(* Copyright 1999-2003 John D. Polstra.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgment:
 *      This product includes software developed by John D. Polstra.
 * 4. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * $Id: StreamRdClass.m3,v 1.3 2003/03/04 19:26:34 jdp Exp $ *)

MODULE StreamRdClass EXPORTS StreamRd, StreamRdClass;

IMPORT RdClass;

CONST
  Threshold = LAST(CARDINAL) DIV 2;

PROCEDURE ByteCount(srd: T): LONGREAL =
  BEGIN
    RdClass.Lock(srd);
    TRY
      RETURN srd.offset + FLOAT(srd.cur, LONGREAL);
    FINALLY
      RdClass.Unlock(srd);
    END;
  END ByteCount;

PROCEDURE DontOverflow(srd: T) =
  (* The reader is already locked. *)
  BEGIN
    IF srd.hi >= Threshold THEN
      srd.offset := srd.offset + FLOAT(srd.lo, LONGREAL);
      DEC(srd.hi, srd.lo);
      DEC(srd.cur, srd.lo);
      srd.lo := 0;
    END;
  END DontOverflow;

BEGIN
END StreamRdClass.