com/vendor/github.com/willf/bitset/trailing_zeros_18.go

// +build !go1.9

package bitset

var deBruijn = [...]byte{
	0, 1, 56, 2, 57, 49, 28, 3, 61, 58, 42, 50, 38, 29, 17, 4,
	62, 47, 59, 36, 45, 43, 51, 22, 53, 39, 33, 30, 24, 18, 12, 5,
	63, 55, 48, 27, 60, 41, 37, 16, 46, 35, 44, 21, 52, 32, 23, 11,
	54, 26, 40, 15, 34, 20, 31, 10, 25, 14, 19, 9, 13, 8, 7, 6,
}

func trailingZeroes64(v uint64) uint {
	return uint(deBruijn[((v&-v)*0x03f79d71b4ca8b09)>>58])
}