On Wed, Feb 5, 2014 at 4:04 PM, West, Nathan <n...@ostatemail.okstate.edu> wrote: > I was doing some work with this kernel and came across an odd result > that I think is caused by a non-saturating add in the generic > proto-kernel, that should also be relevant to the 16i_max_star_16i. > > I haven't looked too much in to the SSE versions, but the generic > versions are doing a comparison by subtracting two values and > comparing the result to 0. At least in the QA on armhf this is causing > wrap-around so that the smaller of the two numbers is returned as the > max. > > Since I'm pretty sure this is part of the max* operator defined by > Viterbi in his "justification and implementation of a MAP decoder" I > think this result is incorrect unless I'm misunderstanding part of the > operator. > > Can somebody with a little more insight in to this kernel ping back if > this is intended behavior? If not, is there some benefit to doing > (x-y)>0 vs x>y as the comparison? > > Thanks, > Nathan
Just from what you've said here, I would agree that (x-y)>0 is a bit dangerous, and I don't see why we can't use x>y. Does it work for you if you make that change? Tom _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
