gcc/ada/libgnat/s-osprim__posix2008.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                 GNAT 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) 1998-2018, 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 3,  or (at your option) any later ver- --
  14 -- sion.  GNAT 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.                                     --
  17 --                                                                          --
  18 -- As a special exception under Section 7 of GPL version 3, you are granted --
  19 -- additional permissions described in the GCC Runtime Library Exception,   --
  20 -- version 3.1, as published by the Free Software Foundation.               --
  21 --                                                                          --
  22 -- You should have received a copy of the GNU General Public License and    --
  23 -- a copy of the GCC Runtime Library Exception along with this program;     --
  24 -- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --
  25 -- <http://www.gnu.org/licenses/>.                                          --
  26 --                                                                          --
  27 -- GNARL was developed by the GNARL team at Florida State University.       --
  28 -- Extensive contributions were provided by Ada Core Technologies, Inc.     --
  29 --                                                                          --
  30 ------------------------------------------------------------------------------
  31
  32 --  This version is for POSIX.1-2008-like operating systems
  33
  34 with System.CRTL;
  35 package body System.OS_Primitives is
  36
  37    --  ??? These definitions are duplicated from System.OS_Interface because
  38    --  we don't want to depend on any package. Consider removing these
  39    --  declarations in System.OS_Interface and move these ones to the spec.
  40
  41    type time_t is new System.CRTL.int64;
  42
  43    type timespec is record
  44       tv_sec  : time_t;
  45       tv_nsec : Long_Integer;
  46    end record;
  47    pragma Convention (C, timespec);
  48
  49    function nanosleep (rqtp, rmtp : not null access timespec) return Integer;
  50    pragma Import (C, nanosleep, "nanosleep");
  51
  52    -----------
  53    -- Clock --
  54    -----------
  55
  56    function Clock return Duration is
  57
  58       type timeval is array (1 .. 3) of Long_Integer;
  59       --  The timeval array is sized to contain Long_Long_Integer sec and
  60       --  Long_Integer usec. If Long_Long_Integer'Size = Long_Integer'Size then
  61       --  it will be overly large but that will not effect the implementation
  62       --  since it is not accessed directly.
  63
  64       procedure timeval_to_duration
  65         (T    : not null access timeval;
  66          sec  : not null access Long_Long_Integer;
  67          usec : not null access Long_Integer);
  68       pragma Import (C, timeval_to_duration, "__gnat_timeval_to_duration");
  69
  70       Micro  : constant := 10**6;
  71       sec    : aliased Long_Long_Integer;
  72       usec   : aliased Long_Integer;
  73       TV     : aliased timeval;
  74       Result : Integer;
  75       pragma Unreferenced (Result);
  76
  77       function gettimeofday
  78         (Tv : access timeval;
  79          Tz : System.Address := System.Null_Address) return Integer;
  80       pragma Import (C, gettimeofday, "gettimeofday");
  81
  82    begin
  83       --  The return codes for gettimeofday are as follows (from man pages):
  84       --    EPERM  settimeofday is called by someone other than the superuser
  85       --    EINVAL Timezone (or something else) is invalid
  86       --    EFAULT One of tv or tz pointed outside accessible address space
  87
  88       --  None of these codes signal a potential clock skew, hence the return
  89       --  value is never checked.
  90
  91       Result := gettimeofday (TV'Access, System.Null_Address);
  92       timeval_to_duration (TV'Access, sec'Access, usec'Access);
  93       return Duration (sec) + Duration (usec) / Micro;
  94    end Clock;
  95
  96    -----------------
  97    -- To_Timespec --
  98    -----------------
  99
 100    function To_Timespec (D : Duration) return timespec;
 101
 102    function To_Timespec (D : Duration) return timespec is
 103       S : time_t;
 104       F : Duration;
 105
 106    begin
 107       S := time_t (Long_Long_Integer (D));
 108       F := D - Duration (S);
 109
 110       --  If F has negative value due to a round-up, adjust for positive F
 111       --  value.
 112
 113       if F < 0.0 then
 114          S := S - 1;
 115          F := F + 1.0;
 116       end if;
 117
 118       return
 119         timespec'(tv_sec  => S,
 120                   tv_nsec => Long_Integer (Long_Long_Integer (F * 10#1#E9)));
 121    end To_Timespec;
 122
 123    -----------------
 124    -- Timed_Delay --
 125    -----------------
 126
 127    procedure Timed_Delay
 128      (Time : Duration;
 129       Mode : Integer)
 130    is
 131       Request    : aliased timespec;
 132       Remaind    : aliased timespec;
 133       Rel_Time   : Duration;
 134       Abs_Time   : Duration;
 135       Base_Time  : constant Duration := Clock;
 136       Check_Time : Duration := Base_Time;
 137
 138       Result : Integer;
 139       pragma Unreferenced (Result);
 140
 141    begin
 142       if Mode = Relative then
 143          Rel_Time := Time;
 144          Abs_Time := Time + Check_Time;
 145       else
 146          Rel_Time := Time - Check_Time;
 147          Abs_Time := Time;
 148       end if;
 149
 150       if Rel_Time > 0.0 then
 151          loop
 152             Request := To_Timespec (Rel_Time);
 153             Result := nanosleep (Request'Access, Remaind'Access);
 154             Check_Time := Clock;
 155
 156             exit when Abs_Time <= Check_Time or else Check_Time < Base_Time;
 157
 158             Rel_Time := Abs_Time - Check_Time;
 159          end loop;
 160       end if;
 161    end Timed_Delay;
 162
 163    ----------------
 164    -- Initialize --
 165    ----------------
 166
 167    procedure Initialize is
 168    begin
 169       null;
 170    end Initialize;
 171
 172 end System.OS_Primitives;