gcc/ada/5oosinte.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                 GNU ADA RUN-TIME LIBRARY (GNARL) COMPONENTS              --
   4 --                                                                          --
   5 --                   S Y S T E M . O S _ I N T E R F A C E                  --
   6 --                                                                          --
   7 --                                  B o d y                                 --
   8 --                                                                          --
   9 --                             $Revision$
  10 --                                                                          --
  11 --            Copyright (C) 1991-2001 Florida State University              --
  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. 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 --  This is the OS/2 version of this package
  38
  39 pragma Polling (Off);
  40 --  Turn off polling, we do not want ATC polling to take place during
  41 --  tasking operations. It causes infinite loops and other problems.
  42
  43 with Interfaces.C.Strings;
  44 with Interfaces.OS2Lib.Errors;
  45 with Interfaces.OS2Lib.Synchronization;
  46
  47 package body System.OS_Interface is
  48
  49    use Interfaces;
  50    use Interfaces.OS2Lib;
  51    use Interfaces.OS2Lib.Synchronization;
  52    use Interfaces.OS2Lib.Errors;
  53
  54    ------------------
  55    -- Timer (spec) --
  56    ------------------
  57
  58    --  Although the OS uses a 32-bit integer representing milliseconds
  59    --  as timer value that doesn't work for us since 32 bits are not
  60    --  enough for absolute timing. Also it is useful to use better
  61    --  intermediate precision when adding/substracting timing intervals.
  62    --  So we use the standard Ada Duration type which is implemented using
  63    --  microseconds.
  64
  65    --  Shouldn't the timer be moved to a separate package ???
  66
  67    type Timer is record
  68       Handle : aliased HTIMER := NULLHANDLE;
  69       Event  : aliased HEV    := NULLHANDLE;
  70    end record;
  71
  72    procedure Initialize (T :    out Timer);
  73    procedure Finalize   (T : in out Timer);
  74    procedure Wait       (T : in out Timer);
  75    procedure Reset      (T : in out Timer);
  76
  77    procedure Set_Timer_For (T : in out Timer; Period : in Duration);
  78    procedure Set_Timer_At  (T : in out Timer; Time   : in Duration);
  79    --  Add a hook to locate the Epoch, for use with Calendar????
  80
  81    -----------
  82    -- Yield --
  83    -----------
  84
  85    --  Give up the remainder of the time-slice and yield the processor
  86    --  to other threads of equal priority. Yield will return immediately
  87    --  without giving up the current time-slice when the only threads
  88    --  that are ready have a lower priority.
  89
  90    --  ???  Just giving up the current time-slice seems not to be enough
  91    --  to get the thread to the end of the ready queue if OS/2 does use
  92    --  a queue at all. As a partial work-around, we give up two time-slices.
  93
  94    --  This is the best we can do now, and at least is sufficient for passing
  95    --  the ACVC 2.0.1 Annex D tests.
  96
  97    procedure Yield is
  98    begin
  99       Delay_For (0);
 100       Delay_For (0);
 101    end Yield;
 102
 103    ---------------
 104    -- Delay_For --
 105    ---------------
 106
 107    procedure Delay_For (Period : in Duration_In_Millisec) is
 108       Result : APIRET;
 109
 110    begin
 111       pragma Assert (Period >= 0, "GNULLI---Delay_For: negative argument");
 112
 113       --  ??? DosSleep is not the appropriate function for a delay in real
 114       --  time. It only gives up some number of scheduled time-slices.
 115       --  Use a timer instead or block for some semaphore with a time-out.
 116       Result := DosSleep (ULONG (Period));
 117
 118       if Result = ERROR_TS_WAKEUP then
 119
 120          --  Do appropriate processing for interrupted sleep
 121          --  Can we raise an exception here?
 122
 123          null;
 124       end if;
 125
 126       pragma Assert (Result = NO_ERROR, "GNULLI---Error in Delay_For");
 127    end Delay_For;
 128
 129    -----------
 130    -- Clock --
 131    -----------
 132
 133    function Clock return Duration is
 134
 135       --  Implement conversion from tick count to Duration
 136       --  using fixed point arithmetic. The frequency of
 137       --  the Intel 8254 timer chip is 18.2 * 2**16 Hz.
