gcc/m2/gm2-libs-pim/Keyboard.mod

   1 (* Keyboard.mod provides compatibility with Logitech 3.0 Keyboard module.
   2
   3 Copyright (C) 2004-2023 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 IMPLEMENTATION MODULE Keyboard ;
  28
  29 FROM Selective IMPORT SetOfFd, InitSet, KillSet, MaxFdsPlusOne, ReadCharRaw,
  30                       Timeval, InitTime, KillTime, FdIsSet, FdZero, FdSet,
  31                       Select ;
  32
  33
  34 CONST
  35    stdin = 0 ;
  36
  37
  38 (*
  39    Read - reads a character from StdIn. If necessary it will wait
  40           for a key to become present on StdIn.
  41 *)
  42
  43 PROCEDURE Read (VAR ch: CHAR) ;
  44 BEGIN
  45    ch := ReadCharRaw(stdin)
  46 END Read ;
  47
  48
  49 (*
  50    KeyPressed - returns TRUE if a character can be read from StdIn
  51                 without blocking the caller.
  52 *)
  53
  54 PROCEDURE KeyPressed () : BOOLEAN ;
  55 VAR
  56    s      : SetOfFd ;
  57    t      : Timeval ;
  58    r      : INTEGER ;
  59    Pressed: BOOLEAN ;
  60 BEGIN
  61    t := InitTime(0, 0) ;
  62    s := InitSet() ;
  63    FdZero(s) ;
  64    FdSet(stdin, s) ;
  65    r := Select(MaxFdsPlusOne(stdin, stdin),
  66                s, NIL, NIL, t) ;
  67    Pressed := FdIsSet(stdin, s) ;
  68    s := KillSet(s) ;
  69    t := KillTime(t) ;
  70    RETURN( Pressed )
  71 END KeyPressed ;
  72
  73
  74 END Keyboard.