Pascal Super Library/Pascal Super Library (CW International)(1997).bin/BORL_TIP/TI1000/TI1761.ASC

Text File | 1994-01-10 | 4KB | 199 lines

  PRODUCT  :  Pascal                                NUMBER  :  1761
  VERSION  :  6.0 & up
       OS  :  DOS
     DATE  :  January 10, 1994                         PAGE  :  1/3

    TITLE  :  How to read an enhanced keyboard




  {
  The code included in this example shows how to read
  an enhanced keyboard using Turbo Pascal. That is, it detects
  if the F11, F12, etc keys are pressed. It provides a substitute
  for the ReadKey and KeyPressed functions.
       This TI includes two source files, the first a unit
  called ENHKEY.PAS and the second a test program called TEST.PAS.
  ENHKEY.PAS contains three routines:

     KeyEPressed: Works just like the CRT routine called
  KeyPressed,
            except it detects keypresses on enhanced keys.

     NewReadKey:  Works very much like ReadKey, except it detects
            enhanced keys.

     ReadEKey:    This is the raw readkey function. It returns a
  word.
            The high order word contains the scan code and the
            low word contains the regular key. Some users might
            not want to call this function directle, but instead
            might want to access it through the NewReadKey
  function,
            which acts much more like the original ReadKey function
            from the CRT unit.

       The code in the EnhKey unit depends on interrupt 16h,
  functions
  10 and 11, both of which assume the presence of AT or better
  computer.
  In this day and age, that's a fairly safe bet, but you should be
  aware
  that this code will not run on an old XT.
       Notice that if NewReadKey returns zero the first time it is
  called, you can grab the scan code in the global variable
  ScanCode,
  or you can call NewReadKey a second time to return the ScanCode.
  }

  unit EnhKey;

  interface














  PRODUCT  :  Pascal                                NUMBER  :  1761
  VERSION  :  6.0 & up
       OS  :  DOS
     DATE  :  January 10, 1994                         PAGE  :  2/3

    TITLE  :  How to read an enhanced keyboard




  var
    ScanCode: Byte;

  function KeyEPressed: Boolean;
  function ReadEKey: Word;
  function NewReadKey: Char;

  implementation

  function KeyEPressed: Boolean; assembler;
  asm
    mov ah, $11
    int 16h
    mov ax, 1
    jnz @@True
    xor ax, ax
  @@True:
  end;

  function ReadEKey: Word; assembler;
  asm
    mov ah, 10h
    int 16h
  end;

  function NewReadKey: Char;
  var
    Ch: Word;
  begin
    if ScanCode <> 0 then begin
      NewReadKey := Char(ScanCode);
      ScanCode := 0;
      exit;
    end;
    Ch := ReadEKey;
    if Lo(Ch) = 0 then begin
      ScanCode := Hi(Ch);
      NewReadKey := #0;
      exit;
    end;
    NewReadKey := Char(Lo(Ch));
  end;














  PRODUCT  :  Pascal                                NUMBER  :  1761
  VERSION  :  6.0 & up
       OS  :  DOS
     DATE  :  January 10, 1994                         PAGE  :  3/3

    TITLE  :  How to read an enhanced keyboard




  begin
    ScanCode := 0;
  end.
  begin
    ScanCode := 0;
  end.

  { ================= The Test Program ================ }

  program Test;
  uses
    EnhKey;

  var
    Ch: Char;
    i: Integer;
  begin
    i := 0;
    while (Ch <> #27) do begin
      if KeyEpressed then begin
        Ch := NewReadKey;
        if Ch = #0 then begin
       Ch := NewReadKey;
       WriteLn('Enhanced: ', Ch)
        end else
       WriteLn('Normal: ', Ch);
        inc(i);
      end;
    end;
  end.

  DISCLAIMER: You have the right to use this technical information
  subject to the terms of the No-Nonsense License Statement that
  you received with the Borland product to which this information
  pertains.