Sorry, I didn't put that right. 0xFF would only be -1 as a signed byte. What I'm saying is that the interaction between the type system of integers and the reader's hexadecimal notation is pretty surprising to me. In particular, (byte 0xFF) throws an error.
-Per On Tue, Mar 23, 2010 at 7:35 PM, Per Vognsen <per.vogn...@gmail.com> wrote: > In addition, right now his Clojure code isn't directly analogous to > his Java code. If he used an array of bytes instead of integers, he > wouldn't need the bit-masking. > > Getting this to work revealed a big surprise to me. Java has only > signed integer types: byte, short, int and long. Clojure reads 0xFF as > the _signed_ integer 255. I would expect it to be -1. For example, > (every? #(= % (bit-and -1 %)) (range -128 128)) evaluates to true. > This looks like a genuine bug. > > -Per > > On Tue, Mar 23, 2010 at 7:08 PM, Konrad Hinsen > <konrad.hin...@fastmail.net> wrote: >> On 23.03.2010, at 08:55, Raph wrote: >> >>> I have tried various hinting methods, but I cannot increase the speed. >>> What can I do to make the clojure operations as fast as the native >>> Java operations? >> >> Get rid of the reduce and unroll the bit-or computations instead: >> >> (defn arr-to-int [#^ints x] >> (bit-or (bit-shift-left (bit-and 0xFF (aget x 0)) 24) >> (bit-or (bit-shift-left (bit-and 0xFF (aget x 1)) 16) >> (bit-or (bit-shift-left (bit-and 0xFF (aget x 2)) 8) >> (bit-and 0xFF (aget x 3)))))) >> >> That makes for a factor 3.3 on my machine. >> >> Konrad. >> >> -- >> 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 >> >> To unsubscribe from this group, send email to >> clojure+unsubscribegooglegroups.com or reply to this email with the words >> "REMOVE ME" as the subject. >> > -- 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 To unsubscribe from this group, send email to clojure+unsubscribegooglegroups.com or reply to this email with the words "REMOVE ME" as the subject.