 138
 139       Tick_Duration : constant := 1.0 / (18.2 * 2**16);
 140       Tick_Count    : aliased QWORD;
 141
 142    begin
 143
 144       --  Read nr of clock ticks since boot time
 145       Must_Not_Fail (DosTmrQueryTime (Tick_Count'Access));
 146
 147       return Tick_Count * Tick_Duration;
 148    end Clock;
 149
 150    ----------------------
 151    -- Initialize Timer --
 152    ----------------------
 153
 154    procedure Initialize (T : out Timer) is
 155    begin
 156       pragma Assert
 157         (T.Handle = NULLHANDLE, "GNULLI---Timer already initialized");
 158
 159       Must_Not_Fail (DosCreateEventSem
 160         (pszName => Interfaces.C.Strings.Null_Ptr,
 161          f_phev  => T.Event'Unchecked_Access,
 162          flAttr  => DC_SEM_SHARED,
 163          fState  => False32));
 164    end Initialize;
 165
 166    -------------------
 167    -- Set_Timer_For --
 168    -------------------
 169
 170    procedure Set_Timer_For
 171      (T         : in out Timer;
 172       Period    : in Duration)
 173    is
 174       Rel_Time  : Duration_In_Millisec :=
 175                     Duration_In_Millisec (Period * 1_000.0);
 176
 177    begin
 178       pragma Assert
 179         (T.Event /= NULLHANDLE, "GNULLI---Timer not initialized");
 180       pragma Assert
 181         (T.Handle = NULLHANDLE, "GNULLI---Timer already in use");
 182
 183       Must_Not_Fail (DosAsyncTimer
 184         (msec      => ULONG (Rel_Time),
 185          F_hsem    => HSEM (T.Event),
 186          F_phtimer => T.Handle'Unchecked_Access));
 187    end Set_Timer_For;
 188
 189    ------------------
 190    -- Set_Timer_At --
 191    ------------------
 192
 193    --  Note that the timer is started in a critical section to prevent the
 194    --  race condition when absolute time is converted to time relative to
 195    --  current time. T.Event will be posted when the Time has passed
 196
 197    procedure Set_Timer_At
 198      (T         : in out Timer;
 199       Time      : in Duration)
 200    is
 201       Relative_Time : Duration;
 202
 203    begin
 204       Must_Not_Fail (DosEnterCritSec);
 205
 206       begin
 207          Relative_Time := Time - Clock;
 208          if Relative_Time >  0.0 then
 209             Set_Timer_For (T, Period => Time - Clock);
 210          else
 211             Sem_Must_Not_Fail (DosPostEventSem (T.Event));
 212          end if;
 213       end;
 214
 215       Must_Not_Fail (DosExitCritSec);
 216    end Set_Timer_At;
 217
 218    ----------
 219    -- Wait --
 220    ----------
 221
 222    procedure Wait (T : in out Timer) is
 223    begin
 224       Sem_Must_Not_Fail (DosWaitEventSem (T.Event, SEM_INDEFINITE_WAIT));
 225       T.Handle := NULLHANDLE;
 226    end Wait;
 227
 228    -----------
 229    -- Reset --
 230    -----------
 231
 232    procedure Reset (T : in out Timer) is
 233       Dummy_Count : aliased ULONG;
 234
 235    begin
 236       if T.Handle /= NULLHANDLE then
 237          Must_Not_Fail (DosStopTimer (T.Handle));
 238          T.Handle := NULLHANDLE;
 239       end if;
 240
 241       Sem_Must_Not_Fail
 242         (DosResetEventSem (T.Event, Dummy_Count'Unchecked_Access));
 243    end Reset;
 244
 245    --------------
 246    -- Finalize --
 247    --------------
 248
 249    procedure Finalize (T : in out Timer) is
 250    begin
 251       Reset (T);
 252       Must_Not_Fail (DosCloseEventSem (T.Event));
 253       T.Event := NULLHANDLE;
 254    end Finalize;
 255
 256 end System.OS_Interface;