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
36with Interfaces.C;                      use Interfaces.C;
37with Interfaces.OS2Lib;                 use Interfaces.OS2Lib;
38with Interfaces.OS2Lib.Synchronization; use Interfaces.OS2Lib.Synchronization;
39
40package 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
170begin
171   Set_Epoch_Offset;
172end System.OS_Primitives;
173