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 --                                                                          --
  10 --            Copyright (C) 1991-2002 Florida State University              --
  11 --                                                                          --
  12 -- GNARL is free software; you can  redistribute it  and/or modify it under --
  13 -- terms of the  GNU General Public License as published  by the Free Soft- --
  14 -- ware  Foundation;  either version 2,  or (at your option) any later ver- --
  15 -- sion. GNARL is distributed in the hope that it will be useful, but WITH- --
  16 -- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
  17 -- or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License --
  18 -- for  more details.  You should have  received  a copy of the GNU General --
  19 -- Public License  distributed with GNARL; see file COPYING.  If not, write --
  20 -- to  the Free Software Foundation,  59 Temple Place - Suite 330,  Boston, --
  21 -- MA 02111-1307, USA.                                                      --
  22 --                                                                          --
  23 -- As a special exception,  if other files  instantiate  generics from this --
  24 -- unit, or you link  this unit with other files  to produce an executable, --
  25 -- this  unit  does not  by itself cause  the resulting  executable  to  be --
  26 -- covered  by the  GNU  General  Public  License.  This exception does not --
  27 -- however invalidate  any other reasons why  the executable file  might be --
  28 -- covered by the  GNU Public License.                                      --
  29 --                                                                          --
  30 -- GNARL was developed by the GNARL team at Florida State University. It is --
  31 -- now maintained by Ada Core Technologies Inc. in cooperation with Florida --
  32 -- State University (http://www.gnat.com).                                  --
  33 --                                                                          --
  34 ------------------------------------------------------------------------------
  35
  36 --  This is the OS/2 version of this package
  37
  38 pragma Polling (Off);
  39 --  Turn off polling, we do not want ATC polling to take place during
  40 --  tasking operations. It causes infinite loops and other problems.
  41
  42 with Interfaces.OS2Lib.Errors;
  43 with Interfaces.OS2Lib.Synchronization;
  44
  45 package body System.OS_Interface is
  46
  47    use Interfaces;
  48    use Interfaces.OS2Lib;
  49    use Interfaces.OS2Lib.Synchronization;
  50    use Interfaces.OS2Lib.Errors;
  51
  52    -----------
  53    -- Yield --
  54    -----------
  55
  56    --  Give up the remainder of the time-slice and yield the processor
  57    --  to other threads of equal priority. Yield will return immediately
  58    --  without giving up the current time-slice when the only threads
  59    --  that are ready have a lower priority.
  60
  61    --  ???  Just giving up the current time-slice seems not to be enough
  62    --  to get the thread to the end of the ready queue if OS/2 does use
  63    --  a queue at all. As a partial work-around, we give up two time-slices.
  64
  65    --  This is the best we can do now, and at least is sufficient for passing
  66    --  the ACVC 2.0.1 Annex D tests.
  67
  68    procedure Yield is
  69    begin
  70       Delay_For (0);
  71       Delay_For (0);
  72    end Yield;
  73
  74    ---------------
  75    -- Delay_For --
  76    ---------------
  77
  78    procedure Delay_For (Period : in Duration_In_Millisec) is
  79       Result : APIRET;
  80
  81    begin
  82       pragma Assert (Period >= 0, "GNULLI---Delay_For: negative argument");
  83
  84       --  ??? DosSleep is not the appropriate function for a delay in real
  85       --  time. It only gives up some number of scheduled time-slices.
  86       --  Use a timer instead or block for some semaphore with a time-out.
  87       Result := DosSleep (ULONG (Period));
  88
  89       if Result = ERROR_TS_WAKEUP then
  90
  91          --  Do appropriate processing for interrupted sleep
  92          --  Can we raise an exception here?
  93
  94          null;
  95       end if;
  96
  97       pragma Assert (Result = NO_ERROR, "GNULLI---Error in Delay_For");
  98    end Delay_For;
  99
 100    -----------
 101    -- Clock --
 102    -----------
 103
 104    function Clock return Duration is
 105
 106       --  Implement conversion from tick count to Duration
 107       --  using fixed point arithmetic. The frequency of
 108       --  the Intel 8254 timer chip is 18.2 * 2**16 Hz.
 109
 110       Tick_Duration : constant := 1.0 / (18.2 * 2**16);
 111       Tick_Count    : aliased QWORD;
 112
 113    begin
 114
 115       --  Read nr of clock ticks since boot time
 116       Must_Not_Fail (DosTmrQueryTime (Tick_Count'Access));
 117
 118       return Tick_Count * Tick_Duration;
 119    end Clock;
 120
 121 end System.OS_Interface;