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 13:56:07 PST 1992 by muller
modified on Wed Sep 11 15:51:02 PDT 1991 by msm
<*PRAGMA LL*>
MODULE InstallQueue;
CONST NormalQSize = 4;
<*INLINE*> PROCEDURE IsEmpty(READONLY rb: T): BOOLEAN =
BEGIN RETURN rb.lo = rb.hi END IsEmpty;
PROCEDURE Insert(VAR rb: T; READONLY e: Closure) =
BEGIN
IF rb.buff = NIL THEN
rb.buff := NEW(REF ARRAY OF Closure, 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 Closure, 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): Closure RAISES {Exhausted} =
VAR res: Closure;
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;
BEGIN END InstallQueue.