func (m *cmap) bin(n int, key keyt) int {
	s := offset64
	for _, c := range key {
		s ^= uint64(c)
		s *= prime64
	}
	for _, i := range intoffs {
		s ^= uint64(n >> i)
		s *= prime64
	}
	return int(s & (uint64(len(m.bins)) - 1))
}
bin returns the nth hash of the given key
package cuckoo
import (
	"sync/atomic"
	"time"
	"unsafe"
)
var offset64 uint64 = 14695981039346656037
var prime64 uint64 = 1099511628211
var intoffs []uint = []uint{0, 8, 16, 24}