Interesting! This is the first time I have had to drop out of Clojure for performance reasons. It is not too surprising, given that I am doing low-level byte bashing in a tight loop to send pixels to a display over USB at sixty frames per second. But it is surprising that nothing like this has happened before in building my Clojure environment for running light shows.
I have created a separate Java library which I am calling Wayang, to make it easy for any Java project to drive this display. Once that’s done, I may add a small Clojure convenience wrapper, or I may just have Afterglow use Wayang directly. https://github.com/brunchboy/wayang But first I have a bunch of Java2D integration to implement! On Thursday, March 13, 2014 at 12:26:33 AM UTC-5, Ignacio Corderi wrote: > > Hey guys, here is a huge performance problem I'm trying to figure out: > > ;; Say you have 2 data arrays sitting out there of 1 MB > > (def one-mb (byte-array (* 1024 1024))) > (def another-mb (byte-array (* 1024 1024))) > > ;; and another one that should have the byte-by-byte XOR of the previous > two > > (def out-mb (byte-array (* 1024 1024))) > > ;; question is... how do you code this guy, so that it doesn't take forever > > (defn inplace-xor [a b out] > (def ln (count a)) > (loop [x 0] > (if (< x ln) > (do > (aset-byte out x (bit-xor (nth a x) (nth b x))) > (recur (+ x 1)) > )))) > > ;; checking the time > > (time (inplace-xor one-mb another-mb out-mb)) > > ;; takes about ~400ms which is.... well... A LOT > > ;; I'm happy to receive a solution that involves calling some java > library... > > Thanks in advance! > -Ignacio > > > -- You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en --- You received this message because you are subscribed to the Google Groups "Clojure" group. To unsubscribe from this group and stop receiving emails from it, send an email to clojure+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
