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21 lines
547 B
Nim
21 lines
547 B
Nim
#
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#
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# Nimrod's Runtime Library
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# (c) Copyright 2006 Andreas Rumpf
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#
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# See the file "copying.txt", included in this
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# distribution, for details about the copyright.
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#
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proc population16(a: int): int {.inline.} =
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var x = a
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x = ((x and 0xAAAA) shr 1) + (x and 0x5555)
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x = ((x and 0xCCCC) shr 2) + (x and 0x3333)
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x = ((x and 0xF0F0) shr 4) + (x and 0x0F0F)
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x = ((x and 0xFF00) shr 8) + (x and 0x00FF)
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return x
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proc countBits(n: int32): int =
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result = population16(n and 0xffff'i32) + population16(n shr 16'i32)
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