gcc/ada/s-osinte-os2.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                  GNAT 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 --             Copyright (C) 1991-1994, Florida State University            --
  10 --                     Copyright (C) 1995-2005, AdaCore                     --
  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,  51  Franklin  Street,  Fifth  Floor, --
  21 -- Boston, MA 02110-1301, 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.       --
  31 -- Extensive contributions were provided by Ada Core Technologies, Inc.     --
  32 --                                                                          --
  33 ------------------------------------------------------------------------------
  34
  35 --  This is the OS/2 version of this package
  36
  37 pragma Polling (Off);
  38 --  Turn off polling, we do not want ATC polling to take place during
  39 --  tasking operations. It causes infinite loops and other problems.
  40
  41 with Interfaces.OS2Lib.Errors;
  42 with Interfaces.OS2Lib.Synchronization;
  43
  44 package body System.OS_Interface is
  45
  46    use Interfaces;
  47    use Interfaces.OS2Lib;
  48    use Interfaces.OS2Lib.Synchronization;
  49    use Interfaces.OS2Lib.Errors;
  50
  51    -----------
  52    -- Yield --
  53    -----------
  54
  55    --  Give up the remainder of the time-slice and yield the processor
  56    --  to other threads of equal priority. Yield will return immediately
  57    --  without giving up the current time-slice when the only threads
  58    --  that are ready have a lower priority.
  59
  60    --  ???  Just giving up the current time-slice seems not to be enough
  61    --  to get the thread to the end of the ready queue if OS/2 does use
  62    --  a queue at all. As a partial work-around, we give up two time-slices.
  63
  64    --  This is the best we can do now, and at least is sufficient for passing
  65    --  the ACVC 2.0.1 Annex D tests.
  66
  67    procedure Yield is
  68    begin
  69       Delay_For (0);
  70       Delay_For (0);
  71    end Yield;
  72
  73    ---------------
  74    -- Delay_For --
  75    ---------------
  76
  77    procedure Delay_For (Period : in Duration_In_Millisec) is
  78       Result : APIRET;
  79
  80    begin
  81       pragma Assert (Period >= 0, "GNULLI---Delay_For: negative argument");
  82
  83       --  ??? DosSleep is not the appropriate function for a delay in real
  84       --  time. It only gives up some number of scheduled time-slices.
  85       --  Use a timer instead or block for some semaphore with a time-out.
  86       Result := DosSleep (ULONG (Period));
  87
  88       if Result = ERROR_TS_WAKEUP then
  89
  90          --  Do appropriate processing for interrupted sleep
  91          --  Can we raise an exception here?
  92
  93          null;
  94       end if;
  95
  96       pragma Assert (Result = NO_ERROR, "GNULLI---Error in Delay_For");
  97    end Delay_For;
  98
  99    -----------
 100    -- Clock --
 101    -----------
 102
 103    function Clock return Duration is
 104
 105       --  Implement conversion from tick count to Duration
 106       --  using fixed point arithmetic. The frequency of
 107       --  the Intel 8254 timer chip is 18.2 * 2**16 Hz.
 108
 109       Tick_Duration : constant := 1.0 / (18.2 * 2**16);
 110       Tick_Count    : aliased QWORD;
 111
 112    begin
 113       --  Read nr of clock ticks since boot time
 114
 115       Must_Not_Fail (DosTmrQueryTime (Tick_Count'Access));
 116
 117       return Tick_Count * Tick_Duration;
 118    end Clock;
 119
 120 end System.OS_Interface;