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https://github.com/nim-lang/Nim.git
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8fddc8e8a1
'countBits32' is now fixed in the same way that
'countBits64' was already patched earlier (by adding 'u32
where needed).
(cherry picked from commit ae32d637f7)
42 lines
1.4 KiB
Nim
42 lines
1.4 KiB
Nim
#
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#
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# Nim's Runtime Library
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# (c) Copyright 2012 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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# set handling
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type
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NimSet = array[0..4*2048-1, uint8]
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# bitops can't be imported here, therefore the code duplication.
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proc countBits32(n: uint32): int {.compilerproc.} =
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# generic formula is from: https://graphics.stanford.edu/~seander/bithacks.html#CountBitsSetParallel
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var v = uint32(n)
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v = v - ((v shr 1'u32) and 0x55555555'u32)
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v = (v and 0x33333333'u32) + ((v shr 2'u32) and 0x33333333'u32)
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result = (((v + (v shr 4'u32) and 0xF0F0F0F'u32) * 0x1010101) shr 24'u32).int
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proc countBits64(n: uint64): int {.compilerproc, inline.} =
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# generic formula is from: https://graphics.stanford.edu/~seander/bithacks.html#CountBitsSetParallel
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var v = uint64(n)
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v = v - ((v shr 1'u64) and 0x5555555555555555'u64)
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v = (v and 0x3333333333333333'u64) + ((v shr 2'u64) and 0x3333333333333333'u64)
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v = (v + (v shr 4'u64) and 0x0F0F0F0F0F0F0F0F'u64)
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result = ((v * 0x0101010101010101'u64) shr 56'u64).int
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proc cardSet(s: NimSet, len: int): int {.compilerproc, inline.} =
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var i = 0
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when defined(x86) or defined(amd64):
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while i < len - 8:
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inc(result, countBits64((cast[ptr uint64](s[i].unsafeAddr))[]))
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inc(i, 8)
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while i < len:
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inc(result, countBits32(uint32(s[i])))
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inc(i, 1)
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