[Tinyos-help] Bug In Arithmetic Ops

[David Gay]

On Nov 20, 2007 2:59 PM, Christophe Braillon
<christophe.braillon at inrialpes.fr> wrote:
> Are you sure that you have no warning like "non-atomic read or write"?
> It would be really surprising if the hardware or compiler had bugs on
> that kind of basic operation...

For msp430-gcc, this would alas be less surprising than it should be -
the -mdisable-hwmul option (disable use of hardware multiply) is used
in the Makefile because msp430-gcc's use of the multiply instruction
is broken :-( (and has been for years)

David Gay

>
> Federico Fiorentin a écrit :
>
> > Bug In Arithmetic Ops
> >
> > I'm developing a synchronization algorithm for Tmote Sky in TinyOS2
> > with a Poller and 2 Clients.
> > The poller sends periodically a Request Packet, and the clients reply it.
> >
> > In the Reply packet there's:
> >  the Request Packet receive timestamp (TS) ,
> >  a time value (TV) always inferior the timestamp
> >  and them difference (TS - TV).
> >
> > I found out that the subtraction evaluated by the mote isn't always
> > correct, sometimes it diverge of 1,2,4,8.... it seems that the mote
> > doesn't calculate correctly when it's stressed.
> >
> > Any suggestion is welcome.
> >
> > Thanks,Regards.
> > ------------------------------------------------------------------------
> >
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