gcc/ada/s-osprim-os2.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                GNU ADA RUN-TIME LIBRARY (GNARL) COMPONENTS               --
   4 --                                                                          --
   5 --                  S Y S T E M . O S _ P R I M I T I V E S                 --
   6 --                                                                          --
   7 --                                  B o d y                                 --
   8 --                                                                          --
   9 --         Copyright (C) 1998-2001 Free Software Foundation, Inc.           --
  10 --                                                                          --
  11 -- GNARL is free software; you can  redistribute it  and/or modify it under --
  12 -- terms of the  GNU General Public License as published  by the Free Soft- --
  13 -- ware  Foundation;  either version 2,  or (at your option) any later ver- --
  14 -- sion. GNARL is distributed in the hope that it will be useful, but WITH- --
  15 -- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
  16 -- or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License --
  17 -- for  more details.  You should have  received  a copy of the GNU General --
  18 -- Public License  distributed with GNARL; see file COPYING.  If not, write --
  19 -- to  the Free Software Foundation,  59 Temple Place - Suite 330,  Boston, --
  20 -- MA 02111-1307, USA.                                                      --
  21 --                                                                          --
  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 --
  26 -- however invalidate  any other reasons why  the executable file  might be --
  27 -- covered by the  GNU Public License.                                      --
  28 --                                                                          --
  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 --  This is the OS/2 version of this package
  35
  36 with Interfaces.C;                      use Interfaces.C;
  37 with Interfaces.OS2Lib;                 use Interfaces.OS2Lib;
  38 with Interfaces.OS2Lib.Synchronization; use Interfaces.OS2Lib.Synchronization;
  39
  40 package body System.OS_Primitives is
  41
  42    ----------------
  43    -- Local Data --
  44    ----------------
  45
  46    Epoch_Offset    : Duration;       --  See Set_Epoch_Offset
  47    Max_Tick_Count  : QWORD := 0.0;
  48    --  This is needed to compensate for small glitches in the
  49    --  hardware clock or the way it is read by the OS
  50
  51    -----------------------
  52    -- Local Subprograms --
  53    -----------------------
  54
  55    procedure Set_Epoch_Offset;
  56    --  Initializes the Epoch_1970_Offset to the offset of the System_Clock
  57    --  relative to the Unix epoch (Jan 1, 1970), such that
  58    --     Clock = System_Clock + Epoch_1970_Offset
  59
  60    function System_Clock return Duration;
  61    pragma Inline (System_Clock);
  62    --  Function returning value of system clock with system-dependent timebase.
  63    --  For OS/2 the system clock returns the elapsed time since system boot.
  64    --  The clock resolution is approximately 838 ns.
  65
  66    ------------------
  67    -- System_Clock --
  68    ------------------
  69
  70    function System_Clock return Duration is
  71
  72       --  Implement conversion from tick count to Duration
  73       --  using fixed point arithmetic. The frequency of
  74       --  the Intel 8254 timer chip is 18.2 * 2**16 Hz.
  75
  76       Tick_Duration : constant := 1.0 / (18.2 * 2**16);
  77       Tick_Count    : aliased QWORD;
  78
  79    begin
  80       Must_Not_Fail (DosTmrQueryTime (Tick_Count'Access));
  81       --  Read nr of clock ticks since boot time
  82
  83       Max_Tick_Count := QWORD'Max (Tick_Count, Max_Tick_Count);
  84
  85       return Max_Tick_Count * Tick_Duration;
  86    end System_Clock;
  87
  88    -----------
  89    -- Clock --
  90    -----------
  91
  92    function Clock return Duration is
  93    begin
  94       return System_Clock + Epoch_Offset;
  95    end Clock;
  96
  97    ---------------------
  98    -- Monotonic_Clock --
  99    ---------------------
 100
 101    function Monotonic_Clock return Duration renames Clock;
 102
 103    ----------------------
 104    -- Set_Epoch_Offset --
 105    ----------------------
 106
 107    procedure Set_Epoch_Offset is
 108
 109       --  Interface to Unix C style gettimeofday
 110
 111       type timeval is record
 112          tv_sec  : long;
 113          tv_usec : long;
 114       end record;
 115
 116       procedure gettimeofday
 117         (time : access timeval;
 118          zone : System.Address := System.Address'Null_Parameter);
 119       pragma Import (C, gettimeofday);
 120
 121       Time_Of_Day       : aliased timeval;
 122       Micro_To_Nano     : constant := 1.0E3;
 123       Sec_To_Nano       : constant := 1.0E9;
 124       Nanos_Since_Epoch : QWORD;
 125
 126    begin
 127       gettimeofday (Time_Of_Day'Access);
 128       Nanos_Since_Epoch := QWORD (Time_Of_Day.tv_sec) * Sec_To_Nano
 129         + QWORD (Time_Of_Day.tv_usec) * Micro_To_Nano;
 130
 131       Epoch_Offset :=
 132          Duration'(Nanos_Since_Epoch / Sec_To_Nano) - System_Clock;
 133
 134    end Set_Epoch_Offset;
 135
 136    -----------------
 137    -- Timed_Delay --
 138    -----------------
 139
 140    procedure Timed_Delay
 141      (Time : Duration;
 142       Mode : Integer)
 143    is
 144       Rel_Time   : Duration;
 145       Abs_Time   : Duration;
 146       Check_Time : Duration := Clock;
 147
 148    begin
 149       if Mode = Relative then
 150          Rel_Time := Time;
 151          Abs_Time := Time + Check_Time;
 152       else
 153          Rel_Time := Time - Check_Time;
 154          Abs_Time := Time;
 155       end if;
 156
 157       if Rel_Time > 0.0 then
 158          loop
 159             Must_Not_Fail (DosSleep (ULONG (Rel_Time * 1000.0)));
 160
 161             Check_Time := Clock;
 162
 163             exit when Abs_Time <= Check_Time;
 164
 165             Rel_Time := Abs_Time - Check_Time;
 166          end loop;
 167       end if;
 168    end Timed_Delay;
 169
 170 begin
 171    Set_Epoch_Offset;
 172 end System.OS_Primitives;