On 6/17/07, Ron Johnson <[EMAIL PROTECTED]> wrote:
On 06/16/07 17:05, Alexander Staubo wrote:
> On 6/16/07, Ron Johnson <[EMAIL PROTECTED]> wrote:
>> > Hardware acceleration for quickly counting the number of
>> > set/unset/matching bits?
>>
>> x86 doesn't already do that?
>
> I don't think so. The fastest way, I believe, is to use precomputed
> lookup tables. Same for finding the least/most significant set/unset
> bit, and other operations useful for dealing with bit vectors.
A couple of new AMD Barcelona opcodes might help do that:
http://www.anandtech.com/showdoc.aspx?i=2939&p=6
Very cool. Thanks for the pointer.
Alexander.
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