Платформа ЦРНП "Мирокод" для разработки проектов
https://git.mirocod.ru
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17 lines
514 B
17 lines
514 B
// +build !go1.9 |
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package roaring |
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// bit population count, take from |
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// https://code.google.com/p/go/issues/detail?id=4988#c11 |
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// credit: https://code.google.com/u/arnehormann/ |
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// credit: https://play.golang.org/p/U7SogJ7psJ |
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// credit: http://graphics.stanford.edu/~seander/bithacks.html#CountBitsSetParallel |
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func popcount(x uint64) uint64 { |
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x -= (x >> 1) & 0x5555555555555555 |
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x = (x>>2)&0x3333333333333333 + x&0x3333333333333333 |
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x += x >> 4 |
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x &= 0x0f0f0f0f0f0f0f0f |
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x *= 0x0101010101010101 |
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return x >> 56 |
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}
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