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#
#
# Nim's Runtime Library
# (c) Copyright 2012 Andreas Rumpf
#
# See the file "copying.txt", included in this
# distribution, for details about the copyright.
#
# set handling
type
NimSet = array[0..4*2048-1, uint8]
# bitops can't be imported here, therefore the code duplication.
proc countBits32(n: uint32): int {.compilerproc.} =
# generic formula is from: https://graphics.stanford.edu/~seander/bithacks.html#CountBitsSetParallel
var v = uint32(n)
v = v - ((v shr 1) and 0x55555555)
v = (v and 0x33333333) + ((v shr 2) and 0x33333333)
result = (((v + (v shr 4) and 0xF0F0F0F) * 0x1010101) shr 24).int
proc countBits64(n: uint64): int {.compilerproc.} =
# generic formula is from: https://graphics.stanford.edu/~seander/bithacks.html#CountBitsSetParallel
var v = uint64(n)
v = v - ((v shr 1'u64) and 0x5555555555555555'u64)
v = (v and 0x3333333333333333'u64) + ((v shr 2'u64) and 0x3333333333333333'u64)
v = (v + (v shr 4'u64) and 0x0F0F0F0F0F0F0F0F'u64)
result = ((v * 0x0101010101010101'u64) shr 56'u64).int
proc cardSet(s: NimSet, len: int): int {.compilerproc, inline.} =
for i in 0..<len:
if likely(s[i] == 0): continue
inc(result, countBits32(uint32(s[i])))
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