(set! *warn-on-reflection* true)
(def buffer-size 1920000)
(def array (byte-array buffer-size))
(defmacro add [m n] `(unchecked-add (int ~m) (int ~n)))
(defmacro uinc [m] `(unchecked-inc ~m))
(defmacro amove[a i j] `(aset ~a ~j (aget ~a ~i)))
(defn java-like0 [^bytes cpu_array]
(loop [i (int 0)]
(if (< i (int buffer-size))
(let [b (byte (aget cpu_array i))
g (byte (aget cpu_array (unchecked-add i (int 1))))
r (byte (aget cpu_array (unchecked-add i (int 2))))
a (byte (aget cpu_array (unchecked-add i (int 3))))]
(aset cpu_array i a)
(aset cpu_array (unchecked-add i (int 1)) b)
(aset cpu_array (unchecked-add i (int 2)) g)
(aset cpu_array (unchecked-add i (int 3)) r)
(recur (unchecked-add i (int 4)))))))
;;; Make buffer-size a local.
(defn java-like1 [^bytes cpu_array]
(let [buffer-size (int buffer-size)]
(loop [i (int 0)]
(if (< i (int buffer-size))
(let [b (byte (aget cpu_array i))
g (byte (aget cpu_array (unchecked-add i (int 1))))
r (byte (aget cpu_array (unchecked-add i (int 2))))
a (byte (aget cpu_array (unchecked-add i (int 3))))]
(aset cpu_array i a)
(aset cpu_array (unchecked-add i (int 1)) b)
(aset cpu_array (unchecked-add i (int 2)) g)
(aset cpu_array (unchecked-add i (int 3)) r)
(recur (unchecked-add i (int 4))))))))
;;; Move byte directly from array[i] to array[j].
;;; Assign index values to local variables.
;;; Eliminate "byte" hint.
(defn java-like2 [^bytes cpu_array]
(let [buffer-size (int buffer-size)]
(loop [i (int 0)]
(if (< i buffer-size)
(let [ i2 (add i 1)
i3 (add i 2)
i4 (add i 3)
a (aget cpu_array i4)
]
(amove cpu_array i3 i4)
(amove cpu_array i2 i3)
(amove cpu_array i i2)
(aset cpu_array i a)
(recur (add i 4)))))))
;;; Use unchecked-inc instead of unchecked-add.
(defn java-like3 [^bytes cpu_array]
(let [buffer-size (int buffer-size)]
(loop [i (int 0)]
(if (< i buffer-size)
(let [ i2 (uinc i)
i3 (uinc i2)
i4 (uinc i3)
a (aget cpu_array i4)
]
(amove cpu_array i3 i4)
(amove cpu_array i2 i3)
(amove cpu_array i i2)
(aset cpu_array i a)
(recur (uinc i4)))))))
(dotimes [i 4]
(let [func-name (str "java-like" i)
func (resolve (symbol func-name))]
(println func-name)
(dotimes [_ 7]
(time
(func array)))))
I think it will be faster on my laptop, but for now here are
the results on a rather old desktop.
Clojure 1.2; Java 1.5.0_07 (server); Pentium 4 3.2GHz (2 cores)
java-like0
"Elapsed time: 81.954298 msecs"
"Elapsed time: 24.381966 msecs"
"Elapsed time: 16.528463 msecs"
"Elapsed time: 12.656007 msecs"
"Elapsed time: 12.666522 msecs"
"Elapsed time: 13.240584 msecs"
"Elapsed time: 12.625828 msecs"
java-like1
"Elapsed time: 56.773426 msecs"
"Elapsed time: 19.099019 msecs"
"Elapsed time: 16.669669 msecs"
"Elapsed time: 6.325035 msecs"
"Elapsed time: 6.400674 msecs"
"Elapsed time: 6.374463 msecs"
"Elapsed time: 6.266154 msecs"
java-like2
"Elapsed time: 46.777715 msecs"
"Elapsed time: 11.840942 msecs"
"Elapsed time: 10.842774 msecs"
"Elapsed time: 5.56714 msecs"
"Elapsed time: 5.655566 msecs"
"Elapsed time: 5.611824 msecs"
"Elapsed time: 5.509589 msecs"
java-like3
"Elapsed time: 37.785107 msecs"
"Elapsed time: 8.711968 msecs"
"Elapsed time: 8.377959 msecs"
"Elapsed time: 7.094104 msecs"
"Elapsed time: 3.637105 msecs"
"Elapsed time: 3.757499 msecs"
"Elapsed time: 3.589582 msecs"
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