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

   1 (* Executive.def provides a simple multitasking 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 Executive ;
  28
  29 EXPORT QUALIFIED SEMAPHORE, DESCRIPTOR,
  30                  InitProcess, KillProcess, Resume, Suspend, InitSemaphore,
  31                  Wait, Signal, WaitForIO, Ps, GetCurrentProcess,
  32                  RotateRunQueue, ProcessName, DebugProcess ;
  33
  34 TYPE
  35    SEMAPHORE ;         (* defines Dijkstra's semaphores *)
  36    DESCRIPTOR ;        (* handle onto a process         *)
  37
  38
  39 (*
  40    InitProcess - initializes a process which is held in the suspended
  41                  state. When the process is resumed it will start executing
  42                  procedure, p. The process has a maximum stack size of,
  43                  StackSize, bytes and its textual name is, Name.
  44                  The StackSize should be at least 5000 bytes.
  45 *)
  46
  47 PROCEDURE InitProcess (p: PROC; StackSize: CARDINAL;
  48                        Name: ARRAY OF CHAR) : DESCRIPTOR ;
  49
  50
  51 (*
  52    KillProcess - kills the current process. Notice that if InitProcess
  53                  is called again, it might reuse the DESCRIPTOR of the
  54                  killed process. It is the responsibility of the caller
  55                  to ensure all other processes understand this process
  56                  is different.
  57 *)
  58
  59 PROCEDURE KillProcess ;
  60
  61
  62 (*
  63    Resume - resumes a suspended process. If all is successful then the process, p,
  64             is returned. If it fails then NIL is returned.
  65 *)
  66
  67 PROCEDURE Resume (d: DESCRIPTOR) : DESCRIPTOR ;
  68
  69
  70 (*
  71    Suspend - suspend the calling process.
  72              The process can only continue running if another process
  73              Resumes it.
  74 *)
  75
  76 PROCEDURE Suspend ;
  77
  78
  79 (*
  80    InitSemaphore - creates a semaphore whose initial value is, v, and
  81                    whose name is, Name.
  82 *)
  83
  84 PROCEDURE InitSemaphore (v: CARDINAL; Name: ARRAY OF CHAR) : SEMAPHORE ;
  85
  86
  87 (*
  88    Wait - performs dijkstra's P operation on a semaphore.
  89           A process which calls this procedure will
  90           wait until the value of the semaphore is > 0
  91           and then it will decrement this value.
  92 *)
  93
  94 PROCEDURE Wait (s: SEMAPHORE) ;
  95
  96
  97 (*
  98    Signal - performs dijkstra's V operation on a semaphore.
  99             A process which calls the procedure will increment
 100             the semaphores value.
 101 *)
 102
 103 PROCEDURE Signal (s: SEMAPHORE) ;
 104
 105
 106 (*
 107    WaitForIO - waits for an interrupt to occur on vector, VectorNo.
 108 *)
 109
 110 PROCEDURE WaitForIO (VectorNo: CARDINAL) ;
 111
 112
 113 (*
 114    Ps - displays a process list together with process status.
 115 *)
 116
 117 PROCEDURE Ps ;
 118
 119
 120 (*
 121    GetCurrentProcess - returns the descriptor of the current running
 122                        process.
 123 *)
 124
 125 PROCEDURE GetCurrentProcess () : DESCRIPTOR ;
 126
 127
 128 (*
 129    RotateRunQueue - rotates the process run queue.
 130                     It does not call the scheduler.
 131 *)
 132
 133 PROCEDURE RotateRunQueue ;
 134
 135
 136 (*
 137    ProcessName - displays the name of process, d, through
 138                  DebugString.
 139 *)
 140
 141 PROCEDURE ProcessName (d: DESCRIPTOR) ;
 142
 143
 144 (*
 145    DebugProcess - gdb debug handle to enable users to debug deadlocked
 146                   semaphore processes.
 147 *)
 148
 149 PROCEDURE DebugProcess (d: DESCRIPTOR) ;
 150
 151
 152 END Executive.