Re:[boost] Re: Re: Re: Using Serialization for binary

From: Dave Harris (brangdon_at_[hidden])
Date: 2004-05-06 14:39:51

In-Reply-To: <20040506033527.A2765313DF_at_[hidden]>
ramey_at_[hidden] (Robert Ramey) wrote (abridged):
> > > Specifically, I'd use a byte oriented scheme where the low 7 bits of
> > > each byte contribute to the current number, and the high bit says
> > > whether there are more bytes to come.
>
> That's the way it's done in demo_portable_binary_archive included in the
> current serialization package.

Yes. Demo_portable_binary_archive stores a length byte followed by the 
bytes needed. I specifically wanted to suggest an alternative to that. 
Using a bit from each byte means that small integers take half as much 
space as with your format. Some numbers of bytes:

     Integer   Length Byte   High Bit
         0         2           1
        10         2           1
       100         2           1
      1000         3           2
     10000         3           2
    100000         4           3

In practice most integers are small. Eg most archive version numbers will 
be below 100.

-- Dave Harris, Nottingham, UK