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Subject: Re: Don't have a native bit-population-count instruction? Here's why.

Author: Robert Hyatt

Date: 06:44:57 01/11/06

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On January 10, 2006 at 18:10:15, Stuart Cracraft wrote:

>Here's Butler Lampson, one of the inventors, of the Parc Alto
>talking about Seymour Cray and population-count units:
>
>http://research.microsoft.com/users/gbell/craytalk/sld051.htm

Seymour said the same thing about the "leading zero" instruction, which was
about the same thing as "find first one bit (starting from left) since the
instruction just counting the leading zeros up to the first one.  The Crypto
folks used both.

And yes, the 7600/Cyber-176 was a fast box in its day.  Chess 4.x used it to
drub other chess programs for a few of years until a certain program moved to
even faster hardware (the Cray-1).  :)



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