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Given a bit vector $v, this: my $c = unpack '%32b*', $v; will count the set bits very efficiently. However, I need to count the set bits preceding (not including) a given bit position within $v. I can do that using:
But that is grossly inefficient for large vectors. Can you do it more efficiently? Note:The rest of the code is pure perl, so I'd rather avoid going to XS to do this if possible. With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'
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In reply to Efficient bit counting with a twist. by BrowserUk
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