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Diffstat (limited to 'gcc/ada/s-osprim-vms.ads')
| -rw-r--r-- | gcc/ada/s-osprim-vms.ads | 106 |
1 files changed, 106 insertions, 0 deletions
diff --git a/gcc/ada/s-osprim-vms.ads b/gcc/ada/s-osprim-vms.ads new file mode 100644 index 00000000000..a777bea3b83 --- /dev/null +++ b/gcc/ada/s-osprim-vms.ads @@ -0,0 +1,106 @@ +------------------------------------------------------------------------------ +-- -- +-- GNU ADA RUN-TIME LIBRARY (GNARL) COMPONENTS -- +-- -- +-- S Y S T E M . O S _ P R I M I T I V E S -- +-- -- +-- S p e c -- +-- -- +-- Copyright (C) 1998-2003 Free Software Foundation, Inc. -- +-- -- +-- GNARL is free software; you can redistribute it and/or modify it under -- +-- terms of the GNU General Public License as published by the Free Soft- -- +-- ware Foundation; either version 2, or (at your option) any later ver- -- +-- sion. GNARL is distributed in the hope that it will be useful, but WITH- -- +-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY -- +-- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License -- +-- for more details. You should have received a copy of the GNU General -- +-- Public License distributed with GNARL; see file COPYING. If not, write -- +-- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, -- +-- MA 02111-1307, USA. -- +-- -- +-- As a special exception, if other files instantiate generics from this -- +-- unit, or you link this unit with other files to produce an executable, -- +-- this unit does not by itself cause the resulting executable to be -- +-- covered by the GNU General Public License. This exception does not -- +-- however invalidate any other reasons why the executable file might be -- +-- covered by the GNU Public License. -- +-- -- +-- GNARL was developed by the GNARL team at Florida State University. -- +-- Extensive contributions were provided by Ada Core Technologies Inc. -- +-- -- +------------------------------------------------------------------------------ + +-- This package provides low level primitives used to implement clock and +-- delays in non tasking applications on Alpha/VMS + +-- The choice of the real clock/delay implementation (depending on whether +-- tasking is involved or not) is done via soft links (see s-tasoli.ads) + +-- NEVER add any dependency to tasking packages here + +package System.OS_Primitives is + + subtype OS_Time is Long_Integer; + -- System time on VMS is used for performance reasons. + -- Note that OS_Time is *not* the same as Ada.Calendar.Time, the + -- difference being that relative OS_Time is negative, but relative + -- Calendar.Time is positive. + -- See Ada.Calendar.Delays for more information on VMS Time. + + Max_Sensible_Delay : constant Duration := + Duration'Min (183 * 24 * 60 * 60.0, + Duration'Last); + -- Max of half a year delay, needed to prevent exceptions for large + -- delay values. It seems unlikely that any test will notice this + -- restriction, except in the case of applications setting the clock at + -- at run time (see s-tastim.adb). Also note that a larger value might + -- cause problems (e.g overflow, or more likely OS limitation in the + -- primitives used). In the case where half a year is too long (which + -- occurs in high integrity mode with 32-bit words, and possibly on + -- some specific ports of GNAT), Duration'Last is used instead. + + function OS_Clock return OS_Time; + -- Returns "absolute" time, represented as an offset + -- relative to "the Epoch", which is Nov 17, 1858 on VMS. + + function Clock return Duration; + pragma Inline (Clock); + -- Returns "absolute" time, represented as an offset + -- relative to "the Epoch", which is Jan 1, 1970 on unixes. + -- This implementation is affected by system's clock changes. + + function Monotonic_Clock return Duration; + pragma Inline (Monotonic_Clock); + -- Returns "absolute" time, represented as an offset + -- relative to "the Epoch", which is Jan 1, 1970. + -- This clock implementation is immune to the system's clock changes. + + Relative : constant := 0; + Absolute_Calendar : constant := 1; + Absolute_RT : constant := 2; + -- Values for Mode call below. Note that the compiler (exp_ch9.adb) + -- relies on these values. So any change here must be reflected in + -- corresponding changes in the compiler. + + procedure Timed_Delay (Time : Duration; Mode : Integer); + -- Implements the semantics of the delay statement when no tasking is + -- used in the application. + -- + -- Mode is one of the three values above + -- + -- Time is a relative or absolute duration value, depending on Mode. + -- + -- Note that currently Ada.Real_Time always uses the tasking run time, so + -- this procedure should never be called with Mode set to Absolute_RT. + -- This may change in future or bare board implementations. + + function To_Duration (T : OS_Time; Mode : Integer) return Duration; + -- Convert VMS system time to Duration + -- Mode is one of the three values above + + function To_OS_Time (D : Duration; Mode : Integer) return OS_Time; + -- Convert Duration to VMS system time + -- Mode is one of the three values above + +end System.OS_Primitives; |