Hello. And, I just finished it. At least it compiled successfully. I'm sure there are a few runtime bugs. I'll try to have a webrev out by today.
Regards, Denis. ----- "Jim Graham" <james.gra...@oracle.com> wrote: > Hi Denis, > > float operations are pretty fast and they are usually done in a > separate > part of the processor so the compiler can schedule a lot of > bookkeeping > instructions to run in parallel with waiting for the results of the FP > > instruction. In the end, they often end up being "free" if there are > > enough bookkeeping instructions (branches, fetching data, etc.) in > amongst the data. > > Given how many alternate instructions you are pointing out for the > fixed > point code it would be very likely that this would be a "win". > > The main reason that Pisces is implemented heavily in fixed point is > that it was originally written for the mobile platform where there are > > no FP instructions. We don't have to worry about that on the desktop > > (any more). > > I strongly support you converting things to fp if you want to do > it... > > ...jim > > On 7/12/2010 8:05 AM, Denis Lila wrote: > > Hello. > > > > Is it ok if I do this? I already started working on it on Friday. > > I think I should be done by tomorrow. > > > > But yes, I agree that we should convert to floating point. As for > > performance, there's also the fact that right now we're trading > > one double multiplication for 2 casts to long, 1 long > multiplication, > > 1 bit shift of a long, and 1 cast back to an int. I don't know much > > about how these are done in hardware, but it doesn't seem like > they'd > > be faster than the double multiplication. > > > > As for large coordinates, there's a bug report about it (one not > > reported by me :) ) here: > https://bugzilla.redhat.com/show_bug.cgi?id=597227 > > I submitted a matching bug report on bugs.sun.com (ID 6967436), but > I > > can't find it when I search for it. > > > > Denis. > > > > ----- "Jim Graham"<james.gra...@oracle.com> wrote: > > > >> Sigh... > >> > >> Pisces could really stand to upgrade to floats/doubles everywhere, > for > >> > >> several reasons: > >> > >> - FPU ops are likely as fast if not faster on modern hardware due > to > >> parallel execution of FP instructions alongside regular > instructions. > >> > >> - Don't have to worry about getting coordinates larger than 32K (I > >> don't > >> think this is well tested, but I imagine that Pisces will not deal > >> with > >> it very gracefully). > >> > >> - Lots of code is greatly simplified not having to deal with the > >> semantics of how to do fixed point multiplies, divides, and > >> conversions. > >> > >> I meant to do this during the original integration, but I wanted > to > >> get > >> the task done as quickly as possible so that we could have an open > >> source alternative to the closed Ductus code so I left that task > for a > >> > >> later update. But, now that a lot of work is being done on the > code > >> to > >> fix it up, it might be better to do the float conversion now so > that > >> the > >> maintenance is easier and before we end up creating a lot of new > fixed > >> > >> point code. > >> > >> My plate is full right now, but hopefully I can interest someone > else > >> in > >> doing a cleanup cycle? (Donning my Tom Sawyer hat... ;-) > >> > >> ...jim
