IFX Mail Archive: RE: IFX> Re: IPP> New data types [why t

RE: IFX> Re: IPP> New data types [why the length of IPP data is s igned short]

From: Hastings, Tom N (hastings@cp10.es.xerox.com)
Date: Tue Mar 06 2001 - 14:09:41 EST

  • Next message: Hastings, Tom N: "IFX> January IPP FAX minutes down-loaded"

    While I agree that in principle lengths should be unsigned, the reason that
    we picked to make them signed, was because some programming languages on
    some platforms have problems with unsigned when the full unsigned integer
    range is used. The compares don't work. So we opted to effectively give up
    half the range and make the data type of the length field be a SIGNED SHORT
    (16-bit) INTEGER.

    Remember our old AD's saying: In theory there is no difference between
    theory and practice, but in practice there is.

    Tom

    P.S. The folks who insisted on a binary format at the pivotal IPP San Diego
    meeting when we made this decision will remain nameless :-)

    -----Original Message-----
    From: pmoore@netreon.com [mailto:pmoore@netreon.com]
    Sent: Monday, January 29, 2001 13:24
    To: Carl Kugler
    Cc: Michael Sweet; Mike Bartman; ipp@pwg.org; ifx@pwg.org
    Subject: Re: IFX> Re: IPP> New data types

    gosh - you are right - the length is signed - thats not right - lengths
    should
    be unsigned.

    "Carl Kugler" <kugler@us.ibm.com> on 01/29/2001 01:08:29 PM

    To: Michael Sweet <mike@easysw.com>
    cc: Paul Moore/AUCO/US@AUCO, Mike Bartman <bartman@process.com>,
    ipp@pwg.org,
          ifx@pwg.org

    Subject: Re: IFX> Re: IPP> New data types

    Since the length field is SIGNED-SHORT (2BYTE). I think it probably only
    goes up to 32,767.

         -Carl

    Michael Sweet <mike@easysw.com>@pwg.org on 01/29/2001 01:17:24 PM

    Sent by: owner-ifx@pwg.org

    To: pmoore@netreon.com
    cc: Mike Bartman <bartman@process.com>, ipp@pwg.org, ifx@pwg.org
    Subject: IFX> Re: IPP> New data types

    pmoore@netreon.com wrote:
    >
    > I had had similar thoughts (I was imagining Text, BigText (16-bit)
    > and HugeText (32-bit))
    > ...

    Except that the length field in the current IPP encoding only
    supports values up to 65535 octets in length... 

    --
______________________________________________________________________
Michael Sweet, Easy Software Products                  mike@easysw.com
Printing Software for UNIX                       http://www.easysw.com

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