Subject: RE: [rohc] TCP packet formats

From: "Finking, Robert" <[email-masked]>
Date: Thu, 7 Oct 2004 09:25:37 +0100

]>  2. there is no reason not to use expression syntax within annotations?
]
]You have just killed any remaining free time that Eilert may have had 
]:-)

=)

]>  3. there is no reason not to use expression syntax to specify the 
]> length of
]> the irregular encoding.
]
]Sounds good, but makes building an implementation so much harder.

IIRC this is needed for the TCP profile. Of course we used to have the
"expression" encoding method and the "derived_value" encoding method, but
they were really cumbersome to use and were both only needed because of the
restriction that only constant values could be used as parameters... which
itself was only a restriction because it was a limitation imposed by the
original Prolog implementation... presumably because it makes the
implementation easier to restrict parameters to constant values. Of course,
if it turns out that we don't need them for the TCP profile, then all the
better for your implementation!

]> I'm sure I've missed something here, so let me know =)
]
]Well, you created what we call "gratuitous generality".
]In your second solution, you lost the property that flag can be either 
]0 or 1.
]So, for a flag value of 4, you now have a 128 bit field.

Ooops! Good catch.

   let(flag >= 0 || flag <= 1)

Raffles

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From: Eilert Brinkmann <[email-masked]>
Date: Thu, 07 Oct 2004 10:29:38 +0200

>    let(flag >= 0 || flag <= 1)

I would suggest

     let(flag >= 0 && flag <= 1)

or

     let(flag == 0 || flag == 1)

instead ;-)

Eilert