tackling sqlite byte-order problem

[David Relson]

On Wed, 09 Feb 2005 10:52:46 +0100
Matthias Andree wrote:

> David Relson <relson at osagesoftware.com> writes:
> 
> >> I wonder if we should add a new token .ENDIAN32 (from datastore) that
> >> stores the hex value 0x01020304 in natural byte order and use that to
> >> figure if the database is byteswapped.
> >
> > .ENDIAN32 sounds fine to me.  Clearly sqlite needs it.  Is it of value
> > for the other DB's we support?
> >
> > Alternatively, since we _know_ that .WORDLIST_VERSION is of form
> > YYYYMMDD, we can split it into YYYY and MMDD and know that YYYY>MMDD is
> > correct while MMDD>YYYY indicates is_swapped.
> 
> Is YYYYMMDD stored in BCD format? That's news to me, I thought it was in
> digital, and in that case, the distinction between YYYY and MMDD doesn't
> fall on a byte boundary.

My bad.  It's binary, not BCD.  Splitting would be "divide by 10000" and
check for reasonable results.  As a sanity check I wrote the little
program I've attached.  It does an endian swap then prints the dates and
their yyyy and mmdd components.  Perhaps it's useful; perhaps it's not.

Run like so:

gcc -o yyyymmdd yyyymmdd.c ; yyyymmdd ; yyyymmdd 20020820 ; yyyymmdd 21050209

David

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