous_Handler_Array is array
 231      (Positive_Static_Handler_Index range <>) of Previous_Handler_Item;
 232
 233    type New_Handler_Item is record
 234       Interrupt : Interrupt_ID;
 235       Handler   : Parameterless_Handler;
 236    end record;
 237    --  Contains all the information from an Attach_Handler pragma.
 238
 239    type New_Handler_Array is
 240      array (Positive_Static_Handler_Index range <>) of New_Handler_Item;
 241    --  Comment needed ???
 242
 243    --  Case (1)
 244
 245    type Dynamic_Interrupt_Protection is new
 246      Tasking.Protected_Objects.Entries.Protection_Entries with null record;
 247
 248    --  ??? Finalize is not overloaded since we currently have no
 249    --  way to detach the handlers during library level finalization.
 250
 251    function Has_Interrupt_Or_Attach_Handler
 252      (Object : access Dynamic_Interrupt_Protection) return Boolean;
 253    --  Returns True.
 254
 255    --  Case (2)
 256
 257    type Static_Interrupt_Protection
 258      (Num_Entries        : Tasking.Protected_Objects.Protected_Entry_Index;
 259       Num_Attach_Handler : Static_Handler_Index)
 260    is new
 261      Tasking.Protected_Objects.Entries.Protection_Entries (Num_Entries) with
 262      record
 263        Previous_Handlers : Previous_Handler_Array (1 .. Num_Attach_Handler);
 264      end record;
 265
 266    function Has_Interrupt_Or_Attach_Handler
 267      (Object : access Static_Interrupt_Protection)
 268       return   Boolean;
 269    --  Returns True.
 270
 271    procedure Finalize (Object : in out Static_Interrupt_Protection);
 272    --  Restore previous handlers as required by C.3.1(12) then call
 273    --  Finalize (Protection).
 274
 275    procedure Install_Handlers
 276      (Object       : access Static_Interrupt_Protection;
 277       New_Handlers : in New_Handler_Array);
 278    --  Store the old handlers in Object.Previous_Handlers and install
 279    --  the new static handlers.
 280
 281 end System.Interrupts;