gcc/ada/s-interr.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 S                    --
   6 --                                                                          --
   7 --                                  S p e c                                 --
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   9 --          Copyright (C) 1992-2008, Free Software Foundation, Inc.         --
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  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 --
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  27 -- covered by the  GNU Public License.                                      --
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  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 --  Note: the compiler generates direct calls to this interface, via Rtsfind.
  35 --  Any changes to this interface may require corresponding compiler changes.
  36
  37 --  This package encapsulates the implementation of interrupt or signal
  38 --  handlers. It is logically an extension of the body of Ada.Interrupts. It
  39 --  is made a child of System to allow visibility of various runtime system
  40 --  internal data and operations.
  41
  42 --  See System.Interrupt_Management for core interrupt/signal interfaces
  43
  44 --  These two packages are separated to allow System.Interrupt_Management to be
  45 --  used without requiring the whole tasking implementation to be linked and
  46 --  elaborated.
  47
  48 with System.Tasking;
  49 with System.Tasking.Protected_Objects.Entries;
  50 with System.OS_Interface;
  51
  52 package System.Interrupts is
  53
  54    pragma Elaborate_Body;
  55    --  Comment needed on why this is here ???
  56
  57    -------------------------
  58    -- Constants and types --
  59    -------------------------
  60
  61    Default_Interrupt_Priority : constant System.Interrupt_Priority :=
  62      System.Interrupt_Priority'Last;
  63    --  Default value used when a pragma Interrupt_Handler or Attach_Handler is
  64    --  specified without an Interrupt_Priority pragma, see D.3(10).
  65
  66    type Ada_Interrupt_ID is range 0 .. System.OS_Interface.Max_Interrupt;
  67    --  Avoid inheritance by Ada.Interrupts.Interrupt_ID of unwanted operations
  68
  69    type Interrupt_ID is range 0 .. System.OS_Interface.Max_Interrupt;
  70
  71    subtype System_Interrupt_Id is Interrupt_ID;
  72    --  This synonym is introduced so that the type is accessible through
  73    --  rtsfind, otherwise the name clashes with its homonym in Ada.Interrupts.
  74
  75    type Parameterless_Handler is access protected procedure;
  76
  77    ----------------------
  78    -- General services --
  79    ----------------------
  80
  81    --  Attempt to attach a Handler to an Interrupt to which an Entry is
  82    --  already bound will raise a Program_Error.
  83
  84    function Is_Reserved (Interrupt : Interrupt_ID) return Boolean;
  85
  86    function Is_Entry_Attached (Interrupt : Interrupt_ID) return Boolean;
  87
  88    function Is_Handler_Attached (Interrupt : Interrupt_ID) return Boolean;
  89
  90    function Current_Handler
  91      (Interrupt : Interrupt_ID) return Parameterless_Handler;
  92
  93    --  Calling the following procedures with New_Handler = null and Static =
  94    --  true means that we want to modify the current handler regardless of the
  95    --  previous handler's binding status. (i.e. we do not care whether it is a
  96    --  dynamic or static handler)
  97
  98    procedure Attach_Handler
  99      (New_Handler : Parameterless_Handler;
 100       Interrupt   : Interrupt_ID;
 101       Static      : Boolean := False);
 102
 103    procedure Exchange_Handler
 104      (Old_Handler : out Parameterless_Handler;
 105       New_Handler : Parameterless_Handler;
 106       Interrupt   : Interrupt_ID;
 107       Static      : Boolean := False);
 108
 109    procedure Detach_Handler
 110      (Interrupt : Interrupt_ID;
 111       Static    : Boolean := False);
 112
 113    function Reference
 114      (Interrupt : Interrupt_ID) return System.Address;
 115
 116    --------------------------------
 117    -- Interrupt Entries Services --
 118    --------------------------------
 119
 120    --  Routines needed for Interrupt Entries
 121
 122    procedure Bind_Interrupt_To_Entry
 123      (T       : System.Tasking.Task_Id;
 124       E       : System.Tasking.Task_Entry_Index;
 125       Int_Ref : System.Address);
 126    --  Bind the given interrupt to the given entry. If the interrupt is
 127    --  already bound to another entry, Program_Error will be raised.
 128
 129    procedure Detach_Interrupt_Entries (T : System.Tasking.Task_Id);
 130    --  This procedure detaches all the Interrupt Entries bound to a task
 131
 132    ------------------------------
 133    -- POSIX.5 Signals Services --
 134    ------------------------------
 135
 136    --  Routines needed for POSIX dot5 POSIX_Signals
 137
 138    procedure Block_Interrupt (Interrupt : Interrupt_ID);
 139    --  Block the Interrupt on the process level
 140
 141    procedure Unblock_Interrupt (Interrupt : Interrupt_ID);
 142
 143    function Unblocked_By
 144      (Interrupt : Interrupt_ID) return System.Tasking.Task_Id;
 145    --  It returns the ID of the last Task which Unblocked this Interrupt.
 146    --  It returns Null_Task if no tasks have ever requested the Unblocking
 147    --  operation or the Interrupt is currently Blocked.
 148
 149    function Is_Blocked (Interrupt : Interrupt_ID) return Boolean;
 150    --  Comment needed ???
 151
 152    procedure Ignore_Interrupt (Interrupt : Interrupt_ID);
 153    --  Set the sigaction for the interrupt to SIG_IGN
 154
 155    procedure Unignore_Interrupt (Interrupt : Interrupt_ID);
 156    --  Comment needed ???
