gcc/m2/gm2-libs-coroutines/TimerHandler.def

   1 (* TimerHandler.def provides a simple timer handler for the Executive.
   2
   3 Copyright (C) 2002-2024 Free Software Foundation, Inc.
   4 Contributed by Gaius Mulley <gaius.mulley@southwales.ac.uk>.
   5
   6 This file is part of GNU Modula-2.
   7
   8 GNU Modula-2 is free software; you can redistribute it and/or modify
   9 it under the terms of the GNU General Public License as published by
  10 the Free Software Foundation; either version 3, or (at your option)
  11 any later version.
  12
  13 GNU Modula-2 is distributed in the hope that it will be useful, but
  14 WITHOUT ANY WARRANTY; without even the implied warranty of
  15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16 General Public License for more details.
  17
  18 Under Section 7 of GPL version 3, you are granted additional
  19 permissions described in the GCC Runtime Library Exception, version
  20 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 DEFINITION MODULE TimerHandler ;
  28
  29 (* It also provides the Executive with a basic round robin scheduler.  *)
  30
  31 EXPORT QUALIFIED TicksPerSecond, GetTicks,
  32                  EVENT,
  33                  Sleep, ArmEvent, WaitOn, Cancel, ReArmEvent ;
  34
  35
  36 CONST
  37    TicksPerSecond =   25 ;  (* Number of ticks per second.  *)
  38
  39 TYPE
  40    EVENT ;
  41
  42
  43 (*
  44    GetTicks - returns the number of ticks since boottime.
  45 *)
  46
  47 PROCEDURE GetTicks () : CARDINAL ;
  48
  49
  50 (*
  51    Sleep - suspends the current process for a time, t.
  52            The time is measured in ticks.
  53 *)
  54
  55 PROCEDURE Sleep (t: CARDINAL) ;
  56
  57
  58 (*
  59    ArmEvent - initializes an event, e, to occur at time, t.
  60               The time, t, is measured in ticks.
  61               The event is NOT placed onto the event queue.
  62 *)
  63
  64 PROCEDURE ArmEvent (t: CARDINAL) : EVENT ;
  65
  66
  67 (*
  68    WaitOn - places event, e, onto the event queue and then the calling
  69             process suspends. It is resumed up by either the event
  70             expiring or the event, e, being cancelled.
  71             TRUE is returned if the event was cancelled
  72             FALSE is returned if the event expires.
  73             The event, e, is always assigned to NIL when the function
  74             finishes.
  75 *)
  76
  77 PROCEDURE WaitOn (VAR e: EVENT) : BOOLEAN ;
  78
  79
  80 (*
  81    Cancel - cancels the event, e, on the event queue and makes
  82             the appropriate process runnable again.
  83             TRUE is returned if the event was cancelled and
  84             FALSE is returned is the event was not found or
  85                   no process was waiting on this event.
  86 *)
  87
  88 PROCEDURE Cancel (e: EVENT) : BOOLEAN ;
  89
  90
  91 (*
  92    ReArmEvent - removes an event, e, from the event queue. A new time
  93                 is given to this event and it is then re-inserted onto the
  94                 event queue in the correct place.
  95                 TRUE is returned if this occurred
  96                 FALSE is returned if the event was not found.
  97 *)
  98
  99 PROCEDURE ReArmEvent (e: EVENT; t: CARDINAL) : BOOLEAN ;
 100
 101
 102 END TimerHandler.