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popcnt.go
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popcnt.go
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package roaring
// bit population count, take from
// https://code.google.com/p/go/issues/detail?id=4988#c11
// credit: https://code.google.com/u/arnehormann/
func popcount(x uint64) (n uint64) {
x -= (x >> 1) & 0x5555555555555555
x = (x>>2)&0x3333333333333333 + x&0x3333333333333333
x += x >> 4
x &= 0x0f0f0f0f0f0f0f0f
x *= 0x0101010101010101
return x >> 56
}
func popcntSliceGo(s []uint64) uint64 {
cnt := uint64(0)
for _, x := range s {
cnt += popcount(x)
}
return cnt
}
func popcntMaskSliceGo(s, m []uint64) uint64 {
cnt := uint64(0)
for i := range s {
cnt += popcount(s[i] &^ m[i])
}
return cnt
}
func popcntAndSliceGo(s, m []uint64) uint64 {
cnt := uint64(0)
for i := range s {
cnt += popcount(s[i] & m[i])
}
return cnt
}
func popcntOrSliceGo(s, m []uint64) uint64 {
cnt := uint64(0)
for i := range s {
cnt += popcount(s[i] | m[i])
}
return cnt
}
func popcntXorSliceGo(s, m []uint64) uint64 {
cnt := uint64(0)
for i := range s {
cnt += popcount(s[i] ^ m[i])
}
return cnt
}