 157
 158    function Is_Ignored (Interrupt : Interrupt_ID) return Boolean;
 159    --  Comment needed ???
 160
 161    --  Note : Direct calls to sigaction, sigprocmask, thr_sigsetmask or any
 162    --  other low-level interface that changes the signal action or signal mask
 163    --  needs a careful thought.
 164
 165    --  One may achieve the effect of system calls first making RTS blocked (by
 166    --  calling Block_Interrupt) for the signal under consideration. This will
 167    --  make all the tasks in RTS blocked for the Interrupt.
 168
 169    ----------------------
 170    -- Protection Types --
 171    ----------------------
 172
 173    --  Routines and types needed to implement Interrupt_Handler and
 174    --  Attach_Handler.
 175
 176    --  There are two kinds of protected objects that deal with interrupts:
 177
 178    --  (1) Only Interrupt_Handler pragmas are used. We need to be able to tell
 179    --  if an Interrupt_Handler applies to a given procedure, so
 180    --  Register_Interrupt_Handler has to be called for all the potential
 181    --  handlers, it should be done by calling Register_Interrupt_Handler with
 182    --  the handler code address. On finalization, which can happen only has
 183    --  part of library level finalization since PO with Interrupt_Handler
 184    --  pragmas can only be declared at library level, nothing special needs to
 185    --  be done since the default handlers have been restored as part of task
 186    --  completion which is done just before global finalization.
 187    --  Dynamic_Interrupt_Protection should be used in this case.
 188
 189    --  (2) Attach_Handler pragmas are used, and possibly Interrupt_Handler
 190    --  pragma. We need to attach the handlers to the given interrupts when the
 191    --  object is elaborated. This should be done by constructing an array of
 192    --  pairs (interrupt, handler) from the pragmas and calling Install_Handlers
 193    --  with it (types to be used are New_Handler_Item and New_Handler_Array).
 194    --  On finalization, we need to restore the handlers that were installed
 195    --  before the elaboration of the PO, so we need to store these previous
 196    --  handlers. This is also done by Install_Handlers, the room for these
 197    --  informations is provided by adding a discriminant which is the number
 198    --  of Attach_Handler pragmas and an array of this size in the protection
 199    --  type, Static_Interrupt_Protection.
 200
 201    procedure Register_Interrupt_Handler
 202      (Handler_Addr : System.Address);
 203    --  This routine should be called by the compiler to allow the handler be
 204    --  used as an Interrupt Handler. That means call this procedure for each
 205    --  pragma Interrupt_Handler providing the address of the handler (not
 206    --  including the pointer to the actual PO, this way this routine is called
 207    --  only once for each type definition of PO).
 208
 209    type Static_Handler_Index is range 0 .. Integer'Last;
 210    subtype Positive_Static_Handler_Index is
 211      Static_Handler_Index range 1 .. Static_Handler_Index'Last;
 212    --  Comment needed ???
 213
 214    type Previous_Handler_Item is record
 215       Interrupt : Interrupt_ID;
 216       Handler   : Parameterless_Handler;
 217       Static    : Boolean;
 218    end record;
 219    --  Contains all the information needed to restore a previous handler
 220
 221    type Previous_Handler_Array is array
 222      (Positive_Static_Handler_Index range <>) of Previous_Handler_Item;
 223
 224    type New_Handler_Item is record
 225       Interrupt : Interrupt_ID;
 226       Handler   : Parameterless_Handler;
 227    end record;
 228    --  Contains all the information from an Attach_Handler pragma
 229
 230    type New_Handler_Array is
 231      array (Positive_Static_Handler_Index range <>) of New_Handler_Item;
 232    --  Comment needed ???
 233
 234    --  Case (1)
 235
 236    type Dynamic_Interrupt_Protection is new
 237      Tasking.Protected_Objects.Entries.Protection_Entries with null record;
 238
 239    --  ??? Finalize is not overloaded since we currently have no
 240    --  way to detach the handlers during library level finalization.
 241
 242    function Has_Interrupt_Or_Attach_Handler
 243      (Object : access Dynamic_Interrupt_Protection) return Boolean;
 244    --  Returns True
 245
 246    --  Case (2)
 247
 248    type Static_Interrupt_Protection
 249      (Num_Entries        : Tasking.Protected_Objects.Protected_Entry_Index;
 250       Num_Attach_Handler : Static_Handler_Index)
 251    is new
 252      Tasking.Protected_Objects.Entries.Protection_Entries (Num_Entries) with
 253      record
 254        Previous_Handlers : Previous_Handler_Array (1 .. Num_Attach_Handler);
 255      end record;
 256
 257    function Has_Interrupt_Or_Attach_Handler
 258      (Object : access Static_Interrupt_Protection) return Boolean;
 259    --  Returns True
 260
 261    procedure Finalize (Object : in out Static_Interrupt_Protection);
 262    --  Restore previous handlers as required by C.3.1(12) then call
 263    --  Finalize (Protection).
 264
 265    procedure Install_Handlers
 266      (Object       : access Static_Interrupt_Protection;
 267       New_Handlers : New_Handler_Array);
 268    --  Store the old handlers in Object.Previous_Handlers and install
 269    --  the new static handlers.
 270
 271    procedure Install_Restricted_Handlers (Handlers : New_Handler_Array);
 272    --  Install the static Handlers for the given interrupts and do not store
 273    --  previously installed handlers. This procedure is used when the Ravenscar
 274    --  restrictions are in place since in that case there are only
 275    --  library-level protected handlers that will be installed at
 276    --  initialization and never be replaced.
 277
 278 end System.Interrupts;