[U-Boot] setting u-boot params based on serial number

[David Collier]

OK,

I concede I can indeed do the one thing I need here by using decimal
values with hex arithmetic, and it will give the right answer.

though it is truly horrible coding :-)

I can see situations where I'd want to do something like "add one to the
last serial number I used" where decimal arithmetic would be needed.

For myself, I don't see any reason why an arithmetic command shouldn't be
a special case ( in having the option to work in various bases ), it's
doing a special job.

Sorry it took me a while to catch onto your clever trick, and thanks for
your help.

David


In article <20091026120130.9538128B9B at gemini.denx.de>, wd at denx.de
(Wolfgang Denk) wrote:

> *From:* Wolfgang Denk <wd at denx.de>
> *To:* from_denx_uboot at dexdyne.com
> *CC:* u-boot at lists.denx.de
> *Date:* Mon, 26 Oct 2009 13:01:30 +0100
> 
> Dear "David Collier",
> 
> In message 
> <memo.20091026103604.2092e at postmaster+dexdyne.com.cix.co.uk> you 
> wrote:
> > > I did not only describe it, I tested it. I just "tricked" a bit.
> > > You asked to extract the last two digits, and I used "% 100" to 
> > do
> > > this. Note that this works correctly in any number base - may 
> > it be > 10 or 16 or whatever :-)
> > > 
> > > Hey, that was clever, wasn't it? :-)
> > 
> > yeah it was - but of course I really wanted the next 2 digits as 
> > well....
> > I'm hoping to make more than 100 units really! pardon me for
> > over-simplifying my question.
> 
> Then do the same with "% 10000" and "/ 100" ?
> 
> > I wonder if it would be useful/helpful to allow the user to 
> > optionally
> > over-ride the number base for reading and separately for writing 
> > by
> > setexpr.
> 
> I don't see a need for it; certainly not here.
> 
> > That would extend it's usefulness without requiring an extra 
> > command or
> > breaking any existing code
> 
> No extra command is needed here.
> 
> > setenv setexpr_in  10 
> > setenv setexpr_out 16
> >  
> > If I wrote a patch would you look favourably on it?
> 
> I don't think so. If we did something like that, it should be 
> generic
> and not restricted to one command. And it would break a LOT of
> existing scripts. And it is not needed at all, at least not for the
> use case you have in mind here. [If anything is worth implementing 
> at
> all, then maybe the regexp handling present in standard expr
> command.]
> 
> Best regards,
> 
> Wolfgang Denk
> 
> -- 
> DENX Software Engineering GmbH,     MD: Wolfgang Denk & Detlev 
> Zundel
> HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, 
> Germany
> Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: 
> wd at denx.de
> Testing can show the presense of bugs, but not their absence.
>                                                    -- Edsger 
> Dijkstra
> 


David Collier

www.dexdyne.com