tcp/src/common/StreamWrClass.m3


 Copyright 1999-2003 John D. Polstra.
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 *      This product includes software developed by John D. Polstra.
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 *    derived from this software without specific prior written permission.
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 * $Id: StreamWrClass.m3.html,v 1.3 2010-04-29 17:20:11 wagner Exp $ 

MODULE StreamWrClass EXPORTS StreamWr, StreamWrClass;

IMPORT WrClass;

CONST
  Threshold = LAST(CARDINAL) DIV 2;

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

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

BEGIN
END StreamWrClass.