Re: [avr-gcc-list] Old bug - ordering of 16 bit assignments

[Bob Paddock]

On Sat, 26 Feb 2005 17:57:40 -0500, Brian Dean <address@hidden> wrote:

> I'm not sure when this bug re-appeared, but when one makes an
> assignment of a value through a 16 bit pointer, avr-gcc is assigning
> the low byte, then high byte.

I filed GCC Bug Number 20288 on this issue.

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20288

I filled the bug because I have had the "pleasure" of debugging this type
of failure on a system I inherited in a past job.

The system was a three-phase motor control for a 200 HP motor on a piece
of Coal Mining equipment.  The first time the control for a 440V/200A SCR
Bridge generates an output that is off by a factor of 256 due to counter
rollovers, you change your underwear.  Not easy to do in a dark wet Coal  
Mine.
Then you spend days waiting for the failure to happen again due to the
apparent "random" nature of the fault.

"Asynchronous Hardware/Firmware" by Jack Ganssle at
http://www.ganssle.com/articles/asynchf.htm goes into
the gory details of why this type of failure in a
embedded device is down right dangerous.