Copyright (C) 1992, Digital Equipment Corporation
All rights reserved.
See the file COPYRIGHT for a full description.
by Steve Glassman, Mark Manasse and Greg Nelson
Last modified on Mon Feb 24 13:59:48 PST 1992 by muller
modified on Fri Sep 13 5:05:45 PDT 1991 by msm
<*PRAGMA LL*>
UNSAFE MODULE XEventQueue;
IMPORT X;
CONST NormalQSize = 8;
<*INLINE*> PROCEDURE IsEmpty (READONLY rb: T): BOOLEAN =
BEGIN
RETURN rb.lo = rb.hi
END IsEmpty;
PROCEDURE Insert (VAR rb: T; READONLY e: X.XEvent) =
BEGIN
IF rb.buff = NIL THEN
rb.buff := NEW(REF ARRAY OF X.XEvent, NormalQSize)
END;
rb.buff[rb.hi] := e;
INC(rb.hi);
WITH n = NUMBER(rb.buff^) DO
IF rb.hi = n THEN rb.hi := 0 END;
IF rb.hi = rb.lo THEN
WITH new = NEW(REF ARRAY OF X.XEvent, 2 * n) DO
FOR i := rb.lo TO n - 1 DO new[i] := rb.buff[i] END;
FOR i := 0 TO rb.hi - 1 DO new[i + n] := rb.buff[i] END;
INC(rb.hi, n);
rb.buff := new
END
END
END
END Insert;
PROCEDURE Remove (VAR rb: T): X.XEvent RAISES {Exhausted} =
VAR res: X.XEvent;
BEGIN
IF rb.lo = rb.hi THEN RAISE Exhausted END;
res := rb.buff[rb.lo];
WITH n = NUMBER(rb.buff^) DO
INC(rb.lo);
IF rb.lo = n THEN rb.lo := 0 END;
IF (rb.lo = rb.hi) AND (n > NormalQSize) THEN rb := Empty END
END;
RETURN res
END Remove;
PROCEDURE Peek (VAR rb: T): X.XEvent RAISES {Exhausted} =
BEGIN
IF rb.lo = rb.hi THEN RAISE Exhausted END;
RETURN rb.buff[rb.lo];
END Peek;
BEGIN
END XEventQueue.