gcc/m2/gm2-libs-iso/COROUTINES.def

   1 (* Library module defined by the International Standard
   2    Information technology - programming languages
   3    BS ISO/IEC 10514-1:1996E Part 1: Modula-2, Base Language.
   4
   5    Copyright ISO/IEC (International Organization for Standardization
   6    and International Electrotechnical Commission) 1996-2021.
   7
   8    It may be freely copied for the purpose of implementation (see page
   9    707 of the Information technology - Programming languages Part 1:
  10    Modula-2, Base Language.  BS ISO/IEC 10514-1:1996).  *)
  11
  12 DEFINITION MODULE COROUTINES;
  13
  14 (* Facilities for coroutines and the handling of interrupts *)
  15
  16 IMPORT SYSTEM ;
  17
  18
  19 CONST
  20   UnassignedPriority = 0 ;
  21
  22 TYPE
  23   COROUTINE ; (* Values of this type are created dynamically by NEWCOROUTINE
  24                  and identify the coroutine in subsequent operations *)
  25   INTERRUPTSOURCE = CARDINAL ;
  26   PROTECTION = [UnassignedPriority..7] ;
  27
  28
  29 PROCEDURE NEWCOROUTINE (procBody: PROC;
  30                         workspace: SYSTEM.ADDRESS;
  31                         size: CARDINAL;
  32                         VAR cr: COROUTINE;
  33                         [initProtection: PROTECTION = UnassignedPriority]);
  34   (* Creates a new coroutine whose body is given by procBody, and
  35      returns the identity of the coroutine in cr. workspace is a
  36      pointer to the work space allocated to the coroutine; size
  37      specifies the size of this workspace in terms of SYSTEM.LOC.
  38
  39      The optarg, initProtection, may contain a single parameter which
  40      specifies the initial protection level of the coroutine.
  41   *)
  42
  43 PROCEDURE TRANSFER (VAR from: COROUTINE; to: COROUTINE);
  44   (* Returns the identity of the calling coroutine in from, and
  45      transfers control to the coroutine specified by to.
  46   *)
  47
  48 PROCEDURE IOTRANSFER (VAR from: COROUTINE; to: COROUTINE);
  49   (* Returns the identity of the calling coroutine in from and
  50      transfers control to the coroutine specified by to.  On
  51      occurrence of an interrupt, associated with the caller, control
  52      is transferred back to the caller, and the identity of the
  53      interrupted coroutine is returned in from.  The calling coroutine
  54      must be associated with a source of interrupts.
  55   *)
  56
  57 PROCEDURE ATTACH (source: INTERRUPTSOURCE);
  58   (* Associates the specified source of interrupts with the calling
  59      coroutine. *)
  60
  61 PROCEDURE DETACH (source: INTERRUPTSOURCE);
  62   (* Dissociates the specified source of interrupts from the calling
  63      coroutine. *)
  64
  65 PROCEDURE IsATTACHED (source: INTERRUPTSOURCE): BOOLEAN;
  66   (* Returns TRUE if and only if the specified source of interrupts is
  67      currently associated with a coroutine; otherwise returns FALSE.
  68   *)
  69
  70 PROCEDURE HANDLER (source: INTERRUPTSOURCE): COROUTINE;
  71   (* Returns the coroutine, if any, that is associated with the source
  72      of interrupts. The result is undefined if IsATTACHED(source) =
  73      FALSE.
  74   *)
  75
  76 PROCEDURE CURRENT (): COROUTINE;
  77   (* Returns the identity of the calling coroutine. *)
  78
  79 PROCEDURE LISTEN (p: PROTECTION);
  80   (* Momentarily changes the protection of the calling coroutine to
  81      p. *)
  82
  83 PROCEDURE PROT (): PROTECTION;
  84   (* Returns the protection of the calling coroutine. *)
  85
  86
  87 (*
  88    TurnInterrupts - switches processor interrupts to the protection
  89                     level, to.  It returns the old value.
  90 *)
  91
  92 PROCEDURE TurnInterrupts (to: PROTECTION) : PROTECTION ;
  93
  94
  95 (*
  96    ListenLoop - should be called instead of users writing:
  97
  98                 LOOP
  99                    LISTEN
 100                 END
 101
 102                 It performs the same function but yields
 103                 control back to the underlying operating system.
 104                 It also checks for deadlock.
 105                 Note that this function does return when an interrupt occurs.
 106                 (File descriptor becomes ready or time event expires).
 107 *)
 108
 109 PROCEDURE ListenLoop ;
 110
 111
 112 END COROUTINES.