On Fri, Jun 24, 2011 at 12:14 PM, Yonik Seeley
<yonik@lucidimagination.com> wrote:
> All that needs to be done is to move the negative index check to the
> bottom (the first index<0 is not needed since we do a signed shift).
>
> public int prevSetBit(int index) {
> int i = index>>6;
> if (i >= wlen) {
> i = wlen - 1;
> }
> if (i < 0) return -1;
> final int subIndex = index & 0x3f; // index within the word
> long word = (bits[i] << (63-subIndex)); // skip all the bits to
> the left of index
And a further minor optimization, if we assume that negative indexes
are not legal, is to move the (i<0) check inside the if (i>=wlen)
block (and just let a negative index passed by the user to cause a
natural AIOOB).
-Yonik
http://www.lucidimagination.com
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