Tigr-m2/modula2/examples/Essai4/essai4.mod

MODULE essai4;

IMPORT	InOut;


TYPE	
  BitFunction		= (set, clr);
	BitResult		= (Set, Clear, Err);

VAR	
  i, j, k, n			: CARDINAL;


PROCEDURE BitTest (pos, val : CARDINAL) : BitResult;

VAR	mask, res	: CARDINAL;

BEGIN
  IF  pos >= 0  THEN
    mask := SHIFT(1,pos);
    res := val AND mask;
    IF  res = 0  THEN  RETURN Clear  ELSE  RETURN Set  END
  END;
  RETURN Err
END BitTest;


PROCEDURE Bit (f : BitFunction; pos, val : CARDINAL) : CARDINAL;

VAR	mask, res		: CARDINAL;

BEGIN
  mask := SHIFT(1,pos);
  CASE  f  OF
     set : res := val OR mask
   | clr : res := val AND (NOT mask)
  END;
  RETURN res
END Bit;


BEGIN
  i := 64;
  j := 127;
  k := 48;
  FOR  n := 0  TO  15  DO
    InOut.WriteString ("Bit ");
    InOut.WriteCard (n, 2);
    InOut.WriteString (" in 127 is ");
    (* IF  BitTest (n, j) = Set  THEN  
      InOut.WriteString ("Set.")
    ELSE
      InOut.WriteString ("Clear")
    END; *)
    InOut.WriteLn
  END;
  (* IF  BitTest (3, j) = Set  THEN  InOut.WriteString ("Bit 3 in 127 is set")  END; *)
  InOut.WriteLn;
  (* IF  BitTest (5, i) = Clear  THEN  InOut.WriteString ("Bit 5 in 64 is clear")  END; *)
  InOut.WriteLn;
  k := VAL (CARDINAL, Bit (set, 1, k));
  InOut.WriteCard (k, 6);
  InOut.WriteLn;
END essai4.