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    SubjectRe: Reading accurate size of recepts from serial port
    On Wed, 27 Aug 2003, Laurent [iso-8859-1] Hugé wrote:

    > Le Mercredi 27 Août 2003 16:50, Herbert Pötzl a écrit :
    > > hmm, why not do simple framing ...
    > > [length]<data>[length]<data> ....
    > That's impossible. CCSDS is the committee for space date systems and it
    > provides standards that I can't overrule (even if I can't really understand
    > why they've done it like that !).
    > --
    > Laurent Hugé.
    >

    The transfer frame in your reference specified, contains all
    the information necessary for the protocol, even if it's stupid
    to use that protocol on a RS-232C link. Nevertheless, there is
    a minimim size for the header (5 octets in length). There is
    also the 3 octets used for sync, which I'm pretty sure will
    not be put onto the RS-232C links. Anyway, you need to read
    40 bytes (always), from that, you will learn the length
    of the rest of the data. So you use poll()/read() until you
    get that header information. Then you will know what the
    total read-length should be.

    Cheers,
    Dick Johnson
    Penguin : Linux version 2.4.22 on an i686 machine (794.73 BogoMips).
    Note 96.31% of all statistics are fiction.


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