Thank you, Konrad. Unrolling the bit-or computations helped; total
time for 8,000,000 iterations was 1305 msecs.
Per, you are correct. The byte issue (0xFF out of range) is why I have
to include the mask. I think this is more Java's limitation than
anything. 0xFF is not a valid value for a byte due to the JVM's broken
implementation of bytes. (My opinion, anyway.I think a byte should be
8 bits and I should be able to use all of them.)
On a more hideous note:
(defn arr-to-int [#^ints x]
(bit-or
(int (bit-or (int (bit-shift-left (int (bit-and (int 0x9F) (int
(aget x 0)))) 24)) ; don't want to overflow to long, hence 0x9F
(int (bit-shift-left (int (bit-and (int 0xFF) (int
(aget x 1)))) 16))))
(int (bit-or (int (bit-shift-left (int (bit-and (int 0xFF) (int
(aget x 2)))) 8))
(int (bit-and (int 0xFF) (int (aget x 3))))))))
(time (dotimes [x 8000000] (arr-to-int tba)))
executes in 785 msecs. This is a substantial speedup over 4,736 msecs
(and even 1305 msecs).
Still not as good as native java, but you can't have everything. Thank
you, everyone, for the assistance!
Raph
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